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Sample records for subglacial water transport

  1. Spatio-temporal evolution of efficient subglacial water discharge at Lemon Creek Glacier, Alaska

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    Bartholomaus, T. C.; Labedz, C. R.; Amundson, J. M.; Gimbert, F.; Tsai, V. C.; Vore, M. E.; Karplus, M. S.

    2017-12-01

    The impact of subglacial hydrology on glacier motion, glacier erosion and sediment transport, and submarine melt is well established. However, despite its importance, critical gaps in our understanding of subglacial hydrology and its seasonal evolution remain, in large part due to the challenge of making observations of glacier beds. Thus far, no spatially extensive, temporally continuous observations of subglacial water discharge exist. Seismic signals produced by subglacial water flow, and which correlate with subglacial water discharge, can meet this need. Here, we present the first observations from a 2017 summer seismic, geodetic, and hydrologic experiment. Our experiment seeks to better understand the evolution of efficient subglacial drainage and water storage through data collection and analysis at Lemon Creek Glacier, a 5.7 km-long glacier with a gauged outlet in Southeast Alaska. Data with nested spatial resolutions create an unparalleled perspective of subglacial discharge and its seasonal evolution. Six broadband seismometers and two GPS receivers installed for 80 days provide a long-term view of subglacial discharge and its impact on glacier dynamics. More than 100 nodes, installed approximately every 250 m over the glacier surface ( 13 nodes per 1 km^2) and deployed for up to 25 days, reveal the detailed spatial pattern of glaciohydraulic tremor amplitudes. These nodes enable us to more precisely infer the locations of subglacial discharge and its change, as well as better interpret long-term patterns of glaciohydraulic tremor observed by the broadband seismometers. We infer the subglacial response to hydraulic transients over the duration of the deployment through examination of intermittent melt and rain events, and the abrupt drainage of a glacier-dammed lake. These observations demonstrate the promise of seismology to significantly advance our understanding of glacier hydrology and associated glaciological processes.

  2. Seismic observations of subglacial water discharge from glacier-dammed lake drainage at Lemon Creek Glacier, Alaska

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    Labedz, C. R.; Bartholomaus, T. C.; Gimbert, F.; Amundson, J. M.; Vore, M. E.; Karplus, M. S.; Tsai, V. C.

    2017-12-01

    Subglacial water flow affects the dynamics of glaciers, influencing basal sliding, sediment transport, fracturing, and terminus dynamics. However, the difficulty of directly observing glacial hydrologic systems creates significant challenges in understanding such glacier behavior. Recently-developed descriptions of ground motion generated by subglacial water flow provide a promising basis for new and unique characterization of glacial hydrologic systems. Particularly, high-frequency ( 1.5-20 Hz) seismic tremor observed near glaciers has been shown to correlate with subglacial runoff. In addition, specific properties of subglacial water flow like water pressure, conduit size, sediment flux, and grain size can be inferred by examining hysteretic behavior over time between different parts of these signals. In this study, we observe the seismic signals generated by subglacial water flow using a high-density array of more than 100 nodes deployed for 10-25 days, and six broadband seismometers deployed for 80 days at Lemon Creek Glacier, Alaska. Specifically, we examine the 36-hour drainage of a glacier-dammed lake into subglacial conduits, comparing hydrologic metrics such as lake level, precipitation, and outlet stream flow rate to the power of seismic signals. Our node array captures this annually-significant hydraulic transient with sensors spaced approximately every 250 m over the majority of the 5.7 km long glacier. This and other lake drainage events provide natural experiments for exploring glaciohydraulic tremor, because the increased water flux through the glacier increases the power of the tremor and hosts the hysteretic behaviors described previously. Analysis of the tremor from events such as this can be extended to further understand subglacial runoff at Lemon Creek glacier and for glacier hydrology in general.

  3. A linked lake system beneath Thwaites Glacier, West Antarctica reveals an efficient mechanism for subglacial water flow.

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    Smith, B. E.; Gourmelen, N.; Huth, A.; Joughin, I. R.

    2016-12-01

    In this presentation we show the results of a multi-sensor survey of a system of subglacial lakes beneath Thwaites Glacier, West Antarctica. This is the first substantial active (meaning draining or filling on annual time scales) lake system detected under the fast-flowing glaciers of the Amundsen Coast. Altimetry data show that over the 2013 calendar year, four subglacial lakes drained, essentially simultaneously, with the bulk of the drainage taking place over the course the first three months of the year. The largest of the lakes appears to have drained around 3.7 km3 of water, with the others each draining less than 1 km3. The high-resolution radar surveys conducted in this area by NASA's IceBridge program allow detailed analysis of the subglacial hydrologic potential, which shows that the potential map in this area is characterized by small closed basins that should not, under the common assumption that water flow is directed down the gradient of the hydropotential, allow long-range water transport. The lakes' discharge demonstrates that, at least in some cases, water can flow out of apparently closed hydropotential basins. Combining a basal-flow routing map with a map of basal melt production suggests that the largest drainage event could recur as often as every 22 years, provided that overflow or leakage of mapped hydropotential basins allows melt water transport to refill the lake. An analysis of ice-surface speed records both around the lakes and at the Thwaites grounding line shows small changes in ice speed, but none clearly associated with the drainage event, suggesting that, at least in this area where subglacial melt is abundant, the addition of further water to the subglacial hydrologic system need not have any significant effect on ice flow. It is likely that the main impact of the lake system on the glacier is that as an efficient mechanism to remove meltwater from the system, it drains water that would otherwise flow through less efficient

  4. Clean subglacial access: prospects for future deep hot-water drilling

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    Pearce, David; Hodgson, Dominic A.; Smith, Andrew M.; Rose, Mike; Ross, Neil; Mowlem, Matt; Parnell, John

    2016-01-01

    Accessing and sampling subglacial environments deep beneath the Antarctic Ice Sheet presents several challenges to existing drilling technologies. With over half of the ice sheet believed to be resting on a wet bed, drilling down to this environment must conform to international agreements on environmental stewardship and protection, making clean hot-water drilling the most viable option. Such a drill, and its water recovery system, must be capable of accessing significantly greater ice depths than previous hot-water drills, and remain fully operational after connecting with the basal hydrological system. The Subglacial Lake Ellsworth (SLE) project developed a comprehensive plan for deep (greater than 3000 m) subglacial lake research, involving the design and development of a clean deep-ice hot-water drill. However, during fieldwork in December 2012 drilling was halted after a succession of equipment issues culminated in a failure to link with a subsurface cavity and abandonment of the access holes. The lessons learned from this experience are presented here. Combining knowledge gained from these lessons with experience from other hot-water drilling programmes, and recent field testing, we describe the most viable technical options and operational procedures for future clean entry into SLE and other deep subglacial access targets. PMID:26667913

  5. Geophysical Investigations of Hypersaline Subglacial Water Systems in the Canadian Arctic: A Planetary Analog

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    Rutishauser, A.; Sharp, M. J.; Blankenship, D. D.; Skidmore, M. L.; Grima, C.; Schroeder, D. M.; Greenbaum, J. S.; Dowdeswell, J. A.; Young, D. A.

    2017-12-01

    Robotic exploration and remote sensing of the solar system have identified the presence of liquid water beneath ice on several planetary bodies, with evidence for elevated salinity in certain cases. Subglacial water systems beneath Earth's glaciers and ice sheets may provide terrestrial analogs for microbial habitats in such extreme environments, especially those with higher salinity. Geological data suggest that several ice caps and glaciers in the eastern Canadian High Arctic are partially underlain by evaporite-rich sedimentary rocks, and subglacial weathering of these rocks is potentially conducive to the formation of hypersaline subglacial waters. Here, we combine airborne geophysical data with geological constraints to identify and characterize hypersaline subglacial water systems beneath ice caps in Canada's Queen Elizabeth Islands. High relative bedrock reflectivity and specularity anomalies that are apparent in radio-echo sounding data indicate multiple locations where subglacial water is present in areas where modeled ice temperatures at the glacier bed are well below the pressure melting point. This suggests that these water systems are hypersaline, with solute concentrations that significantly depress the freezing point of water. From combined interpretations of geological and airborne-magnetic data, we define the geological context within which these systems have developed, and identify possible solute-sources for the inferred brine-rich water systems. We also derive subglacial hydraulic potential gradients using airborne laser altimetry and ice thickness data, and apply water routing models to derive subglacial drainage pathways. These allow us to identify marine-terminating glaciers where outflow of the brine-rich waters may be anticipated. These hypersaline subglacial water systems beneath Canadian Arctic ice caps and glaciers may represent robust microbial habitats, and potential analogs for brines that may exist beneath ice masses on planetary

  6. Can Subglacial Meltwater Films Carve Into the till Beneath? Insights from a Coupled Till-Water Model

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    Kasmalkar, I.; Mantelli, E.; Suckale, J.

    2017-12-01

    Networks of water channels are known to exist beneath regions of the continental ice sheets such as Antarctica and Greenland. These channels are fed by meltwater and form along the interface between the ice and the underlying till layer. Their presence localizes basal strength by reducing pore pressure and hence alters the resistance to ice slip provided by the till. Subglacial channels thus play a major role in determining the rate of ice flow for glaciers and ice streams. It is unclear whether subglacial meltwater can evolve from a thin film into a network of distributed channels by erosion of the sediment bed. Models that involve hard-rock beds can only account for water channels that carve into the ice and not the till. Alternative approaches that include erodible sediment mostly assume viscous behavior in the till layer, which is not well supported by laboratory experiments of till failure. To better understand the physical processes that govern channelization, we couple water flow in a thin film with sediment transport to capture the dynamic interactions between water and till. We present a two-dimensional model which consists of a thin subglacial water film that is in the laminar regime and an erodible till layer that obeys the Shield's criterion. We use analytic techniques to study the long-term behavior of perturbations of the water-till interface. We discuss the stability of the system under such perturbations in the context of channel formation.

  7. Subglacial hydrology and the formation of ice streams.

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    Kyrke-Smith, T M; Katz, R F; Fowler, A C

    2014-01-08

    Antarctic ice streams are associated with pressurized subglacial meltwater but the role this water plays in the dynamics of the streams is not known. To address this, we present a model of subglacial water flow below ice sheets, and particularly below ice streams. The base-level flow is fed by subglacial melting and is presumed to take the form of a rough-bedded film, in which the ice is supported by larger clasts, but there is a millimetric water film which submerges the smaller particles. A model for the film is given by two coupled partial differential equations, representing mass conservation of water and ice closure. We assume that there is no sediment transport and solve for water film depth and effective pressure. This is coupled to a vertically integrated, higher order model for ice-sheet dynamics. If there is a sufficiently small amount of meltwater produced (e.g. if ice flux is low), the distributed film and ice sheet are stable, whereas for larger amounts of melt the ice-water system can become unstable, and ice streams form spontaneously as a consequence. We show that this can be explained in terms of a multi-valued sliding law, which arises from a simplified, one-dimensional analysis of the coupled model.

  8. A balanced water layer concept for subglacial hydrology in large-scale ice sheet models

    Directory of Open Access Journals (Sweden)

    S. Goeller

    2013-07-01

    Full Text Available There is currently no doubt about the existence of a widespread hydrological network under the Antarctic Ice Sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux–basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  9. A balanced water layer concept for subglacial hydrology in large scale ice sheet models

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    Goeller, S.; Thoma, M.; Grosfeld, K.; Miller, H.

    2012-12-01

    There is currently no doubt about the existence of a wide-spread hydrological network under the Antarctic ice sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain inspired by the Gamburtsev Mountains, Antarctica. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux-basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out, that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  10. Investigations into the Regional and Local Timescale Variations of Subglacial Drainage Networks

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    Hiester, Justin

    Subglacial water plays an important role in the regulation of an ice sheet's mass balance. It may be the dominant control on the velocities of ice streams and outlet glaciers on scales of months to millennia. Recent satellite observations of ice surface elevation changes have given researchers new insights into how subglacial water is stored and transported. Localized uplift and settling of the ice surface implies that lakes exist beneath the ice sheet that are being filled and drained on relatively short time scales. At the base of an ice sheet water can be transported through a variety of drainage networks or stored in subglacial lakes. Here, a numerical investigation of the mechanisms of transport and storage of subglacial water and the associated time scales is presented. Experiments are carried out using a finite element model of coupled ice and water flow. The first experiment seeks to understand the relationship between the depth of a basal depression and the area over which the feature affects basal water flow. It is found that as the perturbation to a topographic depression's depth is increased, water is rerouted in response to the perturbation. Additionally it is found that the relationship between perturbation depth and the extent upstream to which its effects reach is nonlinear. The second experiment examines how the aspect ratio of bed features (prolate, oblate, or equidimensional) influences basal water flow. It is found that the systems that develop and their interactions are mediated by both the topography and the feedbacks taken into account by the coupling of the systems in the model. Features oriented parallel to ice and water flow are associated with distributed fan systems that develop branches which migrate laterally across the domain and interact with one another on monthly and yearly timescales. Laterally oriented features develop laterally extensive ponds. As the ratio of longitudinal to lateral dimension of the topography is increased, a

  11. Dissolution of calcite in glacial water; evidence of inhibition and consequences for subglacial speleogenesis.

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    Lauritzen, S.-E.

    2012-04-01

    Subglacial speleogenesis (i.e. formation of caves by ice-contact underneath or along glaciers) is an important speleogenetic modus that have taken place in many previously glaciated areas. It is however controversial how efficient this process is when compared to speleogenesis under non-glacial conditions: Can caves be formed from 'scratch' - from a pristine, microscopic fracture (speleogenesis sensu stricto) - or is this process more intensive under non-glacial conditions, so that ice-contact water can only widen pre-existing conduits (speleogenesis sensu lato)? Subglacial waters are low in CO2 and close to zero degrees. A critical parameter for transforming a fracture into a cave is the breakthrough time, tB, which is the time from commencement of flow until undersaturated water can flow freely through the full length of the flowpath. The breathrough effect (i.e. when radial widening accelerates) is dependent on the switching concentration, Cs, which drops dramatically with low CO2 in the system. Apart from the initial aperture and length of the percolation paths through the rock mass, two additional factors are important for tB: 1) the concentration of glacial rock flour and 2) its ability to interfer with the carbonate chemistry. A series of thermostated dissolution experiments using marble and various additions of authentic glacier silt and crushed metamorphic rocks demonstrate and support theoretical considerations that subglacial speleogenesis in low CO2 waters is slower than first anticipated. The sensu stricto mechanism is also severely hampered by the clogging effect of glacial silt, whilst the sensu lato mechanism is sluggish because corrosion of the large specific area of silt particles consumes aggressiveness thus slowing first-order rates when the water comes in contact with the karst surface. Also, for the same reason, Cs may be exceeded before the water enters karst, so that breakthrough may be totally suppressed. Interglacial waters seem > 50 times

  12. Understanding and Observing Subglacial Friction Using Seismology

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    Tsai, V. C.

    2017-12-01

    Glaciology began with a focus on understanding basic mechanical processes and producing physical models that could explain the principal observations. Recently, however, more attention has been paid to the wealth of recent observations, with many modeling efforts relying on data assimilation and empirical scalings, rather than being based on first-principles physics. Notably, ice sheet models commonly assume that subglacial friction is characterized by a "slipperiness" coefficient that is determined by inverting surface velocity observations. Predictions are usually then made by assuming these slipperiness coefficients are spatially and temporally fixed. However, this is only valid if slipperiness is an unchanging material property of the bed and, despite decades of work on subglacial friction, it has remained unclear how to best account for such subglacial physics in ice sheet models. Here, we describe how basic seismological concepts and observations can be used to improve our understanding and determination of subglacial friction. First, we discuss how standard models of granular friction can and should be used in basal friction laws for marine ice sheets, where very low effective pressures exist. We show that under realistic West Antarctic Ice Sheet conditions, standard Coulomb friction should apply in a relatively narrow zone near the grounding line and that this should transition abruptly as one moves inland to a different, perhaps Weertman-style, dependence of subglacial stress on velocity. We show that this subglacial friction law predicts significantly different ice sheet behavior even as compared with other friction laws that include effective pressure. Secondly, we explain how seismological observations of water flow noise and basal icequakes constrain subglacial physics in important ways. Seismically observed water flow noise can provide constraints on water pressures and channel sizes and geometry, leading to important data on subglacial friction

  13. Modeling subglacial sediment discharge in 1-dimension: comparison with measurments and implications for glacial retreat

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    Delaney, I. A.; Werder, M.; Farinotti, D.

    2017-12-01

    In recent decades increased sedimentation rates have been observed in reservoirs downstream of some retreating glaciers. This material either originates from slopes recently exposed by glacier retreat and no longer stabilized by ice, or subglacially, where pressurized melt water transports sediments from the glacier bed. Some evidence suggests that recently exposed periglacial areas can stablize relatively quickly and in some catchments provides a smaller precentage of the total sediment compared to the subglacial environment. As a result, in order predict and forecast sediment yield from glaciated catchments as glaciers thin and thier hydrology evolves, a subglacial sediment transport model must be implemented. Here a simple 1-dimensional glacio-hydraulic model uses the Darcy-Weissbach relationship to determine shear-stress of presurized water on the glacier bed. This is coupled with a sediment transport relationship to determine quantity of discharged material from the glacier snout. Several tuning factors allow calibration and the model to reproduces processes known to occur subglacially, including seasonal evolution of sediment expulsion and deposition of sediment on adverse slopes of overdeepenings. To asses the model's application to real glaciers, sediment flux data has been collected from Gornergletscher, Aletschgletscher and Griesgletscher in the Swiss Alps over time-scales of up to decades. By calibrating to these data, the skill of the model in recreating sediment trends and volumes is assesed. The outputs capture annual erosion quanities relatively well, however, challenges exist in capturing inter-annual variations in sediment discharge. Many of the model's short comings relate to caputuring the spatial distribution of sediment throughout the glacier bed, which is particularing difficult in 1-dimension. However, this work suggests that a simple models can be used to predict subglacial sediment transport with reasonable ability. Additionally, further

  14. Modeling Antarctic Subglacial Lake Filling and Drainage Cycles

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    Dow, Christine F.; Werder, Mauro A.; Nowicki, Sophie; Walker, Ryan T.

    2016-01-01

    The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to examine internal controls on the filling and drainage of subglacial lakes. Our model outputs suggest that the highly constricted subglacial environment of our idealized ice stream, combined with relatively high rates of water flow funneled from a large catchment, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water beneath the ice stream drives lake growth. As the water body builds up, it steepens the hydraulic gradient out of the overdeepened lake basin and allows greater flux. Eventually this flux is large enough to melt channels that cause the lake to drain. Lake drainage also depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

  15. Subglacial drainage patterns of Devon Island, Canada: detailed comparison of rivers and subglacial meltwater channels

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    Grau Galofre, Anna; Jellinek, A. Mark; Osinski, Gordon R.; Zanetti, Michael; Kukko, Antero

    2018-04-01

    Subglacial meltwater channels (N-channels) are attributed to erosion by meltwater in subglacial conduits. They exert a major control on meltwater accumulation at the base of ice sheets, serving as drainage pathways and modifying ice flow rates. The study of exposed relict subglacial channels offers a unique opportunity to characterize the geomorphologic fingerprint of subglacial erosion as well as study the structure and characteristics of ice sheet drainage systems. In this study we present detailed field and remote sensing observations of exposed subglacial meltwater channels in excellent preservation state on Devon Island (Canadian Arctic Archipelago). We characterize channel cross section, longitudinal profiles, and network morphologies and establish the spatial extent and distinctive characteristics of subglacial drainage systems. We use field-based GPS measurements of subglacial channel longitudinal profiles, along with stereo imagery-derived digital surface models (DSMs), and novel kinematic portable lidar data to establish a detailed characterization of subglacial channels in our field study area, including their distinction from rivers and other meltwater drainage systems. Subglacial channels typically cluster in groups of ˜ 10 channels and are oriented perpendicular to active or former ice margins. Although their overall direction generally follows topographic gradients, channels can be oblique to topographic gradients and have undulating longitudinal profiles. We also observe that the width of first-order tributaries is 1 to 2 orders of magnitude larger than in Devon Island river systems and approximately constant. Furthermore, our findings are consistent with theoretical expectations drawn from analyses of flow driven by gradients in effective water pressure related to variations in ice thickness. Our field and remote sensing observations represent the first high-resolution study of the subglacial geomorphology of the high Arctic, and provide

  16. Landscape evolution by subglacial quarrying

    DEFF Research Database (Denmark)

    Ugelvig, Sofie Vej; Egholm, D.L.; Iverson, Neal R.

    In glacial landscape evolution models, subglacial erosion rates are often related to basal sliding or ice discharge by a power-law. This relation can be justified for bedrock abrasion because rock debris transported in the basal ice drives the erosion. However, a simple relation between rates of ...... evolution models. Geology, v. 40, no. 8, 679-682 (2012). Schoof, C. The effect of cavitation on glacier sliding. Proc. R. Soc. A , 461, 609-627 (2005). Jaeger, J.C., and Cook, N.G.W. Fundamentals of rock mechanics: New York, Chapman and Hall, 593 p. (1979)......In glacial landscape evolution models, subglacial erosion rates are often related to basal sliding or ice discharge by a power-law. This relation can be justified for bedrock abrasion because rock debris transported in the basal ice drives the erosion. However, a simple relation between rates...... of sliding and erosion is not well supported when considering models for quarrying of rock blocks from the bed. Iverson (2012) introduced a new subglacial quarrying model that operates from the theory of adhesive wear. The model is based on the fact that cavities, with a high level of bedrock differential...

  17. Direct observations of evolving subglacial drainage beneath the Greenland Ice Sheet.

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    Andrews, Lauren C; Catania, Ginny A; Hoffman, Matthew J; Gulley, Jason D; Lüthi, Martin P; Ryser, Claudia; Hawley, Robert L; Neumann, Thomas A

    2014-10-02

    Seasonal acceleration of the Greenland Ice Sheet is influenced by the dynamic response of the subglacial hydrologic system to variability in meltwater delivery to the bed via crevasses and moulins (vertical conduits connecting supraglacial water to the bed of the ice sheet). As the melt season progresses, the subglacial hydrologic system drains supraglacial meltwater more efficiently, decreasing basal water pressure and moderating the ice velocity response to surface melting. However, limited direct observations of subglacial water pressure mean that the spatiotemporal evolution of the subglacial hydrologic system remains poorly understood. Here we show that ice velocity is well correlated with moulin hydraulic head but is out of phase with that of nearby (0.3-2 kilometres away) boreholes, indicating that moulins connect to an efficient, channelized component of the subglacial hydrologic system, which exerts the primary control on diurnal and multi-day changes in ice velocity. Our simultaneous measurements of moulin and borehole hydraulic head and ice velocity in the Paakitsoq region of western Greenland show that decreasing trends in ice velocity during the latter part of the melt season cannot be explained by changes in the ability of moulin-connected channels to convey supraglacial melt. Instead, these observations suggest that decreasing late-season ice velocity may be caused by changes in connectivity in unchannelized regions of the subglacial hydrologic system. Understanding this spatiotemporal variability in subglacial pressures is increasingly important because melt-season dynamics affect ice velocity beyond the conclusion of the melt season.

  18. Effect of Topography on Subglacial Discharge and Submarine Melting During Tidewater Glacier Retreat

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    Amundson, J. M.; Carroll, D.

    2018-01-01

    To first order, subglacial discharge depends on climate, which determines precipitation fluxes and glacier mass balance, and the rate of glacier volume change. For tidewater glaciers, large and rapid changes in glacier volume can occur independent of climate change due to strong glacier dynamic feedbacks. Using an idealized tidewater glacier model, we show that these feedbacks produce secular variations in subglacial discharge that are influenced by subglacial topography. Retreat along retrograde bed slopes (into deep water) results in rapid surface lowering and coincident increases in subglacial discharge. Consequently, submarine melting of glacier termini, which depends on subglacial discharge and ocean thermal forcing, also increases during retreat into deep water. Both subglacial discharge and submarine melting subsequently decrease as glacier termini retreat out of deep water and approach new steady state equilibria. In our simulations, subglacial discharge reached peaks that were 6-17% higher than preretreat values, with the highest values occurring during retreat from narrow sills, and submarine melting increased by 14% for unstratified fjords and 51% for highly stratified fjords. Our results therefore indicate that submarine melting acts in concert with iceberg calving to cause tidewater glacier termini to be unstable on retrograde beds. The full impact of submarine melting on tidewater glacier stability remains uncertain, however, due to poor understanding of the coupling between submarine melting and iceberg calving.

  19. Greenland Subglacial Drainage Evolution Regulated by Weakly Connected Regions of the Bed

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    Hoffman, Matthew J.; Andrews, Lauren C.; Price, Stephen F.; Catania, Ginny A.; Neumann, Thomas A.; Luthi, Martin P.; Gulley, Jason; Ryser, Claudia; Hawley, Robert L.; Morriss, Blaine

    2016-01-01

    Penetration of surface meltwater to the bed of the Greenland Ice Sheet each summer causes an initial increase in ice speed due to elevated basal water pressure, followed by slowdown in late summer that continues into fall and winter. While this seasonal pattern is commonly explained by an evolution of the subglacial drainage system from an inefficient distributed to efficient channelized configuration, mounting evidence indicates that subglacial channels are unable to explain important aspects of hydrodynamic coupling in late summer and fall. Here we use numerical models of subglacial drainage and ice flow to show that limited, gradual leakage of water and lowering of water pressure in weakly connected regions of the bed can explain the dominant features in late and post melt season ice dynamics. These results suggest that a third weakly connected drainage component should be included in the conceptual model of subglacial hydrology.

  20. Properties of the subglacial till inferred from supraglacial lake drainage

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    Neufeld, J. A.; Hewitt, D.

    2017-12-01

    The buildup and drainage of supraglacial lakes along the margins of the Greenland ice sheet has been previously observed using detailed GPS campaigns which show that rapid drainage events are often preceded by localised, transient uplift followed by rapid, and much broader scale, uplift and flexure associated with the main drainage event [1,2]. Previous models of these events have focused on fracturing during rapid lake drainage from an impermeable bedrock [3] or a thin subglacial film [4]. We present a new model of supraglacial drainage that couples the water flux from rapid lake drainage events to a simplified model of the pore-pressure in a porous, subglacial till along with a simplified model of the flexure of glacial ice. Using a hybrid mathematical model we explore the internal transitions between turbulent and laminar flow throughout the evolving subglacial cavity and porous till. The model predicts that an initially small water flux may locally increase pore-pressure in the till leading to uplift and a local divergence in the ice velocity that may ultimately be responsible for large hydro-fracturing and full-scale drainage events. Furthermore, we find that during rapid drainage while the presence of a porous, subglacial till is crucial for propagation, the manner of spreading is remarkably insensitive to the properties of the subglacial till. This is in stark contrast to the post-drainage relaxation of the pore pressure, and hence sliding velocity, which is highly sensitive to the permeability, compressibility and thickness of subglacial till. We use our model, and the inferred sensitivity to the properties of the subglacial till after the main drainage event, to infer the properties of the subglacial till. The results suggest that a detailed interpretation of supraglacial lake drainage may provide important insights into the hydrology of the subglacial till along the margins of the Greenland ice sheet, and the coupling of pore pressure in subglacial till

  1. Representing Glaciations and Subglacial Processes in Hydrogeological Models: A Numerical Investigation

    Directory of Open Access Journals (Sweden)

    Arnaud Sterckx

    2017-01-01

    Full Text Available The specific impact of glacial processes on groundwater flow and solute transport under ice-sheets was determined by means of numerical simulations. Groundwater flow and the transport of δ18O, TDS, and groundwater age were simulated in a generic sedimentary basin during a single glacial event followed by a postglacial period. Results show that simulating subglacial recharge with a fixed flux boundary condition is relevant only for small fluxes, which could be the case under partially wet-based ice-sheets. Glacial loading decreases overpressures, which appear only in thick and low hydraulic diffusivity layers. If subglacial recharge is low, glacial loading can lead to underpressures after the retreat of the ice-sheet. Isostasy reduces considerably the infiltration of meltwater and the groundwater flow rates. Below permafrost, groundwater flow is reduced under the ice-sheet but is enhanced beyond the ice-sheet front. Accounting for salinity-dependent density reduces the infiltration of meltwater at depth. This study shows that each glacial process is potentially relevant in models of subglacial groundwater flow and solute transport. It provides a good basis for building and interpreting such models in the future.

  2. Lasting Effects of Glacial Lake Outburst Floods on Subglacial Drainage Networks

    Science.gov (United States)

    Robbins, M.; Hendy, I. L.; Bassis, J. N.; Aciego, S.; Stevenson, E. I.

    2017-12-01

    Supraglacial lakes forming in the ablation zone around the Greenland Ice Sheet will likely migrate toward higher elevations as polar temperatures rise through the 21st century. Present understanding of lake drainage shows it can temporarily enhance ice sheet motion, but other possible effects and interactions - especially with older pre-existing subglacial reservoirs - remain unexamined. Here we investigate possible enduring effects of the record high 2012 melt year on the en/subglacial hydrologic network, how this network responds to immediate high fluxes of water from floods, and how these phenomena might connect to previously isolated subglacial pools. Lake Hullet is a large ice dammed lake situated in south Greenland 22km up-ice from where Kiattuut Sermiat (KS) branches from a larger outlet glacier. Lake Hullet rests on bedrock and is contained by a bedrock ridge. It drains roughly annually through Lake Hullet's hydrologic network in a glacial lake outburst flood (GLOF) when water level rises such that it can flow over the obstructive ridge. Subglacial water samples collected from the toe of KS in July 2013 pre-flood were dated using U isotopes with 222Rn concentrations as well as noble gas ratios. These two independent methods reveal an exceedingly old water age of > 1000 years, indicating existence of isolated enduring subglacial meltwater pool(s). A comparison field study at the KS toe in August and September 2015 re-examined glacial hydrochemistry in a time series. 2015 222Rn concentrations are lower than 2013 values, suggesting less water-rock interaction, a reduction in residence time, and a proximal meltwater source. Increased water volume from the record high 2012 melt year may have enlarged the existing en/subglacial drainage network further into the ice sheet releasing meltwater with longer residence times beneath the ice, with effects lasting into subsequent melt seasons due to the stability of channels maintained from recurrent floods. These

  3. Tracking seasonal subglacial drainage evolution of alpine glaciers using radiogenic Nd and Sr isotope systematics: Lemon Creek Glacier, Alaska

    Science.gov (United States)

    Clinger, A. E.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.

    2014-12-01

    The transport pathways of water beneath a glacier are subject to change as melt seasons progress due to variability in the balance between basal water pressure and water flux. Subglacial hydrology has been well studied, but the understanding of spatial distribution is less well constrained. Whereas radiogenic isotopic tracers have been traditionally used as proxies to track spatial variability and weathering rates in fluvial and riverine systems, these techniques have yet to be applied extensively to the subglacial environment and may help resolve ambiguity in subglacial hydrology. Research has shown the 143Nd/144Nd values can reflect variation in source provenance processes due to variations in the age of the continental crust. Correlating the 143Nd/144Nd with other radiogenic isotope systematics such as strontium (87Sr/86Sr) provides important constraints on the role of congruent and incongruent weathering processes. Our study presents the application of Nd and Sr systematics using isotopic ratios to the suspended load of subglacial meltwater collected over a single melt season at Lemon Creek Glacier, USA (LCG). The time-series data show an average ɛNd ~ -6.83, indicating a young bedrock (~60 MYA). Isotopic variation helps track the seasonal expansion of the subglacial meltwater channels and subsequent return to early season conditions due to the parabolic trend towards less radiogenic Nd in June and towards more radiogenic Nd beginning in mid-August. However, the high variability in July and early August may reflect a mixture of source as the channels diverge and derive sediment from differently aged lithologies. We find a poor correlation between 143Nd/144Nd and 87Sr/86Sr (R2= 0.38) along with a slight trend towards more radiogenic 87Sr/86Sr values with time ((R2= 0.49). This may indicate that, even as the residence time decreases over the melt season, the LCG subglacial system is relatively stable and that the bedrock is congruently weathered. Our study

  4. Potential Activity of Subglacial Microbiota Transported to Anoxic River Delta Sediments

    DEFF Research Database (Denmark)

    Cameron, Karen A.; Stibal, Marek; Olsen, Nikoline S.

    2017-01-01

    -related organisms. Later, a reduction in methane was observed to be paired with the depletion of sulphate, and we hypothesise that sulphate reduction out competed hydrogenotrophic methanogenesis. The structure and diversity of the original CO2/H2-amended incubation communities changed dramatically with a major......The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers...... of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without CO2/H2 enrichment. Within CO2/H2-amended incubations, sulphate depletion and a shift in the microbial community to a 52% predominance...

  5. Incorporating modelled subglacial hydrology into inversions for basal drag

    Directory of Open Access Journals (Sweden)

    C. P. Koziol

    2017-12-01

    Full Text Available A key challenge in modelling coupled ice-flow–subglacial hydrology is initializing the state and parameters of the system. We address this problem by presenting a workflow for initializing these values at the start of a summer melt season. The workflow depends on running a subglacial hydrology model for the winter season, when the system is not forced by meltwater inputs, and ice velocities can be assumed constant. Key parameters of the winter run of the subglacial hydrology model are determined from an initial inversion for basal drag using a linear sliding law. The state of the subglacial hydrology model at the end of winter is incorporated into an inversion of basal drag using a non-linear sliding law which is a function of water pressure. We demonstrate this procedure in the Russell Glacier area and compare the output of the linear sliding law with two non-linear sliding laws. Additionally, we compare the modelled winter hydrological state to radar observations and find that it is in line with summer rather than winter observations.

  6. International Planning for Subglacial Lake Exploration

    Science.gov (United States)

    Kennicutt, M.; Priscu, J.

    2003-04-01

    As one of the last unexplored frontiers on our planet, subglacial lakes offer a unique and exciting venue for exploration and research. Over the past several years, subglacial lakes have captured the imagination of the scientific community and public, evoking images of potential exotic life forms surviving under some of the most extreme conditions on earth. Various planning activities have recognized that due to the remote and harsh conditions, that a successful subglacial lake exploration program will entail a concerted effort for a number of years. It will also require an international commitment of major financial and human resources. To begin a detailed planning process, the Scientific Committee on Antarctic Research (SCAR) convened the Subglacial Antarctic Lake Exploration Group of Specialists (SALEGOS) in Tokyo in 2000. The group was asked to build on previous workshops and meetings to develop a plan to explore subglacial lake environments. Its mandate adopted the guiding principles as agreed in Cambridge in 1999 that the program would be interdisciplinary in scope, be designed for minimum contamination and disturbance of the subglacial lake environment, have as a goal lake entry and sample retrieval, and that the ultimate target of the program should be Lake Vostok exploration. Since its formation SALEGOS has met three times and addressed some of the more intractable issues related to subglacial lake exploration. Topics under discussion include current state-of-the-knowledge of subglacial environments, technological needs, international management and organizational strategies, a portfolio of scientific projects, "clean" requirements, and logistical considerations. In this presentation the actvities of SALEGOS will be summarized and recommendations for an international subglacial lake exploration program discussed.

  7. Landscape evolution by subglacial quarrying

    Science.gov (United States)

    Ugelvig, Sofie V.; Egholm, David L.; Iverson, Neal R.

    2014-05-01

    In glacial landscape evolution models, subglacial erosion rates are often related to basal sliding or ice discharge by a power-law. This relation can be justified for bedrock abrasion because rock debris transported in the basal ice drives the erosion. However, a simple relation between rates of sliding and erosion is not well supported when considering models for quarrying of rock blocks from the bed. Iverson (2012) introduced a new subglacial quarrying model that operates from the theory of adhesive wear. The model is based on the fact that cavities, with a high level of bedrock differential stress, form along the lee side of bed obstacles when the sliding velocity is to high to allow for the ice to creep around the obstacles. The erosion rate is quantified by considering the likelihood of rock fracturing on topographic bumps. The model includes a statistical treatment of the bedrock weakness: larger rock bodies have lower strengths since they have greater possibility of containing a large flaw [Jaeger and Cook, 1979]. Inclusion of this effect strongly influences the erosion rates and questions the dominant role of sliding rate in standard models for subglacial erosion. Effective pressure, average bedslope, and bedrock fracture density are primary factors that, in addition to sliding rate, influence the erosion rate of this new quarrying model [Iverson, 2012]. We have implemented the quarrying model in a depth-integrated higher-order ice-sheet model [Egholm et al. 2011], coupled to a model for glacial hydrology. In order to also include the effects of cavitation on the subglacial sliding rate, we use a sliding law proposed by Schoof (2005), which includes an upper limit for the stress that can be supported at the bed. Computational experiments show that the combined influence of pressure, sliding rate and bed slope leads to realistically looking landforms such as U-shaped valleys, cirques, hanging valleys and overdeepenings. Compared to model results using a

  8. Ice-Shelf Tidal Flexure and Subglacial Pressure Variations

    Science.gov (United States)

    Walker, Ryan T.; Parizek, Byron R.; Alley, Richard B.; Anandakrishnan, Sridhar; Riverman, Kiya L.; Christianson, Knut

    2013-01-01

    We develop a model of an ice shelf-ice stream system as a viscoelastic beam partially supported by an elastic foundation. When bed rock near the grounding line acts as a fulcrum, leverage from the ice shelf dropping at low tide can cause significant (approx 1 cm) uplift in the first few kilometers of grounded ice.This uplift and the corresponding depression at high tide lead to basal pressure variations of sufficient magnitude to influence subglacial hydrology.Tidal flexure may thus affect basal lubrication, sediment flow, and till strength, all of which are significant factors in ice-stream dynamics and grounding-line stability. Under certain circumstances, our results suggest the possibility of seawater being drawn into the subglacial water system. The presence of sea water beneath grounded ice would significantly change the radar reflectivity of the grounding zone and complicate the interpretation of grounded versus floating ice based on ice-penetrating radar observations.

  9. Physiological ecology of microorganisms in Subglacial Lake Whillans

    Directory of Open Access Journals (Sweden)

    Trista J Vick-Majors

    2016-10-01

    Full Text Available Subglacial microbial habitats are widespread in glaciated regions of our planet. Some of these environments have been isolated from the atmosphere and from sunlight for many thousands of years. Consequently, ecosystem processes must rely on energy gained from the oxidation of inorganic substrates or detrital organic matter. Subglacial Lake Whillans (SLW is one of more than 400 subglacial lakes known to exist under the Antarctic ice sheet; however, little is known about microbial physiology and energetics in these systems. When it was sampled through its 800 m thick ice cover in 2013, the SLW water column was shallow (~2 m deep, oxygenated, and possessed sufficient concentrations of C, N, and P substrates to support microbial growth. Here, we use a combination of physiological assays and models to assess the energetics of microbial life in SLW. In general, SLW microorganisms grew slowly in this energy-limited environment. Heterotrophic cellular carbon turnover times, calculated from 3H-thymidine and 3H-leucine incorporation rates, were long (60 to 500 days while cellular doubling times averaged 196 days. Inferred growth rates (average ~0.006 d-1 obtained from the same incubations were at least an order of magnitude lower than those measured in Antarctic surface lakes and oligotrophic areas of the ocean. Low growth efficiency (8% indicated that heterotrophic populations in SLW partition a majority of their carbon demand to cellular maintenance rather than growth. Chemoautotrophic CO2-fixation exceeded heterotrophic organic C-demand by a factor of ~1.5. Aerobic respiratory activity associated with heterotrophic and chemoautotrophic metabolism surpassed the estimated supply of oxygen to SLW, implying that microbial activity could deplete the oxygenated waters, resulting in anoxia. We used thermodynamic calculations to examine the biogeochemical and energetic consequences of environmentally imposed switching between aerobic and anaerobic metabolisms

  10. Oxygen 18 isotopic analysis of sub-glacial concentrations of the Laurentide Ice Sheet

    Energy Technology Data Exchange (ETDEWEB)

    Hillaire-Marcel, C [Quebec Univ., Montreal (Canada); Cailleux, A [Observatoire de Paris, Section de Meudon, 92 (France); Soucy, J

    1979-07-01

    Calcareous concretions occuring on Grenvillian gneiss have been discovered north of Hull, Quebec. Their structure and isotopic composition (delta/sub PDB//sup 18/O approximately equal to -26%; delta/sub PDB//sup 13/C approximately equal to 0%; /sup 14/C age > 35,000 BP) indicate subglacial conditions of precipitation. It is concluded that they were deposited at the base of the Laurentide ice sheet. Assuming equilibrium conditions with the subglacial film of water during precipitation of calcite, it is possible to define a -27.5 to -31.8% (vs. 'standard mean ocean water' (SMOW)) range for the oxygen-18 content of ice.

  11. Investigating palaeo-subglacial lakes in the central Barents Sea

    Science.gov (United States)

    Esteves, M.; Shackleton, C.; Winsborrow, M.; Andreassen, K.; Bjarnadóttir, L. R.

    2017-12-01

    In the past decade hundreds of subglacial lakes have been detected beneath the Antarctic Ice Sheet, and several more beneath the Greenland Ice Sheet. These are important components of the subglacial hydrological system and can influence basal shear stress, with implications for ice sheet dynamics and mass balance, potentially on rapid timescales. Improvements in our understanding of subglacial hydrological systems are therefore important, but challenging due to the inaccessibility of contemporary subglacial environments. Whilst the beds of palaeo-ice sheets are easier to access, few palaeo-subglacial lakes have been identified due to uncertainties in the sedimentological and geomorphological diagnostic criteria. In this study we address these uncertainties, using a suite of sedimentological, geomorphological and modelling approaches to investigate sites of potential palaeo-subglacial lakes in the central Barents Sea. Geomorphological signatures of hydraulic activity in the area include large meltwater channels, tunnel valleys, and several interlinked basins. Modelling efforts indicate the potential for subglacial hydraulic sinks within the area during the early stages of ice retreat since the Last Glacial Maximum. In support of this, sedimentological observations indicate the presence of a dynamic glaciolacustrine depositional environment. Using the combined results of the modelling, geomorphology, and sedimentological analyses, we conclude that palaeo-subglacial lakes are likely to have formed on the northwestern banks of Thor Iversenbanken, central Barents Sea, and suggest that numerous other subglacial lakes may have been present beneath the Barents Sea Ice Sheet. Furthermore, we investigate and refine the existing diagnostic criteria for the identification of palaeo-subglacial lakes.

  12. Modeling the response of subglacial drainage at Paakitsoq, west Greenland, to 21st century climate change

    Science.gov (United States)

    Mayaud, Jerome R.; Banwell, Alison F.; Arnold, Neil S.; Willis, Ian C.

    2014-12-01

    Although the Greenland Ice Sheet (GrIS) is losing mass at an accelerating rate, much uncertainty remains about how surface runoff interacts with the subglacial drainage system and affects water pressures and ice velocities, both currently, and into the future. Here, we apply a physically based, subglacial hydrological model to the Paakitsoq region, west Greenland, and run it into the future to calculate patterns of daily subglacial water pressure fluctuations in response to climatic warming. The model is driven with moulin input hydrographs calculated by a surface routing model, forced with distributed runoff. Surface runoff and routing are simulated for a baseline year (2000), before the model is forced with future climate scenarios for the years 2025, 2050, and 2095, based on the IPCC's Representative Concentration Pathways (RCPs). Our results show that as runoff increases throughout the 21st century, and/or as RCP scenarios become more extreme, the subglacial drainage system makes an earlier transition from a less efficient network operating at high water pressures, to a more efficient network with lower pressures. This will likely cause an overall decrease in ice velocities for marginal areas of the GrIS. However, short-term variations in runoff, and therefore subglacial pressure, can still cause localized speedups, even after the system has become more efficient. If these short-term pressure fluctuations become more pronounced as future runoff increases, the associated late-season speedups may help to compensate for the drop in overall summer velocities, associated with earlier transitioning from a high to a low pressure system.

  13. A varied subglacial landscape under Thwaites Glacier, West Antarctica

    Science.gov (United States)

    Christianson, K. A.; Holschuh, N.; Paden, J. D.; Sprick, J.; Peters, L. E.; Anandakrishnan, S.; Alley, R. B.

    2017-12-01

    Deglaciated landscapes, whether subaerial or submarine, are often host to a rich panoply of subglacial landforms, such as drumlims, crags, megascale glacial lineations, grounding-line wedges, deep meltwater channels, and more. These landforms are formed and shaped by interactions between the ice and underlying substrate, and thus have implications for the flow of the overlying ice. Robust interpretations of the relationship between the ice and its substrate based on subglacial landforms that remain after deglaciation have been inhibited by a dearth of high-resolution observations of currently glaciated subglacial landscapes, where ice flow speed is known and where subglacial conditions can be ascertained using geophysical methods. Past direct observations of landforms under currently fast-flowing ice have been limited to a few ice streams, where relatively homogeneous, thick dilatant till layers may favor formation of specific subglacial features, i.e., megascale glacial lineations and grounding-zone wedges. Here we present two detailed gridded subglacial topographies, obtained from ice-penetrating radar measurements, from Thwaites Glacier, West Antarctica, where ice flows over a highly variable bed (in both topography and model-inferred basal shear stress). One grid is located ˜170 km downstream from the ice divide where ice is moving ˜100 m/yr. Here the ice advects over a broad basin and then flows into a subglacial ridge (of several hundred meters amplitude) oriented orthogonally to flow. A deep canyon ( 400 m) that cuts through this ridge in roughly the ice-flow direction and relatively soft sediments on the downstream side of the basin (immediately upstream of the canyon) suggest that a large subglacial lake may have formed in this location and drained catastrophically, as has been hypothesized as the formation mechanism for the deep canyons observed on the Amundsen Sea continental shelf. Numerous multiscale glacial lineations are also observed in the

  14. Representing glaciations and subglacial processes in hydrogeological models : a numerical investigation

    OpenAIRE

    Sterckx, Arnaud; Lemieux, Jean-Michel; Vaikmäe, Rein

    2017-01-01

    The specific impact of glacial processes on groundwater flow and solute transport under ice-sheets was determined by means of numerical simulations. Groundwater flow and the transport of δ18O, TDS, and groundwater age were simulated in a generic sedimentary basin during a single glacial event followed by a postglacial period. Results show that simulating subglacial recharge with a fixed flux boundary condition is relevant only for small fluxes, which could be the case under partially wet-base...

  15. ENVIRONMENT PROTECTION AND ENVIRONMENT MONITORING ISSUES IN THE PROJECTS OF SUBGLACIAL LAKES STUDIES IN ANTARCTICA

    Directory of Open Access Journals (Sweden)

    I. A. Alekhina

    2012-01-01

    Full Text Available Antarctic subglacial lakes can represent extreme natural habitats for microorganisms from the position of their evolution and adaptation, as well as they can contain the information on Antarctic ice sheet history and climatic changes in their sediments. Now only direct measurements and sampling from these habitats can answer on many fundamental questions. Special precaution should be complied at penetration into these unique relic environments without unfavorable impacts and contamination. A number of recommendations were developed on levels of cleanliness and sterility during direct exploration and research of subglacial environments. Documents considered in the article are the first and necessary steps for appropriate and long-term ecological management of subglacial Antarctic environments. Today there are three projects of subglacial aquatic environment research which are in preparation and realization – the Russian project of Lake Vostok, the similar British project of Lake Ellsworth and the American project on Whillans Ice Stream. The programs of ecological stewardship for direct exploration of these lakes are discussed. All these subglacial aquatic objects of further exploration and research are so various on their structure, age and regime, that only results of all programs as a whole can help to draw us a uniform picture of a subglacial ecological system. Ecological stewardship of these should provide the minimal ecological impact with maximal scientific results. On the basis of existing documents and recommendations the general approaches and the program of ecological stewardship for Lake Vostok research are discussed. Study of drilling fluid, drilling chips, Vostok ice core and the fresh frozen water will allow to make an assessment of biological and chemical contamination as a result of the first penetration and to modify the further stewardship program for the second penetration and direct exploration of lake water.

  16. Nye Lecture: Water Under Ice: Curiosities, Complexities, and Catastrophes

    Science.gov (United States)

    Clarke, G. K.

    2006-12-01

    Meltwater beneath glaciers and ice sheets activates some of the most curious and impressive phenomena known to glaciology. These range from the generation of miniscule electrokinetic currents by water flow through subglacial sediment to massive outburst floods that rearrange landscapes and deliver freshwater pulses to the ocean. The source of this water varies but is some mix of surface water and water melted from the glacier base by geothermal and frictional heating. The outflow of subglacial water is somewhat affected by bed topography but the dominant influence is from gradients in ice overburden pressure and thus from the surface topography of the ice sheet. Upslope water flow is possible and large adverse bed slopes are required before topographic water traps can exist. As a consequence, subglacial topographic basins tend to be leaky and less than 5% of the area of the contemporary Antarctic Ice Sheet provides suitable habitat for subglacial lakes. Following a variety of subglacial pathways, water can migrate toward the ice margins, either as a liquid or as refrozen meltwater accreted to the ice base. The morphology of the subglacial water system is thought to comprise a combination of sheet-like, channel-like, and vein-like elements, all of which lend themselves to mathematical representation. Water transport processes need not operate in a steady fashion and morphological switching between sheet-like and channel-like endmembers is linked to spectacular events such as glacier surges and outburst floods. Large outbursts of proglacially or subglacially-stored meltwater, the classic Icelandic j{ö}kulhaups, continue to occur in glaciated regions of the world and much larger floods were released during the Late Pleistocene--Early Holocene deglaciation of the Northern Hemisphere. Whether large subglacial lakes like Lake Vostok, Earth's seventh largest lake, have similar potential for delivering cataclysmic floods remains uncertain. The recent detection of a small

  17. Meltwater drainage beneath ice sheets: What can we learn from uniting observations of paleo- and contemporary subglacial hydrology?

    Science.gov (United States)

    Simkins, L. M.; Carter, S. P.; Greenwood, S. L.; Schroeder, D. M.

    2017-12-01

    Understanding meltwater at the base of ice sheets is critical for predicting ice flow and subglacial sediment deformation. Whereas much progress has been made with observing contemporary systems, these efforts have been limited by the short temporal scales of remote sensing data, the restricted spatial coverage of radar sounding data, and the logistical challenges of direct access. Geophysical and sedimentological data from deglaciated continental shelves reveal broad spatial and temporal perspectives of subglacial hydrology, that complement observations of contemporary systems. Massive bedrock channels, such as those on the sediment-scoured inner continental shelf of the Amundsen Sea and the western Antarctic Peninsula, are up to hundreds of meters deep, which indicate either catastrophic drainage events or slower channel incision over numerous glaciations or sub-bank full drainage events. The presence of these deep channels has implications for further ice loss as they may provide conduits today for warm water incursion into sub-ice shelf cavities. Sediment-based subglacial channels, widespread in the northern hemisphere terrestrial domain and increasingly detected on both Arctic and Antarctic marine margins, help characterize more ephemeral drainage systems active during ice sheet retreat. Importantly, some observed sediment-based channels are connected to upstream subglacial lakes and terminate at paleo-grounding lines. From these records of paleo-subglacial hydrology, we extract the relative timing of meltwater drainage, estimate water fluxes, and contemplate the sources and ultimate fate of basal meltwater, refining predictive models for modern systems. These insights provided by geological data fill a gap in knowledge regarding spatial and temporal dynamics of subglacial hydrology and offer hindsight into meltwater drainage influence/association with ice flow and retreat behavior. The union of information gathered from paleo- and contemporary subglacial

  18. Subglacial discharge at tidewater glaciers revealed by seismic tremor

    Science.gov (United States)

    Bartholomaus, Timothy C.; Amundson, Jason M.; Walter, Jacob I.; O'Neel, Shad; West, Michael E.; Larsen, Christopher F.

    2015-01-01

    Subglacial discharge influences glacier basal motion and erodes and redeposits sediment. At tidewater glacier termini, discharge drives submarine terminus melting, affects fjord circulation, and is a central component of proglacial marine ecosystems. However, our present inability to track subglacial discharge and its variability significantly hinders our understanding of these processes. Here we report observations of hourly to seasonal variations in 1.5–10 Hz seismic tremor that strongly correlate with subglacial discharge but not with basal motion, weather, or discrete icequakes. Our data demonstrate that vigorous discharge occurs from tidewater glaciers during summer, in spite of fast basal motion that could limit the formation of subglacial conduits, and then abates during winter. Furthermore, tremor observations and a melt model demonstrate that drainage efficiency of tidewater glaciers evolves seasonally. Glaciohydraulic tremor provides a means by which to quantify subglacial discharge variations and offers a promising window into otherwise obscured glacierized environments.

  19. Subglacial hydrology of the lake district ice lobe during the Younger Dryas (ca. 12 500 - 11 600 years ago) in the Kylaeniemi area, SE Finland

    Energy Technology Data Exchange (ETDEWEB)

    Lunkka, J. P.; Moisio, K.; Vainio, A. [Univ. of Oulu (Finland)

    2013-07-15

    It is essential to gain knowledge on the subglacial hydrological conditions at the glacier bed / bedrock interface when assessing how bedrock fracture zones affect subglacial melt water flow and in which subglacial zones pressurized and oxygen-rich melt water penetrates into the bedrock fracture systems. In the warm-based glacier zones, a part of subglacial melt water will penetrate deep into the fracture systems although the major part of melt water is drained to and beyond the ice margin via subglacial tunnel networks especially in the areas where ice is flowing on the crystalline bedrock. During the last deglaciation phase of the former Scandinavian Ice Sheet, glaciofluvial accumulations were deposited and these sediment accumulations are highly important when picturing the subglacial hydrology of different ice streams during deglaciation in the crystalline bedrock area. The aim of the present work was to map the bedrock fracture zones in the Kylaeniemi area and to shed light on the subglacial hydrology of the Scandinavian Ice Sheet's Lake District Ice Stream that occupied the Kylaeniemi area during the Younger Dryas between ca. 12 500 - 11 600 years ago. The special emphasis within this general aim was to study the relationship between bedrock fracture zones and the routes of subglacial drainage paths. The methods used to map and study bedrock fracture zones and subglacial drainage paths included remotes sensing methods, field observations, ground penetrating radar (GPR) investigations and GIS-based reconstructions. Conventional geological field methods aided by the GPR-method were also used to map bedrock exposures and their structures and to define the type of glaciofluvial sediments and glaciofluvial landform associations. Two main fracture zone sets occur in the study area. The most prominent bedrock fracture zone set trends NW-SE while the other, less prominent fracture zone set is aligned in NE-SW direction. The majority of the minor joint sets in

  20. Subglacial hydrology of the lake district ice lobe during the Younger Dryas (ca. 12 500 - 11 600 years ago) in the Kylaeniemi area, SE Finland

    International Nuclear Information System (INIS)

    Lunkka, J. P.; Moisio, K.; Vainio, A.

    2013-07-01

    It is essential to gain knowledge on the subglacial hydrological conditions at the glacier bed / bedrock interface when assessing how bedrock fracture zones affect subglacial melt water flow and in which subglacial zones pressurized and oxygen-rich melt water penetrates into the bedrock fracture systems. In the warm-based glacier zones, a part of subglacial melt water will penetrate deep into the fracture systems although the major part of melt water is drained to and beyond the ice margin via subglacial tunnel networks especially in the areas where ice is flowing on the crystalline bedrock. During the last deglaciation phase of the former Scandinavian Ice Sheet, glaciofluvial accumulations were deposited and these sediment accumulations are highly important when picturing the subglacial hydrology of different ice streams during deglaciation in the crystalline bedrock area. The aim of the present work was to map the bedrock fracture zones in the Kylaeniemi area and to shed light on the subglacial hydrology of the Scandinavian Ice Sheet's Lake District Ice Stream that occupied the Kylaeniemi area during the Younger Dryas between ca. 12 500 - 11 600 years ago. The special emphasis within this general aim was to study the relationship between bedrock fracture zones and the routes of subglacial drainage paths. The methods used to map and study bedrock fracture zones and subglacial drainage paths included remotes sensing methods, field observations, ground penetrating radar (GPR) investigations and GIS-based reconstructions. Conventional geological field methods aided by the GPR-method were also used to map bedrock exposures and their structures and to define the type of glaciofluvial sediments and glaciofluvial landform associations. Two main fracture zone sets occur in the study area. The most prominent bedrock fracture zone set trends NW-SE while the other, less prominent fracture zone set is aligned in NE-SW direction. The majority of the minor joint sets in

  1. A new methodology to simulate subglacial deformation of water saturated granular material

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Piotrowski, Jan A.

    2015-01-01

    The dynamics of glaciers are to a large degree governed by processes operating at the ice-bed interface, and one of the primary mechanisms of glacier flow over soft unconsolidated sediments is subglacial deformation. However, it has proven difficult to constrain the mechanical response of subglac......The dynamics of glaciers are to a large degree governed by processes operating at the ice-bed interface, and one of the primary mechanisms of glacier flow over soft unconsolidated sediments is subglacial deformation. However, it has proven difficult to constrain the mechanical response...... or weakening components, depending on the rate of deformation, the material state, clay mineral content, and the hydrological properties of the material. The influence of the fluid phase is negligible when relatively permeable sediment is deformed. However, by reducing the local permeability, fast deformation...... can cause variations in the pore-fluid pressure. The pressure variations weaken or strengthen the granular phase, and in turn influence the distribution of shear strain with depth. In permeable sediments the strain distribution is governed by the grain-size distribution and effective normal stress...

  2. Modeling of subglacial hydrological development following rapid supraglacial lake drainage

    OpenAIRE

    Dow, C F; Kulessa, B; Rutt, I C; Tsai, V C; Pimentel, S; Doyle, S H; van As, D; Lindb?ck, K; Pettersson, R; Jones, G A; Hubbard, A

    2015-01-01

    The rapid drainage of supraglacial lakes injects substantial volumes of water to the bed of the Greenland ice sheet over short timescales. The effect of these water pulses on the development of basal hydrological systems is largely unknown. To address this, we develop a lake drainage model incorporating both (1) a subglacial radial flux element driven by elastic hydraulic jacking and (2) downstream drainage through a linked channelized and distributed system. Here we present the model and exa...

  3. Investigating the hydrological origins of Blood Falls - geomicrobiological insights into a briny subglacial Antarctic aquifer

    Science.gov (United States)

    Mikucki, J.; Tulaczyk, S. M.; Purcell, A. M.; Dachwald, B.; Lyons, W. B.; Welch, K. A.; Auken, E.; Dugan, H. A.; Walter, J. I.; Pettit, E. C.; Doran, P. T.; Virginia, R. A.; Schamper, C.; Foley, N.; Feldmann, M.; Espe, C.; Ghosh, D.; Francke, G.

    2015-12-01

    Subglacial waters tend to accumulate solutes from extensive rock-water interactions, which, when released to the surface, can provide nutrients to surface ecosystems providing a 'hot spot' for microbial communities. Blood Falls, an iron-rich, saline feature at the terminus of Taylor Glacier in the McMurdo Dry Valleys, Antarctica is a well-studied subglacial discharge. Here we present an overview of geophysical surveys, thermomechanical drilling exploration and geomicrobiological analyses of the Blood Falls system. A helicopter-borne transient electromagnetic system (SkyTEM) flown over the Taylor Glacier revealed a surprisingly extensive subglacial aquifer and indicates that Blood Falls may be the only surface manifestation of this extensive briny groundwater. Ground-based temperature sensing and GPR data combined with the helicopter-borne TEM data enabled targeted drilling into the englacial conduit that delivers brine to the surface. During the 2014-15 austral summer field season, we used a novel ice-melting drill (the IceMole) to collect englacial brine for geomicrobiological analyses. Results from previously collected outflow and more recent samples indicate that the brine harbors a metabolically active microbial community that persists, despite cold, dark isolation. Isotope geochemistry and molecular analysis of functional genes from BF suggested that a catalytic or 'cryptic' sulfur cycle was linked to iron reduction. Recent metagenomic analysis confirms the presence of numerous genes involved in oxidative and reductive sulfur transformations. Metagenomic and metabolic activity data also indicate that subglacial dark CO2 fixation occurs via various pathways. Genes encoding key steps in CO2 fixation pathways including the Calvin Benson Basham and Wood Ljungdahl pathway were present and brine samples showed measureable uptake of 14C-labeled bicarbonate. These results support the notion that, like the deep subsurface, subglacial environments are chemosynthetic

  4. Evolution of Pine Island Glacier subglacial conditions in response to 18 years of ice flow acceleration

    Science.gov (United States)

    Brisbourne, A.; Bougamont, M. H.; Christoffersen, P.; Cornford, S. L.; Nias, I.; Vaughan, D.; Smith, A.

    2017-12-01

    Antarctica's main contribution to sea-level rise originates from the Amundsen Coast, when warm ocean water intrudes onto the continental shelf. As a result, strong melting beneath the ice shelves induces thinning near the grounding line of glaciers, which is ensued by large ice flow speed up diffusing rapidly inland. In particular, ice loss from Pine Island Glacier (PIG) accounts for 20% of the total ice loss in West Antarctica, amounting to 0.12 mm yr-1 of global sea-level rise. Forecasting the future flow of Amundsen Coast glaciers is however hindered by large uncertainties regarding how the thinning initiated at the grounding line is transmitted upstream, and how the grounded flow will ultimately respond. This work aims at elucidating the role of subglacial processes beneath PIG tributaries in modulating the ice flow response to frontal perturbations. We used the Community Ice Sheet Model (CISM 2.0) to perform numerical inversions of PIG surface velocity as observed in 1996 and 2014. Over that time period, ice flow acceleration has been widespread over PIG's basin, and the inversions provide insights into the related evolution of the basal thermal and stress conditions. We assume the latter to be directly related to changes in the properties of a soft sediment (till) layer known to exist beneath PIG. We find that the overall bed strength has weakened by 18% in the region of enhanced flow, and that the annual melt production for PIG catchment increased by 25% between 1996 and 2014. Specifically, regions of high melt production are located in the southern tributaries, where the overall stronger bed allows for more frictional melting. However, we find no significant and widespread change in the basal strength of that region, and we infer that the water produced is transported away in a concentrated hydrological system, without much interaction with the till layer. In contrast, we find that relatively less basal melting occurs elsewhere in the catchment, where the

  5. Crushing of Subglacial Lake Sediment as a Source of Bio-utilisable Gases.

    Science.gov (United States)

    Gill Olivas, B.; Telling, J.; Michaud, A. B.; Skidmore, M. L.; Priscu, J. C.; Tranter, M.

    2017-12-01

    Recent research has shown microbial ecosystems exist under glaciers and ice sheets. The sources of energy to support these ecosystems are still not fully understood, particularly beneath the Antarctic Ice Sheet, where direct access to the atmosphere and in-washed organic matter and oxidising agents does not occur. Hence, sub-ice sheet energy sources are restricted to those in subglacial environments, except for ice-margin environments. This study focuses on sediments from Subglacial Lake Whillans (SLW), the first subglacial lake to be directly and cleanly sampled. Sediment from three depths in a shallow core extracted from SLW were used to assess the possible energy contributions from mechanochemical reactions to this subglacial ecosystem. To do this, the samples were crushed under an anoxic atmosphere using a ball mill. The sediments were then transferred into serum bottles under anoxic conditions. They were wetted and the headspace gas was subsequently sampled and analysed during a 40 day incubation. Results show the release of substantial amounts of hydrogen, which could potentially serve as an abiotic source of energy to microbes, in particular, methanogenic archaea. Significant amounts of short chain hydrocarbons (including methane and ethylene), possibly from the reactivation of ancient organic carbon, were also observed. Crushed samples showed a significant concentration of hydrogen peroxide produced on contact with water, as well as significant amounts of Si radicals, showing comminution of these sediments unlocks the potential for a wide range of redox conditions and reactions to develop within glacially eroded sediment under ice. This in turn provides a previously overlooked source of nutrients and energy for microbes to utilise.

  6. Stable water isotopic composition of the Antarctic subglacial Lake Vostok: implications for understanding the lake's hydrology.

    Science.gov (United States)

    Ekaykin, Alexey A; Lipenkov, Vladimir Y; Kozachek, Anna V; Vladimirova, Diana O

    2016-01-01

    We estimated the stable isotopic composition of water from the subglacial Lake Vostok using two different sets of samples: (1) water frozen on the drill bit immediately after the first lake unsealing and (2) water frozen in the borehole after the unsealing and re-drilled one year later. The most reliable values of the water isotopic composition are: -59.0 ± 0.3 ‰ for oxygen-18, -455 ± 1 ‰ for deuterium and 17 ± 1 ‰ for d-excess. This result is also confirmed by the modelling of isotopic transformations in the water which froze in the borehole, and by a laboratory experiment simulating this process. A comparison of the newly obtained water isotopic composition with that of the lake ice (-56.2 ‰ for oxygen-18, -442.4 ‰ for deuterium and 7.2 ‰ for d-excess) leads to the conclusion that the lake ice is very likely formed in isotopic equilibrium with water. In turn, this means that ice is formed by a slow freezing without formation of frazil ice crystals and/or water pockets. This conclusion agrees well with the observed physical and chemical properties of the lake's accreted ice. However, our estimate of the water's isotopic composition is only valid for the upper water layer and may not be representative for the deeper layers of the lake, so further investigations are required.

  7. Automatic detection of subglacial lakes in radar sounder data acquired in Antarctica

    Science.gov (United States)

    Ilisei, Ana-Maria; Khodadadzadeh, Mahdi; Dalsasso, Emanuele; Bruzzone, Lorenzo

    2017-10-01

    Subglacial lakes decouple the ice sheet from the underlying bedrock, thus facilitating the sliding of the ice masses towards the borders of the continents, consequently raising the sea level. This motivated increasing attention in the detection of subglacial lakes. So far, about 70% of the total number of subglacial lakes in Antarctica have been detected by analysing radargrams acquired by radar sounder (RS) instruments. Although the amount of radargrams is expected to drastically increase, from both airborne and possible future Earth observation RS missions, currently the main approach to the detection of subglacial lakes in radargrams is by visual interpretation. This approach is subjective and extremely time consuming, thus difficult to apply to a large amount of radargrams. In order to address the limitations of the visual interpretation and to assist glaciologists in better understanding the relationship between the subglacial environment and the climate system, in this paper, we propose a technique for the automatic detection of subglacial lakes. The main contribution of the proposed technique is the extraction of features for discriminating between lake and non-lake basal interfaces. In particular, we propose the extraction of features that locally capture the topography of the basal interface, the shape and the correlation of the basal waveforms. Then, the extracted features are given as input to a supervised binary classifier based on Support Vector Machine to perform the automatic subglacial lake detection. The effectiveness of the proposed method is proven both quantitatively and qualitatively by applying it to a large dataset acquired in East Antarctica by the MultiChannel Coherent Radar Depth Sounder.

  8. Blood Falls: A novel management approach for a subglacial feature of outstanding scientific importance

    Science.gov (United States)

    Carr, J. R.; Penhale, P. A.; Dahood, A.; Biletnikoff, N.; Harris, C. M.

    2012-04-01

    Blood Falls is a subglacial feature located in the ablation zone of the Taylor Glacier, Taylor Valley, McMurdo Dry Valleys, Antarctica. Blood Falls has a unique physical configuration, microbial ecology and geochemistry and consists of a subglacial brine reservoir and an iron-rich, saline surface discharge at the Taylor Glacier terminus. The feature provides a rare opportunity to sample properties of a subglacial reservoir and its ecosystem without the need for direct contact and is a key site for exobiological studies. The Blood Falls subglacial feature is globally unique and of outstanding scientific importance. As such, it warrants special protection from potential damage by drilling and/or surface activities. Moreover, currently subglacial environments are not represented in the Antarctic protected area network. To address these points, the United States National Science Foundation is working with the scientific community to develop at Blood Falls the first subglacial protected area in Antarctica. The protected area aims to maintain the integrity of the Blood Falls system, whilst allowing continued access for scientific and management purposes. Novel management approaches are being designed to protect the values of the site in three dimensions. Specific guidelines on activities conducted within the area, most notably drilling and coring, are being defined in a management plan. This new approach incorporates uncertainties in the location of the Blood Falls brine reservoir and the connectivity of the subglacial hydrological system of the Taylor Glacier. The management approaches employed at Blood Falls draw on the experience of the subglacial research community and potentially offer an effective framework for the protection of other subglacial environments.

  9. Subglacial sediment mechanics investigated by computer simulation of granular material

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Tulaczyk, Slawek

    The mechanical properties of subglacial sediments are known to directly influence the stability of ice streams and fast-moving glaciers, but existing models of granular sediment deformation are poorly constrained. In addition, upscaling to generalized mathematical models is difficult due to the m......The mechanical properties of subglacial sediments are known to directly influence the stability of ice streams and fast-moving glaciers, but existing models of granular sediment deformation are poorly constrained. In addition, upscaling to generalized mathematical models is difficult due....... The numerical method is applied to better understand the mechanical properties of the subglacial sediment and its interaction with meltwater. The computational approach allows full experimental control and offers insights into the internal kinematics, stress distribution, and mechanical stability. During...

  10. Numerical Modeling of Subglacial Sediment Deformation

    DEFF Research Database (Denmark)

    Damsgaard, Anders

    2015-01-01

    may cause mass loss in the near future to exceed current best estimates. Ice flow in larger ice sheets focuses in fast-moving streams due to mechanical non-linearity of ice. These ice streams often move at velocities several magnitudes larger than surrounding ice and consequentially constitute...... glaciers move by deforming their sedimentary beds. Several modern ice streams, in particular, move as plug flows due to basal sediment deformation. An intense and long-winded discussion about the appropriate description for subglacial sediment mechanics followed this discovery, with good reason...... incompatible with commonly accepted till rheology models. Variation in pore-water pressure proves to cause reorganization in the internal stress network and leads to slow creeping deformation. The rate of creep is non-linearly dependent on the applied stresses. Granular creep can explain slow glacial...

  11. Penicillium mycobiota in Arctic subglacial ice

    DEFF Research Database (Denmark)

    Sonjak, S.; Frisvad, Jens Christian; Gunde-Cimerman, N.

    2006-01-01

    , representing on the average half of all isolated strains from all three glaciers. The other most frequently isolated species were P. bialowiezense, P. chrysogenum, P. thomii, P. solitum, P. palitans, P. echinulatum, P. polonicum, P. commune, P. discolor, P. expansum, and new Penicillium species (sp. 1). Twelve...... to be inhabited exclusively by heterotrophic bacteria. In this study we report on the very high occurrence (up to 9000 CFU L-1) and diversity of filamentous Penicillium spp. in the sediment-rich subglacial ice of three different polythermal Arctic glaciers (Svalbard, Norway). The dominant species was P. crustosum...... more Penicillium species were occasionally isolated. The fungi isolated produced consistent profiles of secondary metabolites, not different from the same Penicillium species from other habitats. This is the first report on the presence of large populations of Penicillium spp. in subglacial sediment...

  12. Sensitivity analysis for the coupling of a subglacial hydrology model with a 3D ice-sheet model.

    Science.gov (United States)

    Bertagna, L.; Perego, M.; Gunzburger, M.; Hoffman, M. J.; Price, S. F.

    2017-12-01

    When studying the movement of ice sheets, one of the most important factors that influence the velocity of the ice is the amount of friction against the bedrock. Usually, this is modeled by a friction coefficient that may depend on the bed geometry and other quantities, such as the temperature and/or water pressure at the ice-bedrock interface. These quantities are often assumed to be known (either by indirect measurements or by means of parameter estimation) and constant in time. Here, we present a 3D computational model for the simulation of the ice dynamics which incorporates a 2D model proposed by Hewitt (2011) for the subglacial water pressure. The hydrology model is fully coupled with the Blatter-Pattyn model for the ice sheet flow, as the subglacial water pressure appears in the expression for the ice friction coefficient, and the ice velocity appears as a source term in the hydrology model. We will present results on real geometries, and perform a sensitivity analysis with respect to the hydrology model parameters.

  13. Viable cold-tolerant iron-reducing microorganisms in geographically diverse subglacial environments

    Science.gov (United States)

    Nixon, Sophie L.; Telling, Jon P.; Wadham, Jemma L.; Cockell, Charles S.

    2017-03-01

    Subglacial environments are known to harbour metabolically diverse microbial communities. These microbial communities drive chemical weathering of underlying bedrock and influence the geochemistry of glacial meltwater. Despite its importance in weathering reactions, the microbial cycling of iron in subglacial environments, in particular the role of microbial iron reduction, is poorly understood. In this study we address the prevalence of viable iron-reducing microorganisms in subglacial sediments from five geographically isolated glaciers. Iron-reducing enrichment cultures were established with sediment from beneath Engabreen (Norway), Finsterwalderbreen (Svalbard), Leverett and Russell glaciers (Greenland), and Lower Wright Glacier (Antarctica). Rates of iron reduction were higher at 4 °C compared with 15 °C in all but one duplicated second-generation enrichment culture, indicative of cold-tolerant and perhaps cold-adapted iron reducers. Analysis of bacterial 16S rRNA genes indicates Desulfosporosinus were the dominant iron-reducing microorganisms in low-temperature Engabreen, Finsterwalderbreen and Lower Wright Glacier enrichments, and Geobacter dominated in Russell and Leverett enrichments. Results from this study suggest microbial iron reduction is widespread in subglacial environments and may have important implications for global biogeochemical iron cycling and export to marine ecosystems.

  14. Unveiling the Antarctic subglacial landscape.

    Science.gov (United States)

    Warner, Roland; Roberts, Jason

    2010-05-01

    Better knowledge of the subglacial landscape of Antarctica is vital to reducing uncertainties regarding prediction of the evolution of the ice sheet. These uncertainties are associated with bedrock geometry for ice sheet dynamics, including possible marine ice sheet instabilities and subglacial hydrological pathways (e.g. Wright et al., 2008). Major collaborative aerogeophysics surveys motivated by the International Polar Year (e.g. ICECAP and AGAP), and continuing large scale radar echo sounding campaigns (ICECAP and NASA Ice Bridge) are significantly improving the coverage. However, the vast size of Antarctica and logistic difficulties mean that data gaps persist, and ice thickness data remains spatially inhomogeneous. The physics governing large scale ice sheet flow enables ice thickness, and hence bedrock topography, to be inferred from knowledge of ice sheet surface topography and considerations of ice sheet mass balance, even in areas with sparse ice thickness measurements (Warner and Budd, 2000). We have developed a robust physically motivated interpolation scheme, based on these methods, and used it to generate a comprehensive map of Antarctic bedrock topography, using along-track ice thickness data assembled for the BEDMAP project (Lythe et al., 2001). This approach reduces ice thickness biases, compared to traditional inverse distance interpolation schemes which ignore the information available from considerations of ice sheet flow. In addition, the use of improved balance fluxes, calculated using a Lagrangian scheme, eliminates the grid orientation biases in ice fluxes associated with finite difference methods (Budd and Warner, 1996, Le Brocq et al., 2006). The present map was generated using a recent surface DEM (Bamber et al., 2009, Griggs and Bamber, 2009) and accumulation distribution (van de Berg et al., 2006). Comparing our results with recent high resolution regional surveys gives confidence that all major subglacial topographic features are

  15. Water-transporting proteins

    DEFF Research Database (Denmark)

    Zeuthen, Thomas

    2010-01-01

    . In the K(+)/Cl(-) and the Na(+)/K(+)/2Cl(-) cotransporters, water is entirely cotransported, while water transport in glucose uniporters and Na(+)-coupled transporters of nutrients and neurotransmitters takes place by both osmosis and cotransport. The molecular mechanism behind cotransport of water...... transport. Epithelial water transport is energized by the movements of ions, but how the coupling takes place is uncertain. All epithelia can transport water uphill against an osmotic gradient, which is hard to explain by simple osmosis. Furthermore, genetic removal of aquaporins has not given support...... to osmosis as the exclusive mode of transport. Water cotransport can explain the coupling between ion and water transport, a major fraction of transepithelial water transport and uphill water transport. Aquaporins enhance water transport by utilizing osmotic gradients and cause the osmolarity...

  16. PROSPECTS FOR LIFE IN THE SUBGLACIAL LAKE VOSTOK, EAST ANTARCTICA

    Directory of Open Access Journals (Sweden)

    S. A. Bulat

    2012-01-01

    Full Text Available The objective was to estimate the genuine microbial content of ice samples from refrozen water (accretion ice from the subglacialLakeVostok(Antarctica buried beneath the 4-km thick East Antarctic ice sheet as well as surface snow nearby Vostok station. The lake ice samples were extracted by heavy deep ice drilling from3764 mbelow the surface reaching the depth3769.3 mby February 2011 (lake entering. High pressure, an ultra low carbon and chemical content, isolation, complete darkness and the probable excess of oxygen in water for millions of years characterize this extreme environment. A decontamination protocol was first applied to samples selected for the absence of cracks to remove the outer part contaminated by handling and drilling fluid. Preliminary indications showed the accretion ice samples to be almost gas free with the very low impurity content. Flow cytometry showed the very low unevenly distributed biomass in both accretion (0–19 cells per ml and glacier (0–24 cells per ml ice and surface snow (0–0.02 cells per ml as well while repeated microscopic observations were unsuccessful meaning that the whole Central East Antarctic ice sheet seems to be microbial cell-free.We used strategies of Ancient DNA research that include establishing contaminant databases and criteria to validate the amplification results. To date, positive results that passed the artifacts and contaminant databases have been obtained for a few bacterial phylotypes only in accretion ice samples featured by some bedrock sediments. Amongst them are the chemolithoautotrophic thermophile Hydrogenophilus thermoluteolus of beta-Proteobacteria, the actinobacterium rather related (95% to Ilumatobacter luminis and one unclassified phylotype distantly related (92% to soil-inhabiting uncultured bacteria. Combined with geochemical and geophysical considerations, our results suggest the presence of a deep biosphere, possibly thriving within some active faults of the bedrock

  17. Constraining local subglacial bedrock erosion rates with cosmogenic nuclides

    Science.gov (United States)

    Wirsig, Christian; Ivy-Ochs, Susan; Christl, Marcus; Reitner, Jürgen; Reindl, Martin; Bichler, Mathias; Vockenhuber, Christof; Akcar, Naki; Schlüchter, Christian

    2014-05-01

    The constant buildup of cosmogenic nuclides, most prominently 10Be, in exposed rock surfaces is routinely employed for dating various landforms such as landslides or glacial moraines. One fundamental assumption is that no cosmogenic nuclides were initially present in the rock, before the event to be dated. In the context of glacially formed landscapes it is commonly assumed that subglacial erosion of at least a few meters of bedrock during the period of ice coverage is sufficient to remove any previously accumulated nuclides, since the production of 10Be ceases at a depth of 2-3 m. Insufficient subglacial erosion leads to overestimation of surface exposure ages. If the time since the retreat of the glacier is known, however, a discordant concentration of cosmogenic nuclides delivers information about the depth of subglacial erosion. Here we present data from proglacial bedrock at two sites in the Alps. Goldbergkees in the Hohe Tauern National Park in Austria and Gruebengletscher in the Grimsel Pass area in Switzerland. Samples were taken inside as well as outside of the glaciers' Little Ice Age extent. Measured nuclide concentrations are analyzed with the help of a MATLAB model simulating periods of exposure or glacial cover of user-definable length and erosion rates.

  18. Long-term subglacial sliding patterns based on a sliding law with cavitation

    DEFF Research Database (Denmark)

    Ugelvig, Sofie Vej; Egholm, D.L.

    In ice-sheet models and glacial landscape evolution models, subglacial sliding rates are often related to basal shear stress by a power-law. However, the power-law relationship implies that the subglacial bed can provide unlimited levels of basal drag as sliding rates increases, which is recognized...... as an inadequate assumption, particularly when the effects of subglacial cavities are considered (Schoof 2005). We have implemented a glacial sliding law suggested by Schoof (2005) in a depth-integrated higher-order ice-sheet model (Egholm et al. 2011) and coupled this to a model for glacial hydrology. The sliding...... law includes an upper bound to the basal drag and depends on the effects of longitudinal and transverse stress components for obtaining force balance along the glacier bed. Computational experiments indicate that high annually averaged sliding rates concentrate along valley sides when basal melt...

  19. Subglacial tunnel valleys in the Alpine foreland: an example from Bern, Switzerland

    International Nuclear Information System (INIS)

    Duerst Stucki, M.; Reber, R.; Schlunegger, F.

    2010-01-01

    The morphology of the Alpine and adjacent landscapes is directly related to glacial erosion and associated sediment transport. Here we report the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau. Specifically, we identify the presence of subsurface valleys beneath the city of Bern and discuss their genesis. Stratigraphic investigations of more than 4'000 borehole data within a 430 km 2 -large area reveal the presence of a network of >200 m-deep and 1'000 m-wide valleys. They are flat floored with steep sided walls and are filled by Quaternary glacial deposits. The central valley beneath Bern is straight and oriented towards the NNW, with valley flanks more than 20 o steep. The valley bottom has an irregular undulating profile along the thalweg, with differences between sills and hollows higher than 50-100 m over a reach of 4 km length. Approximately 500 m high bedrock highlands flank the valley network. The highlands are dissected by up to 80 m-deep and 500 m-broad hanging valleys that currently drain away from the axis of the main valley. We interpret the valleys beneath the city of Bern to be a tunnel valley network which originated from subglacial erosion by melt water. The highland valleys served as proglacial meltwater paths and are hanging with respect to the trunk system, indicating that these incipient highland systems as well as the main gorge beneath Bern formed by glacial melt water under pressure. (authors)

  20. Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland

    Directory of Open Access Journals (Sweden)

    A. D. Booth

    2012-08-01

    Full Text Available Seismic amplitude-versus-angle (AVA methods are a powerful means of quantifying the physical properties of subglacial material, but serious interpretative errors can arise when AVA is measured over a thinly-layered substrate. A substrate layer with a thickness less than 1/4 of the seismic wavelength, λ, is considered "thin", and reflections from its bounding interfaces superpose and appear in seismic data as a single reflection event. AVA interpretation of subglacial till can be vulnerable to such thin-layer effects, since a lodged (non-deforming till can be overlain by a thin (metre-scale cap of dilatant (deforming till. We assess the potential for misinterpretation by simulating seismic data for a stratified subglacial till unit, with an upper dilatant layer between 0.1–5.0 m thick (λ / 120 to > λ / 4, with λ = 12 m. For dilatant layers less than λ / 6 thick, conventional AVA analysis yields acoustic impedance and Poisson's ratio that indicate contradictory water saturation. A thin-layer interpretation strategy is proposed, that accurately characterises the model properties of the till unit. The method is applied to example seismic AVA data from Russell Glacier, West Greenland, in which characteristics of thin-layer responses are evident. A subglacial till deposit is interpreted, having lodged till (acoustic impedance = 4.26±0.59 × 106 kg m−2 s−1 underlying a water-saturated dilatant till layer (thickness < 2 m, Poisson's ratio ~ 0.5. Since thin-layer considerations offer a greater degree of complexity in an AVA interpretation, and potentially avoid misinterpretations, they are a valuable aspect of quantitative seismic analysis, particularly for characterising till units.

  1. Exploration of Gamburtsev Subglacial Mountains, East Antarctica: Background and Plans for the Near Future

    Science.gov (United States)

    Talalay, Pavel; Sun, Youhong; Zhao, Yue; Li, Yuansheng; Cao, Pinlu; Xu, Huiwen; Zheng, Zhichuan; Wang, Rusheng; Zhang, Nan; Markov, Alexey; Yu, Dahui; Fan, Xiaopeng; Hu, Zhengyi; Yang, Cheng; Gong, Da; Hong, Jialing; Liu, Chunpeng; Han, Junjie; Yu, Chengfeng; Wang, Lili

    2014-05-01

    drilling of upper permeable snow-firn layer with bottom-air reverse circulation; (2) reaming; (3) casing installation; (4) fluid core drilling of glacial ice with bottom-fluid reverse circulation; (5) bedrock core drilling. All drilling equipment will be installed inside a movable sledge-mounted warm-keeping and wind-protecting drilling shelter that is transported to the chosen site with crawler-tractor. The new approaches of subglacial bedrock drilling technology are connected with utilization of environmental friendly, low-toxic drilling fluids, e.g. low-molecular dimethyl siloxane oils or ester type. They have suitable density-viscosity properties, and can be consider as a viable alternative for drilling in glacial ice and subglacial bedrock. According to approved schedule, the first field tests are planned to carry out just outside Zhongshan Station near Antarctic coast in season 2015-2016. Next season 2016-2017 the movable drilling shelter is planned to be transported to the chosen drilling site in the GSM region, and drilling to the bedrock would be finished during two seasons.

  2. Antarctic Active Subglacial Lake Inventory from ICESat Altimetry, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains lake boundaries, volume changes, and gridded elevations for 124 active subglacial lakes beneath the Antarctic ice sheet. Lakes were identified...

  3. Phenol compounds in the borehole 5G, Vostok station, after the unlocking of the subglacial lake

    Directory of Open Access Journals (Sweden)

    I. A. Alekhina

    2017-01-01

    Full Text Available The main results after the first unlocking into the subglacial Lake Vostok were as follows: the Lake had been opened and not polluted; the water pressure within the lake was not balanced by a column of the drilling liquid that resulted in unplanned rise of water in the borehole up to 340 m. The main problem during the drilling in the lake ice was to prevent a pollution of water by the drilling fluid, which filled the borehole, and thus, to avoid a compression of the fluid which could be the main source of chemical and biological pollution of not only the Lake itself, but also the Lake water samples and ice cores. The article presents results of analysis of causes for the occurrence of phenolic compounds in the central channel in the core of secondary ice, being formed by the lake water that rose into the well after the first penetration (the range of depths was 3426–3450 m. It was found that the process, running within the borehole during the drilling, can be described as the fractionation of phenolic compounds, being contained in the filling liquid, to the water phase with its subsequent freezing. We have developed methods for the determination of concentrations of phenolic compounds in the original aviation kerosene and Freon HCFC-141b: 6. mg·l−1 and 0.032 mg·l−1, respectively. To analyze the composition of phenolic compounds in the extract of real filling liquid, located at the bottom of the borehole, the method of gas chromatography-mass spectrometry (GC-MS was used. The corresponding peaks were quite well resolved and identified as phenol and its derivatives. The main components of the extract were phenol (20%, 2.5-dimethyl phenol (23,8%, 2,4,6-trimethylphenol, and other congeners of phenol. In our case, the Lake Vostok was not polluted during both, the first and second penetrations, however, the problem of human impact on these pristine and unique subglacial reservoirs remains extremely relevant. This impact includes not only

  4. Subglacial tunnel valleys in the Alpine foreland: an example from Bern, Switzerland

    Energy Technology Data Exchange (ETDEWEB)

    Duerst Stucki, M.; Reber, R.; Schlunegger, F.

    2010-12-15

    The morphology of the Alpine and adjacent landscapes is directly related to glacial erosion and associated sediment transport. Here we report the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau. Specifically, we identify the presence of subsurface valleys beneath the city of Bern and discuss their genesis. Stratigraphic investigations of more than 4'000 borehole data within a 430 km{sup 2}-large area reveal the presence of a network of >200 m-deep and 1'000 m-wide valleys. They are flat floored with steep sided walls and are filled by Quaternary glacial deposits. The central valley beneath Bern is straight and oriented towards the NNW, with valley flanks more than 20 {sup o} steep. The valley bottom has an irregular undulating profile along the thalweg, with differences between sills and hollows higher than 50-100 m over a reach of 4 km length. Approximately 500 m high bedrock highlands flank the valley network. The highlands are dissected by up to 80 m-deep and 500 m-broad hanging valleys that currently drain away from the axis of the main valley. We interpret the valleys beneath the city of Bern to be a tunnel valley network which originated from subglacial erosion by melt water. The highland valleys served as proglacial meltwater paths and are hanging with respect to the trunk system, indicating that these incipient highland systems as well as the main gorge beneath Bern formed by glacial melt water under pressure. (authors)

  5. Subglacial groundwater flow at Aespoe as governed by basal melting and ice tunnels

    International Nuclear Information System (INIS)

    Svensson, Urban

    1999-02-01

    A high resolution three dimensional numerical model of subglacial groundwater flow is described. The model uses conductivity data from the Aespoe region and is thus site specific. It is assumed that the groundwater flow is governed by the basal melting and ice tunnels; ice surface melting is not considered. Results are presented for the meltwater transport time (to the ice margin) and maximum penetration depth. Conditions at repository depth, i.e. about 500 metres, are also analysed. The general conclusion from the study is that the model presented gives plausible results, considering the basic conceptual assumptions made. It is however questioned if the hydraulics of the ice tunnels is well enough understood; this is a topic that is suggested for further studies

  6. Feedbacks between subglacial dynamics and long-term glacial landscape evolution

    DEFF Research Database (Denmark)

    Brædstrup, Christian; Egholm, D.L.; Ugelvig, Sofie Vej

    focus this presentation on feedbacks between the evolving bed topography and the subglacial erosion patterns. We have performed our experiments with different sliding and erosion laws, including highly non-linear rules representing coulomb-type slip at the bed (Schoof, 2010) and a quarrying model...

  7. Prospects of obtaining samples of bottom sediments from subglacial lake Vostok

    Directory of Open Access Journals (Sweden)

    Н. И. Васильев

    2017-04-01

    Full Text Available The paper proves the timeliness of obtaining and examining bottom sediments from subglacial Lake Vostok. Predictive geological section of Lake Vostok and information value of bottom sediments have been examined. Severe requirements towards environmental security of lake examinations and sampling of bottom sediments rule out the use of conventional drilling technologies, as they would pollute the lake with injection liquid from the borehole. In order to carry out sampling of bottom sediments from the subglacial lake, it is proposed to use a dynamically balanced tool string, which enables rotary drilling without any external support on borehole walls to transmit counter torque.     A theoretical analysis has been carried out to assess the operation of the tool string, which is a two-mass oscillatory electromechanical system of reciprocating and rotating motion (RRM with two degrees of freedom.

  8. Fun at Antarctic grounding lines: Ice-shelf channels and sediment transport

    Science.gov (United States)

    Drews, Reinhard; Mayer, Christoph; Eisen, Olaf; Helm, Veit; Ehlers, Todd A.; Pattyn, Frank; Berger, Sophie; Favier, Lionel; Hewitt, Ian H.; Ng, Felix; Fürst, Johannes J.; Gillet-Chaulet, Fabien; Bergeot, Nicolas; Matsuoka, Kenichi

    2017-04-01

    Meltwater beneath the polar ice sheets drains, in part, through subglacial conduits. Landforms created by such drainages are abundant in areas formerly covered by ice sheets during the last glacial maximum. However, observations of subglacial conduit dynamics under a contemporary ice sheet are lacking. We present results from ice-penetrating radar to infer the existence of subglacial conduits upstream of the grounding line of Roi Baudouin Ice Shelf, Antarctica. The conduits are aligned with ice-shelf channels, and underlain by esker ridges formed from sediment deposition due to reduced water outflow speed near the grounding line. In turn, the eskers modify local ice flow to initiate the bottom topography of the ice-shelf channels, and create small surface ridges extending onto the shelf. Relict features on the shelf are interpreted to indicate a history of these interactions and variability of past subglacial drainages. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation, and ice-shelf stability. To investigate the role of sediment transport beneath ice sheets further, we model the sheet-shelf system of the Ekstömisen catchment, Antarctica. A 3D finite element model (Elmer/ICE) is used to solve the transients full Stokes equation for isotropic, isothermal ice with a dynamic grounding line. We initialize the model with surface topography from the TanDEM-X satellites and by inverting simultaneously for ice viscosity and basal drag using present-day surface velocities. Results produce a flow field which is consitent with sattelite and on-site observations. Solving the age-depth relationship allows comparison with radar isochrones from airborne data, and gives information about the atmospheric/dynamic history of this sector. The flow field will eventually be used to identify potential sediment sources and sinks which we compare with more than 400 km of

  9. Detection of subglacial lakes in airborne radar sounding data from East Antarctica.

    Science.gov (United States)

    Carter, S. P.; Blankenship, D. D.; Peters, M. E.; Morse, D. L.

    2004-12-01

    Airborne ice penetrating radar is an essential tool for the identification of subglacial lakes. With it, we can measure the ice thickness, the amplitude of the reflected signal from the base of the ice, the depth to isochronous surfaces and, with high quality GPS, the elevation of the ice surface. These four measurements allow us to calculate the reflection coefficient from the base of the ice, the hydrostatic head, the surface slope and basal temperature. A subglacial lake will be characterized by: a consistently high reflection coefficient from the base of the ice, a nearly flat hydraulic gradient at a relative minimum in the hydraulic potential, an exceptionally smooth ice surface, and an estimated basal temperature that is at or near the pressure melting point of ice. We have developed a computerized algorithm to identify concurrences of the above-mentioned criteria in the radar data sets for East Antarctica collected by the University of Texas (UT). This algorithm is henceforth referred to as the "lake detector". Regions which meet three or more of the above mentioned criteria are identified as subglacial lakes, contingent upon a visual inspection by the human operator. This lake detector has added over 40 lakes to the most recent inventory of subglacial lakes for Antarctica. In locations where the UT flight lines approach or intersect flight lines from other airborne radar surveys, there is generally good agreement between the "lake detector" lakes and lakes identified in these data sets. In locations where the "lake detector" fails to identify a lake which is present in another survey, the most common failing is the estimated basal temperature. However, in some regions where a bright, smooth basal reflector is shown to exist, the lake detector may be failing due to a persistent slope in the hydraulic gradient. The nature of these "frozen" and "sloping" lakes is an additional focus of this presentation.

  10. A Viable Microbial Community in a Subglacial Volcanic Crater Lake, Iceland

    Science.gov (United States)

    Gaidos, Eric; Lanoil, Brian; Thorsteinsson, Thorsteinn; Graham, Andrew; Skidmore, Mark; Han, Suk-Kyun; Rust, Terri; Popp, Brian

    2004-09-01

    We describe a viable microbial community in a subglacial lake within the Grímsvötn volcanic caldera, Iceland. We used a hot water drill to penetrate the 300-m ice shelf and retrieved lake water and volcanic tephra sediments. We also acquired samples of borehole water before and after penetration to the lake, overlying glacial ice and snow, and water from a nearby subaerial geothermal lake for comparative analyses. Lake water is at the freezing point and fresh (total dissolved solids = 260 mg L-1). Detectable numbers of cells were found in samples of the lake water column and tephra sediments: 2 × 104 ml-1 and 4 × 107 g-1, respectively. Plate counts document abundant cold-adapted cultivable organisms in the lake water, but not in the borehole (before penetration) or glacial ice. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from genomic DNA extracted from Gr??msv??tn samples indicates that the lake community is distinct from the assemblages of organisms in borehole water (before penetration) and the overlying ice and snow. Sequencing of selected DGGE bands revealed that many sequences are highly similar to known psychrophilic organisms or cloned DNA from other cold environments. Significant uptake of 14C-labeled bicarbonate occurred in dark, low-temperature incubations of lake water samples, indicating the presence of autotrophs. Acetylene reduction assays under similar incubation conditions showed no significant nitrogen fixation potential by lake water samples. This may be a consequence of the inhibition of diazotrophy by nitrogen in the lake.

  11. Clastic dykes in over-consolidated tills: evidence for subglacial hydrofracturing at Killiney Bay, eastern Ireland

    Science.gov (United States)

    Rijsdijk, Kenneth F.; Owen, Geraint; Warren, William P.; McCarroll, Danny; van der Meer, Jaap J. M.

    1999-11-01

    A swarm of vertical gravel-filled dykes up to 6 m high and several decimetres wide, cut through an over-consolidated till at Killiney Bay. The dykes are rooted in a gravel layer and many display plumes of clastic debris ejected into the overlying sediments — `burst-out structures'. Such features have not previously been described. These clastic dykes are interpreted as the infillings of hydrofractures which formed when water pressures in the basal gravel layer exceeded the overburden pressure and tensile shear strength of the capping till. The burst-out structures extend up to 7 m from the tops of the dykes and provide strong evidence for forceful upward flow. Evidence suggests that the hydrofractures formed subglacially, probably during a minor re-advance. Their presence in Late Devensian (26-13 ka BP) tills with an Irish Sea provenance (`Irish Sea till') may have important implications for the subglacial hydrology of the last Irish Sea ice sheet. These hydrofractures cannot form in unconsolidated glacimarine sediment and their presence precludes a glacimarine origin for these deposits. They greatly affect the geotechnical properties of Irish Sea tills, in particular providing very permeable routes through otherwise impermeable layers, with important consequences in situations elsewhere in the Irish Sea basin, where they have been used as aquicludes in landfill and low-level nuclear waste disposal sites.

  12. Fluid transport with time on peritoneal dialysis: the contribution of free water transport and solute coupled water transport

    NARCIS (Netherlands)

    Coester, Annemieke M.; Smit, Watske; Struijk, Dirk G.; Krediet, Raymond T.

    2009-01-01

    Ultrafiltration in peritoneal dialysis occurs through endothelial water channels (free water transport) and together with solutes across small pores: solute coupled water transport. A review is given of cross-sectional studies and on the results of longitudinal follow-up

  13. Identification and analysis of low molecular weight dissolved organic carbon in subglacial basal ice ecosystems by ion chromatography

    Science.gov (United States)

    Lawson, E. C.; Wadham, J. L.; Lis, G. P.; Tranter, M.; Pickard, A. E.; Stibal, M.; Dewsbury, P.; Fitzsimons, S.

    2015-08-01

    Glacial runoff is an important source of dissolved organic carbon (DOC) for downstream heterotrophic activity, despite the low overall DOC concentrations. This is because of the abundance of bioavailable, low molecular weight (LMW) DOC species. However, the provenance and character of LMW-DOC is not fully understood. We investigated the abundance and composition of DOC in subglacial environments via a molecular level DOC analysis of basal ice, which forms by water/sediment freeze-on to the glacier sole. Spectrofluorometry and a novel ion chromatographic method, which has been little utilised in glacial science for LMW-DOC determinations, were employed to identify and quantify the major LMW fractions (free amino acids, carbohydrates and carboxylic acids) in basal ice from four glaciers, each with a different basal debris type. Basal ice from Joyce Glacier (Antarctica) was unique in that 98 % of the LMW-DOC was derived from the extremely diverse FAA pool, comprising 14 FAAs. LMW-DOC concentrations in basal ice were dependent on the bioavailability of the overridden organic carbon (OC), which in turn, was influenced by the type of overridden material. Mean LMW-DOC concentrations in basal ice from Russell Glacier (Greenland), Finsterwalderbreen (Svalbard) and Engabreen (Norway) were low (0-417 nM C), attributed to the relatively refractory nature of the OC in the overridden paleosols and bedrock. In contrast, mean LMW-DOC concentrations were an order of magnitude higher (4430 nM C) in basal ice from Joyce Glacier, a reflection of the high bioavailability of the overridden lacustrine material (>17 % of the sediment OC comprised extractable carbohydrates, a proxy for bioavailable OC). We find that the overridden material may act as a direct (via abiotic leaching) and indirect (via microbial cycling) source of DOC to the subglacial environment and provides a range of LMW-DOC compounds that may stimulate microbial activity in wet sediments in current subglacial

  14. Water transport and energy.

    Science.gov (United States)

    Fricke, Wieland

    2017-06-01

    Water transport in plants occurs along various paths and is driven by gradients in its free energy. It is generally considered that the mode of transport, being either diffusion or bulk flow, is a passive process, although energy may be required to sustain the forces driving water flow. This review aims at putting water flow at the various organisational levels (cell, organ, plant) in the context of the energy that is required to maintain these flows. In addition, the question is addressed (1) whether water can be transported against a difference in its chemical free energy, 'water potential' (Ψ), through, directly or indirectly, active processes; and (2) whether the energy released when water is flowing down a gradient in its energy, for example during day-time transpiration and cell expansive growth, is significant compared to the energy budget of plant and cell. The overall aim of review is not so much to provide a definite 'Yes' and 'No' to these questions, but rather to stimulate discussion and raise awareness that water transport in plants has its real, associated, energy costs and potential energy gains. © 2016 John Wiley & Sons Ltd.

  15. Osmotic water transport in aquaporins

    DEFF Research Database (Denmark)

    Zeuthen, Thomas; Alsterfjord, Magnus; Beitz, Eric

    2013-01-01

    Abstract  We test a novel, stochastic model of osmotic water transport in aquaporins. A solute molecule present at the pore mouth can either be reflected or permeate the pore. We assume that only reflected solute molecules induce osmotic transport of water through the pore, while permeating solute...... molecules give rise to no water transport. Accordingly, the rate of water transport is proportional to the reflection coefficient σ, while the solute permeability, P(S), is proportional to 1 - σ. The model was tested in aquaporins heterologously expressed in Xenopus oocytes. A variety of aquaporin channel...... sizes and geometries were obtained with the two aquaporins AQP1 and AQP9 and mutant versions of these. Osmotic water transport was generated by adding 20 mM of a range of different-sized osmolytes to the outer solution. The osmotic water permeability and the reflection coefficient were measured...

  16. Water Transport Mediated by Other Membrane Proteins.

    Science.gov (United States)

    Huang, Boyue; Wang, Hongkai; Yang, Baoxue

    2017-01-01

    Water transport through membrane is so intricate that there are still some debates. (Aquaporins) AQPs are entirely accepted to allow water transmembrane movement depending on osmotic gradient. Cotransporters and uniporters , however, are also concerned in water homeotatsis. Urea transporter B (UT-B) has a single-channel water permeability that is similar to AQP1. Cystic fibrosis transmembrane conductance regulator (CFTR ) was initially thought as a water channel but now not believed to transport water directly. By cotranporters, water is transported by water osmosis coupling with substrates, which explains how water is transported across the isolated small intestine. This chapter provides information about water transport mediated by other membrane proteins except AQPs .

  17. Free water transport, small pore transport and the osmotic pressure gradient

    NARCIS (Netherlands)

    Parikova, Alena; Smit, Watske; Zweers, Machteld M.; Struijk, Dirk G.; Krediet, Raymond T.

    2008-01-01

    BACKGROUND: Water transport in peritoneal dialysis (PD) patients occurs through the small pores and water channels, the latter allowing free water transport (FWT). The osmotic gradient is known to be one of the major determinants of water transport. The objective of the study was to analyse the

  18. Burning water: The water footprint of biofuel-based transport

    NARCIS (Netherlands)

    Gerbens-Leenes, Winnie; Hoekstra, Arjen Ysbert

    2010-01-01

    The trend towards substitution of conventional transport fuels by biofuels requires additional water. The EU aims to replace 10 percent of total transport fuels by biofuels by 2020. This study calculates the water footprint (WF) of different transport modes using bio-ethanol, biodiesel or

  19. Geology and environments of subglacial Lake Vostok.

    Science.gov (United States)

    Leitchenkov, German L; Antonov, Anton V; Luneov, Pavel I; Lipenkov, Vladimir Ya

    2016-01-28

    The reconstruction of the geological (tectonic) structure and environments of subglacial Lake Vostok is based on geophysical surveys and the study of mineral particles found in cores of accreted ice and frozen lake water (sampled after the lake was unsealed). Seismic reflection and refraction investigations conducted in the southern part of Lake Vostok show very thin (200-300 m) sedimentary cover overlying a crystalline basement. Most of this thin veneer is thought to have been deposited during temperate-glacial conditions in Oligocene to Middle Miocene time (ca 34-14 Ma). The composition of the lake-bottom sediments can be deduced from mineral inclusions found in cores of accreted ice. Inclusions are represented by soft aggregates consisting mainly of clay-mica minerals and micrometre-sized quartz grains. Some of these inclusions contain subangular to semi-rounded rock clasts (siltstones and sandstones) ranging from 0.3 to 8 mm in size. In total, 31 zircon grains have been identified in two rock clasts and dated using SHRIMP-II. The ages of the studied zircons range from 0.6 to 2.0 Ga with two distinct clusters between 0.8 and 1.15 Ga and between 1.6 and 1.8 Ga. Rock clasts obviously came from the western lake shore, which is thus composed of terrigenous strata with an age of not older than 600 Ma. The sedimentary nature of the western lake shore is also confirmed by seismic refraction data showing seismic velocities there of 5.4-5.5 km s(-1) at the bedrock surface. After Lake Vostok was unsealed, its water (frozen and sampled next season) was also studied with scanning electron microscopy and X-ray microprobe analysis. This study showed the existence of calcium carbonate and silica microparticles (10-20 μm across) in frozen water. © 2015 The Author(s).

  20. Leaf water stable isotopes and water transport outside the xylem.

    Science.gov (United States)

    Barbour, M M; Farquhar, G D; Buckley, T N

    2017-06-01

    How water moves through leaves, and where the phase change from liquid to vapour occurs within leaves, remain largely mysterious. Some time ago, we suggested that the stable isotope composition of leaf water may contain information on transport pathways beyond the xylem, through differences in the development of gradients in enrichment within the various pathways. Subsequent testing of this suggestion provided ambiguous results and even questioned the existence of gradients in enrichment within the mesophyll. In this review, we bring together recent theoretical developments in understanding leaf water transport pathways and stable isotope theory to map a path for future work into understanding pathways of water transport and leaf water stable isotope composition. We emphasize the need for a spatially, anatomically and isotopically explicit model of leaf water transport. © 2016 John Wiley & Sons Ltd.

  1. Continental-scale transport of sediments by the Baltic Ice Stream elucidated by coupled grain size and Nd provenance analyses

    Science.gov (United States)

    Boswell, Steven M.; Toucanne, Samuel; Creyts, Timothy T.; Hemming, Sidney R.

    2018-05-01

    We introduce a methodology for determining the transport distance of subglacially comminuted and entrained sediments. We pilot this method on sediments from the terminal margin of the Baltic Ice Stream, the largest ice stream of the Fennoscandian Ice Sheet during the Last Glacial Maximum. A strong correlation (R2 = 0.83) between the εNd and latitudes of circum-Baltic river sediments enables us to use εNd as a calibrated measure of distance. The proportion of subglacially transported sediments in a sample is estimated from grain size ratios in the silt fraction (investigations of Fennoscandinavian erosion, and is consistent with rapid ice flow into the Baltic basins prior to the Last Glacial Maximum. The methodology introduced here could be used to infer the distances of glacigenic sediment transport from Late Pleistocene and earlier glaciations.

  2. Cascading water underneath Wilkes Land, East Antarctic ice sheet, observed using altimetry and digital elevation models

    Science.gov (United States)

    Flament, T.; Berthier, E.; Rémy, F.

    2014-04-01

    We describe a major subglacial lake drainage close to the ice divide in Wilkes Land, East Antarctica, and the subsequent cascading of water underneath the ice sheet toward the coast. To analyse the event, we combined altimetry data from several sources and subglacial topography. We estimated the total volume of water that drained from Lake CookE2 by differencing digital elevation models (DEM) derived from ASTER and SPOT5 stereo imagery acquired in January 2006 and February 2012. At 5.2 ± 1.5 km3, this is the largest single subglacial drainage event reported so far in Antarctica. Elevation differences between ICESat laser altimetry spanning 2003-2009 and the SPOT5 DEM indicate that the discharge started in November 2006 and lasted approximately 2 years. A 13 m uplift of the surface, corresponding to a refilling of about 0.6 ± 0.3 km3, was observed between the end of the discharge in October 2008 and February 2012. Using the 35-day temporal resolution of Envisat radar altimetry, we monitored the subsequent filling and drainage of connected subglacial lakes located downstream of CookE2. The total volume of water traveling within the theoretical 500-km-long flow paths computed with the BEDMAP2 data set is similar to the volume that drained from Lake CookE2, and our observations suggest that most of the water released from Lake CookE2 did not reach the coast but remained trapped underneath the ice sheet. Our study illustrates how combining multiple remote sensing techniques allows monitoring of the timing and magnitude of subglacial water flow beneath the East Antarctic ice sheet.

  3. Development and Antarctic Testing of a Maneuverable Probe for Clean In-Situ Analysis and Sampling of Subsurface Ice and Subglacial Aquatic Ecosystems

    Science.gov (United States)

    Francke, G.; Dachwald, B.; Kowalski, J.; Digel, I.; Tulaczyk, S. M.; Mikucki, J.; Feldmann, M.; Espe, C.; Schöngarth, S.; Hiecker, S.; Blandfort, D.; Schüller, K.; Plescher, E.

    2016-12-01

    There is significant interest in sampling subglacial environments for geochemical and microbiological studies, but those environments are difficult to access. Such environments exist not only on Earth but are also expected beneath the icy crusts of some outer solar system bodies, like the Jovian moon Europa and the Saturnian moon Enceladus. Existing ice drilling technologies make it cumbersome to maintain microbiologically clean access for sample acquisition and environmental stewardship of potentially fragile subglacial aquatic ecosystems. The "IceMole" is a maneuverable subsurface ice probe for clean in-situ analysis and sampling of glacial ice and subglacial materials. The design is based on combining melting and mechanical propulsion, using an ice screw at the tip of the melting head to maintain firm contact between the melting head and the ice. It can change melting direction by differential heating of the melting head and optional side wall heaters. The first two prototypes were successfully tested between 2010 and 2012 on glaciers in Switzerland and Iceland, where they demonstrated downward, horizontal and upward melting, as well as curve driving and dirt layer penetration. Hence, the IceMole allows maneuvers which may be necessary for obstacle avoidance or target selection. Maneuverability, however, necessitates a sophisticated on-board navigation system capable of autonomous operations. Therefore, between 2012 and 2014, a more advanced probe was developed as part of the "Enceladus Explorer" (EnEx) project. The EnEx-IceMole offers systems for relative positioning based on in-ice attitude determination, acoustic positioning, ultrasonic obstacle and target detection, which is all integrated through a high-level sensor fusion. In December 2014, it was used for clean access into a unique subglacial aquatic environment at Blood Falls, Antarctica, where a subglacial brine sample was successfully obtained after about 17 meters of oblique melting. Particular

  4. Characterization of subglacial Lake Vostok as seen from physical and isotope properties of accreted ice.

    Science.gov (United States)

    Lipenkov, Vladimir Ya; Ekaykin, Alexey A; Polyakova, Ekaterina V; Raynaud, Dominique

    2016-01-28

    Deep drilling at the Vostok Station has reached the surface of subglacial Lake Vostok (LV) twice-in February 2012 and January 2015. As a result, three replicate cores from boreholes 5G-1, 5G-2 and 5G-3 became available for detailed and revalidation analyses of the 230 m thickness of the accreted ice, down to its contact with water at 3769 m below the surface. The study reveals that the concentration of gases in the lake water beneath Vostok is unexpectedly low. A clear signature of the melt water in the surface layer of the lake, which is subject to refreezing on the icy ceiling of LV, has been discerned in the three different properties of the accreted ice: the ice texture, the isotopic and the gas content of the ice. These sets of data indicate in concert that poor mixing of the melt (and hydrothermal) water with the resident lake water and pronounced spatial and/or temporal variability of local hydrological conditions are likely to be the characteristics of the southern end of the lake. The latter implies that the surface water may be not representative enough to study LV's behaviour, and that direct sampling of the lake at different depths is needed in order to move ahead with our understanding of the lake's hydrological regime. © 2015 The Author(s).

  5. Passive water and ion transport by cotransporters

    DEFF Research Database (Denmark)

    Loo, D D; Hirayama, B A; Meinild, A K

    1999-01-01

    the Lp of control oocytes. Passive Na+ transport (Na+ leak) was obtained from the blocker-sensitive Na+ currents in the absence of substrates (glucose and GABA). 2. Passive Na+ and water transport through SGLT1 were blocked by phlorizin with the same sensitivity (inhibitory constant (Ki), 3-5 micro......1. The rabbit Na+-glucose (SGLT1) and the human Na+-Cl--GABA (GAT1) cotransporters were expressed in Xenopus laevis oocytes, and passive Na+ and water transport were studied using electrical and optical techniques. Passive water permeabilities (Lp) of the cotransporters were determined from......M). When Na+ was replaced with Li+, phlorizin also inhibited Li+ and water transport, but with a lower affinity (Ki, 100 microM). When Na+ was replaced by choline, which is not transported, the SGLT1 Lp was indistinguishable from that in Na+ or Li+, but in this case water transport was less sensitive...

  6. Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations

    Directory of Open Access Journals (Sweden)

    Pierre-Marie Lefeuvre

    2018-01-01

    Full Text Available We used a finite element model to interpret anti-correlated pressure variations at the base of a glacier to demonstrate the importance of stress redistribution in the basal ice. We first investigated two pairs of load cells installed 20 m apart at the base of the 210 m thick Engabreen glacier in Northern Norway. The load cell data for July 2003 showed that pressurisation of a subglacial channel located over one load cell pair led to anti-correlation in pressure between the two pairs. To investigate the cause of this anti-correlation, we used a full Stokes 3D model of a 210 m thick and 25–200 m wide glacier with a pressurised subglacial channel represented as a pressure boundary condition. The model reproduced the anti-correlated pressure response at the glacier bed and variations in pressure of the same order of magnitude as the load cell observations. The anti-correlation pattern was shown to depend on the bed/surface slope. On a flat bed with laterally constrained cross-section, the resulting bridging effect diverted some of the normal forces acting on the bed to the sides. The anti-correlated pressure variations were then reproduced at a distance >10–20 m from the channel. In contrast, when the bed was inclined, the channel support of the overlying ice was vertical only, causing a reduction of the normal stress on the bed. With a bed slope of 5 degrees, the anti-correlation occurred within 10 m of the channel. The model thus showed that the effect of stress redistribution can lead to an opposite response in pressure at the same distance from the channel and that anti-correlation in pressure is reproduced without invoking cavity expansion caused by sliding.

  7. The water footprint of biofuel-based transport

    NARCIS (Netherlands)

    Gerbens-Leenes, Winnie; Hoekstra, Arjen Ysbert

    2011-01-01

    The EU target to replace 10 percent of transport fuels by renewables by 2020 requires additional water. This study calculates water footprints (WFs) of transport modes using first generation bio-ethanol, biodiesel or bio-electricity and of European transport if 10 percent of transport fuels is

  8. Recent technical developments at the IMAU: A new generation of AWS and wireless subglacial measurements

    NARCIS (Netherlands)

    Smeets, C.J.P.P.; Boot, W.; van den Broeke, M.R.; van de Wal, R.S.W.

    2011-01-01

    Two technical developments are presented: a new generation of AWS and a wireless subglacial measurement system. Both systems build on the experience of the IMAU in developing GPS systems (Den Ouden et al., 2010). Combining methods to minimize energy consumption and wireless communication form the

  9. Modelling Ballast Water Transport

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, S.; Babu, M.T.; Vethamony, P.

    Ballast water discharges in the coastal environs have caused a great concern over the recent periods as they account for transporting marine organisms from one part of the world to the other. The movement of discharged ballast water as well...

  10. The coordinated development of China' s inland water transport%The coordinated development of China' s inland water transport

    Institute of Scientific and Technical Information of China (English)

    Deng Aimin; Tian Feng; Haasis H.D; Mao Lang; Cai Jia

    2012-01-01

    The coordinated development is the core of sustainable development and the hot issue of international research. Inland water transport (IWT) is an important part of the water resources exploiting system and comprehensive transport system under socio-economic context of river basin, and also the country' s sustainable development priorities to achieve resource-conserving and environment-friendly strategy. Based on the coordinated development content, the paper combined Germany' s successful development experience, explored the elements and problem of the coordinated development of IWT system of China' s national economic strategy and basin economy, water resourse system, comprehensive transport system, and system itself, and their countermeasures and suggestions, in order to facilitate rapid and coordinated development of China' s inland water transport.

  11. Transport of Water in Semicrystalline Block Copolymer Membranes

    Science.gov (United States)

    Hallinan, Daniel; Oparaji, Onyekachi

    Poly(styrene)-block-poly(ethylene oxide) (PS- b-PEO) is a semicrystalline block copolymer (BCP) with interesting properties. It is mechanically tough, amphiphilic, and has a polar phase. The mechanical toughness is due to the crystallinity of PEO and the high glass transition temperature of PS, as well as the morphological structure of the BCP. The polymer has high CO2, water, and salt solubility that derive from the polar PEO component. Potential applications include CO2 separation, water purification, and lithium air batteries. In all of the aforementioned applications, water transport is an important parameter. The presence of water can also affect thermal and mechanical properties. Water transport and thermal and mechanical properties of a lamellar PS- b-PEO copolymer have been measured as a function of water activity. Water transport can be affected by the heterogeneous nature of a semicrystalline BCP. Therefore, Fourier transform infrared - attenuated total reflectance (FTIR-ATR) spectroscopy has been employed, because water transport and polymer swelling can be measured simultaneously. The effect of BCP structure on transport has been investigated by comparing water transport in PS- b-PEO to a PEO homopolymer. The crystalline content of the PEO and the presence of glassy PS lamellae will be used to explain the transport results.

  12. Molecular mechanisms of water transport in the eye

    DEFF Research Database (Denmark)

    Hamann, Steffen

    2002-01-01

    The four major sites for ocular water transport, the corneal epithelium and endothelium, the ciliary epithelium, and the retinal pigment epithelium, are reviewed. The cornea has an inherent tendency to swell, which is counteracted by its two surface cell layers, the corneal epithelium...... and endothelium. The bilayered ciliary epithelium secretes the aqueous humor into the posterior chamber, and the retinal pigment epithelium transports water from the retinal to the choroidal site. For each epithelium, ion transport mechanisms are associated with fluid transport, but the exact molecular coupling...... sites between ion and water transport remain undefined. In the retinal pigment epithelium, a H+-lactate cotransporter transports water. This protein could be the site of coupling between salt and water in this epithelium. The distribution of aquaporins does not suggest a role for these proteins...

  13. Joint Geodetic and Seismic Analysis of the effects of Englacial and Subglacial Hydraulics on Surface Crevassing near a Seasonal, Glacier-Dammed Lake on Gornergletscher, Switzerland

    Science.gov (United States)

    Garcia, L.; Luttrell, K. M.; Kilb, D. L.; Walter, F.

    2017-12-01

    light on crevasse formation on short time scales where glacier flow is controlled by sliding variations in response to water input into the subglacial drainage system. Coupled seismic and GPS monitoring can thus make a key contribution to our understanding of brittle deformation and crevassing of glacier ice.

  14. Water and solute transport across the peritoneal membrane.

    Science.gov (United States)

    Morelle, Johann; Devuyst, Olivier

    2015-09-01

    We review the molecular mechanisms of peritoneal transport and discuss how a better understanding of these mechanisms is relevant for dialysis therapy. Peritoneal dialysis involves diffusion and osmosis through the highly vascularized peritoneal membrane. Computer simulations, expression studies and functional analyses in Aqp1 knockout mice demonstrated the critical role of the water channel aquaporin-1 (AQP1) in water removal during peritoneal dialysis. Pharmacologic regulation of AQP1, either through increased expression or gating, is associated with increased water transport in rodent models of peritoneal dialysis. Water transport is impaired during acute peritonitis, despite unchanged expression of AQP1, resulting from the increased microvascular area that dissipates the osmotic gradient across the membrane. In long-term peritoneal dialysis patients, the fibrotic interstitium also impairs water transport, resulting in ultrafiltration failure. Recent data suggest that stroke and drug intoxications might benefit from peritoneal dialysis and could represent novel applications of peritoneal transport in the future. A better understanding of the regulation of osmotic water transport across the peritoneum offers novel insights into the role of water channels in microvascular endothelia, the functional importance of structural changes in the peritoneal interstitium and the transport of water and solutes across biological membranes in general.

  15. Composite Transport Model and Water and Solute Transport across Plant Roots: An Update.

    Science.gov (United States)

    Kim, Yangmin X; Ranathunge, Kosala; Lee, Seulbi; Lee, Yejin; Lee, Deogbae; Sung, Jwakyung

    2018-01-01

    The present review examines recent experimental findings in root transport phenomena in terms of the composite transport model (CTM). It has been a well-accepted conceptual model to explain the complex water and solute flows across the root that has been related to the composite anatomical structure. There are three parallel pathways involved in the transport of water and solutes in roots - apoplast, symplast, and transcellular paths. The role of aquaporins (AQPs), which facilitate water flows through the transcellular path, and root apoplast is examined in terms of the CTM. The contribution of the plasma membrane bound AQPs for the overall water transport in the whole plant level was varying depending on the plant species, age of roots with varying developmental stages of apoplastic barriers, and driving forces (hydrostatic vs. osmotic). Many studies have demonstrated that the apoplastic barriers, such as Casparian bands in the primary anticlinal walls and suberin lamellae in the secondary cell walls, in the endo- and exodermis are not perfect barriers and unable to completely block the transport of water and some solute transport into the stele. Recent research on water and solute transport of roots with and without exodermis triggered the importance of the extension of conventional CTM adding resistances that arrange in series (epidermis, exodermis, mid-cortex, endodermis, and pericycle). The extension of the model may answer current questions about the applicability of CTM for composite water and solute transport of roots that contain complex anatomical structures with heterogeneous cell layers.

  16. Active water exchange and life near the grounding line of an Antarctic outlet glacier

    Science.gov (United States)

    Sugiyama, Shin; Sawagaki, Takanobu; Fukuda, Takehiro; Aoki, Shigeru

    2014-08-01

    The grounding line (GL) of the Antarctic ice sheet forms the boundary between grounded and floating ice along the coast. Near this line, warm oceanic water contacts the ice shelf, producing the ice sheet's highest basal-melt rate. Despite the importance of this region, water properties and circulations near the GL are largely unexplored because in-situ observations are difficult. Here we present direct evidence of warm ocean-water transport to the innermost part of the subshelf cavity (several hundred meters seaward from the GL) of Langhovde Glacier, an outlet glacier in East Antarctica. Our measurements come from boreholes drilled through the glacier's ∼400-m-thick grounding zone. Beneath the grounding zone, we find a 10-24-m-deep water layer of uniform temperature and salinity (-1.45 °C; 34.25 PSU), values that roughly equal those measured in the ocean in front of the glacier. Moreover, living organisms are found in the thin subglacial water layer. These findings indicate active transport of water and nutrients from the adjacent ocean, meaning that the subshelf environment interacts directly and rapidly with the ocean.

  17. WATER SUPPLY OF TRANSPORT OBJECTS

    OpenAIRE

    Badyuk, N. S.

    2009-01-01

    Badyuk N. S. WATER SUPPLY OF TRANSPORT OBJECTS. АКТУАЛЬНЫЕ ПРОБЛЕМЫ ТРАНСПОРТНОЙ МЕДИЦИНЫ № 3 (17), 2009 г. P. 96-104 DOI http://dx.doi.org/10.5281/zenodo.1020024 http://dspace.nbuv.gov.ua/bitstream/handle/123456789/23091/13-Badyuk.pdf?sequence=1 WATER SUPPLY OF TRANSPORT OBJECTS Badyuk N. S. Ukrainian Research Institute for Medicine of Transport, Odessa, Ukraine Summary In the work presented they discuss several peculiarities of wa...

  18. Water transport by the renal Na(+)-dicarboxylate cotransporter

    DEFF Research Database (Denmark)

    Meinild, A K; Loo, D D; Pajor, A M

    2000-01-01

    . This solute-coupled influx of water took place in the absence of, and even against, osmotic gradients. There was a strict stoichiometric relationship between Na(+), substrate, and water transport of 3 Na(+), 1 dicarboxylate, and 176 water molecules/transport cycle. These results indicate that the renal Na......This study investigated the ability of the renal Na(+)-dicarboxylate cotransporter, NaDC-1, to transport water. Rabbit NaDC-1 was expressed in Xenopus laevis oocytes, cotransporter activity was measured as the inward current generated by substrate (citrate or succinate), and water transport...... was monitored by the changes in oocyte volume. In the absence of substrates, oocytes expressing NaDC-1 showed an increase in osmotic water permeability, which was directly correlated with the expression level of NaDC-1. When NaDC-1 was transporting substrates, there was a concomitant increase in oocyte volume...

  19. Contributions of an ancient evaporitic-type reservoir to subglacial Lake Vostok chemistry

    Science.gov (United States)

    De Angelis, M.; Petit, J.-R.; Savarino, J.; Souchez, R.; Thiemens, M. H.

    2004-06-01

    We present here the first comprehensive study of the chemical composition of accretion ice from Lake Vostok. Ion chromatographic analyses were performed on samples obtained along the deeper part of the Vostok ice core. Samples were taken from 3350 down to 3611 m depth, both in glacier ice and subglacial lake ice. The total ionic contents of two accretion ice layers—a few meters thick and centered around 3540 and 3590 m depth—are several times lower than those of glacier ice. Very low concentrations were also observed in the deeper part of accretion ice, below 3609 m depth. Elsewhere, the total ionic content is variable but remains 5 to 50 times higher than in glacier ice. Whatever its total ionic content, the ionic composition of accretion ice is significantly different from what is observed in glacier ice. It is dominated by sodium chloride, homogeneously distributed throughout the ice lattice, as well as calcium and magnesium sulfate, likely located in solid inclusions, or to a lesser extent at grain boundaries. Chemical considerations combined with additional studies of sulfur and oxygen isotopes in sulfate, and iron measurements strongly suggest that glacier water recycling and bedrock hydrolysis do not play a prominent role in providing impurities to accretion ice. It is more likely that NaCl rich water carrying fine sulfate salt particles is sporadically incorporated in the ice accreting in a shallow bay upstream from Vostok. The origin of such salty water, which should also contribute to Lake salinity, is discussed.

  20. Composite Transport Model and Water and Solute Transport across Plant Roots: An Update

    Directory of Open Access Journals (Sweden)

    Yangmin X. Kim

    2018-02-01

    Full Text Available The present review examines recent experimental findings in root transport phenomena in terms of the composite transport model (CTM. It has been a well-accepted conceptual model to explain the complex water and solute flows across the root that has been related to the composite anatomical structure. There are three parallel pathways involved in the transport of water and solutes in roots – apoplast, symplast, and transcellular paths. The role of aquaporins (AQPs, which facilitate water flows through the transcellular path, and root apoplast is examined in terms of the CTM. The contribution of the plasma membrane bound AQPs for the overall water transport in the whole plant level was varying depending on the plant species, age of roots with varying developmental stages of apoplastic barriers, and driving forces (hydrostatic vs. osmotic. Many studies have demonstrated that the apoplastic barriers, such as Casparian bands in the primary anticlinal walls and suberin lamellae in the secondary cell walls, in the endo- and exodermis are not perfect barriers and unable to completely block the transport of water and some solute transport into the stele. Recent research on water and solute transport of roots with and without exodermis triggered the importance of the extension of conventional CTM adding resistances that arrange in series (epidermis, exodermis, mid-cortex, endodermis, and pericycle. The extension of the model may answer current questions about the applicability of CTM for composite water and solute transport of roots that contain complex anatomical structures with heterogeneous cell layers.

  1. Water transport in desert alluvial soil

    International Nuclear Information System (INIS)

    Kearl, P.M.

    1982-04-01

    Safe storage of radioactive waste buried in an arid alluvial soil requires extensive site characterization of the physical process influencing moisture movement which could act as a transport medium for the migration of radionuclides. The field portion of this study included an infiltration plot instrumented with thermocouple psychrometers and neturon moisture probe access holes. Baseline information shows a zone of higher moisture content at approximately 1.5 m (5 ft) in depth. A sprinkler system simulated a 500-year precipitation event. Results revealed water penetrated the soil to 0.9 m (2.9 ft). Due to the low moisture content, vapor transport was primarily responsible for water movement at this depth. Temperature gradients are substantially responsible for vapor transport by preferentially sorting water-vapor molecules from the surrounding air by using the soil as a molecular sieve. Adsorbed and capillary water vapor pressure increases in response to a temperature increase and releases additional water to the soil pore atmosphere to be diffused away

  2. Eddy transport of water vapor in the Martian atmosphere

    Science.gov (United States)

    Murphy, J. R.; Haberle, Robert M.

    1993-01-01

    Viking orbiter measurements of the Martian atmosphere suggest that the residual north polar water-ice cap is the primary source of atmospheric water vapor, which appears at successively lower northern latitudes as the summer season progresses. Zonally symmetric studies of water vapor transport indicate that the zonal mean meridional circulation is incapable of transporting from north polar regions to low latitudes the quantity of water vapor observed. This result has been interpreted as implying the presence of nonpolar sources of water. Another possibility is the ability of atmospheric wave motions, which are not accounted for in a zonally symmetric framework, to efficiently accomplish the transport from a north polar source to the entirety of the Northern Hemisphere. The ability or inability of the full range of atmospheric motions to accomplish this transport has important implications regarding the questions of water sources and sinks on Mars: if the full spectrum of atmospheric motions proves to be incapable of accomplishing the transport, it strengthens arguments in favor of additional water sources. Preliminary results from a three dimensional atmospheric dynamical/water vapor transport numerical model are presented. The model accounts for the physics of a subliming water-ice cap, but does not yet incorporate recondensation of this sublimed water. Transport of vapor away from this water-ice cap in this three dimensional framework is compared with previously obtained zonally symmetric (two dimensional) results to quantify effects of water vapor transport by atmospheric eddies.

  3. Heat Transfer in Directional Water Transport Fabrics

    Directory of Open Access Journals (Sweden)

    Chao Zeng

    2016-10-01

    Full Text Available Directional water transport fabrics can proactively transfer moisture from the body. They show great potential in making sportswear and summer clothing. While moisture transfer has been previously reported, heat transfer in directional water transport fabrics has been little reported in research literature. In this study, a directional water transport fabric was prepared using an electrospraying technique and its heat transfer properties under dry and wet states were evaluated, and compared with untreated control fabric and the one pre-treated with NaOH. All the fabric samples showed similar heat transfer features in the dry state, and the equilibrium temperature in the dry state was higher than for the wet state. Wetting considerably enhanced the thermal conductivity of the fabrics. Our studies indicate that directional water transport treatment assists in moving water toward one side of the fabric, but has little effect on thermal transfer performance. This study may be useful for development of “smart” textiles for various applications.

  4. Students' Conceptions of Water Transport

    Science.gov (United States)

    Rundgren, Carl-Johan; Rundgren, Shu-Nu Chang; Schonborn, Konrad J.

    2010-01-01

    Understanding diffusion of water into and out of the cell through osmosis is fundamental to the learning and teaching of biology. Although this process is thought of as occurring directly across the lipid bilayer, the majority of water transport is actually mediated by specialised transmembrane water-channels called aquaporins. This study…

  5. Well-to-Wheels Water Consumption: Tracking the Virtual Flow of Water into Transportation

    Science.gov (United States)

    Lampert, D. J.; Elgowainy, A.; Hao, C.

    2015-12-01

    Water and energy resources are fundamental to life on Earth and essential for the production of consumer goods and services in the economy. Energy and water resources are heavily interdependent—energy production consumes water, while water treatment and distribution consume energy. One example of this so-called energy-water nexus is the consumption of water associated with the production of transportation fuels. The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model is an analytical tool that can be used to compare the environmental impacts of different transportation fuels on a consistent basis. In this presentation, the expansion of GREET to perform life cycle water accounting or the "virtual flow" of water into transportation and other energy sectors and the associated implications will be discussed. The results indicate that increased usage of alternative fuels may increase freshwater resource consumption. The increased water consumption must be weighed against the benefits of decreased greenhouse gas and fossil energy consumption. Our analysis highlights the importance of regionality, co-product allocation, and consistent system boundaries when comparing the water intensity of alternative transportation fuel production pathways such as ethanol, biodiesel, compressed natural gas, hydrogen, and electricity with conventional petroleum-based fuels such as diesel and gasoline.

  6. Transport parameters for the modelling of water transport in ionomer membranes for PEM-fuel cells

    International Nuclear Information System (INIS)

    Meier, Frank; Eigenberger, Gerhart

    2004-01-01

    The water transport number (drag coefficient) and the hydraulic permeability were measured for Nafion. The results show a significant increase of both parameters with increasing water content indicating that they are strongly influenced by the membrane microstructure. Based on these experimental studies a new model approach to describe water transport in the H 2 -PEFC membrane is presented. This approach considers water transport by electro-osmosis caused by the proton flux through the membrane and by osmosis caused by a gradient in the chemical potential of water. It is parametrized by the measured data for the water transport number and the hydraulic permeability of Nafion. First simulation results applying this approach to a one-dimensional model of the H 2 -PEFC show good agreement with experimental data. Therefore, the developed model can be used for a new insight into the dominating mechanisms of water transport in the membrane

  7. Fuel cell water transport

    Science.gov (United States)

    Vanderborgh, Nicholas E.; Hedstrom, James C.

    1990-01-01

    The moisture content and temperature of hydrogen and oxygen gases is regulated throughout traverse of the gases in a fuel cell incorporating a solid polymer membrane. At least one of the gases traverses a first flow field adjacent the solid polymer membrane, where chemical reactions occur to generate an electrical current. A second flow field is located sequential with the first flow field and incorporates a membrane for effective water transport. A control fluid is then circulated adjacent the second membrane on the face opposite the fuel cell gas wherein moisture is either transported from the control fluid to humidify a fuel gas, e.g., hydrogen, or to the control fluid to prevent excess water buildup in the oxidizer gas, e.g., oxygen. Evaporation of water into the control gas and the control gas temperature act to control the fuel cell gas temperatures throughout the traverse of the fuel cell by the gases.

  8. Subglacial drainage effects on surface motion on a small surge type alpine glacier on the St. Elias range, Yukon Territory, Canada.

    Science.gov (United States)

    Rada, C.; Schoof, C.; King, M. A.; Flowers, G. E.; Haber, E.

    2017-12-01

    Subglacial drainage is known to play an important role in glacier dynamics trough its influence on basal sliding. However, drainage is also one of the most poorly understood process in glacier flow due to the difficulties of observing, identifying and modeling the physics involved. In an effort to improve understanding of subglacial processes, we have monitored a small, approximately 100 m thick surge-type alpine glacier for nine years. Over 300 boreholes were instrumented with pressure transducers over a 0.5 km² in its upper ablation area, in addition to a weather station and a permanent GPS array consisting on 16 dual-frequency receivers within the study area. We study the influence of the subglacial drainage system on the glacier surface velocity. However, pressure variations in the drainage system during the melt season are dominated by diurnal oscillations.Therefore, GPS solutions have to be computed at sub-diurnal time intervals in order to explore the effects of transient diurnal pressure variations. Due to the small displacements of the surface of the glacier over those periods (4-10 cm/day), sub-diurnal solutions are dominated by errors, making it impossible to observe the diurnal variations in glacier motion. We have found that the main source of error is GPS multipath. This error source does largely cancel out when solutions are computed over 24 hour periods (or more precisely, over a sidereal day), but solution precisions decrease quickly when computed over shorter periods of time. Here we present an inverse problem approach to remove GPS multipath errors on glaciers, and use the reconstructed glacier motion to explore how the subglacial drainage morphology and effective pressure influence glacier dynamics at multiple time scales.

  9. Subglacial bed conditions during Late Pleistocene glaciations and their impact on ice dynamics in the southern North Sea

    NARCIS (Netherlands)

    Passchier, S.; Laban, C.; Mesdag, C.S.; Rijsdijk, K.F.

    2010-01-01

    Changes in subglacial bed conditions through multiple glaciations and their effect on ice dynamics are addressed through an analysis of glacigenic sequences in the Upper Pleistocene stratigraphy of the southern North Sea basin. During Elsterian (MIS 12) ice growth, till deposition was subdued when

  10. Plant–Water Relations (1): Uptake and Transport

    Science.gov (United States)

    2014-01-01

    Summary Plants, like all living things, are mostly water. Water is the matrix of life, and its availability determines the distribution and productivity of plants on earth. Vascular plants evolved structures that enable them to transport water long distances with little input of energy, but the hollow tracheary elements are just one of many adaptations that enable plants to cope with a very dry atmosphere. This lecture examines the physical laws that govern water uptake and transport, the biological properties of cells and plant tissues that facilitate it, and the strategies that enable plants to survive in diverse environments

  11. Quantification of free water transport in peritoneal dialysis

    NARCIS (Netherlands)

    Smit, Watske; Struijk, Dirk G.; Ho-Dac-Pannekeet, Marja M.; Krediet, Raymond T.

    2004-01-01

    BACKGROUND: In peritoneal dialysis (PD) total net ultrafiltration (NUF) is dependent on transport through small pores and through water channels in the peritoneum. These channels are impermeable to solutes, and therefore, crystalloid osmotic-induced free water transport occurs through them. Several

  12. Experimental Rock-on-Rock Abrasive Wear Under Aqueous Conditions: its Role in Subglacial Abrasion

    Science.gov (United States)

    Rutter, E. H.; Lee, A. G.

    2003-12-01

    We have determined experimentally the rate of abrasive wear of rock on rock for a range of rock types as a function of normal stress and shear displacement. Unlike abrasive wear in fault zones, where wear products accumulate as a thickening gouge zone, in our experiments wear particles were removed by flowing water. The experiments are thus directly pertinent to one of the most important processes in subglacial erosion, and to some extent in river incision. Wear was produced between rotating discs machined from rock samples and measured from the progressive approach of the disc axes towards each other under various levels of normal load. Shear displacements of several km were produced. Optical and scanning electron microscopy were used to study the worn rock surfaces, and particle size distributions in wear products were characterized using a laser particle size analyzer. Rock types studied were sandstones of various porosities and cement characteristics, schists and a granite. In all cases abrasion rate decreased logarithmically with displacement by up to 2 orders of magnitude until a steady state was approached, but only after at least 1 km displacement. The more porous, less-well cemented rocks wore fastest. Amount of abrasion could be characterized quantitatively using an exponentially decaying plus a steady-state term. Wear rate increased non-linearly with normal contact stress, apparently to an asymptote defined by the unconfined compressive strength. Microstructural study showed that the well-cemented and/or lowest porosity rocks wore by progressive abrasion of grains without plucking, whereas whole grains were plucked out of weakly-cemented and/or more porous rocks. This difference in behavior was reflected in wear-product particle size distributions. Where whole-grain plucking was possible, wear products were dominated by particles of the original grain size rather than finer rock flour. Comparison of our results to glacier basal abrasive wear estimated

  13. The Economics of Bulk Water Transport in Southern California

    Directory of Open Access Journals (Sweden)

    Andrew Hodges

    2014-12-01

    Full Text Available Municipalities often face increasing demand for limited water supplies with few available alternative sources. Under some circumstances, bulk water transport may offer a viable alternative. This case study documents a hypothetical transfer between a water utility district in northern California and urban communities located on the coast of central and southern California. We compare bulk water transport costs to those of constructing a new desalination facility, which is the current plan of many communities for increasing supplies. We find that using water bags to transport fresh water between northern and southern California is in some instances a low-cost alternative to desalination. The choice is constrained, however, by concerns about reliability and, thus, risk. Case-study results demonstrate the challenges of water supply augmentation in water-constrained regions.

  14. Subglacial hydrothermal alteration minerals in Jökulhlaup deposits of Southern Iceland, with implications for detecting past or present habitable environments on Mars.

    Science.gov (United States)

    Warner, Nicholas H; Farmer, Jack D

    2010-06-01

    Jökulhlaups are terrestrial catastrophic outfloods, often triggered by subglacial volcanic eruptions. Similar volcano-ice interactions were likely important on Mars where magma/lava may have interacted with the planet's cryosphere to produce catastrophic floods. As a potential analogue to sediments deposited during martian floods, the Holocene sandurs of Iceland are dominated by basaltic clasts derived from the subglacial environment and deposited during jökulhlaups. Palagonite tuffs and breccias, present within the deposits, represent the primary alteration lithology. The surface abundance of palagonite on the sandurs is 1-20%. X-ray diffraction (XRD) analysis of palagonite breccias confirms a mineral assemblage of zeolites, smectites, low-quartz, and kaolinite. Oriented powder X-ray diffractograms (habitable environments for microbial life may be found.

  15. The contribution of free water transport and small pore transport to the total fluid removal in peritoneal dialysis

    NARCIS (Netherlands)

    Parikova, Alena; Smit, Watske; Struijk, Dirk G.; Zweers, Machteld M.; Krediet, Raymond T.

    2005-01-01

    BACKGROUND: Water transport in peritoneal dialysis (PD) patients is across the small pores and water channels, the latter allowing free water transport. The objective of the study was to investigate the contribution of each transport route on transcapillary ultrafiltration (TCUF). METHODS: Standard

  16. Implications for carbon processing beneath the Greenland Ice Sheet from dissolved CO2 and CH4 concentrations of subglacial discharge

    Science.gov (United States)

    Pain, A.; Martin, J.; Martin, E. E.

    2017-12-01

    Subglacial carbon processes are of increasing interest as warming induces ice melting and increases fluxes of glacial meltwater into proglacial rivers and the coastal ocean. Meltwater may serve as an atmospheric source or sink of carbon dioxide (CO2) or methane (CH4), depending on the magnitudes of subglacial organic carbon (OC) remineralization, which produces CO2 and CH4, and mineral weathering reactions, which consume CO2 but not CH4. We report wide variability in dissolved CO2 and CH4 concentrations at the beginning of the melt season (May-June 2017) between three sites draining land-terminating glaciers of the Greenland Ice Sheet. Two sites, located along the Watson River in western Greenland, drain the Isunnguata and Russell Glaciers and contained 1060 and 400 ppm CO2, respectively. In-situ CO2 flux measurements indicated that the Isunnguata was a source of atmospheric CO2, while the Russell was a sink. Both sites had elevated CH4 concentrations, at 325 and 25 ppm CH4, respectively, suggesting active anaerobic OC remineralization beneath the ice sheet. Dissolved CO2 and CH4 reached atmospheric equilibrium within 2.6 and 8.6 km downstream of Isunnguata and Russell discharge sites, respectively. These changes reflect rapid gas exchange with the atmosphere and/or CO2 consumption via instream mineral weathering. The third site, draining the Kiagtut Sermiat in southern Greenland, had about half atmospheric CO2 concentrations (250 ppm), but approximately atmospheric CH4 concentrations (2.1 ppm). Downstream CO2 flux measurements indicated ingassing of CO2 over the entire 10-km length of the proglacial river. CO2 undersaturation may be due to more readily weathered lithologies underlying the Kiagtut Sermiat compared to Watson River sites, but low CH4 concentrations also suggest limited contributions of CO2 and CH4 from OC remineralization. These results suggest that carbon processing beneath the Greenland Ice Sheet may be more variable than previously recognized

  17. Water induced sediment levitation enhances downslope transport on Mars.

    Science.gov (United States)

    Raack, Jan; Conway, Susan J; Herny, Clémence; Balme, Matthew R; Carpy, Sabrina; Patel, Manish R

    2017-10-27

    On Mars, locally warm surface temperatures (~293 K) occur, leading to the possibility of (transient) liquid water on the surface. However, water exposed to the martian atmosphere will boil, and the sediment transport capacity of such unstable water is not well understood. Here, we present laboratory studies of a newly recognized transport mechanism: "levitation" of saturated sediment bodies on a cushion of vapor released by boiling. Sediment transport where this mechanism is active is about nine times greater than without this effect, reducing the amount of water required to transport comparable sediment volumes by nearly an order of magnitude. Our calculations show that the effect of levitation could persist up to ~48 times longer under reduced martian gravity. Sediment levitation must therefore be considered when evaluating the formation of recent and present-day martian mass wasting features, as much less water may be required to form such features than previously thought.

  18. Characterizing the transplanar and in-plane water transport properties of fabrics under different sweat rate: Forced Flow Water Transport Tester

    Science.gov (United States)

    Tang, K. P. M.; Chau, K. H.; Kan, C. W.; Fan, J. T.

    2015-11-01

    The water absorption and transport properties of fabrics are critical to wear comfort, especially for sportswear and protective clothing. A new testing apparatus, namely Forced Flow Water Transport Tester (FFWTT), was developed for characterizing the transplanar and in-plane wicking properties of fabrics based on gravimetric and image analysis technique. The uniqueness of this instrument is that the rate of water supply is adjustable to simulate varying sweat rates with reference to the specific end-use conditions ranging from sitting, walking, running to other strenuous activities. This instrument is versatile in terms of the types of fabrics that can be tested. Twenty four types of fabrics with varying constructions and surface finishes were tested. The results showed that FFWTT was highly sensitive and reproducible in differentiating these fabrics and it suggests that water absorption and transport properties of fabrics are sweat rate-dependent. Additionally, two graphic methods were proposed to map the direction of liquid transport and its relation to skin wetness, which provides easy and direct comparison among different fabrics. Correlation analysis showed that FFWTT results have strong correlation with subjective wetness sensation, implying validity and usefulness of the instrument.

  19. Plant water relations I: uptake and transport

    Science.gov (United States)

    Plants, like all living things, are mostly water. Water is the matrix of life, and its availability determines the distribution and productivity of plants on earth. Vascular plants evolved structures that enable them to transport water long distances with little input of energy, but the hollow trach...

  20. Quantification of osmotic water transport in vivo using fluorescent albumin.

    Science.gov (United States)

    Morelle, Johann; Sow, Amadou; Vertommen, Didier; Jamar, François; Rippe, Bengt; Devuyst, Olivier

    2014-10-15

    Osmotic water transport across the peritoneal membrane is applied during peritoneal dialysis to remove the excess water accumulated in patients with end-stage renal disease. The discovery of aquaporin water channels and the generation of transgenic animals have stressed the need for novel and accurate methods to unravel molecular mechanisms of water permeability in vivo. Here, we describe the use of fluorescently labeled albumin as a reliable indicator of osmotic water transport across the peritoneal membrane in a well-established mouse model of peritoneal dialysis. After detailed evaluation of intraperitoneal tracer mass kinetics, the technique was validated against direct volumetry, considered as the gold standard. The pH-insensitive dye Alexa Fluor 555-albumin was applied to quantify osmotic water transport across the mouse peritoneal membrane resulting from modulating dialysate osmolality and genetic silencing of the water channel aquaporin-1 (AQP1). Quantification of osmotic water transport using Alexa Fluor 555-albumin closely correlated with direct volumetry and with estimations based on radioiodinated ((125)I) serum albumin (RISA). The low intraperitoneal pressure probably accounts for the negligible disappearance of the tracer from the peritoneal cavity in this model. Taken together, these data demonstrate the appropriateness of pH-insensitive Alexa Fluor 555-albumin as a practical and reliable intraperitoneal volume tracer to quantify osmotic water transport in vivo. Copyright © 2014 the American Physiological Society.

  1. Liquid water transport mechanism in the gas diffusion layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, P.; Wu, C.W. [State Key Laboratory of Structure Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, Dalian 116024 (China)

    2010-03-01

    We developed an equivalent capillary model of a microscale fiber-fence structure to study the microscale evolution and transport of liquid in a porous media and to reveal the basic principles of water transport in gas diffusion layer (GDL). Analytical solutions using the model show that a positive hydraulic pressure is needed to drive the liquid water to penetrate through the porous GDL even consisting of the hydrophilic fibers. Several possible contributions for the water configuration, such as capillary pressure, gravity, vapor condensation, wettability and microstructures of the GDL, are discussed using the lattice Boltzmann method (LBM). It is found that the distribution manners of the fibers and the spatial mixed-wettability in the GDL also play an important role in the transport of liquid water. (author)

  2. Radiation inactivation studies of renal brush border water and urea transport

    International Nuclear Information System (INIS)

    Verkman, A.S.; Dix, J.A.; Seifter, J.L.; Skorecki, K.L.; Jung, C.Y.; Ausiello, D.A.

    1985-01-01

    Radiation inactivation was used to determine the nature and molecular weight of water and urea transport pathways in brush border membrane vesicles (BBMV) isolated from rabbit renal cortex. BBMV were frozen to -50 degrees C, irradiated with 1.5 MeV electrons, thawed, and assayed for transport or enzyme activity. The freezing process had no effect on enzyme or transport kinetics. BBMV alkaline phosphatase activity gave linear ln(activity) vs. radiation dose plots with a target size of 68 +/- 3 kDa, similar to previously reported values. Water and solute transport were measured using the stopped-flow light-scattering technique. The rates of acetamide and osmotic water transport did not depend on radiation dose (0-7 Mrad), suggesting that transport of these substances does not require a protein carrier. In contrast, urea and thiourea transport gave linear ln(activity) vs. dose curves with a target size of 125-150 kDa; 400 mM urea inhibited thiourea flux by -50% at 0 and 4.7 Mrad, showing that radiation does not affect inhibitor binding to surviving transporters. These studies suggest that BBMV urea transport requires a membrane protein, whereas osmotic water transport does not

  3. Barriers to Superfast Water Transport in Carbon Nanotube Membranes

    DEFF Research Database (Denmark)

    Walther, Jens Honore; Ritos, Konstantinos; Cruz-Chu, Eduardo R.

    2013-01-01

    Carbon nanotube (CNT) membranes hold the promise of extraordinary fast water transport for applications such as energy efficient filtration and molecular level drug delivery. However, experiments and computations have reported flow rate enhancements over continuum hydrodynamics that contradict each...... over the continuum predictions. These rates are far below those reported experimentally. The results suggest that the reported superfast water transport rates cannot be attributed to interactions of water with pristine CNTs alone....

  4. Examination of water quality changes during transportation of different fish

    Directory of Open Access Journals (Sweden)

    Istvan Nemeth

    2015-12-01

    Full Text Available Introduction The growth of population is increasing intensively (7.3 billion people in 2015 and it generates growing importance of fish farming. Primarily, fish meat could provide protein requirements for population so more and more attention must be paid to each sections of farming, for example fish transportation. A badly organized transportation technology can significantly reduce high quality stocks which were produced over several years. Deterioration of transport may occur on each fish distinctly. Bacterial or fungal diseases appear either immediately or days later. During our work, changes in several freshwater (peaceful or predator fish species (of different ages were monitored and analyzed during transport. There were two reasons why we examined the main physical and chemical parameters of the water. On one hand, we were curious to know how much the individuals exposed to heavy loads, which we tried to identify with some stress tests. On the other hand, we would develop a national water carrier monitoring system for the practice. Materials and methods Delivery technologies (foil sack and transport tankers used in practice was applied in the experiment of the study in a real road transport. The physical and chemical data were monitored and checked with the use of multiparameter instruments and photometrial tests. Physiological and stress tests were analyzed from blood plasma of each fish, primarily plasma glucose determination was used. Results After analysis of examined fish species and each ages, it is obvious that either short or long delivery times we choose physical and chemical properties of the transport water would change dramatically, even adequate oxygen balance was ensured. Values of individuals exposed to stress were more significant compared to baseline values. Conclusion We could define concrete changes in key parameters of the transport water with the number of realtime transport implementation which is a good help to

  5. X-radiation effect on water transport in ascite cells of Ehrlich carcinoma

    International Nuclear Information System (INIS)

    Barnov, V.A.; Ajvazishvili, M.A.; Kartvelishvili, I.I.; Tushishvili, D.I.

    1988-01-01

    Effect of local X radiation with doses 0.05 and 0.15 C/kg on water transport in ascitic cells of Erlich carcinoma is studied in rats. To study water transport through cell membranes, tritium mark was used. It is concluded that radiation effect on water transport in cells of Erlich carcinoma may be related to change in ionic permittivity of the membrane, because small changes in transmembrane ion transport affect immediately the osmotic motion of water. 5 refs

  6. GOES WATER VAPOR TRANSPORT V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOES Water Vapor Transport CD contains nineteen months of geostationary satellite-derived products spanning the 1987/1988 El Nino Southern Oscillation (ENSO)...

  7. Interfacial Water-Transport Effects in Proton-Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kienitz, Brian; Yamada, Haruhiko; Nonoyama, Nobuaki; Weber, Adam

    2009-11-19

    It is well known that the proton-exchange membrane is perhaps the most critical component of a polymer-electrolyte fuel cell. Typical membranes, such as Nafion(R), require hydration to conduct efficiently and are instrumental in cell water management. Recently, evidence has been shown that these membranes might have different interfacial morphology and transport properties than in the bulk. In this paper, experimental data combined with theoretical simulations will be presented that explore the existence and impact of interfacial resistance on water transport for Nafion(R) 21x membranes. A mass-transfer coefficient for the interfacial resistance is calculated from experimental data using different permeation cells. This coefficient is shown to depend exponentially on relative humidity or water activity. The interfacial resistance does not seem to exist for liquid/membrane or membrane/membrane interfaces. The effect of the interfacial resistance is to flatten the water-content profiles within the membrane during operation. Under typical operating conditions, the resistance is on par with the water-transport resistance of the bulk membrane. Thus, the interfacial resistance can be dominant especially in thin, dry membranes and can affect overall fuel-cell performance.

  8. Nano and Mesoscale Ion and Water Transport in Perfluorosulfonic AcidMembranes

    Science.gov (United States)

    2017-10-01

    Nano- and Mesoscale Ion and Water Transport in Perfluorosulfonic-Acid Membranes A. R. Crothers a,b , C. J. Radke a,b , A. Z. Weber a a...Berkeley, CA 94720, USA Water and aqueous cations transport along multiple length scales in perfluorosulfonic-acid membranes. Molecular interactions...as a function of hydration. A resistor network upscales the nanoscale properties to predict effective membrane ion and water transport and their

  9. Active water transport in unicellular algae: where, why, and how.

    Science.gov (United States)

    Raven, John A; Doblin, Martina A

    2014-12-01

    The occurrence of active water transport (net transport against a free energy gradient) in photosynthetic organisms has been debated for several decades. Here, active water transport is considered in terms of its roles, where it is found, and the mechanisms by which it could occur. First there is a brief consideration of the possibility of active water transport into plant xylem in the generation of root pressure and the refilling of embolized xylem elements, and from an unsaturated atmosphere into terrestrial organisms living in habitats with limited availability of liquid water. There is then a more detailed consideration of volume and osmotic regulation in wall-less freshwater unicells, and the possibility of generation of buoyancy in marine phytoplankton such as large-celled diatoms. Calculations show that active water transport is a plausible mechanism to assist cells in upwards vertical movements, requires less energy than synthesis of low-density organic solutes, and potentially on a par with excluding certain ions from the vacuole. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  10. GOES WATER VAPOR TRANSPORT V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOES Water Vapor Transport CD contains nineteen months of geostationary satellite-derived products from the GOES-8 satellite spanning the 1987-1988 El Nino...

  11. Modelling of water and chloride transport in concrete during yearly wetting/drying cycles

    NARCIS (Netherlands)

    Van Der Zanden, A.J.J.; Taher, A.; Arends, T.

    2015-01-01

    The simultaneous transport of water and chloride in concrete has been modelled. The water transport is described with a concentration dependent diffusion coefficient. The chloride transport is modelled with a convective part, caused by the water transport, and a diffusive part, caused by the

  12. Concerted orientation induced unidirectional water transport through nanochannels.

    Science.gov (United States)

    Wan, Rongzheng; Lu, Hangjun; Li, Jinyuan; Bao, Jingdong; Hu, Jun; Fang, Haiping

    2009-11-14

    The dynamics of water inside nanochannels is of great importance for biological activities as well as for the design of molecular sensors, devices, and machines, particularly for sea water desalination. When confined in specially sized nanochannels, water molecules form a single-file structure with concerted dipole orientations, which collectively flip between the directions along and against the nanotube axis. In this paper, by using molecular dynamics simulations, we observed a net flux along the dipole-orientation without any application of an external electric field or external pressure difference during the time period of the particular concerted dipole orientations of the molecules along or against the nanotube axis. We found that this unique special-directional water transportation resulted from the asymmetric potential of water-water interaction along the nanochannel, which originated from the concerted dipole orientation of the water molecules that breaks the symmetry of water orientation distribution along the channel within a finite time period. This finding suggests a new mechanism for achieving high-flux water transportation, which may be useful for nanotechnology and biological applications.

  13. Water transport in graphene nano-channels

    DEFF Research Database (Denmark)

    Wagemann, Enrique; Oyarzua, Elton; Walther, J. H.

    The transport of water in nanopores is of both fundamental and practical interest. Graphene Channels (GCs) are potential building blocks for nanofluidic devices dueto their molecularly smooth walls and exceptional mechanical properties. Numerous studies have found a significant flow rate enhancem......The transport of water in nanopores is of both fundamental and practical interest. Graphene Channels (GCs) are potential building blocks for nanofluidic devices dueto their molecularly smooth walls and exceptional mechanical properties. Numerous studies have found a significant flow rate...... between the chirality of the graphene walls and the slip length has not been established. In this study, we perform non-equilibrium molecular dynamics simulations of water flow in single- and multi-walled GCs. We examine the influence on the flow rates of dissipating the viscous heat produced...... by connecting the thermostat to the water molecules, the CNT wall atoms or both of them. From the atomic trajectories, we compute the fluid flow rates in GCs with zig-zag and armchair walls, heights from 1 to 4 nm and different number of graphene layers on the walls. A relation between the chirality, slip...

  14. Transport of hydrate slurry at high water cut

    OpenAIRE

    Melchuna , Aline; Cameirão , Ana; Herri , Jean-Michel; Ouabbas , Yamina; Glenat , Philippe

    2014-01-01

    Poster; International audience; Oil transportation in pipelines at the end of field production life implies to flow high quantities of water which represents the dominant phase. The process of crystallization of gas hydrates in this system needs to be studied and compared to the opposite one widely studied in the literature where water is the dispersed phase. The laboratory is equipped with the Archimede flow loop where the hydrate crystallization and transport are monitored. The flow loop is...

  15. Transport and transformation of surface water masses across the ...

    African Journals Online (AJOL)

    Transport and transformation of surface water masses across the Mascarene Plateau during the Northeast Monsoon season. ... Mixing occurs in the central gap between intermediate water masses (Red Sea Water [RSW] and Antarctic Intermediate Water [AAIW]) as well as in the upper waters (Subtropical Surface Water ...

  16. Modelling anisotropic water transport in polymer composite

    Indian Academy of Sciences (India)

    This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were ...

  17. A model for radionuclide transport in the Cooling Water System

    International Nuclear Information System (INIS)

    Kahook, S.D.

    1992-08-01

    A radionuclide transport model developed to assess radiological levels in the K-reactor Cooling Water System (CWS) in the event of an inadvertent process water (PW) leakage to the cooling water (CW) in the heat exchangers (HX) is described. During and following a process water leak, the radionuclide transport model determines the time-dependent release rates of radionuclide from the cooling water system to the environment via evaporation to the atmosphere and blow-down to the Savannah River. The developed model allows for delay times associated with the transport of the cooling water radioactivity through cooling water system components. Additionally, this model simulates the time-dependent behavior of radionuclides levels in various CWS components. The developed model is incorporated into the K-reactor Cooling Tower Activity (KCTA) code. KCTA allows the accident (heat exchanger leak rate) and the cooling tower blow-down and evaporation rates to be described as time-dependent functions. Thus, the postulated leak and the consequence of the assumed leak can be modelled realistically. This model is the first of three models to be ultimately assembled to form a comprehensive Liquid Pathway Activity System (LPAS). LPAS will offer integrated formation, transport, deposition, and release estimates for radionuclides formed in a SRS facility. Process water and river water modules are forthcoming as input and downstream components, respectively, for KCTA

  18. Water Transport and Removal in PEMFC Gas Flow Channel with Various Water Droplet Locations and Channel Surface Wettability

    Directory of Open Access Journals (Sweden)

    Yanzhou Qin

    2018-04-01

    Full Text Available Water transport and removal in the proton exchange membrane fuel cell (PEMFC is critically important to fuel cell performance, stability, and durability. Water emerging locations on the membrane-electrode assembly (MEA surface and the channel surface wettability significantly influence the water transport and removal in PEMFC. In most simulations of water transport and removal in the PEMFC flow channel, liquid water is usually introduced at the center of the MEA surface, which is fortuitous, since water droplet can emerge randomly on the MEA surface in PEMFC. In addition, the commonly used no-slip wall boundary condition greatly confines the water sliding features on hydrophobic MEA/channel surfaces, degrading the simulation accuracy. In this study, water droplet is introduced with various locations along the channel width direction on the MEA surface, and water transport and removal is investigated numerically using an improved model incorporating the sliding flow property by using the shear wall boundary condition. It is found that the water droplet can be driven to the channel sidewall by aerodynamics when the initial water location deviates from the MEA center to a certain amount, forming the water corner flow in the flow channel. The channel surface wettability on the water transport is also studied and is shown to have a significant impact on the water corner flow in the flow channel.

  19. Transport of water through the tropical tropopause

    Science.gov (United States)

    Kley, D.; Schmeltekopf, A. L.; Kelly, K.; Winkler, R. H.; Thompson, T. L.; Mcfarland, M.

    1982-01-01

    Total water was measured in the high troposphere and low stratosphere over Panama during ten aircraft flights. The results show that convective storms provide the means of transporting water into the stratosphere. From a consideration of the anvil heights over different areas of the tropical zone, it follows that a negative gradient of water vapor mixing ratio with altitude must exist over most of the lower stratosphere.

  20. Evidence for multiphase water-escape during rafting of shelly marine sediments at Clava, Inverness-shire, NE Scotland

    Science.gov (United States)

    Phillips, Emrys; Merritt, Jon

    2008-05-01

    The Pleistocene shelly glaciomarine sediments exposed at Clava, near Inverness, northeast Scotland, occur in a series of thrust-bound rafts accreted at on the up-ice side of a bedrock high (150 m above OD) on the SE side of the valley of the River Nairn. These sediments originally formed part of a coarsening upwards deltaic or subaqueous fan sequence deposited in the marine fjord of the Loch Ness basin, located some 50 km to the SW. The geometry of these allochthonous rafts, coupled with the associated thrusting and large-scale folding of these bodies, are typical of many glacially transported rafts described in literature. However, at Clava, macro- and microscopic evidence indicates that these ice-rafted sediments were not frozen, with liquefaction, hydrofracturing and water-escape occurring repeatedly during their transport and accretion. The presence of large-scale detachments within the sequence has led to the development of a purely glacitectonic model for rafting at Clava. The detachments acted as a focus for fluid flow which lubricated these décollement surfaces, aiding in the subglacial transport of the rafts.

  1. P-Cable 3D high-resolution seismic data as a powerful tool to characterize subglacial landforms and their genesis: A case study from the SW Barents Sea

    Science.gov (United States)

    Bellwald, Benjamin; Planke, Sverre; Matar, Mohammed; Daria Piasecka, Emilia

    2017-04-01

    High-resolution 3D seismic data have significantly increased our knowledge about petroleum reservoirs and submarine geohazards. However, little effort has been undertaken to evaluate the potential of such data for mapping subglacial landforms. The Barents Sea has been subjected to repeated Pleistocene glaciations, which intensively eroded the region, resulting in a generally thin (geology. The seismic data cover an area of 200 km2 in water depths of 380-470 m with a recorded in-line spacing of geology. Therefore high-resolution seismic data is beneficial in identifying and analyzing small-scale glacial structures and their expression in the underlying strata in great detail, contributing to the understanding of processes involved in paleo-ice stream dynamics.

  2. Studies and research concerning BNFP: transportation of radioactive material by water

    International Nuclear Information System (INIS)

    Anderson, R.T.

    1980-11-01

    Currently there are many limitations imposed on the shipment of radioactive material from nuclear power plants. In this regard, many questions have arisen related to the feasibility of substituting water transportation of these materials as a backup or supplement to the highway and rail modes which are now in use. This study addresses the results of studies performed by Allied-General Nuclear Services concerning the water transportation of spent nuclear fuel and radwaste materials. The report presents both an overview of the possible applications, problems, and means of solution, and specific information related to one particular site. In particular, a detailed case study of a nuclear plant site located on a navigable waterway (Chesapeake Bay) was made. The study concludes that there are some real advantages in using water transport, which are particularly evident if a site is not served by rail or its primary transport route lies near populous areas. Whereas, water transport has been used extensively in Europe and Japan, it has been virtually bypassed in the United States. A recommendation is made to continue examination of water transport, including the development of necessary standards for possible future operations

  3. Searching for traces of life in subglacial Lake Vostok (Antarctica) in terms of forward contamination: the lessons for exploration of icy environments on Mars

    Science.gov (United States)

    Bulat, S. A.; Alekhina, I. A.; Lipenkov, V. Ya.; Petit, J.-R.

    Bacterial 16S ribosomal gene analysis guarded by criteria for trace DNA analysis and Ancient DNA research clearly testifies for the very low biomass in accretion ice from giant subglacial Lake Vostok buried beneath 4-km thick East Antarctic ice sheet. It seems that the accretion ice is essentially germ-free indicating that the water body should also be hosting a highly sparse life, if any, unless the lake water lost its biological contents during accretion process. Due to this the search for life in Lake Vostok is constrained by a high chance of contamination similar to forward-contamination upon searching for life on Mars and other icy planets. Of 16 bacterial phylotypes initially recovered from the accretion ice the only one was kept with confident relevance to the lake environment while 15 others were presumed to be contaminants on the basis of indexing contaminant criteria developed for Lake Vostok and similar icy environments. The current way to avoid contamination appears to use stringent ice chemistry-based decontamination procedures and comprehensive biological controls including establishment of contemporary contaminant database as a prerequisite to identify and categorize sources of contaminants. More challenge would be to advance cleanliness and sterilization approaches and procedures in order to achieve and measure the level of cleanliness appropriate for tools exploring environments like Lake Vostok. As a guide for searching for life in (sub)glacial environments on Earth or Mars and Jovian's Europa our recommendations can be summarized as follows: (i) apply stringent ice decontamination procedures to meet chemistry and trace DNA analysis standards, (ii) document biological contents of various environments including humans in contact with ice samples (development of contaminant database), (iii) ensure in using relevant methods to cover both known and expected biodiversity and (iv) verify microbial findings through their possible metabolic profiles

  4. Arctic water tracks retain phosphorus and transport ammonium

    Science.gov (United States)

    Harms, T.; Cook, C. L.; Wlostowski, A. N.; Godsey, S.; Gooseff, M. N.

    2017-12-01

    Hydrologic flowpaths propagate biogeochemical signals among adjacent ecosystems, but reactions may attenuate signals by retaining, removing, or transforming dissolved and suspended materials. The theory of nutrient spiraling describes these simultaneous reaction and transport processes, but its application has been limited to stream channels. We applied nutrient spiraling theory to water tracks, zero-order channels draining Arctic hillslopes that contain perennially saturated soils and flow at the surface either perennially or in response to precipitation. In the Arctic, experimental warming results in increased availability of nitrogen, the limiting nutrient for hillslope vegetation at the study site, which may be delivered to aquatic ecosystems by water tracks. Increased intensity of rain events, deeper snowpack, earlier snowmelt, and increasing thaw depth resulting from climate change might support increased transport of nutrients, but the reactive capacity of hillslope flowpaths, including sorption and uptake by plants and microbes, could counter transport to regulate solute flux. Characteristics of flowpaths might influence the opportunity for reaction, where slower flowpaths increase the contact time between solutes and soils or roots. We measured nitrogen and phosphorus uptake and transient storage of water tracks through the growing season and found that water tracks retain inorganic phosphorus, but transport ammonium. Nutrient uptake was unrelated to transient storage, suggesting high capacity for nutrient retention by shallow organic soils and vegetation. These observations indicate that increased availability of ammonium, the biogeochemical signal of warming tundra, is propagated by hillslope flowpaths, whereas water tracks attenuate delivery of phosphorus to aquatic ecosystems, where its availability typically limits production.

  5. Kinetic Theory and Simulation of Single-Channel Water Transport

    Science.gov (United States)

    Tajkhorshid, Emad; Zhu, Fangqiang; Schulten, Klaus

    Water translocation between various compartments of a system is a fundamental process in biology of all living cells and in a wide variety of technological problems. The process is of interest in different fields of physiology, physical chemistry, and physics, and many scientists have tried to describe the process through physical models. Owing to advances in computer simulation of molecular processes at an atomic level, water transport has been studied in a variety of molecular systems ranging from biological water channels to artificial nanotubes. While simulations have successfully described various kinetic aspects of water transport, offering a simple, unified model to describe trans-channel translocation of water turned out to be a nontrivial task.

  6. Chancellor Water Colloids: Characterization and Radionuclide Associated Transport

    Energy Technology Data Exchange (ETDEWEB)

    Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Boukhalfa, Hakim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-09-26

    Column transport experiments were conducted in which water from the Chancellor nuclear test cavity was transported through crushed volcanic tuff from Pahute Mesa. In one experiment, the cavity water was spiked with solute 137Cs, and in another it was spiked with 239/240Pu(IV) nanocolloids. A third column experiment was conducted with no radionuclide spike at all, although the 137Cs concentrations in the water were still high enough to quantify in the column effluent. The radionuclides strongly partitioned to natural colloids present in the water, which were characterized for size distribution, mass concentration, zeta potential/surface charge, critical coagulation concentration, and qualitative mineralogy. In the spiked water experiments, the unanalyzed portion of the high-concentration column effluent samples were combined and re-injected into the respective columns as a second pulse. This procedure was repeated again for a third injection. Measurable filtration of the colloids was observed after each initial injection of the Chancellor water into the columns, but the subsequent injections (spiked water experiments only) exhibited no apparent filtration, suggesting that the colloids that remained mobile after relatively short transport distances were more resistant to filtration than the initial population of colloids. It was also observed that while significant desorption of 137Cs from the colloids occurred after the first injection in both the spiked and unspiked waters, subsequent injections of the spiked water exhibited much less 137Cs desorption (much greater 137Cs colloid-associated transport). This result suggests that the 137Cs that remained associated with colloids during the first injection represented a fraction that was more strongly adsorbed to the mobile colloids than the initial 137Cs associated with the colloids. A greater amount of the 239/240

  7. Visualization of root water uptake: quantification of deuterated water transport in roots using neutron radiography and numerical modeling.

    Science.gov (United States)

    Zarebanadkouki, Mohsen; Kroener, Eva; Kaestner, Anders; Carminati, Andrea

    2014-10-01

    Our understanding of soil and plant water relations is limited by the lack of experimental methods to measure water fluxes in soil and plants. Here, we describe a new method to noninvasively quantify water fluxes in roots. To this end, neutron radiography was used to trace the transport of deuterated water (D2O) into roots. The results showed that (1) the radial transport of D2O from soil to the roots depended similarly on diffusive and convective transport and (2) the axial transport of D2O along the root xylem was largely dominated by convection. To quantify the convective fluxes from the radiographs, we introduced a convection-diffusion model to simulate the D2O transport in roots. The model takes into account different pathways of water across the root tissue, the endodermis as a layer with distinct transport properties, and the axial transport of D2O in the xylem. The diffusion coefficients of the root tissues were inversely estimated by simulating the experiments at night under the assumption that the convective fluxes were negligible. Inverse modeling of the experiment at day gave the profile of water fluxes into the roots. For a 24-d-old lupine (Lupinus albus) grown in a soil with uniform water content, root water uptake was higher in the proximal parts of lateral roots and decreased toward the distal parts. The method allows the quantification of the root properties and the regions of root water uptake along the root systems. © 2014 American Society of Plant Biologists. All Rights Reserved.

  8. Impact of carbonation on water transport properties of cement-based materials

    International Nuclear Information System (INIS)

    Auroy, M.; Poyet, S.; Le Bescop, P.; Torrenti, J.M.

    2015-01-01

    Cement-based materials would be commonly used for nuclear waste management and, particularly for geological disposal vaults as well as containers in France. Under service conditions, the structures would be subjected to simultaneous drying and carbonation. Carbonation relates to the reaction between CO 2 and the hydrated cement phases (mainly portlandite and C-S-H). It induces mineralogical and microstructural changes (due to hydrates dissolution and calcium carbonate precipitation). It results in transport properties modifications, which can have important consequences on the durability of reinforced concrete structures. Concrete durability is greatly influenced by water: water is necessary for chemical reactions to occur and significantly impacts transport. The evaluation of the unsaturated water transport properties in carbonated materials is then an important issue. That is the aim of this study. A program has been established to assess the water transport properties in carbonated materials. In this context, four mature hardened cement pastes (CEM I, CEM III/A, CEM V/A according to European standards and a Low-pH blend) are carbonated. Accelerated carbonation tests are performed in a specific device, controlling environmental conditions: (i) CO 2 content of 3%, to ensure representativeness of the mineralogical evolution compared to natural carbonation and (ii) 25 C. degrees and 55% RH, to optimize carbonation rate. After carbonation, the data needed to describe water transport are evaluated in the framework of simplified approach. Three physical parameters are required: (1) the concrete porosity, (2) the water retention curve and, (3) the effective permeability. The obtained results allow creating link between water transport properties of non-carbonated materials to carbonated ones. They also provide a better understanding of the effect of carbonation on water transport in cementitious materials and thus, complement literature data. (authors)

  9. Transport behavior of water molecules through two-dimensional nanopores

    International Nuclear Information System (INIS)

    Zhu, Chongqin; Li, Hui; Meng, Sheng

    2014-01-01

    Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules

  10. A Mathematical Model of Solute Coupled Water Transport in Toad Intestine Incorporating Recirculation of the Actively Transported Solute

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Sørensen, Jakob Balslev; Sørensen, Jens Nørkær

    2000-01-01

    those of tight junction and interspace basement membrane by convection-diffusion. With solute permeability of paracellular pathway large relative to paracellular water flow, the paracellular flux ratio of the solute (influx/outflux) is small (2-4) in agreement with experiments. The virtual solute......A mathematical model of an absorbing leaky epithelium is developed for analysis of solute coupled water transport. The non-charged driving solute diffuses into cells and is pumped from cells into the lateral intercellular space (lis). All membranes contain water channels with the solute passing...... increases with hydraulic conductance of the pathway carrying water from mucosal solution into lis. Uphill water transport is accomplished, but with high hydraulic conductance of cell membranes strength of transport is obscured by water flow through cells. Anomalous solvent drag occurs when back flux...

  11. Co-regulation of water and K(+) transport in sunflower plants during water stress recovery.

    Science.gov (United States)

    Benlloch, Manuel; Benlloch-González, María

    2016-06-01

    16-day-old sunflower (Helianthus annuus L.) plants were subjected to deficit irrigation for 12 days. Following this period, plants were rehydrated for 2 days to study plant responses to post-stress recovery. The moderate water stress treatment applied reduced growth in all plant organs and the accumulation of K(+) in the shoot. After the rehydration period, the stem recovered its growth and reached a similar length to the control, an effect which was not observed in either root or leaves. Moreover, plant rehydration after water stress favored the accumulation of K(+) in the apical zone of the stem and expanding leaves. In the roots of plants under water stress, watering to field capacity, once the plants were de- topped, rapidly favored K(+) and water transport in the excised roots. This quick and short-lived response was not observed in roots of plants recovered from water stress for 2 days. These results suggest that the recovery of plant growth after water stress is related to coordinated water and K(+) transport from the root to the apical zone of the ​​stem and expanding leaves. This stimulation of K(+) transport in the root and its accumulation in the cells of the growing zones of the ​​stem must be one of the first responses induced in the plant during water stress recovery. Copyright © 2016 Elsevier GmbH. All rights reserved.

  12. Storm-induced water dynamics and thermohaline structure at the tidewater Flade Isblink Glacier outlet to the Wandel Sea (NE Greenland)

    Science.gov (United States)

    Kirillov, Sergei; Dmitrenko, Igor; Rysgaard, Søren; Babb, David; Toudal Pedersen, Leif; Ehn, Jens; Bendtsen, Jørgen; Barber, David

    2017-11-01

    In April 2015, an ice-tethered conductivity-temperature-depth (CTD) profiler and a down-looking acoustic Doppler current profiler (ADCP) were deployed from the landfast ice near the tidewater glacier terminus of the Flade Isblink Glacier in the Wandel Sea, NE Greenland. The 3-week time series showed that water dynamics and the thermohaline structure were modified considerably during a storm event on 22-24 April, when northerly winds exceeded 15 m s-1. The storm initiated downwelling-like water dynamics characterized by on-shore water transport in the surface (0-40 m) layer and compensating offshore flow at intermediate depths. After the storm, currents reversed in both layers, and the relaxation phase of downwelling lasted ˜ 4 days. Although current velocities did not exceed 5 cm s-1, the enhanced circulation during the storm caused cold turbid intrusions at 75-95 m depth, which are likely attributable to subglacial water from the Flade Isblink Ice Cap. It was also found that the semidiurnal periodicities in the temperature and salinity time series were associated with the lunar semidiurnal tidal flow. The vertical structure of tidal currents corresponded to the first baroclinic mode of the internal tide with a velocity minimum at ˜ 40 m. The tidal ellipses rotate in opposite directions above and below this depth and cause a divergence of tidal flow, which was observed to induce semidiurnal internal waves of about 3 m height at the front of the glacier terminus. Our findings provide evidence that shelf-basin interaction and tidal forcing can potentially modify coastal Wandel Sea waters even though they are isolated from the atmosphere by landfast sea ice almost year-round. The northerly storms over the continental slope cause an enhanced circulation facilitating a release of cold and turbid subglacial water to the shelf. The tidal flow may contribute to the removal of such water from the glacial terminus.

  13. Storm-induced water dynamics and thermohaline structure at the tidewater Flade Isblink Glacier outlet to the Wandel Sea (NE Greenland

    Directory of Open Access Journals (Sweden)

    S. Kirillov

    2017-11-01

    Full Text Available In April 2015, an ice-tethered conductivity–temperature–depth (CTD profiler and a down-looking acoustic Doppler current profiler (ADCP were deployed from the landfast ice near the tidewater glacier terminus of the Flade Isblink Glacier in the Wandel Sea, NE Greenland. The 3-week time series showed that water dynamics and the thermohaline structure were modified considerably during a storm event on 22–24 April, when northerly winds exceeded 15 m s−1. The storm initiated downwelling-like water dynamics characterized by on-shore water transport in the surface (0–40 m layer and compensating offshore flow at intermediate depths. After the storm, currents reversed in both layers, and the relaxation phase of downwelling lasted ∼ 4 days. Although current velocities did not exceed 5 cm s−1, the enhanced circulation during the storm caused cold turbid intrusions at 75–95 m depth, which are likely attributable to subglacial water from the Flade Isblink Ice Cap. It was also found that the semidiurnal periodicities in the temperature and salinity time series were associated with the lunar semidiurnal tidal flow. The vertical structure of tidal currents corresponded to the first baroclinic mode of the internal tide with a velocity minimum at ∼ 40 m. The tidal ellipses rotate in opposite directions above and below this depth and cause a divergence of tidal flow, which was observed to induce semidiurnal internal waves of about 3 m height at the front of the glacier terminus. Our findings provide evidence that shelf–basin interaction and tidal forcing can potentially modify coastal Wandel Sea waters even though they are isolated from the atmosphere by landfast sea ice almost year-round. The northerly storms over the continental slope cause an enhanced circulation facilitating a release of cold and turbid subglacial water to the shelf. The tidal flow may contribute to the removal of such water from the glacial terminus.

  14. Ocean impact on Nioghalvfjerdsfjorden Glacier, Northeast Greenland

    Science.gov (United States)

    Schaffer, Janin; Kanzow, Torsten; von Appen, Wilken-Jon; Mayer, Christoph

    2017-04-01

    The ocean plays an important role in modulating the mass balance of the Greenland Ice Sheet by delivering heat to the marine-terminating outlet glaciers around Greenland. The largest of three outlet glaciers draining the Northeast Greenland Ice Stream is Nioghalvfjerdsfjorden Glacier (also referred to as 79 North Glacier). Historic observations showed that warm waters of Atlantic origin are present in the subglacial cavity below the 80 km long floating ice tongue of the Nioghalvfjerdsfjorden Glacier and cause strong basal melt at the grounding line, but to date it has been unknown how those warm water enter the cavity. In order to understand how Atlantic origin waters carry heat into the subglacial cavity beneath Nioghalvfjerdsfjorden Glacier, we performed bathymetric, hydrographic, and velocity observations in the vicinity of the main glacier calving front aboard RV Polarstern in summer 2016. The bathymetric multibeam data shows a 500 m deep and 2 km narrow passage downstream of a 310 m deep sill. This turned out to be the only location deep enough for an exchange of Atlantic waters between the glacier cavity and the continental shelf. Hydrographic and velocity measurements revealed a density driven plume in the vicinity of the glacier calving front causing a rapid flow of waters of Atlantic origin warmer 1°C into the subglacial cavity through the 500 m deep passage. In addition, glacially modified waters flow out of the glacier cavity below the 80 m deep ice base. In the vicinity of the glacier, the glacially modified waters form a distinct mixed layer situated above the Atlantic waters and below the ambient Polar water. At greater distances from the glacier this layer is eroded by lateral mixing with ambient water. Based on our observations we will present an estimate of the ocean heat transport into the subglacial cavity. In comparison with historic observations we find an increase in Atlantic water temperatures throughout the last 20 years. The resulting

  15. Relative transport of water (H2O) and tritiated water (HTO) across cellulose acetate (CA) membranes

    International Nuclear Information System (INIS)

    Prabhakar, S.; Misra, B.M.; Ramani, M.P.S.

    1986-01-01

    The relative transport characteristics of water (H 2 O) and tritiated water (HTO) were evaluated through cellulose acetate membranes under osmosis, reverse osmosis and pervaporation. The results indicate that the relative transport is independent of the process. The anamolous observations under osmotic conditions are explained. (orig.)

  16. Evidence for Subglacial Deformation and Deposition during a Complete Advance-Stagnation Cycle of Kötlujökull, Iceland – A Case Study

    DEFF Research Database (Denmark)

    Klint, K E S; Richardt, N; Krüger, Johannes

    2010-01-01

    A geological section, 70 m long and 3–4 m high, cut into dead-ice moraine in front of Kötlujökull, has been described. Five-sediment associations were recognized representing (1) proglacial glacio-fluvial sedimentation, (2) deposition and deformation in ice-marginal environment, (3) subglacial...

  17. Assessing the efficiency of carbide drill bits and factors influencing their application to debris-rich subglacial ice

    Science.gov (United States)

    Yang, Cheng; Jiang, Jianliang; Cao, Pinlu; Wang, Jinsong; Fan, Xiaopeng; Shang, Yuequan; Talalay, Pavel

    2017-09-01

    When drilling into subglacial bedrock, drill operators commonly encounter basal ice containing high concentrations of rock debris and melt water. As such conditions can easily damage conventional ice drills, researchers have experimented with carbide, diamond, and polycrystalline diamond compact drill bits, with varying degrees of success. In this study, we analyzed the relationship between drilling speed and power consumption for a carbide drill bit penetrating debris-rich ice. We also assessed drill load, rotation speed, and various performance parameters for the cutting element, as well as the physical and mechanical properties of rock and ice, to construct mathematical models. We show that our modeled results are in close agreement with the experimental data, and that both penetration speed and power consumption are positively correlated with drill speed and load. When used in ice with 30% rock content, the maximum penetration speed of the carbide bit is 3.4 mm/s with a power consumption of ≤0.5 kW, making the bit suitable for use with existing electromechanical drills. Our study also provides a guide for further research into cutting heat and equipment design.

  18. New methods For Modeling Transport Of Water And Solutes In Soils

    DEFF Research Database (Denmark)

    Møldrup, Per

    Recent models for water and solute transport in unsaturated soils have been mechanistically based but numerically very involved. This dissertation concerns the development of mechanistically-based but numerically simple models for calculating and analyzing transport of water and solutes in soil...

  19. Interannual Variability in the Meridional Transport of Water Vapor

    Science.gov (United States)

    Cohen, Judah L.; Salstein, David A.; Rosen, Richard D.

    2000-01-01

    The zonal-mean meridional transport of water vapor across the globe is evaluated using the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis for 1948-97. The shape of the meridional profile of the climatological mean transport closely resembles that of previous mean climate descriptions, but values tend to be notably larger than in climatologies derived from radiosonde-only-based analyses. The unprecedented length of the NCEP-NCAR dataset invites a focus on interannual variations in the zonal-mean moisture transport, and these results for northern winter are highlighted here. Although interannual variability in the transport is typically small at most latitudes, a significant ENSO signal is present, marked by a strengthening of water vapor transports over much of the winter hemisphere during warm events. Because of an increase in tropical sea surface temperatures and in the frequency of warm events relative to cold events in the latter half of the 50-yr record, this interannual signal projects onto an overall trend toward enhanced meridional moisture transports in the global hydrological cycle.

  20. Impact of Interfacial Water Transport in PEMFCs on Cell Performance

    International Nuclear Information System (INIS)

    Kotaka, Toshikazu; Tabuchi, Yuichiro; Pasaogullari, Ugur; Wang, Chao-Yang

    2014-01-01

    Coupled cell performance evaluation, liquid water visualization by neutron radiography (NRG) and numerical modeling based on multiphase mixture (M2) model were performed with three types of GDMs: Micro Porous Layer (MPL) free; Carbon Paper (CP) with MPL; and CP free to investigate interfacial liquid water transport phenomena in PEMFCs and its effect on cell performance. The visualized results of MPL free GDM with different wettability of bi-polar plates (BPPs) showed hydrophilic BPP improved liquid water transport at the interface between CP and channel. Numerical modeling results indicated that this difference with BPP wettability was caused by the liquid water coverage difference on CP surface. Thus, controlling liquid water coverage is the one of the key strategies for improving cell performance. Additionally, liquid water distributions across the cell for three types of GDMs were compared and significant difference in liquid water content at the interface between Catalyst Layer (CL) and GDM was observed. Numerical modeling suggests this difference is influenced by the gap at the interface and that the MPL could minimize this effect. The CP free cell (i.e. only MPL) showed the best performance and the lowest liquid water content. There were multiple impacts of interfacial liquid water transport both at CL-GDM and GDM-channel interfaces. High hydrophobicity and fine structure of MPLs contributed to enhanced liquid water transport at GDM-channel interface and as a result reduced the liquid water coverage. At the same time, MPL improves contact at the CL-GDM interface in the same manner as seen in CP with MPL case. Thus, the CP free concept showed the best performance. It is suggested that the design of the interface between each component of the PEMFC has a great impact on cell performance and plays a significant role in achievement of high current density operation and cost reduction in FCEVs

  1. Investigating water transport through the xylem network in vascular plants.

    Science.gov (United States)

    Kim, Hae Koo; Park, Joonghyuk; Hwang, Ildoo

    2014-04-01

    Our understanding of physical and physiological mechanisms depends on the development of advanced technologies and tools to prove or re-evaluate established theories, and test new hypotheses. Water flow in land plants is a fascinating phenomenon, a vital component of the water cycle, and essential for life on Earth. The cohesion-tension theory (CTT), formulated more than a century ago and based on the physical properties of water, laid the foundation for our understanding of water transport in vascular plants. Numerous experimental tools have since been developed to evaluate various aspects of the CTT, such as the existence of negative hydrostatic pressure. This review focuses on the evolution of the experimental methods used to study water transport in plants, and summarizes the different ways to investigate the diversity of the xylem network structure and sap flow dynamics in various species. As water transport is documented at different scales, from the level of single conduits to entire plants, it is critical that new results be subjected to systematic cross-validation and that findings based on different organs be integrated at the whole-plant level. We also discuss the functional trade-offs between optimizing hydraulic efficiency and maintaining the safety of the entire transport system. Furthermore, we evaluate future directions in sap flow research and highlight the importance of integrating the combined effects of various levels of hydraulic regulation.

  2. Ground-water solute transport modeling using a three-dimensional scaled model

    International Nuclear Information System (INIS)

    Crider, S.S.

    1987-01-01

    Scaled models are used extensively in current hydraulic research on sediment transport and solute dispersion in free surface flows (rivers, estuaries), but are neglected in current ground-water model research. Thus, an investigation was conducted to test the efficacy of a three-dimensional scaled model of solute transport in ground water. No previous results from such a model have been reported. Experiments performed on uniform scaled models indicated that some historical problems (e.g., construction and scaling difficulties; disproportionate capillary rise in model) were partly overcome by using simple model materials (sand, cement and water), by restricting model application to selective classes of problems, and by physically controlling the effect of the model capillary zone. Results from these tests were compared with mathematical models. Model scaling laws were derived for ground-water solute transport and used to build a three-dimensional scaled model of a ground-water tritium plume in a prototype aquifer on the Savannah River Plant near Aiken, South Carolina. Model results compared favorably with field data and with a numerical model. Scaled models are recommended as a useful additional tool for prediction of ground-water solute transport

  3. The aeromagnetic method as a tool to identify Cenozoic magmatism in the West Antarctic Rift System beneath the West Antarctic Ice Sheet: a review; Thiel subglacial volcano as possible source of the ash layer in the WAISCOR

    Science.gov (United States)

    Behrendt, John C.

    2013-01-01

    The West Antarctic Ice Sheet (WAIS) flows through the volcanically active West Antarctic Rift System (WARS). The aeromagnetic method has been the most useful geophysical tool for identification of subglacial volcanic rocks, since 1959–64 surveys, particularly combined with 1978 radar ice-sounding. The unique 1991–97 Central West Antarctica (CWA) aerogeophysical survey covering 354,000 km2 over the WAIS, (5-km line-spaced, orthogonal lines of aeromagnetic, radar ice-sounding, and aerogravity measurements), still provides invaluable information on subglacial volcanic rocks, particularly combined with the older aeromagnetic profiles. These data indicate numerous 100–>1000 nT, 5–50-km width, shallow-source, magnetic anomalies over an area greater than 1.2 × 106 km2, mostly from subglacial volcanic sources. I interpreted the CWA anomalies as defining about 1000 “volcanic centers” requiring high remanent normal magnetizations in the present field direction. About 400 anomaly sources correlate with bed topography. At least 80% of these sources have less than 200 m relief at the WAIS bed. They appear modified by moving ice, requiring a younger age than the WAIS (about 25 Ma). Exposed volcanoes in the WARS are The present rapid changes resulting from global warming, could be accelerated by subglacial volcanism.

  4. 41 CFR 302-10.5 - May I transport a mobile home over water?

    Science.gov (United States)

    2010-07-01

    ... transport a mobile home over water? Yes, you may transport a mobile home over water when both the points of... 41 Public Contracts and Property Management 4 2010-07-01 2010-07-01 false May I transport a mobile home over water? 302-10.5 Section 302-10.5 Public Contracts and Property Management Federal Travel...

  5. On water transport in polymer electrolyte membranes during the passage of current

    DEFF Research Database (Denmark)

    Berning, Torsten

    2011-01-01

    This article discusses an approach to model the water transport in the membranes of PEM fuel cells during operation. Starting from a frequently utilized equation the various transport mechanisms are analyzed in detail. It is shown that the commonly used approach to simply balance the electro......-osmotic drag (EOD) with counter diffusion and/or hydraulic permeation is flawed, and that any net transport of water through the membrane is caused by diffusion. Depending on the effective drag the cathode side of the membrane may experience a lower hydration than the anode side. The effect of a water......-uptake layer on the net water transport will also be pictured. Finally, the effect of EOD is visualized using “Newton’s cradle”....

  6. Water vapor and Gas Transport through Polymeric Membranes

    NARCIS (Netherlands)

    Metz, S.J.

    2003-01-01

    Water vapor transport through polymeric materials plays an important role in a large number of applications such as: food packaging, breathable clothing, roofing membranes, diapers, and the removal of water vapor from gas streams (e.g. dehydration of natural gas or the drying of compressed air).

  7. Mathematical Model to Predict the Permeability of Water Transport in Concrete Structure

    OpenAIRE

    Solomon Ndubuisi Eluozo

    2013-01-01

    Mathematical model to predict the permeability of water transport in concrete has been established, the model is to monitor the rate of water transport in concrete structure. The process of this water transport is based on the constituent in the mixture of concrete. Permeability established a relation on the influence of the micropores on the constituent that made of concrete, the method of concrete placement determine the rate of permeability deposition in concrete structure, permeability es...

  8. Diurnal dynamics of the CO2 concentration in water of the coastal zone of lake Baikal in the ice period (testing of the DIEL - CO2 method for assessment of lake metabolic rate)

    Science.gov (United States)

    Panchenko, M. V.; Domysheva, V. M.; Pestunov, D. A.; Sakirko, M. V.; Ivanov, V. G.; Shamrin, A. M.

    2017-11-01

    Results of three long cycles of 24-hour measurements of the carbon dioxide content in the surface and bottom water in the ice period of 2014-2016 in the Baikal coastal zone are analyzed. The diurnal dynamics of the CO2 concentration in the subglacial water, in which photosynthesis plays the leading role, is described. It is found that, in comparison with the surface subglacial water (that is, directly adjacent to the ice bottom), the more pronounced diurnal rhythm of CO2 is observed in the bottom layer in all realizations. This rhythm is well correlated with pyranometer readings. The data on the diurnal dynamics of CO2 are used to estimate the gross primary production in the bottom water with the DIEL method based on the analysis of temporal variability of the carbon dioxide concentration in water in situ.

  9. Tracer water transport and subgrid precipitation variation within atmospheric general circulation models

    Science.gov (United States)

    Koster, Randal D.; Eagleson, Peter S.; Broecker, Wallace S.

    1988-03-01

    A capability is developed for monitoring tracer water movement in the three-dimensional Goddard Institute for Space Science Atmospheric General Circulation Model (GCM). A typical experiment with the tracer water model follows water evaporating from selected grid squares and determines where this water first returns to the Earth's surface as precipitation or condensate, thereby providing information on the lateral scales of hydrological transport in the GCM. Through a comparison of model results with observations in nature, inferences can be drawn concerning real world water transport. Tests of the tracer water model include a comparison of simulated and observed vertically-integrated vapor flux fields and simulations of atomic tritium transport from the stratosphere to the oceans. The inter-annual variability of the tracer water model results is also examined.

  10. Tracer water transport and subgrid precipitation variation within atmospheric general circulation models

    Science.gov (United States)

    Koster, Randal D.; Eagleson, Peter S.; Broecker, Wallace S.

    1988-01-01

    A capability is developed for monitoring tracer water movement in the three-dimensional Goddard Institute for Space Science Atmospheric General Circulation Model (GCM). A typical experiment with the tracer water model follows water evaporating from selected grid squares and determines where this water first returns to the Earth's surface as precipitation or condensate, thereby providing information on the lateral scales of hydrological transport in the GCM. Through a comparison of model results with observations in nature, inferences can be drawn concerning real world water transport. Tests of the tracer water model include a comparison of simulated and observed vertically-integrated vapor flux fields and simulations of atomic tritium transport from the stratosphere to the oceans. The inter-annual variability of the tracer water model results is also examined.

  11. Ecological aspects of water coal fuel transportation and application

    Directory of Open Access Journals (Sweden)

    Anna SHVORNIKOVA

    2010-01-01

    Full Text Available This paper deals with the aspects of influence of transportation process and burning of water coal fuel on an ecological condition of environment. Also mathematical dependences between coal ash level and power consumption for transportation are presented.

  12. Ebullition, Plant-Mediated Transport, and Subsurface Horizontal Water Flow Dominate Methane Transport in an Arctic Sphagnum Bog

    Science.gov (United States)

    Wehr, R. A.; McCalley, C. K.; Logan, T. A.; Chanton, J.; Crill, P. M.; Rich, V. I.; Saleska, S. R.

    2017-12-01

    Emission of the greenhouse gas methane from wetlands is of prime concern in the prediction of climate change - especially emission associated with thawing permafrost, which may drive a positive feedback loop of emission and warming. In addition to the biochemistry of methane production and consumption, wetland methane emission depends critically on the transport mechanisms by which methane moves through and out of the ecosystem. We therefore developed a model of methane biochemistry and transport for a sphagnum bog representing an intermediate permafrost thaw stage in Stordalen Mire, Sweden. In order to simultaneously reproduce measured profiles of both the concentrations and isotopic compositions of both methane and carbon dioxide in the peat pore water (Fig. 1) - as well as the surface methane emission - it was necessary for the model to include ebullition, plant-mediated transport via aerenchyma, and subsurface horizontal water flow. Diffusion of gas through the pore water was relatively unimportant. As a result, 90% of the produced methane escaped the wetland rather than being consumed by methanotrophic organisms in the near-surface pore water. Our model provides a comprehensive picture of methane emission from this bog site by quantifying the vertical profiles of: acetoclastic methanogenesis, hydrogenotrophic methanogenesis, methane oxidation, aerobic respiration, ebullition, plant-mediated transport, subsurface horizontal water flow, and diffusion.

  13. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

    Onishi, Yasuo; Mayer, D.W.; Argo, R.S.

    1982-01-01

    Models are presented to estimate the migration of toxic contaminants in coastal waters. Ocean current is simulated by the vertically-averaged, finite element, two-demensional model known as CAFE-I with the Galerkin weighted residual technique. The refraction of locally generated waves or swells is simulated by the wave refraction model, LO3D. Using computed current, depth, and wave characteristics, the finite element model, FETRA, simulated sediment and contaminant transport in coastal waters, estuaries and rivers. Prior to the application of these models to the Irish Sea and other coastal waters, the finite element model, FETRA, was tested to demonstrate its ability to simulate sediment and contaminant interaction, and the mechanism governing the transport, deposition, and resuspension of contaminated sediment. Several simple equations such as the unsteady, advection-diffusion equation, the equation for noncohesive-sediment load due to wind-induced waves in offshore and surf zones, and the equation for sediment-radionuclide transport simulation were solved during the preliminary testing of the model. (Kato, T.)

  14. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    Parameters for Fickian diffusion and polymer relaxation models were determined by .... Water transport process of resin and polymer composite specimens at ..... simulation. ... Kwon Y W and Bang H 1997 Finite element method using matlab.

  15. Modelling of the reactive transport of organic pollutants in ground water; Modellierung des reaktiven Transports organischer Schadstoffe im Grundwasser

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, W [Heidelberg Univ. (Germany). Inst. fuer Umweltphysik

    1999-07-01

    The book describes reactive transport of organic pollutants in ground water and its quantitative monitoring by means of numerical reaction transport models. A brief introduction dealing with the importance of and hazards to ground water and opportunities for making use of ground water models is followed by a more detailed chapter on organic pollutants in ground water. Here the focus is on organochlorine compounds and mineral oil products. Described are propagation mechanisms for these substances in the ground and, especially, their degradability in ground water. A separate chapter is dedicated to possibilities for cleaning up polluted ground water aquifers. The most important decontamination techniques are presented, with special emphasis on in-situ processes with hydraulic components. Moreover, this chapter discusses the self-cleaning capability of aquifers and the benefits of the application of models to ground water cleanup. In the fourth chapter the individual components of reaction transport models are indicated. Here it is, inter alia, differences in the formulation of reaction models as to their complexity, and coupling between suspended matter transport and reaction processes that are dealt with. This chapter ends with a comprehensive survey of literature regarding the application of suspended matter transport models to real ground water accidents. Chapter 5 consists of a description of the capability and principle of function of the reaction transport model TBC (transport biochemism/chemism). This model is used in the two described applications to the reactive transport of organic pollutants in ground water. (orig.) [German] Inhalt des vorliegenden Buches ist die Darstellung des reaktiven Transports organischer Schadstoffe im Grundwasser und dessen quantitative Erfassung mithilfe numerischer Reaktions-Transportmodelle. Auf eine kurze Einleitung zur Bedeutung und Gefaehrdung von Grundwasser und zu den Einsatzmoeglichkeiten von Grundwassermodellen folgt ein

  16. Transient Conditions at the Ice/bed Interface Under a Palaeo-ice Stream Derived from Numerical Simulation of Groundwater Flow and Sedimentological Observations in a Drumlin Field, NW Poland

    Science.gov (United States)

    Hermanowski, P.; Piotrowski, J. A.

    2017-12-01

    Evacuation of glacial meltwater through the substratum is an important agent modulating the ice/bed interface processes. The amount of meltwater production, subglacial water pressure, flow patterns and fluxes all affect the strength of basal coupling and thus impact the ice-sheet dynamics. Despite much research into the subglacial processes of past ice sheets which controlled sediment transport and the formation of specific landforms, our understanding of the ice/bed interface remains fragmentary. In this study we numerically simulated, using finite difference and finite element codes, groundwater flow pattern and fluxes during an ice advance in the Stargard Drumlin Field, NW Poland to examine the potential influence of groundwater drainage on the landforming processes. The results are combined with sedimentological observations of the internal composition of the drumlins to validate the outcome of the numerical model. Our numerical experiments of groundwater flow suggest a highly time-dependent response of the subglacial hydrogeological system to the advancing ice margin. This is manifested as diversified areas of downward- and upward-oriented groundwater flows whereby the drumlin field area experienced primarily groundwater discharge towards the ice sole. The investigated drumlins are composed of (i) mainly massive till with thin stringers of meltwater sand, and (ii) sorted sediments carrying ductile deformations. The model results and sedimentological observations suggest a high subglacial pore-water pressure in the drumlin field area, which contributed to sediment deformation intervening with areas of basal decoupling and enhanced basal sliding.

  17. Does water transport scale universally with tree size?

    Science.gov (United States)

    F.C. Meinzer; B.J. Bond; J.M. Warren; D.R. Woodruff

    2005-01-01

    1. We employed standardized measurement techniques and protocols to describe the size dependence of whole-tree water use and cross-sectional area of conducting xylem (sapwood) among several species of angiosperms and conifers. 2. The results were not inconsistent with previously proposed 314-power scaling of water transport with estimated above-...

  18. RIVER-RAD, Radionuclide Transport in Surface Waters

    International Nuclear Information System (INIS)

    1996-01-01

    1 - Description of program or function: RIVER-RAD assesses the potential fate of radionuclides released to rivers. The model is simplified in nature and is intended to provide guidance in determining the potential importance of the surface water pathway, relevant transport mechanisms, and key radionuclides in estimating radiological dose to man. 2 - Method of solution: A compartmental linear transfer model is used in RIVER-RAD. The river system model in the code is divided into reaches (compartments) of equal size, each with a sediment compartment below it. The movement of radionuclides is represented by a series of transfers between the reaches, and between the water and sediment compartments of each reach. Within each reach (for both the water and sediment compartments), the radionuclides are assumed to be uniformly mixed. Upward volatilization is allowed from the water compartment, and the transfer of radionuclides between the reaches is determined by the flow rate of the river. Settling and resuspension velocities determine the transfer of absorbed radionuclides between the water and sediment compartments. Radioactive decay and decay-product buildup are incorporated into all transport calculations for all radionuclide chains specified by the user. Each nuclide may have unique input and removal rates. Volatilization and radiological decay are considered as linear rate constants in the model. 3 - Restrictions on the complexity of the problem: None noted

  19. Unrest at Bárdarbunga: Preparations for possible flooding due to subglacial volcanism

    Science.gov (United States)

    Hardardottir, Jorunn; Roberts, Matthew; Pagneux, Emmanuel; Einarsson, Bergur; Thorarinsdottir, Tinna; Johannesson, Tomas; Sigurdsson, Oddur; Egilson, David; Sigurdsson, Gunnar; Imo hydrological-monitoring-team

    2015-04-01

    Located partly beneath northwest Vatnajökull, Iceland, the Bárdarbunga volcanic system comprises an ice-capped central volcano and a fissure swarm extending beyond the ice margin. During the last 1100 years the volcano has erupted on at least 26 occasions. Outburst floods (jökulhlaups) on a scale of >100,000 m3 s-1 are known to have occurred during major explosive eruptions. Repeated jökulhlaups from Bárdarbunga have inundated the Jökulsá á Fjöllum River, which drains over 200 km northwards from the Dyngjujökull outlet glacier to the north coast of Iceland. Depending on the location of the eruption within the 80 km2 caldera, jökulhlaups could also flow northwards along Skjálfandafljót River and towards west and southwest into present-day tributaries of the extensively hydropower-harnessed Thjórsá River. On 16 August 2014, an intense earthquake swarm began within the Bárdarbunga caldera. Seismicity propagated from the caldera, extending ~10 km northwards of the ice margin where a fissure eruption developed in late August and remains ongoing in early January 2015. In connection with the lateral migration of magma from the caldera, the ice surface of Bárdarbunga has lowered by over 60 m; also associated with increased geothermal heat on the caldera rim, as manifested by the development of ice-surface depressions. In preparation for a subglacial eruption in the Bárdarbunga volcanic system, the Icelandic Meteorological Office (IMO) has made several assessments of likely hydrological hazards. Assessments were undertaken on Jökulsá á Fjöllum and Skjálfandafljót at key locations where preliminary evacuation plans for populated areas were made in cooperation with the local police. Floodwater extent was estimated for key infrastructures, such as bridges, telecommunication and power lines for maximum discharge levels ranging from 3,000 to 20,000 m3 s-1. The estimations were made using either simple Manning's calculations or HEC-RAS modelling

  20. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

    Onishi, Y.; Mayer, D.W.; Argo, R.S.

    1982-02-01

    A hydrodynamic model, CAFE-I, a wave refraction model, LO3D, and a sediment and contaminant transport model, FETRA, were selected as tools for evaluating exposure levels of radionuclides, heavy metals, and other toxic chemicals in coastal waters. Prior to the application of these models to the Irish Sea and other coastal waters, the finite element model, FETRA, was tested to demonstrate its ability to simulate sediment and contaminant interactions (e.g., adsorption and desorption), and the mechanisms governing the transport, deposition, and resuspension of contaminated sediments

  1. Assessment of thermobaric state and change of the mass balance in the subgkacial Lake Vostok after drilling-in

    Directory of Open Access Journals (Sweden)

    A. N. Markov

    2014-01-01

    Full Text Available Estimation of temperature and pressure conditions in the subglacial reservoirs is one of the most important tasks of modern subglacial research, since it provides an adequate tool for predicting the process of their accessing. This paper presents the estimation of pressure in the subglacial reservoirs for different baric system statuses. Opening of isolated subglacial reservoirs is attended by disturbance of their thermobaric equilibrium, thus the conditions of phase transition are changed on the entire surface of the ice-water contact. At the same time reducing the pressure in the subglacial reservoirs leads to «lowering» of the phase transition of ice-water boundary and to the growth of additional layer of congelation ice on the entire bottom surface of the ice sheet contact with water. Realized accessing of Lake Vostok and technology re-entry involves water rise into the borehole from the lake as one of the steps to prevent pollution of relict water system. With the use of this technology the reliability of estimate the pressure in Lake Vostok is extremely important and, consequently, the value of the differential pressure when the borehole accesses with lake. The paper presents analysis of the possible consequences of incorrect estimation of the pressure in isolated water system of Lake Vostok, when the borehole accesses in conditions of incomplete compensation of subglacial water pressure by hydrostatic pressure of the drilling fluid column.

  2. Intact plant MRI for the study of cell water relations, membrane permeability, cell-to-cell and long distance water transport

    NARCIS (Netherlands)

    As, van H.

    2007-01-01

    Water content and hydraulic conductivity, including transport within cells, over membranes, cell-to-cell, and long-distance xylem and phloem transport, are strongly affected by plant water stress. By being able to measure these transport processes non-invasely in the intact plant situation in

  3. Critical review: Radionuclide transport, sediment transport, and water quality mathematical modeling; and radionuclide adsorption/desorption mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Y.; Serne, R.J.; Arnold, E.M.; Cowan, C.E.; Thompson, F.L. [Pacific Northwest Lab., Richland, WA (United States)

    1981-01-01

    This report describes the results of a detailed literature review of radionuclide transport models applicable to rivers, estuaries, coastal waters, the Great Lakes, and impoundments. Some representatives sediment transport and water quality models were also reviewed to evaluate if they can be readily adapted to radionuclide transport modeling. The review showed that most available transport models were developed for dissolved radionuclide in rivers. These models include the mechanisms of advection, dispersion, and radionuclide decay. Since the models do not include sediment and radionuclide interactions, they are best suited for simulating short-term radionuclide migration where: (1) radionuclides have small distribution coefficients; (2) sediment concentrations in receiving water bodies are very low. Only 5 of the reviewed models include full sediment and radionuclide interactions: CHMSED developed by Fields; FETRA SERATRA, and TODAM developed by Onishi et al, and a model developed by Shull and Gloyna. The 5 models are applicable to cases where: (1) the distribution coefficient is large; (2) sediment concentrations are high; or (3) long-term migration and accumulation are under consideration. The report also discusses radionuclide absorption/desorption distribution ratios and addresses adsorption/desorption mechanisms and their controlling processes for 25 elements under surface water conditions. These elements are: Am, Sb, C, Ce, Cm, Co, Cr, Cs, Eu, I, Fe, Mn, Np, P, Pu, Pm, Ra, Ru, Sr, Tc, Th, {sup 3}H, U, Zn and Zr.

  4. Water transport inside carbon nanotubes mediated by phonon-induced oscillating friction.

    Science.gov (United States)

    Ma, Ming; Grey, François; Shen, Luming; Urbakh, Michael; Wu, Shuai; Liu, Jefferson Zhe; Liu, Yilun; Zheng, Quanshui

    2015-08-01

    The emergence of the field of nanofluidics in the last decade has led to the development of important applications including water desalination, ultrafiltration and osmotic energy conversion. Most applications make use of carbon nanotubes, boron nitride nanotubes, graphene and graphene oxide. In particular, understanding water transport in carbon nanotubes is key for designing ultrafiltration devices and energy-efficient water filters. However, although theoretical studies based on molecular dynamics simulations have revealed many mechanistic features of water transport at the molecular level, further advances in this direction are limited by the fact that the lowest flow velocities accessible by simulations are orders of magnitude higher than those measured experimentally. Here, we extend molecular dynamics studies of water transport through carbon nanotubes to flow velocities comparable with experimental ones using massive crowd-sourced computing power. We observe previously undetected oscillations in the friction force between water and carbon nanotubes and show that these oscillations result from the coupling between confined water molecules and the longitudinal phonon modes of the nanotube. This coupling can enhance the diffusion of confined water by more than 300%. Our results may serve as a theoretical framework for the design of new devices for more efficient water filtration and osmotic energy conversion devices.

  5. Limited Impact of Subglacial Supercooling Freeze-on for Greenland Ice Sheet Stratigraphy

    Science.gov (United States)

    Dow, Christine F.; Karlsson, Nanna B.; Werder, Mauro A.

    2018-02-01

    Large units of disrupted radiostratigraphy (UDR) are visible in many radio-echo sounding data sets from the Greenland Ice Sheet. This study investigates whether supercooling freeze-on rates at the bed can cause the observed UDR. We use a subglacial hydrology model to calculate both freezing and melting rates at the base of the ice sheet in a distributed sheet and within basal channels. We find that while supercooling freeze-on is a phenomenon that occurs in many areas of the ice sheet, there is no discernible correlation with the occurrence of UDR. The supercooling freeze-on rates are so low that it would require tens of thousands of years with minimal downstream ice motion to form the hundreds of meters of disrupted radiostratigraphy. Overall, the melt rates at the base of the ice sheet greatly overwhelm the freeze-on rates, which has implications for mass balance calculations of Greenland ice.

  6. A transportable system for radioactivity contaminated water treatment

    International Nuclear Information System (INIS)

    2013-01-01

    Contaminated water treatment system called SARRY for retrieval and recovery of water in operation at the site of Fukushima Daiichi Nuclear Power Plant since August 2011 has been modified by compacting the system size to develop a mobile system SARRY-Aqua that can process Cs-contaminated water (one ton/hour) to the level of 10 Bq/kg. Installing the system in a small container with dimensions conforming to the international standards facilitates transportation by truck and enables the contaminated water treatment occurring in a variety of locations. (S. Ohno)

  7. The potential importance of water pathways for spent fuel transportation accident risk

    International Nuclear Information System (INIS)

    Ostmeyer, R.M.

    1986-01-01

    This paper analyzes the potential importance of water pathway contamination for spent fuel transportation accident risk using a ''worst-case'' water contamination scenario. The scenario used for the analysis involves an accident release that occurs near a reservoir. Water pathway doses are compared to doses for accident releases in urban or agricultural areas. The results of the analysis indicate that water pathways are not important for assessing the risk of transporting spent reactor fuel by truck or by rail

  8. Transport of Mars atmospheric water into high northern latitudes during a polar warming

    Science.gov (United States)

    Barnes, J. R.; Hollingsworth, J. L.

    1988-01-01

    Several numerical experiments were conducted with a simplified tracer transport model in order to attempt to examine the poleward transport of Mars atmospheric water during a polar warming like that which occurred during the winter solstice dust storm of 1977. The flow for the transport experiments was taken from numerical simulations with a nonlinear beta-plane dynamical model. Previous studies with this model have demonstrated that a polar warming having essential characteristics like those observed during the 1977 dust storm can be produced by a planetary wave mechanism analogous to that responsible for terrestrial sudden stratospheric warmings. Several numerical experiments intended to simulate water transport in the absence of any condensation were carried out. These experiments indicate that the flow during a polar warming can transport very substantial amounts of water to high northern latitudes, given that the water does not condense and fall out before reaching the polar region.

  9. Sodium and chloride transport in soft water and hard water acclimated zebrafish (Danio rerio)

    DEFF Research Database (Denmark)

    Boisen, A M Z; Amstrup, J; Novak, I

    2003-01-01

    pump activity, changes in abundance and possibly localization of this protein did not appear to contribute to soft water acclimation. Active Cl(-) uptake was strongly dependent on branchial carbonic anhydrase (CA) activity regardless of water type, while the response of Na(+) transport to a CA...

  10. Structure-function relationships in sapwood water transport and storage.

    Science.gov (United States)

    Barbara L. Gartner; Frederick C. Meinzer

    2005-01-01

    Primary production by plants requires the loss of substantial quantities of water when the stomata are open for carbon assimilation. The delivery of that water to the leaves occurs through the xylem. The structure, condition, and quantity of the xylem control not only the transport efficiency but also the release of water from storage. For example, if there is high...

  11. Online estimation of radionuclide transportation in water environment

    International Nuclear Information System (INIS)

    Yi-Jing Zhang; Li-Sheng Hu

    2017-01-01

    Transportation evaluation of the radionuclide waste discharged from nuclear power plants is an essential licensing issue, especially for inland sites. Basically, the dynamics of radionuclide transportation are nonlinear and time-varying. Motivated by its time-consuming computation, the work proposed an online estimation method for the radionuclide waste in water surface. After extracting the nonlinearity of factors influencing radionuclide transportation, the method utilizes transfer function and generalized autoregressive conditional heteroskedasticity models to perform deterministic and probabilistic estimations. It turns out that, the resulting predictions show high accuracy and can optimize the online discharge management of radioactive waste for nuclear power plants. (author)

  12. Enhanced water transport and salt rejection through hydrophobic zeolite pores

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N.

    2017-12-01

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  13. Spent nuclear fuel transportation casks evaluation for water in-leakage

    International Nuclear Information System (INIS)

    Shah, M.J.; Huang, D.T.; Guttmann, J.; Klymyshyn, N.A.; Koeppel, B.J.; Adkins, H.E.

    2004-01-01

    The United States Nuclear Regulatory Commission (USNRC) is responsible for licensing commercial spent fuel storage and transportation systems. To ensure that the regulations are risk-informed, and do not place unnecessary regulatory burden on the industry, the USNRC has been examining its regulations that apply to spent fuel transportation casks for maintaining sub-criticality under hypothetical accident conditions. Code of Federal Regulations, Title 10, Part 71[1] (10 CFR 71), section 71.55(b) requires that, for evaluation of sub-criticality for fissile material packages, water moderation should be assumed to occur to the most reactive credible extent consistent with the chemical and physical form of the contents. This requirement is based on a defense-in-depth policy, and accounts for any possibility of water intrusion into the package. This program is designed to quantify the margins of safety of certified transportation casks to water intrusion following hypothetical accident conditions. This paper describes the current status of analytical work being performed to evaluate two USNRC-certified spent fuel transportation casks, HI-STAR 100[2] and TN-68[3]. The analytical work is performed using the ANSYS registered [4] and LS-DYNA trademark [5] finite element analysis (FEA) codes. The models are sufficiently detailed in the areas of bolt closure interfaces and containment boundaries to evaluate the likelihood water in-leakage under free drop hypothetical accident conditions of 10 CFR 71.73

  14. Enhanced water transport and salt rejection through hydrophobic zeolite pores.

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N

    2017-12-15

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  15. An Isotopic view of water and nitrogen transport through the ...

    Science.gov (United States)

    Groundwater nitrate contamination affects thousands of households in Oregon’s southern Willamette Valley and many more across the Pacific Northwest. The southern Willamette Valley Groundwater Management Area (SWV GWMA) was established in 2004 due to nitrate levels in the groundwater exceeding the human health standard of 10 mg nitrate-N L-1. Much of the nitrogen inputs to the GWMA comes from agricultural nitrogen use, and thus efforts to reduce N inputs to groundwater are focused upon improving N management. However, the effectiveness of these improvements on groundwater quality is unclear because of the complexity of nutrient transport through the vadose zone and long groundwater residence times. Our objective was to focus on vadose zone transport and understand the dynamics and timing of N and water movement below the rooting zone in relation to N management and water inputs. Stable isotopes are a powerful tool for tracking water movement, and understanding nitrogen transformations within the vadose zone. In partnership with local farmers, and state agencies, we established lysimeters and groundwater wells in multiple agricultural fields in the GWMA, and have monitored nitrate, nitrate isotopes, and water isotopes weekly for multiple years. Our results indicate that vadose zone transport is highly complex, and the residence time of water collected in lysimeters was much longer than expected. While input precipitation water isotopes were highly variab

  16. CFD Model of Water Droplet Transport for ISS Hygiene Activity

    Science.gov (United States)

    Son, Chang H.

    2011-01-01

    The goal of the study is to assess the impacts of free water propagation in the Waste and Hygiene Compartment (WHC). Free water can be generated inside the WHC in small quantities due to crew hygiene activity. To mitigate potential impact of free water in Node 3 cabin the WHC doorway is enclosed by a waterproof bump-out, Kabin, with openings at the top and bottom. At the overhead side of the rack, there is a screen that prevents large drops of water from exiting. However, as the avionics fan in the WHC causes airflow toward the deck side of the rack, small quantities of free water may exit at the bottom of the Kabin. A Computational Fluid Dynamics (CFD) analysis of Node 3 cabin airflow made possible to identify the paths of water transport. The Node 3 airflow was computed for several ventilation scenarios. To simulate the droplet transport the Lagrangian discrete phase approach was used. Various initial droplet distributions were considered in the study. The droplet diameter was varied in the range of 2-20 mm. The results of the computations showed that most of the drops fall to the rack surface not far from the WHC curtain. The probability of the droplet transport to the adjacent rack surface with electronic equipment was predicted.

  17. Dynamic model of ion and water transport in ionic polymer-metal composites

    Directory of Open Access Journals (Sweden)

    Zicai Zhu

    2011-12-01

    Full Text Available In the process of electro-mechanical transduction of ionic polymer-metal composites (IPMCs, the transport of ion and water molecule plays an important role. In this paper, the theoretical transport models of IPMCs are critically reviewed, with particular emphasis on the recent developments in the latest decade. The models can be divided into three classes, thermodynamics of irreversible process model, frictional model and Nernst-Planck (NP equation model. To some extent the three models can be transformed into each other, but their differences are also obvious arising from the various mechanisms that considered in different models. The transport of ion and water molecule in IPMCs is compared with that in membrane electrode assembly and electrodialysis membrane to identify and clarify the fundamental transport mechanisms in IPMCs. And an improved transport model is proposed and simplified for numerical analysis. The model considers the convection effect rather than the diffusion as the major transport mechanism, and both the self-diffusion and the electroosmosis drag are accounted for in the water flux equation.

  18. Model for radionuclide transport in running waters

    International Nuclear Information System (INIS)

    Jonsson, Karin; Elert, Mark

    2005-11-01

    Two sites in Sweden are currently under investigation by SKB for their suitability as places for deep repository of radioactive waste, the Forsmark and Simpevarp/Laxemar area. As a part of the safety assessment, SKB has formulated a biosphere model with different sub-models for different parts of the ecosystem in order to be able to predict the dose to humans following a possible radionuclide discharge from a future deep repository. In this report, a new model concept describing radionuclide transport in streams is presented. The main difference from the previous model for running water used by SKB, where only dilution of the inflow of radionuclides was considered, is that the new model includes parameterizations also of the exchange processes present along the stream. This is done in order to be able to investigate the effect of the retention on the transport and to be able to estimate the resulting concentrations in the different parts of the system. The concentrations determined with this new model could later be used for order of magnitude predictions of the dose to humans. The presented model concept is divided in two parts, one hydraulic and one radionuclide transport model. The hydraulic model is used to determine the flow conditions in the stream channel and is based on the assumption of uniform flow and quasi-stationary conditions. The results from the hydraulic model are used in the radionuclide transport model where the concentration is determined in the different parts of the stream ecosystem. The exchange processes considered are exchange with the sediments due to diffusion, advective transport and sedimentation/resuspension and uptake of radionuclides in biota. Transport of both dissolved radionuclides and sorbed onto particulates is considered. Sorption kinetics in the stream water phase is implemented as the time scale of the residence time in the stream water probably is short in comparison to the time scale of the kinetic sorption. In the sediment

  19. Model for radionuclide transport in running waters

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, Karin; Elert, Mark [Kemakta Konsult AB, Stockholm (Sweden)

    2005-11-15

    Two sites in Sweden are currently under investigation by SKB for their suitability as places for deep repository of radioactive waste, the Forsmark and Simpevarp/Laxemar area. As a part of the safety assessment, SKB has formulated a biosphere model with different sub-models for different parts of the ecosystem in order to be able to predict the dose to humans following a possible radionuclide discharge from a future deep repository. In this report, a new model concept describing radionuclide transport in streams is presented. The main difference from the previous model for running water used by SKB, where only dilution of the inflow of radionuclides was considered, is that the new model includes parameterizations also of the exchange processes present along the stream. This is done in order to be able to investigate the effect of the retention on the transport and to be able to estimate the resulting concentrations in the different parts of the system. The concentrations determined with this new model could later be used for order of magnitude predictions of the dose to humans. The presented model concept is divided in two parts, one hydraulic and one radionuclide transport model. The hydraulic model is used to determine the flow conditions in the stream channel and is based on the assumption of uniform flow and quasi-stationary conditions. The results from the hydraulic model are used in the radionuclide transport model where the concentration is determined in the different parts of the stream ecosystem. The exchange processes considered are exchange with the sediments due to diffusion, advective transport and sedimentation/resuspension and uptake of radionuclides in biota. Transport of both dissolved radionuclides and sorbed onto particulates is considered. Sorption kinetics in the stream water phase is implemented as the time scale of the residence time in the stream water probably is short in comparison to the time scale of the kinetic sorption. In the sediment

  20. Dissolution of subglacial volcanic glasses from Iceland: laboratory study and modelling

    International Nuclear Information System (INIS)

    Crovisier, J.-L.; Honnorez, J.; Fritz, B.; Petit, J.-C.

    1992-01-01

    Subglacial hyaloclastites from Iceland with ages ranging from 2 ka to 2.2 Ma have been studied from a mineralogical and geochemical standpoint. The chemical composition of palagonite (alteration crust formed on the surface of the glass) is almost identical with that of the clayey material filling the intergranular spaces of the rock. The clayey material is made up of two particle populations: the first is Si-, Mg-and Ca-rich with a smectite structure, while the second is amorphous, Fe-, Ti- and Al-rich, and has a smectite-like morphology. It is suggested that these two types of particles can be formed simultaneously, in the same solution, such that it is not necessary to explain their existence by local or temporary equilibria. The mineralogical sequences observed in natural samples were reproduced using the geochemical computer code DISSOL. The geochemical mass balances calculated with DISSOL also fit quite well with those calculated from Icelandic samples, illustrating the predictive capability of such a calculation code and give us confidence in applying a similar approach to nuclear waste-form glass problems. (author)

  1. PREDICTED SEDIMENTARY SECTION OF SUBGLACIAL LAKE VOSTOK

    Directory of Open Access Journals (Sweden)

    G. I. Leychenkov

    2012-01-01

    Full Text Available In early February 2012, the drill hole at the Vostok Station encountered theLakeVostokwater. This step is important to study the lake composition including possible microbial life and to model subglacial environments however, the next ambitious target of the Vostok Drilling Project is sampling of bottom sediments, which contain the unique record of ice sheet evolution and environmental changes in centralAntarcticafor millions of years. In this connection, the forecast of sedimentary succession based on existing geophysical data, study of mineral inclusions in the accretion ice cores and tectonic models is important task. Interpretation of Airborne geophysical data suggests thatLakeVostokis the part of spacious rift system, which exists at least from Cretaceous. Reflection and refraction seismic experiments conducted in the southern part ofLakeVostokshow very thin (200–300 m stratified sedimentary cover overlying crystalline basement with velocity of 6.0–6.2 km/s. At present, deposition in southernLakeVostokis absent and similar conditions occurred likely at least last3 m.y. when ice sheet aboveLakeVostokchanged insignificantly. It can be also inferred that from the Late Miocene the rate of deposition inLakeVostokwas extremely low and so the most of sedimentary section is older being possibly of Oligocene to early to middle Miocene age when ice sheet oscillated and deposition was more vigorous. If so, the sampling of upper few meters of this condensed section is very informative in terms of history of Antarctic glaciation. Small thickness of sedimentary cover raises a question about existence of lake (rift depression during preglacial and early glacial times.

  2. Modeling of radiocesium transport kinetics in system water-aquatic plants

    International Nuclear Information System (INIS)

    Svadlenkova, M.

    1988-01-01

    Compartment models were used to describe the kinetics of the transport of radionuclides in the system water-biomass of aquatic plants. Briefly described are linear models and models with time variable parameters. The model was tested using data from a locality in the environs of the Bohunice nuclear power plant. Cladophora glomerata algae were the monitored plants, 137 Cs the monitored radionuclide. The models may be used when aquatic plants serve as bioindicators of the radioactive contamination of surface waters, for monitoring the transport of radionuclides in food chains. (M.D.). 10 refs

  3. Climatic Analysis of Oceanic Water Vapor Transports Based on Satellite E-P Datasets

    Science.gov (United States)

    Smith, Eric A.; Sohn, Byung-Ju; Mehta, Vikram

    2004-01-01

    Understanding the climatically varying properties of water vapor transports from a robust observational perspective is an essential step in calibrating climate models. This is tantamount to measuring year-to-year changes of monthly- or seasonally-averaged, divergent water vapor transport distributions. This cannot be done effectively with conventional radiosonde data over ocean regions where sounding data are generally sparse. This talk describes how a methodology designed to derive atmospheric water vapor transports over the world oceans from satellite-retrieved precipitation (P) and evaporation (E) datasets circumvents the problem of inadequate sampling. Ultimately, the method is intended to take advantage of the relatively complete and consistent coverage, as well as continuity in sampling, associated with E and P datasets obtained from satellite measurements. Independent P and E retrievals from Special Sensor Microwave Imager (SSM/I) measurements, along with P retrievals from Tropical Rainfall Measuring Mission (TRMM) measurements, are used to obtain transports by solving a potential function for the divergence of water vapor transport as balanced by large scale E - P conditions.

  4. Water transport mechanisms across inorganic membranes in rad waste treatment by electro dialysis

    International Nuclear Information System (INIS)

    Andalaft, E.; Labayru, R.

    1992-01-01

    The work described in this paper deals with effects and mechanisms of water transport across an inorganic membrane, as related to some studied on the concentration of caesium, strontium, plutonium and other cations of interest to radioactive waste treatment. Several different water transport mechanisms are analysed and assessed as to their individual contribution towards the total transference of water during electro-dialysis using inorganic membranes. Water transfer assisted by proton jump mechanism, water of hydration transferred along with the ions, water related to thermo-osmotic effect, water transferred by concentration gradient and water transferred electrolytically under zeta potential surface charge drive are some of the different mechanism discussed. (author)

  5. Unsaturated water flow and tracer transport modeling with Alliances

    Energy Technology Data Exchange (ETDEWEB)

    Constantin, Alina, E-mail: alina.constantin@nuclear.ro [Institute for Nuclear Research, Campului Str, No. 1, PO Box 78, Postal Code 115400 Mioveni, Arges County (Romania); Genty, Alain, E-mail: alain.genty@cea.fr [CEA Saclay, DM2S/SFME/LSE, Gif-sur-Yvette 91191 cedex (France); Diaconu, Daniela; Bucur, Crina [Institute for Nuclear Research, Campului Str, No. 1, PO Box 78, Postal Code 115400 Mioveni, Arges County (Romania)

    2013-12-15

    Highlights: • Simulation of water flow and solute transport at Saligny site, Romania was done. • Computation was based on the available experimental data with Alliances platform. • Very good results were obtained for the saturation profile in steady state. • Close fit to experimental data for saturation profile at 3 m in transient state. • Large dispersivity coefficients were fitted to match tracer experiment. - Abstract: Understanding water flow and solute transport in porous media is of central importance in predicting the radionuclide fate in the geological environment, a topic of interest for the performance and safety assessment studies for nuclear waste disposal. However, it is not easy to predict transport properties in real systems because they are geologically heterogeneous from the pore scale upwards. This paper addresses the simulation of water flow and solute transport in the unsaturated zone of the Saligny site, the potential location for the Romanian low and intermediate level waste (LILW) disposal. Computation was based on the current available experimental data for this zone and was performed within Alliances, a software platform initially jointly developed by French organizations CEA, ANDRA and EDF. The output of the model developed was compared with the measured values in terms of saturation profile of the soil for water movement, in both steady and transient state. Very good results were obtained for the saturation profile in steady state and a close fit of the simulation over experimental data for the water saturation profile at a depth of 3 m in transient state. In order to obtain information regarding the solute migration in depth and the solute lateral dispersion, a tracer test was launched on site and dispersivity coefficients of the solute were fitted in order to match the experimental concentration determined on samples from different locations of the site. Results much close to the experiment were obtained for a longitudinal

  6. Fast Water Transport in CNTs: length dependence and entrane/exit effects

    DEFF Research Database (Denmark)

    Walther, Jens Honore; Koumoutsakos, Petros

    Superfast water transport in carbon nanotube (CNT) membranes has been reported in experimental studies. We use Molecular Dynamics simulations to elucidate the mechanisms of water entry, exit and transport in 2nm-diameter hydrophobic CNTs embedded in a hydrophilic membrane matrix. We demonstrate......, for the first time, that under imposed pressures of the order of 1 bar, water entry into the CNT cavity and exit from the CNT end, can occur only on pre-wetted membranes. We conduct large scale simulations for up to 500nm long CNTs and observe a previously unseen dependence of the flow enhancement rates...

  7. Describing the Components of the Water Transport in the Martian Atmosphere

    Science.gov (United States)

    Montmessin, F.; Haberle, R. M.; forget, F.; Rannou, P.; Cabane, M.

    2003-01-01

    In this paper, we examine the meteorological components driving water transport in the Martian atmosphere. A particular emphasis is given to the role of residual mean circulation and water ice clouds in determining the geographical partitioning of water vapor and frost.

  8. Field-scale water flow and solute transport : SWAP model concepts, parameter estimation and case studies = [Waterstroming en transport van opgeloste stoffen op veldschaal

    NARCIS (Netherlands)

    Dam, van J.C.

    2000-01-01

    Water flow and solute transport in top soils are important elements in many environmental studies. The agro- and ecohydrological model SWAP (Soil-Water-Plant-Atmosphere) has been developed to simulate simultaneously water flow, solute transport, heat flow and crop growth at field scale

  9. Effect of sunlight, transport and storage vessels on drinking water ...

    African Journals Online (AJOL)

    Effect of sunlight, transport and storage vessels on drinking water quality in rural Ghana. ... on drinking water quality in rural Ghana. K Obiri-Danso, E Amevor, LA Andoh, K Jones ... Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  10. Simulating liquid water for determining its structural and transport properties

    International Nuclear Information System (INIS)

    Arismendi-Arrieta, Daniel; Medina, Juan S.; Fanourgakis, George S.; Prosmiti, Rita; Delgado-Barrio, Gerardo

    2014-01-01

    Molecular dynamics simulations are carried out for calculating structural and transport properties of pure liquid water, such as radial distribution functions and self-diffusion and viscosity coefficients, respectively. We employed reparameterized versions of the ab initio water potential by Niesar, Clementi and Corongiu (NCC). In order to investigate the role of the electrostatic contribution, the partial charges of the NCC model are adjusted so that to reproduce the dipole moment values of the SPC/E, SPC/Fw and TIP4P/2005 water models. The single and collective transport coefficients are obtained by employing the Green–Kubo relations at various temperatures. Additionally, in order to overcome convergence difficulties arising from the long correlation times of the stress-tensor autocorrelation functions, a previously reported fitting scheme was employed. The present results indicate that there is a significant relationship between the dipole moment value of the model, and the calculated transport coefficients. We found that by adjusting the molecular dipole moment of the NCC to the value of the TIP4P/2005, the obtained values for the self-diffusion and viscosity coefficients are in better agreement with experiment, compared to the values obtained with the original NCC model. Even though the predictions of the present model exhibits an overall correct behavior, we conclude that further improvements are still required. In order to achieve that, a careful reparameterization of the repulsion–dispersion terms of the potential model is proposed. Also, the effect of the inclusion of many-body effects such as polarizability, should also be investigated. - Highlights: ► Transport properties of liquid water are important in bio-simulations. ► Self-diffusion coefficient, shear and bulk viscosities calculations from NVE molecular dynamics simulations. ► Their comparison with experimental data provides information on intermolecular forces, and serve to develop water

  11. Development of a Life Cycle Inventory of Water Consumption Associated with the Production of Transportation Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lampert, David J. [Argonne National Lab. (ANL), Argonne, IL (United States); Cai, Hao [Argonne National Lab. (ANL), Argonne, IL (United States); Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States); Keisman, Jennifer [Argonne National Lab. (ANL), Argonne, IL (United States); Wu, May [Argonne National Lab. (ANL), Argonne, IL (United States); Han, Jeongwoo [Argonne National Lab. (ANL), Argonne, IL (United States); Dunn, Jennifer [Argonne National Lab. (ANL), Argonne, IL (United States); Sullivan, John L. [Argonne National Lab. (ANL), Argonne, IL (United States); Elgowainy, Amgad [Argonne National Lab. (ANL), Argonne, IL (United States); Wang, Michael [Argonne National Lab. (ANL), Argonne, IL (United States); Keisman, Jennifer [American Association for the Advancemetn of Science (AAAS), Washington, DC (United States)

    2015-10-01

    The production of all forms of energy consumes water. To meet increased energy demands, it is essential to quantify the amount of water consumed in the production of different forms of energy. By analyzing the water consumed in different technologies, it is possible to identify areas for improvement in water conservation and reduce water stress in energy-producing regions. The transportation sector is a major consumer of energy in the United States. Because of the relationships between water and energy, the sustainability of transportation is tied to management of water resources. Assessment of water consumption throughout the life cycle of a fuel is necessary to understand its water resource implications. To perform a comparative life cycle assessment of transportation fuels, it is necessary first to develop an inventory of the water consumed in each process in each production supply chain. The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model is an analytical tool that can used to estimate the full life-cycle environmental impacts of various transportation fuel pathways from wells to wheels. GREET is currently being expanded to include water consumption as a sustainability metric. The purpose of this report was to document data sources and methodologies to estimate water consumption factors (WCF) for the various transportation fuel pathways in GREET. WCFs reflect the quantity of freshwater directly consumed per unit production for various production processes in GREET. These factors do not include consumption of precipitation or low-quality water (e.g., seawater) and reflect only water that is consumed (i.e., not returned to the source from which it was withdrawn). The data in the report can be combined with GREET to compare the life cycle water consumption for different transportation fuels.

  12. Model for tritiated water transport in soil

    International Nuclear Information System (INIS)

    Galeriu, D.; Paunescu, N.

    1999-01-01

    Chemical forms of tritium released from nuclear facilities are mostly water (HTO) and hydrogen (HT, TT). Elemental tritium is inert in vegetation and superior animals, but the microorganisms from soil oxidize HT to HTO. After an atmospheric HT emission, in short time an equivalent quantity of HTO is re-emitted from soil. In the vicinity of a tritium source the spatial and temporary distribution of HTO is dependent on the chemical form of tritium releases. During routine tritium releases (continuously and constant releases), the local distribution of tritium reaches equilibrium, and specific activities of tritium in environmental compartments are almost equal. The situation is very different after an accidental emission. Having in view, harmful effects of tritium when it is incorporated into the body several models were developed for environmental tritium transport and dose assessment. The tritium transport into the soil is an important part of the environmental tritium behavior, but, unfortunately, in spite of the importance of this problem the corresponding modeling is unsatisfactory. The aim of this paper was the improvement of the TRICAIAP model, and the application of the model to BIOMOVS scenario. The BIOMOVS scenario predicts HTO concentrations in soil during 30 days, after one hour atmospheric HTO emission. The most important conclusions of the paper are: the principal carrier of tritium into the soil is water; the transfer processes are the reactions of water in soil and the diffusion due to concentration gradient; atmosphere-soil transport is dependent of surface characteristics (granulation, humidity, roughness, etc.); the conversion rate of HT to HTO is not well known and is dependent on active microorganism concentration in soil and on soil humidity. More experimental data are needed to decrease the uncertainty of transfer parameter, for the definition of the influence of vegetation, etc. (authors)

  13. Modeling water flow and solute transport in unsaturated zone inside NSRAWD project

    International Nuclear Information System (INIS)

    Constantin, A.; Diaconu, D.; Bucur, C.; Genty, A.

    2015-01-01

    The NSRAWD project (2010-2013) - Numerical Simulations for Radioactive Waste Disposal was initiated under a collaboration agreement between the Institute for Nuclear Research and the French Alternative Energies and Atomic Energy Commission (CEA). The context of the project was favorable to combine the modeling activities with an experimental part in order to improve and validate the numerical models used so far to simulate water flow and solute transport at Saligny site, Romania. The numerical models developed in the project were refined and validated on new hydrological data gathered between 2010-2012 by a monitoring station existent on site which performs automatic determination of soil water content and matrix potential, as well as several climate parameters (wind, temperature and precipitations). Water flow and solute transport was modeled in transient conditions, by taking into consideration, as well as neglecting the evapotranspiration phenomenon, on the basis of a tracer test launched on site. The determination of dispersivities for solute transport was targeted from the solute plume. The paper presents the main results achieved in the NSRAWD project related to water flow and solute transport in the unsaturated area of the Saligny site. The results indicated satisfactory predictions for the simulation of water flow in the unsaturated area, in steady state and transient conditions. In the case of tracer transport modeling, dispersivity coefficients could not be finally well fitted for the data measured on site and in order to obtain a realistic preview over the values of these parameters, further investigations are recommended. The article is followed by the slides of the presentation

  14. Transport mechanisms in capillary condensation of water at a single-asperity nanoscopic contact.

    Science.gov (United States)

    Sirghi, Lucel

    2012-02-07

    Transport mechanisms involved in capillary condensation of water menisci in nanoscopic gaps between hydrophilic surfaces are investigated theoretically and experimentally by atomic force microscopy (AFM) measurements of capillary force. The measurements showed an instantaneous formation of a water meniscus by coalescence of the water layers adsorbed on the AFM tip and sample surfaces, followed by a time evolution of meniscus toward a stationary state corresponding to thermodynamic equilibrium. This dynamics of the water meniscus is indicated by time evolution of the meniscus force, which increases with the contact time toward its equilibrium value. Two water transport mechanisms competing in this meniscus dynamics are considered: (1) Knudsen diffusion and condensation of water molecules in the nanoscopic gap and (2) adsorption of water molecules on the surface region around the contact and flow of the surface water toward the meniscus. For the case of very hydrophilic surfaces, the dominant role of surface water transportation on the meniscus dynamics is supported by the results of the AFM measurements of capillary force of water menisci formed at sliding tip-sample contacts. These measurements revealed that fast movement of the contact impedes on the formation of menisci at thermodynamic equilibrium because the flow of the surface water is too slow to reach the moving meniscus.

  15. Axial and radial water transport and internal water storage in tropical forest canopy trees.

    Science.gov (United States)

    Shelley A. James; Frederick C. Meinzer; Guillermo Goldstein; David Woodruff; Timothy Jones; Teresa Restom; Monica Mejia; Michael Clearwater; Paula. Campanello

    2003-01-01

    Heat and stable isotope tracers were used to study axial and radial water transport in relation to sapwood anatomical characteristics and internal water storage in four canopy tree species of a seasonally dry tropical forest in Panama. Anatomical characteristics of the wood and radial profiles of sap flow were measured at the base, upper trunk, and crown of a single...

  16. Mathematical model of water transport in Bacon and alkaline matrix-type hydrogen-oxygen fuel cells

    Science.gov (United States)

    Prokopius, P. R.; Easter, R. W.

    1972-01-01

    Based on general mass continuity and diffusive transport equations, a mathematical model was developed that simulates the transport of water in Bacon and alkaline-matrix fuel cells. The derived model was validated by using it to analytically reproduce various Bacon and matrix-cell experimental water transport transients.

  17. Water Transport in Lower Hillsborough Bay, Florida, 1995-96

    National Research Council Canada - National Science Library

    Levesque, Victor A; Hammett, K. M

    1997-01-01

    .... Beginning in December 1994, a series of reconnaissance measurements were made to define the probable maximum extent of the area where it could be possible to discern water transport associated...

  18. Assessment the effect of homogenized soil on soil hydraulic properties and soil water transport

    Science.gov (United States)

    Mohawesh, O.; Janssen, M.; Maaitah, O.; Lennartz, B.

    2017-09-01

    Soil hydraulic properties play a crucial role in simulating water flow and contaminant transport. Soil hydraulic properties are commonly measured using homogenized soil samples. However, soil structure has a significant effect on the soil ability to retain and to conduct water, particularly in aggregated soils. In order to determine the effect of soil homogenization on soil hydraulic properties and soil water transport, undisturbed soil samples were carefully collected. Five different soil structures were identified: Angular-blocky, Crumble, Angular-blocky (different soil texture), Granular, and subangular-blocky. The soil hydraulic properties were determined for undisturbed and homogenized soil samples for each soil structure. The soil hydraulic properties were used to model soil water transport using HYDRUS-1D.The homogenized soil samples showed a significant increase in wide pores (wCP) and a decrease in narrow pores (nCP). The wCP increased by 95.6, 141.2, 391.6, 3.9, 261.3%, and nCP decreased by 69.5, 10.5, 33.8, 72.7, and 39.3% for homogenized soil samples compared to undisturbed soil samples. The soil water retention curves exhibited a significant decrease in water holding capacity for homogenized soil samples compared with the undisturbed soil samples. The homogenized soil samples showed also a decrease in soil hydraulic conductivity. The simulated results showed that water movement and distribution were affected by soil homogenizing. Moreover, soil homogenizing affected soil hydraulic properties and soil water transport. However, field studies are being needed to find the effect of these differences on water, chemical, and pollutant transport under several scenarios.

  19. Some analytic diagnostic models for transport processes in estuarine and coastal waters

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2001-03-01

    Advection and dispersion processes in estuarine and coastal waters are briefly reviewed. Beginning from the basic macroscopic equations of transport for a substance diluted or suspended in the considered body of water,several levels of filtering in time and space are described and applied to obtain suitable diagnostic mathematical models both with scale effects and gaussian.The solutions of the aforementioned models,for initial distributions and boundary conditions with enough symmetry,are discussed, as well as their applications to a parameter characterization of the transport properties of the receiving body of water

  20. Lagrangian study of transport of subarctic water across the Subpolar Front in the Japan Sea

    Science.gov (United States)

    Prants, Sergey V.; Uleysky, Michael Yu.; Budyansky, Maxim V.

    2018-05-01

    The southward near-surface transport of transformed subarctic water across the Subpolar Front in the Japan Sea is simulated and analyzed based on altimeter data from January 1, 1993 to December 31, 2017. Computing Lagrangian indicators for a large number of synthetic particles, advected by the AVISO velocity field, we find preferred transport pathways across the Subpolar Front. The southward transport occurs mainly in the central part of the frontal zone due to suitable dispositions of mesoscale eddies promoting propagation of subarctic water to the south. It is documented with the help of Lagrangian origin and L-maps and verified by the tracks of available drifters. The transport of transformed subarctic water to the south is compared with the transport of transformed subtropical water to the north simulated by Prants et al. (Nonlinear Process Geophys 24(1):89-99, 2017c).

  1. Pupils' Response to a Model for Water Transport.

    Science.gov (United States)

    Johnstone, A. H.; Mahmoud, N. A.

    1981-01-01

    Described is a model, based on the physical sciences, designed to teach secondary students about water transport through the use of an animated film. Pupils (N=440) taught by this method developed a self-consistent, although reduced, picture and understanding of osmosis. (Author/DC)

  2. Speciation and transport of radionuclides in ground water

    International Nuclear Information System (INIS)

    Robertson, D.E.; Toste, A.P.; Abel, K.H.; Cowan, C.E.; Jenne, E.A.; Thomas, C.W.

    1984-01-01

    Studies of the chemical speciation of a number of radionuclides migrating in a slightly contaminated ground water plume are identifying the most mobile species and providing an opportunity to test and/or validate geochemical models of radionuclide transport in ground waters. Results to date have shown that most of the migrating radionuclides are present in anionic or nonionic forms. These include anionic forms of 55 Fe, 60 Co, /sup 99m/Tc, 106 Ru, 131 I, and nonionic forms of 63 Ni and 125 Sb. Strontium-70 and a small fraction of the mobile 60 Co are the only cationic radionuclides which have been detected moving in the ground water plume beyond 30 meters from the source. A comparison of the observed chemical forms with the predicted species calculated from modeling thermodynamic data and ground water chemical parameters has indicated a good agreement for most of the radioelements in the system, including Tc, Np, Cs, Sr, Ce, Ru, Sb, Zn, and Mn. The discrepancies between observed and calculated solutions species were noted for Fe, Co, Ni and I. Traces of Fe, Co, and Ni were observed to migrate in anionic or nonionic forms which the calculations failed to predict. These anionic/nonionic species may be organic complexes having enhanced mobility in ground waters. The radioiodine, for example, was shown to behave totally as an anion but further investigation revealed that 49-57% of this anionic iodine was organically bound. The ground water and aqueous extracts of trench sediments contain a wide variety of organic compounds, some of which could serve as complexing agents for the radionuclides. These results indicate the need for further research at a variety of field sites in defining precisely the chemical forms of the mobile radionuclide species, and in better understanding the role of dissolved organic materials in ground water transport of radionuclides

  3. Managing erosion, sediment transport and water quality in drained peatland catchments

    Energy Technology Data Exchange (ETDEWEB)

    Marttila, H.

    2010-07-01

    Peatland drainage changes catchment conditions and increases the transport of suspended solids (SS) and nutrients. New knowledge and management methods are needed to reduce SS loading from these areas. This thesis examines sediment delivery and erosion processes in a number of peatland drainage areas and catchments in order to determine the effects of drainage on sediment and erosion dynamics and mechanics. Results from studies performed in peat mining, peatland forestry and disturbed headwater catchments in Finland are presented and potential sediment load management methods are discussed for drainage areas and headwater brooks. Particular attention is devoted to erosion of organic peat, sediment transport and methods to reduce the impacts of peatland drainage in boreal headwaters. This thesis consists of six articles. The first and second papers focus on the erosion and sediment transport processes at peat harvesting and peatland forestry drainage networks. The results indicate that in-channel processes are important in drained peatland, since the drainage network often constitutes temporary inter-storm storage for eroding and transporting material. Sediment properties determine the bed sediment erosion sensitivity, as fluffy organic peat sediment consolidates over time. As flashiness and peak runoff control sediment entrainment and transport from drained peatland areas, water quality management should include peak runoff management. The third, fourth and fifth papers studies use and application of peak runoff control (PRC) method to the peat harvesting and peatland forestry conditions for water protection. Results indicate that effective water quality management in drained peatland areas can be achieved using this method. Installation of the PRC structures is a useful and cost-effective way of storing storm runoff waters temporarily in the ditch system and providing a retention time for eroded sediment to settle to the ditch bed and drainage network. The main

  4. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

    International Nuclear Information System (INIS)

    Tucci, P.

    2001-01-01

    This Analysis/Model Report (AMR) documents an updated analysis of water-level data performed to provide the saturated-zone, site-scale flow and transport model (CRWMS M and O 2000) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for model calibration. The previous analysis was presented in ANL-NBS-HS-000034, Rev 00 ICN 01, Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (USGS 2001). This analysis is designed to use updated water-level data as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain. The objectives of this revision are to develop computer files containing (1) water-level data within the model area (DTN: GS010908312332.002), (2) a table of known vertical head differences (DTN: GS0109083 12332.003), and (3) a potentiometric-surface map (DTN: GS010608312332.001) using an alternate concept from that presented in ANL-NBS-HS-000034, Rev 00 ICN 01 for the area north of Yucca Mountain. The updated water-level data include data obtained from the Nye County Early Warning Drilling Program (EWDP) and data from borehole USW WT-24. In addition to being utilized by the SZ site-scale flow and transport model, the water-level data and potentiometric-surface map contained within this report will be available to other government agencies and water users for ground-water management purposes. The potentiometric surface defines an upper boundary of the site-scale flow model, as well as provides information useful to estimation of the magnitude and direction of lateral ground-water flow within the flow system. Therefore, the analysis documented in this revision is important to SZ flow and transport calculations in support of total system performance assessment

  5. Simulation of water movement and NaCl transport

    International Nuclear Information System (INIS)

    Li Xun; Zheng Zhihong; Yang Zeping

    2008-01-01

    Modeling of water flow and solute transport in the near-field of a high-level radioactive waste repository with TOUGH2 is done. The results show that salt accumulation in buffer material is not so significant, precipitation does not occur throughout the period covered by our simualtions. Further more, the changeable law of volumetric water content, liquid velocity and dissolved concentration of sodium chloride with simulated time or distance are attained, which is the base of understanding evolvement of near-field. (authors)

  6. Impact of carbonation on water transport properties of cementitious materials

    International Nuclear Information System (INIS)

    Auroy, Martin

    2014-01-01

    Carbonation is a very well-known cementitious materials pathology. It is the major cause of reinforced concrete structures degradation. It leads to rebar corrosion and consequent concrete cover cracking. In the framework of radioactive waste management, cement-based materials used as building materials for structures or containers would be simultaneously submitted to drying and atmospheric carbonation. Although scientific literature regarding carbonating is vast, it is clearly lacking information about the influence of carbonation on water transport properties. This work then aimed at studying and understanding the change in water transport properties induced by carbonation. Simultaneously, the representativeness of accelerated carbonation (in the laboratory) was also studied. (author) [fr

  7. Models of Fate and Transport of Pollutants in Surface Waters

    Science.gov (United States)

    Okome, Gloria Eloho

    2013-01-01

    There is the need to answer very crucial questions of "what happens to pollutants in surface waters?" This question must be answered to determine the factors controlling fate and transport of chemicals and their evolutionary state in surface waters. Monitoring and experimental methods are used in establishing the environmental states.…

  8. Numerical analysis of coupled water transport in wood with a focus on the coupling parameter sorption

    DEFF Research Database (Denmark)

    Hozjan, T.; Turk, G.; Rodman, U.

    2011-01-01

    This paper presents a study of sorption rate function in a so-called multi-Fickian or multi-phase model. This model describes the complex moisture transport system in wood, which consists of separate water-vapour and bound-water diffusion interacting through sorption. In the numerical example inf...... influence of the sorption rate function on water transport is presented. It can be seen that the sorption rate function has a noticeable influence on coupled water transport in wood....

  9. Measuring and modelling water transport on Skaftafellsheioi, Iceland

    NARCIS (Netherlands)

    Dijksma, R.; Avis, Lisette

    2017-01-01

    Areas with thick basaltic aquifers are used for drinking water supply and irrigation purposes, such as the Columbia River Basalt group in northwest USA and the Deccan Traps in India. However, rainfall-runoff processes in these basaltic areas are poorly understood. Cooling joints can transport large

  10. Measuring Transport of Water Across the Peritoneal Membrane

    Czech Academy of Sciences Publication Activity Database

    Asghar, R. B.; Diskin, A. M.; Španěl, Patrik; Smith, D.; Davies, S. J.

    2003-01-01

    Roč. 64, - (2003), s. 1911-1915 ISSN 0085-2538 R&D Projects: GA ČR GA202/03/0827 Institutional research plan: CEZ:AV0Z4040901 Keywords : deuterium * total body water * solute transport Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.302, year: 2003

  11. Monthly Variation of Taiwan Strait Through-flow Transports and Associated Water Masses

    Science.gov (United States)

    Jan, S.; Sheu, D.; Kuo, H.

    2005-05-01

    Through-flow transports and associated water masses are analyzed using current data measured by bottom-mounted and ship-board ADCP (1999-2001) across the central Taiwan Strait and strait-wide hydrographic data acquired from 79 CTD survey cruises (1986-2003). The East Asian monsoon, from southwest in July to August and northeast in October to March, controls the transport fluctuation which peaks in August (2.34 Sv northward), is hampered by the northeast monsoon after September and diminishes to the minimum (0.26 Sv southward) in December. The standard deviation of the calculated transport ranges from 0.56 to 1.05 Sv during northeast monsoon months and is relatively small in other months. A cluster analysis together with conventional T-S diagrams identifies the saline and warm Kuroshio Branch Water (KBW), the less saline South China Sea Surface Water (SCSSW), the brackish and cold China Coastal Water (CCW), the saline Subsurface Water (SW) (depth > 100 m) and the Diluted Coastal Water (DCW). The majority of the northward transport in summer carries the SCSSW to the East China Sea. Meanwhile, the DCW appears off the northwest bank of the strait and the SW resides in the bottom layer of a deep trench in the southeastern strait. The onset of the northeast monsoon in September drives the CCW from the Yangtze river mouth to the northern strait. In the southern strait, the northward-moving KBW replaces the SCSSW and meets the southward-intruding CCW in the middle strait during November to April.

  12. Osmoregulation and epithelial water transport: lessons from the intestine of marine teleost fish.

    Science.gov (United States)

    Whittamore, Jonathan M

    2012-01-01

    For teleost fish living in seawater, drinking the surrounding medium is necessary to avoid dehydration. This is a key component of their osmoregulatory strategy presenting the challenge of excreting excess salts while achieving a net retention of water. The intestine has an established role in osmoregulation, and its ability to effectively absorb fluid is crucial to compensating for water losses to the hyperosmotic environment. Despite this, the potential for the teleost intestine to serve as a comparative model for detailed, integrative experimental studies on epithelial water transport has so far gone largely untapped. The following review aims to present an assessment of the teleost intestine as a fluid-transporting epithelium. Beginning with a brief overview of marine teleost osmoregulation, emphasis shifts to the processing of ingested seawater by the gastrointestinal tract and the characteristics of intestinal ion and fluid transport. Particular attention is given to acid-base transfers by the intestine, specifically bicarbonate secretion, which creates the distinctly alkaline gut fluids responsible for the formation of solid calcium carbonate precipitates. The respective contributions of these unique features to intestinal fluid absorption, alongside other recognised ion transport processes, are then subsequently considered within the wider context of the classic physiological problem of epithelial water transport.

  13. The subglacial Lake Vostok (East Antarctica) surface snow is Earth-bound DNA (and dust)-free

    Science.gov (United States)

    Bulat, S.; Marie, D.; Bulat, E.; Alekhina, I.; Petit, J.-R.

    2012-09-01

    came up with only contaminant bacterial phylotypes (mostly of human source). The bioexposure trials showed that even in one day of open exposure the gDNA of rather complex microbial community composition was fatally damaged in terms of long-, mid-range and short-size amplicon generation in PCR. All this testify for very harsh conditions for life to survive the climate conditions of Central East Antarctica which could be considered as a presentday 'zone mortale' or 'polar desert' for known Earthbound microbial life forms. In addition this means that no life seeds are expected to reach subglacial lakes and water reservoirs and establish indigenous lake microbiota during their transit through the thick and aged Antarctic ice sheet upon its bottom melting. In general the subglacial Lake Vostok surface (ice sheet as well) environ represents the unique test area (sterile - in fact Earth-bound DNA-free and clean - in fact Earth-bound dust-free) for advancing extraterrestrial (ET) life detection technologies and searching for ET life indices in AMMs and IDPs.

  14. Erosion and Sediment Transport Modelling in Shallow Waters: A Review on Approaches, Models and Applications

    Directory of Open Access Journals (Sweden)

    Mohammad Hajigholizadeh

    2018-03-01

    Full Text Available The erosion and sediment transport processes in shallow waters, which are discussed in this paper, begin when water droplets hit the soil surface. The transport mechanism caused by the consequent rainfall-runoff process determines the amount of generated sediment that can be transferred downslope. Many significant studies and models are performed to investigate these processes, which differ in terms of their effecting factors, approaches, inputs and outputs, model structure and the manner that these processes represent. This paper attempts to review the related literature concerning sediment transport modelling in shallow waters. A classification based on the representational processes of the soil erosion and sediment transport models (empirical, conceptual, physical and hybrid is adopted, and the commonly-used models and their characteristics are listed. This review is expected to be of interest to researchers and soil and water conservation managers who are working on erosion and sediment transport phenomena in shallow waters. The paper format should be helpful for practitioners to identify and generally characterize the types of available models, their strengths and their basic scope of applicability.

  15. Erosion and Sediment Transport Modelling in Shallow Waters: A Review on Approaches, Models and Applications.

    Science.gov (United States)

    Hajigholizadeh, Mohammad; Melesse, Assefa M; Fuentes, Hector R

    2018-03-14

    The erosion and sediment transport processes in shallow waters, which are discussed in this paper, begin when water droplets hit the soil surface. The transport mechanism caused by the consequent rainfall-runoff process determines the amount of generated sediment that can be transferred downslope. Many significant studies and models are performed to investigate these processes, which differ in terms of their effecting factors, approaches, inputs and outputs, model structure and the manner that these processes represent. This paper attempts to review the related literature concerning sediment transport modelling in shallow waters. A classification based on the representational processes of the soil erosion and sediment transport models (empirical, conceptual, physical and hybrid) is adopted, and the commonly-used models and their characteristics are listed. This review is expected to be of interest to researchers and soil and water conservation managers who are working on erosion and sediment transport phenomena in shallow waters. The paper format should be helpful for practitioners to identify and generally characterize the types of available models, their strengths and their basic scope of applicability.

  16. Water transport and functional dynamics of aquaporins in osmoregulatory organs of fishes

    DEFF Research Database (Denmark)

    Madsen, Steffen S; Engelund, Morten B; Cutler, Christopher P

    2015-01-01

    salty desert lakes, the challenge to obtain consensus as well as specific knowledge about aquaporin physiology in these vertebrate clades is overwhelming. Because the integumental surfaces of these animals are in intimate contact with the surrounding milieu, passive water loss and uptake represent two......Aquaporins play distinct roles for water transport in fishes as they do in mammals-both at the cellular, organ, and organismal levels. However, with over 32,000 known species of fishes inhabiting almost every aquatic environment, from tidal pools, small mountain streams, to the oceans and extreme...... of the major osmoregulatory challenges that need compensation. However, neither obligatory nor regulatory water transport nor their mechanisms have been elucidated to the same degree as, for example, ion transport in fishes. Currently fewer than 60 papers address fish aquaporins. Most of these papers identify...

  17. Some in-reactor loop experiments on corrosion product transport and water chemistry

    International Nuclear Information System (INIS)

    Balakrishnan, P.V.; Allison, G.M.

    1978-01-01

    A study of the transport of activated corrosion products in the heat transport circuit of pressurized water-cooled nuclear reactors using an in-reactor loop showed that the concentration of particulate and dissolved corrosion products in the high-temperature water depends on such chemical parameters as pH and dissolved hydrogen concentration. Transients in these parameters, as well as in temperature, generally increase the concentration of suspended corrosion products. The maximum concentration of particles observed is much reduced when high-flow, high-temperature filtration is used. Filtration also reduces the steady-state concentration of particles. Dissolved corrosion products are mainly responsible for activity accumulation on surfaces. The data obtained from this study were used to estimate the rate constants for some of the transfer processes involved in the contamination of the primary heat transport circuit in water-cooled nuclear power reactors

  18. Molecular Dynamics Investigation of Cl− and Water Transport through a Eukaryotic CLC Transporter

    Science.gov (United States)

    Cheng, Mary Hongying; Coalson, Rob D.

    2012-01-01

    Early crystal structures of prokaryotic CLC proteins identified three Cl– binding sites: internal (Sint), central (Scen), and external (Sext). A conserved external GLU (GLUex) residue acts as a gate competing for Sext. Recently, the first crystal structure of a eukaryotic transporter, CmCLC, revealed that in this transporter GLUex competes instead for Scen. Here, we use molecular dynamics simulations to investigate Cl– transport through CmCLC. The gating and Cl–/H+ transport cycle are inferred through comparative molecular dynamics simulations with protonated and deprotonated GLUex in the presence/absence of external potentials. Adaptive biasing force calculations are employed to estimate the potential of mean force profiles associated with transport of a Cl– ion from Sext to Sint, depending on the Cl– occupancy of other sites. Our simulations demonstrate that protonation of GLUex is essential for Cl– transport from Sext to Scen. The Scen site may be occupied by two Cl– ions simultaneously due to a high energy barrier (∼8 Kcal/mol) for a single Cl– ion to translocate from Scen to Sint. Binding two Cl– ions to Scen induces a continuous water wire from Scen to the extracellular solution through the side chain of the GLUex gate. This may initiate deprotonation of GLUex, which then drives the two Cl– ions out of Scen toward the intracellular side via two putative Cl– transport paths. Finally, a conformational cycle is proposed that would account for the exchange stoichiometry. PMID:22455919

  19. Measurements of water uptake of maize roots: insights for traits that influence water transport from the soil

    Science.gov (United States)

    Ahmed, Mutez A.; Zarebanadkouki, Mohsen; Kroener, Eva; Carminati, Andrea

    2015-04-01

    Water availability is a primary constraint to the global crop production. Although maize (Zea mays L.) is one of the most important crops worldwide, there is limited information on the function of different root segments and types in extracting water from soils. Aim of this study was to investigate the location of water uptake in maize roots. We used neutron radiography to: 1) image the spatial distribution of maize roots in soil and 2) trace the transport of injected deuterated water (D2O) in soil and roots. Maize plants were grown in aluminum containers (40×38×1 cm) filled with sandy soil. The soil was partitioned into different compartments using 1-cm-thick layers of coarse sand. When the plants were two weeks-old we injected D2O into selected soil compartments. The experiments were performed during the day (transpiring plants) and night (non transpiring plants). The transport of D2O into roots was simulated using a convection-diffusion numerical model of D2O transport into roots. By fitting the observed D2O transport we quantified the diffusion coefficient and the water uptake of the different root segments. The maize root architecture consisted of a primary root, 4-5 seminal roots and many lateral roots connected to the primary and seminal roots. Laterals emerged from the proximal 15 cm of the primary and seminal roots. Both during day and night measurements, D2O entered more quickly into lateral roots than into primary and seminal roots. The quick transport of D2O into laterals was caused by the small radius of lateral roots. The diffusion coefficient of lateral roots (4.68×10-7cm2s-1)was similar to that of the distal segments of seminal roots (4.72×10-7cm2s-1) and higher than of the proximal segments (1.42×10-7cm2s-1). Water uptake of lateral roots (1.64×10-5cms-1)was much higher than that of the distal segments of seminal roots (1.18×10-12cms-1). Water uptake of the proximal seminal segments was negligible. We conclude that the function of lateral

  20. Functional characterization of water transport and cellular localization of three aquaporin paralogs in the salmonid intestine

    DEFF Research Database (Denmark)

    Madsen, Steffen S; Olesen, Jesper H; Bedal, Konstanze

    2011-01-01

    Intestinal water absorption is greatly enhanced in salmonids upon acclimation from freshwater (FW) to seawater (SW); however, the molecular mechanism for water transport is unknown. We conducted a pharmacological characterization of water absorption in the rainbow trout intestine along......%), 0.1 ouabain (72%), and 0.1 bumetanide (82%) suggesting that active transport, Na(+), K(+)-ATPase and Na(+), K(+), 2Cl(-)-co-transport are involved in establishing the driving gradient for water transport. J(v) was also inhibited by 1 mmol L(-1) HgCl(2), serosally (23% in M and 44% in P), mucosally...... (27% in M), or both (61% in M and 58% in P), suggesting involvement of both apical and basolateral aquaporins in water transport. The inhibition was antagonized by 5 mmol L(-1) mercaptoethanol. By comparison, 10 mmol L(-1) mucosal tetraethylammonium, an inhibitor of certain aquaporins, inhibited J...

  1. Dynamics of water transport and storage in conifers studied with deuterium and heat tracing techniques.

    Science.gov (United States)

    F.C. Meinzer; J.R. Brooks; J.-C. Domec; B.L. Gartner; J.M. Warren; D.R. Woodruff; K. Bible; D.C. Shaw

    2006-01-01

    The volume and complexity of their vascular systems make the dynamics of tong-distance water transport in large trees difficult to study. We used heat and deuterated water (D20) as tracers to characterize whole-tree water transport and storage properties in individual trees belonging to the coniferous species Pseudotsuga menziesii...

  2. Hydrogeochemical transport modeling of 24 years of Rhine water infiltration in the dunes of the Amsterdam Water Supply.

    NARCIS (Netherlands)

    van Breukelen, B.M.; Appelo, C.A.J.; Olsthoorn, T.N.

    1998-01-01

    Water quality changes were modelled along a flowpath in a plume of artificially recharged, pretreated Rhine water in the dunes of the Amsterdam Water Supply, after 24 years of infiltration. The hydrogeochemical transport model PHREEQC was extended with dispersion/diffusion and kinetics for selected

  3. Water mass distributions and transports for the 2014 GEOVIDE cruise in the North Atlantic

    Science.gov (United States)

    García-Ibáñez, Maribel I.; Pérez, Fiz F.; Lherminier, Pascale; Zunino, Patricia; Mercier, Herlé; Tréguer, Paul

    2018-04-01

    We present the distribution of water masses along the GEOTRACES-GA01 section during the GEOVIDE cruise, which crossed the subpolar North Atlantic Ocean and the Labrador Sea in the summer of 2014. The water mass structure resulting from an extended optimum multiparameter (eOMP) analysis provides the framework for interpreting the observed distributions of trace elements and their isotopes. Central Waters and Subpolar Mode Waters (SPMW) dominated the upper part of the GEOTRACES-GA01 section. At intermediate depths, the dominant water mass was Labrador Sea Water, while the deep parts of the section were filled by Iceland-Scotland Overflow Water (ISOW) and North-East Atlantic Deep Water. We also evaluate the water mass volume transports across the 2014 OVIDE line (Portugal to Greenland section) by combining the water mass fractions resulting from the eOMP analysis with the absolute geostrophic velocity field estimated through a box inverse model. This allowed us to assess the relative contribution of each water mass to the transport across the section. Finally, we discuss the changes in the distribution and transport of water masses between the 2014 OVIDE line and the 2002-2010 mean state. At the upper and intermediate water levels, colder end-members of the water masses replaced the warmer ones in 2014 with respect to 2002-2010, in agreement with the long-term cooling of the North Atlantic Subpolar Gyre that started in the mid-2000s. Below 2000 dbar, ISOW increased its contribution in 2014 with respect to 2002-2010, with the increase being consistent with other estimates of ISOW transports along 58-59° N. We also observed an increase in SPMW in the East Greenland Irminger Current in 2014 with respect to 2002-2010, which supports the recent deep convection events in the Irminger Sea. From the assessment of the relative water mass contribution to the Atlantic Meridional Overturning Circulation (AMOC) across the OVIDE line, we conclude that the larger AMOC intensity in

  4. Numerical investigations for insulation particle transport phenomena in water flow

    International Nuclear Information System (INIS)

    Krepper, E.; Grahn, A.; Alt, S.; Kaestner, W.; Kratzsch, A.; Seeliger, A.

    2005-01-01

    The investigation of insulation debris generation, transport and sedimentation gains importance regarding the reactor safety research for PWR and BWR considering the long term behaviour of emergency core coolant systems during all types of LOCA. The insulation debris released near the break during LOCA consists of a mixture of very different particles concerning size, shape, consistence and other properties. Some fraction of the released insulation debris will be transported into the reactor sump where it may affect emergency core cooling. Open questions of generic interest are e.g. the sedimentation of the insulation debris in a water pool, possible re-suspension, transport in the sump water flow, particle load on strainers and corresponding difference pressure. A joint research project in cooperation with Institute of Process Technology, Process Automation and Measuring Technology (IPM) Zittau deals with the experimental investigation and the development of CFD models for the description of particle transport phenomena in coolant flow. While experiments are performed at the IPM-Zittau, theoretical work is concentrated at Forschungszentrum Rossendorf. In the present paper the basic concepts for CFD modelling are described and first results including feasibility studies are shown. During the ongoing work further results are expected. (author)

  5. Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water

    Science.gov (United States)

    Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.

    2012-01-01

    Characterization of diel variability of fecal indicator bacteria concentration in nearshore waters is of particular importance for development of water sampling standards and protection of public health. Significant nighttime increase in Escherichia coli (E. coli) concentration in beach water, previously observed at marine sites, has also been identified in summer 2000 from fixed locations in waist- and knee-deep waters at Chicago 63rd Street Beach, an embayed, tideless, freshwater beach with low currents at night (approximately 0.015 m s–1). A theoretical model using wave-induced mass transport velocity for advection was developed to assess the contribution of surface waves to the observed nighttime E. coli replenishment in the nearshore water. Using average wave conditions for the summer season of year 2000, the model predicted an amount of E. coli transported from water of intermediate depth, where sediment resuspension occurred intermittently, that would be sufficient to have elevated E. coli concentration in the surf and swash zones as observed. The nighttime replenishment of E. coli in the surf and swash zones revealed here is an important phase in the cycle of diel variations of E. coli concentration in nearshore water. According to previous findings in Ge et al. (Environ. Sci. Technol. 2010, 44, 6731–6737), enhanced current circulation in the embayment during the day tends to displace and deposit material offshore, which partially sets up the system by the early evening for a new period of nighttime onshore movement. This wave-induced mass transport effect, although facilitating a significant base supply of material shoreward, can be perturbed or significantly influenced by high currents (orders of magnitude larger than a typical wave-induced mass transport velocity), current-induced turbulence, and tidal forcing.

  6. Finite-bias electronic transport of molecules in a water solution

    KAUST Repository

    Rungger, Ivan

    2010-06-04

    The effects of water wetting conditions on the transport properties of molecular nanojunctions are investigated theoretically by using a combination of empirical-potential molecular-dynamics and first-principles electronic-transport calculations. These are at the level of the nonequilibrium Green’s-function method implemented for self-interaction corrected density-functional theory. We find that water effectively produces electrostatic gating to the molecular junction with a gating potential determined by the time-averaged water dipole field. Such a field is large for the polar benzene-dithiol molecule, resulting in a transmission spectrum shifted by about 0.6 eV with respect to that of the dry junction. The situation is drastically different for carbon nanotubes (CNTs). In fact, because of their hydrophobic nature the gating is almost negligible so that the average transmission spectrum of wet Au/CNT/Au junctions is essentially the same as that in dry conditions. This suggests that CNTs can be used as molecular interconnects also in water-wet situations, for instance, as tips for scanning tunnel microscopy in solution or in biological sensors.

  7. Finite-bias electronic transport of molecules in a water solution

    KAUST Repository

    Rungger, Ivan; Chen, X.; Sanvito, Stefano; Schwingenschlö gl, Udo

    2010-01-01

    The effects of water wetting conditions on the transport properties of molecular nanojunctions are investigated theoretically by using a combination of empirical-potential molecular-dynamics and first-principles electronic-transport calculations. These are at the level of the nonequilibrium Green’s-function method implemented for self-interaction corrected density-functional theory. We find that water effectively produces electrostatic gating to the molecular junction with a gating potential determined by the time-averaged water dipole field. Such a field is large for the polar benzene-dithiol molecule, resulting in a transmission spectrum shifted by about 0.6 eV with respect to that of the dry junction. The situation is drastically different for carbon nanotubes (CNTs). In fact, because of their hydrophobic nature the gating is almost negligible so that the average transmission spectrum of wet Au/CNT/Au junctions is essentially the same as that in dry conditions. This suggests that CNTs can be used as molecular interconnects also in water-wet situations, for instance, as tips for scanning tunnel microscopy in solution or in biological sensors.

  8. Water Transport in Trees--An Artificial Laboratory Tree

    Science.gov (United States)

    Susman, K.; Razpet, N.; Cepic, M.

    2011-01-01

    Water transport in tall trees is an everyday phenomenon, seldom noticed and not completely understood even by scientists. As a topic of current research in plant physiology it has several advantages for presentation within school physics lectures: it is interdisciplinary and clearly shows the connection between physics and biology; the…

  9. ESTIMATION OF THE WANDA GLACIER (SOUTH SHETLANDS SEDIMENT EROSION RATE USING NUMERICAL MODELLING

    Directory of Open Access Journals (Sweden)

    Kátia Kellem Rosa

    2013-09-01

    Full Text Available Glacial sediment yield results from glacial erosion and is influenced by several factors including glacial retreat rate, ice flow velocity and thermal regime. This paper estimates the contemporary subglacial erosion rate and sediment yield of Wanda Glacier (King George Island, South Shetlands. This work also examines basal sediment evacuation mechanisms by runoff and glacial erosion processes during the subglacial transport. This is small temperate glacier that has seen retreating for the last decades. In this work, we examine basal sediment evacuation mechanisms by runoff and analyze glacial erosion processes occurring during subglacial transport. The glacial erosion rate at Wanda Glacier, estimated using a numerical model that consider sediment evacuated to outlet streams, ice flow velocity, ice thickness and glacier area, is 1.1 ton m yr-1.

  10. Impact of carbonation on the durability of cementitious materials: water transport properties characterization

    Directory of Open Access Journals (Sweden)

    Le Bescop P.

    2013-07-01

    Full Text Available Within the context of long-lived intermediate level radioactive waste geological disposal, reinforced concrete would be used. In service life conditions, the concrete structures would be subjected to drying and carbonation. Carbonation relates to the reaction between carbon dioxide (CO2 and the main hydrates of the cement paste (portlandite and C-S-H. Beyond the fall of the pore solution pH, indicative of steel depassivation, carbonation induces mineralogical and microstructural changes (due to portlandite and C-S-H dissolution and calcium carbonate precipitation. This results in the modification of the transport properties, which can impact the structure durability. Because concrete durability depends on water transport, this study focuses on the influence of carbonation on water transport properties. In fact, the transport properties of sound materials are known but they still remain to be assessed for carbonated ones. An experimental program has been designed to investigate the transport properties in carbonated materials. Four hardened cement pastes, differing in mineralogy, are carbonated in an accelerated carbonation device (in controlled environmental conditions at CO2 partial pressure of about 3%. Once fully carbonated, all the data needed to describe water transport, using a simplified approach, will be evaluated.

  11. The Sodium Glucose Cotransporter SGLT1 Is an Extremely Efficient Facilitator of Passive Water Transport.

    Science.gov (United States)

    Erokhova, Liudmila; Horner, Andreas; Ollinger, Nicole; Siligan, Christine; Pohl, Peter

    2016-04-29

    The small intestine is void of aquaporins adept at facilitating vectorial water transport, and yet it reabsorbs ∼8 liters of fluid daily. Implications of the sodium glucose cotransporter SGLT1 in either pumping water or passively channeling water contrast with its reported water transporting capacity, which lags behind that of aquaporin-1 by 3 orders of magnitude. Here we overexpressed SGLT1 in MDCK cell monolayers and reconstituted the purified transporter into proteoliposomes. We observed the rate of osmotic proteoliposome deflation by light scattering. Fluorescence correlation spectroscopy served to assess (i) SGLT1 abundance in both vesicles and plasma membranes and (ii) flow-mediated dilution of an aqueous dye adjacent to the cell monolayer. Calculation of the unitary water channel permeability, pf, yielded similar values for cell and proteoliposome experiments. Neither the absence of glucose or Na(+), nor the lack of membrane voltage in vesicles, nor the directionality of water flow grossly altered pf Such weak dependence on protein conformation indicates that a water-impermeable occluded state (glucose and Na(+) in their binding pockets) lasts for only a minor fraction of the transport cycle or, alternatively, that occlusion of the substrate does not render the transporter water-impermeable as was suggested by computational studies of the bacterial homologue vSGLT. Although the similarity between the pf values of SGLT1 and aquaporin-1 makes a transcellular pathway plausible, it renders water pumping physiologically negligible because the passive flux would be orders of magnitude larger. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Peritoneal Water Transport Characteristics of Diabetic Patients Undergoing Peritoneal Dialysis: A Longitudinal Study.

    Science.gov (United States)

    Fernandes, Ana; Ribera-Sanchez, Roi; Rodríguez-Carmona, Ana; López-Iglesias, Antía; Leite-Costa, Natacha; Pérez Fontán, Miguel

    2017-01-01

    Volume overload is frequent in diabetics undergoing peritoneal dialysis (PD), and may play a significant role in the excess mortality observed in these patients. The characteristics of peritoneal water transport in this population have not been studied sufficiently. Following a prospective, single-center design we made cross-sectional and longitudinal comparisons of peritoneal water transport in 2 relatively large samples of diabetic and nondiabetic PD patients. We used 3.86/4.25% glucose-based peritoneal equilibration tests (PET) with complete drainage at 60 min, for these purposes. We scrutinized 59 diabetic and 120 nondiabetic PD patients. Both samples showed relatively similar characteristics, although diabetics were significantly more overhydrated than nondiabetics. The baseline PET disclosed lower ultrafiltration (mean 439 mL diabetics vs. 532 mL nondiabetics, p = 0.033) and sodium removal (41 vs. 53 mM, p = 0.014) rates in diabetics. One hundred and nine patients (36 diabetics) underwent a second PET after 12 months, and 45 (14 diabetics) underwent a third one after 24 months. Longitudinal analyses disclosed an essential stability of water transport in both groups, although nondiabetic patients showed a trend where an increase in free water transport (p = 0.033) was observed, which was not the case in diabetics. Diabetic patients undergoing PD present lower capacities of ultrafiltration and sodium removal than their nondiabetic counterparts. Longitudinal analyses disclose an essential stability of water transport capacities, both in diabetics and nondiabetics. The clinical significance of these differences deserves further analysis. © 2017 S. Karger AG, Basel.

  13. The direction of water transport on Mars: A possible pumping mechanism

    Science.gov (United States)

    James, P. B.

    1987-01-01

    It is suggested that an atmospheric pumping mechanism might be at work in which water is preferentially transported into the north by a mass outflow wind (due to sublimation from polar cap) that is stronger during southern spring than it is during northern spring. The mechanism is provided by the asymmetric seasonal temperature distribution produced by the eccentric martial orbit and by the associated seasonal asymmetry in the carbon dioxide cycle. The alternating condensation and sublimation of CO2 at the poles produces condensation winds which, in turn, contribute to the meridional transport of water vapor.

  14. Hydrology, microbiology and carbon cycling at a high Arctic polythermal glacier, (John Evans Glacier, Ellesmere Island, Canada)

    Science.gov (United States)

    Skidmore, Mark Leslie

    Analysis of the hydrology, hydrochemistry and microbiology at polythermal John Evans Glacier and geochemical and isotopic data from Haut Glacier d'Arolla demonstrates that certain subglacial chemical weathering processes are microbially mediated. Subglacial drainage is likely an annual occurrence beneath John Evans Glacier and solute rich subglacial waters indicate over winter storage at the glacier bed. Subglacial microbial populations are also present, and are viable under simulated near in situ conditions at 0.3°C. This suggests that temperate subglacial environments at a polythermal glacier, which are isolated by cold ice above and around them, provide a viable habitat for life where basal water and organic carbon are present throughout the year. Thus, a subglacial microbial ecosystem based upon legacy carbon, (from old soils or surface inputs) rather than primary production may exist, where redox processes are a key component, and seasonal anoxia may occur. The existence of anoxic environments is supported by the presence of strictly anaerobic bacteria (sulphate reducing bacteria and methanogens) in the basal sediments---which are viable in culture at 4°C---and also argues that these bacteria are not washed in with oxygenated surface meltwaters, but are present in the subglacial environment. During the summer meltseason there is a large input of surficial waters to the subglacial system and water residence times are drastically reduced. Hence, kinetic weathering processes dominate, resulting in light delta 13C-DIC (dissolved inorganic carbon) in glacial runoff, as verified by experimental work on CaCO3 and John Evans Glacier sediments. The experiments demonstrate kinetic bedrock fractionation (KBF) during carbonate hydrolysis and that kinetic fractionation of CO2 (KFC) is proportional to the rate of CO2 draw down during the carbonation of carbonates. This results in significantly depleted delta13C-DIC values (≤-16 ‰) relative to the bedrock carbonate

  15. Water and Solute Transport in Arid Vadose Zones: Innovations in Measurement and Analysis

    International Nuclear Information System (INIS)

    Tyler, S W.; Scanlon, Bridget R.; Gee, Glendon W.; Allison, G B.; Parlange, M. B.; Hopmans, J. W.

    1999-01-01

    Understanding the physics of flow and transport through the vadose zone has advanced significantly in the last three decades. These advances have been made primarily in humid regions or in irrigated agricultural settings. While some of the techniques are useful, many are not suited to arid regions. The fluxes of water and solutes typically found in arid regions are often orders of magnitude smaller than those found in agricultural settings, while the time scales for transport can be orders of magnitude larger. The depth over which transport must be characterized is also often much greater than in humid regions. Rather than relying on advances in applied tracers, arid-zone researchers have developed natural tracer techniques that are capable of quantifying transport over tens to thousands of years. Techniques have been developed to measure the hydraulic properties of sediments at all water contents, including the very dry range and at far greater depths. As arid and semiarid regions come under increased development pressures for such activities as hazardous- and radioactive-waste disposal, the development of techniques and the understanding of water and solute transport have become crucial components in defining the environmental impacts of activities at the landsurface

  16. Unstirred Water Layers and the Kinetics of Organic Cation Transport

    Science.gov (United States)

    Shibayama, Takahiro; Morales, Mark; Zhang, Xiaohong; Martinez, Lucy; Berteloot, Alfred; Secomb, Timothy W.; Wright, Stephen H.

    2015-01-01

    Purpose Unstirred water layers (UWLs) present an unavoidable complication in the measurement of transport kinetics in cultured cells and the high rates of transport achieved by overexpressing heterologous transporters exacerbate the UWL effect. This study examined the correlation between measured Jmax and Kt values and the effect of manipulating UWL thickness or transport Jmax on the accuracy of experimentally determined kinetics of the multidrug transporters, OCT2 and MATE1. Methods Transport of TEA and MPP was measured in CHO cells that stably expressed human OCT2 or MATE1. UWL thickness was manipulated by vigorous reciprocal shaking. Several methods were used to manipulate maximal transport rates. Results Vigorous stirring stimulated uptake of OCT2-mediated transport by decreasing apparent Kt (Ktapp) values. Systematic reduction in transport rates was correlated with reduction in Ktapp values. The slope of these relationships indicated a 1500 µm UWL in multiwell plates. Reducing the influence of UWLs (by decreasing either their thickness or the Jmax of substrate transport) reduced Ktapp by 2-fold to >10-fold. Conclusions Failure to take into account the presence of UWLs in experiments using cultured cells to measure transport kinetics can result in significant underestimates of the affinity of multidrug transporters for substrates. PMID:25791216

  17. A High-Resolution Model of Water Mass Transformation and Transport in the Weddell Sea

    Science.gov (United States)

    Hazel, J.; Stewart, A.

    2016-12-01

    The ocean circulation around the Antarctic margins has a pronounced impact on the global ocean and climate system. One of these impacts includes closing the global meridional overturning circulation (MOC) via formation of dense Antarctic Bottom Water (AABW), which ventilates a large fraction of the subsurface ocean. AABW is also partially composed of modified Circumpolar Deep Water (CDW), a warm, mid-depth water mass whose transport towards the continent has the potential to induce rapid retreat of marine-terminating glaciers. Previous studies suggest that these water mass exchanges may be strongly influenced by high-frequency processes such as downslope gravity currents, tidal flows, and mesoscale/submesoscale eddy transport. However, evaluating the relative contributions of these processes to near-Antarctic water mass transports is hindered by the region's relatively small scales of motion and the logistical difficulties in taking measurements beneath sea ice.In this study we develop a regional model of the Weddell Sea, the largest established source of AABW. The model is forced by an annually-repeating atmospheric state constructed from the Antarctic Mesoscale Prediction System data and by annually-repeating lateral boundary conditions constructed from the Southern Ocean State Estimate. The model incorporates the full Filchner-Ronne cavity and simulates the thermodynamics and dynamics of sea ice. To analyze the role of high-frequency processes in the transport and transformation of water masses, we compute the model's overturning circulation, water mass transformations, and ice sheet basal melt at model horizontal grid resolutions ranging from 1/2 degree to 1/24 degree. We temporally decompose the high-resolution (1/24 degree) model circulation into components due to mean, eddy and tidal flows and discuss the geographical dependence of these processes and their impact on water mass transformation and transport.

  18. Classroom Techniques to Illustrate Water Transport in Plants

    Science.gov (United States)

    Lakrim, Mohamed

    2013-01-01

    The transport of water in plants is among the most difficult and challenging concepts to explain to students. It is even more difficult for students enrolled in an introductory general biology course. An easy approach is needed to demonstrate this complex concept. I describe visual and pedagogical examples that can be performed quickly and easily…

  19. Impacts of transportation infrastructure on storm water and surfaces waters in Chittenden County, Vermont, USA.

    Science.gov (United States)

    2014-06-01

    Transportation infrastructure is a major source of stormwater runoff that can alter hydrology and : contribute significant loading of nutrients, sediment, and other pollutants to surface waters. These : increased loads can contribute to impairment of...

  20. Water mass distributions and transports for the 2014 GEOVIDE cruise in the North Atlantic

    Directory of Open Access Journals (Sweden)

    M. I. García-Ibáñez

    2018-04-01

    Full Text Available We present the distribution of water masses along the GEOTRACES-GA01 section during the GEOVIDE cruise, which crossed the subpolar North Atlantic Ocean and the Labrador Sea in the summer of 2014. The water mass structure resulting from an extended optimum multiparameter (eOMP analysis provides the framework for interpreting the observed distributions of trace elements and their isotopes. Central Waters and Subpolar Mode Waters (SPMW dominated the upper part of the GEOTRACES-GA01 section. At intermediate depths, the dominant water mass was Labrador Sea Water, while the deep parts of the section were filled by Iceland–Scotland Overflow Water (ISOW and North-East Atlantic Deep Water. We also evaluate the water mass volume transports across the 2014 OVIDE line (Portugal to Greenland section by combining the water mass fractions resulting from the eOMP analysis with the absolute geostrophic velocity field estimated through a box inverse model. This allowed us to assess the relative contribution of each water mass to the transport across the section. Finally, we discuss the changes in the distribution and transport of water masses between the 2014 OVIDE line and the 2002–2010 mean state. At the upper and intermediate water levels, colder end-members of the water masses replaced the warmer ones in 2014 with respect to 2002–2010, in agreement with the long-term cooling of the North Atlantic Subpolar Gyre that started in the mid-2000s. Below 2000 dbar, ISOW increased its contribution in 2014 with respect to 2002–2010, with the increase being consistent with other estimates of ISOW transports along 58–59° N. We also observed an increase in SPMW in the East Greenland Irminger Current in 2014 with respect to 2002–2010, which supports the recent deep convection events in the Irminger Sea. From the assessment of the relative water mass contribution to the Atlantic Meridional Overturning Circulation (AMOC across the OVIDE line, we conclude

  1. Electricity resonance-induced fast transport of water through nanochannels.

    Science.gov (United States)

    Kou, Jianlong; Lu, Hangjun; Wu, Fengmin; Fan, Jintu; Yao, Jun

    2014-09-10

    We performed molecular dynamics simulations to study water permeation through a single-walled carbon nanotube with electrical interference. It was found that the water net flux across the nanochannel is greatly affected by the external electrical interference, with the maximal net flux occurred at an electrical interference frequency of 16670 GHz being about nine times as high as the net flux at the low or high frequency range of (80,000 GHz). The above phenomena can be attributed to the breakage of hydrogen bonds as the electrical interference frequency approaches to the inherent resonant frequency of hydrogen bonds. The new mechanism of regulating water flux across nanochannels revealed in this study provides an insight into the water transportation through biological water channels and has tremendous potential in the design of high-flux nanofluidic systems.

  2. Superconductivity and fast proton transport in nanoconfined water

    Science.gov (United States)

    Johnson, K. H.

    2018-04-01

    A real-space molecular-orbital density-wave description of Cooper pairing in conjunction with the dynamic Jahn-Teller mechanism for high-Tc superconductivity predicts that electron-doped water confined to the nanoscale environment of a carbon nanotube or biological macromolecule should superconduct below and exhibit fast proton transport above the transition temperature, Tc ≅ 230 K (-43 °C).

  3. Improvement of water transport mechanisms during potato drying by applying ultrasound.

    Science.gov (United States)

    Ozuna, César; Cárcel, Juan A; García-Pérez, José V; Mulet, Antonio

    2011-11-01

    The drying rate of vegetables is limited by internal moisture diffusion and convective transport mechanisms. The increase of drying air temperature leads to faster water mobility; however, it provokes quality loss in the product and presents a higher energy demand. Therefore, the search for new strategies to improve water mobility during convective drying constitutes a topic of relevant research. The aim of this work was to evaluate the use of power ultrasound to improve convective drying of potato and quantify the influence of the applied power in the water transport mechanisms. Drying kinetics of potato cubes were increased by the ultrasonic application. The influence of power ultrasound was dependent on the ultrasonic power (from 0 to 37 kW m(-3) ), the higher the applied power, the faster the drying kinetic. The diffusion model considering external resistance to mass transfer provided a good fit of drying kinetics. From modelling, it was observed a proportional and significant (P mass transfer coefficient. The ultrasonic application during drying represents an interesting alternative to traditional convective drying by shortening drying time, which may involve an energy saving concerning industrial applications. In addition, the ultrasonic effect in the water transport is based on mechanical phenomena with a low heating capacity, which is highly relevant for drying heat sensitive materials and also for obtaining high-quality dry products. Copyright © 2011 Society of Chemical Industry.

  4. Water transport by the bacterial channel alpha-hemolysin

    Science.gov (United States)

    Paula, S.; Akeson, M.; Deamer, D.

    1999-01-01

    This study is an investigation of the ability of the bacterial channel alpha-hemolysin to facilitate water permeation across biological membranes. alpha-Hemolysin channels were incorporated into rabbit erythrocyte ghosts at varying concentrations, and water permeation was induced by mixing the ghosts with hypertonic sucrose solutions. The resulting volume decrease of the ghosts was followed by time-resolved optical absorption at pH 5, 6, and 7. The average single-channel permeability coefficient of alpha-hemolysin for water ranged between 1.3x10-12 cm/s and 1.5x10-12 cm/s, depending on pH. The slightly increased single-channel permeability coefficient at lower pH-values was attributed to an increase in the effective pore size. The activation energy of water transport through the channel was low (Ea=5.4 kcal/mol), suggesting that the properties of water inside the alpha-hemolysin channel resemble those of bulk water. This conclusion was supported by calculations based on macroscopic hydrodynamic laws of laminar water flow. Using the known three-dimensional structure of the channel, the calculations accurately predicted the rate of water flow through the channel. The latter finding also indicated that water permeation data can provide a good estimate of the pore size for large channels.

  5. Arsenic transport in irrigation water across rice-field soils in Bangladesh

    International Nuclear Information System (INIS)

    Polizzotto, Matthew L.; Lineberger, Ethan M.; Matteson, Audrey R.; Neumann, Rebecca B.; Badruzzaman, A. Borhan M.; Ashraf Ali, M.

    2013-01-01

    Experiments were conducted to analyze processes impacting arsenic transport in irrigation water flowing over bare rice-field soils in Bangladesh. Dissolved concentrations of As, Fe, P, and Si varied over space and time, according to whether irrigation water was flowing or static. Initially, under flowing conditions, arsenic concentrations in irrigation water were below well-water levels and showed little spatial variability across fields. As flowing-water levels rose, arsenic concentrations were elevated at field inlets and decreased with distance across fields, but under subsequent static conditions, concentrations dropped and were less variable. Laboratory experiments revealed that over half of the initial well-water arsenic was removed from solution by oxidative interaction with other water-column components. Introduction of small quantities of soil further decreased arsenic concentrations in solution. At higher soil-solution ratios, however, soil contributed arsenic to solution via abiotic and biotic desorption. Collectively, these results suggest careful design is required for land-based arsenic-removal schemes. -- Highlights: •We analyzed the processes impacting arsenic transport in flowing irrigation water. •Arsenic in Bangladesh rice-field irrigation water varied over space and time. •Arsenic was correlated with Fe, P, and Si in flowing and static water. •Oxidation, adsorption and desorption reactions controlled arsenic concentrations. •Land-based arsenic removal from water will be impacted by hydraulic conditions. -- Arsenic concentrations in flowing and static irrigation water in Bangladesh varied over space and time, suggesting careful design is required for land-based pre-treatment schemes that aim to remove As from solution

  6. Patterned gradient surface for spontaneous droplet transportation and water collection: simulation and experiment

    International Nuclear Information System (INIS)

    Tan, Xianhua; Zhu, Yiying; Shi, Tielin; Tang, Zirong; Liao, Guanglan

    2016-01-01

    We demonstrate spontaneous droplet transportation and water collection on wedge-shaped gradient surfaces consisting of alternating hydrophilic and hydrophobic regions. Droplets on the surfaces are modeled and simulated to analyze the Gibbs free energy and free energy gradient distributions. Big half-apex angle and great wettability difference result in considerable free energy gradient, corresponding to large driving force for spontaneous droplet transportation, thus causing the droplets to move towards the open end of the wedge-shaped hydrophilic regions, where the Gibbs free energy is low. Gradient surfaces are then fabricated and tested. Filmwise condensation begins on the hydrophilic regions, forming wedge-shaped tracks for water collection. Dropwise condensation occurs on the hydrophobic regions, where the droplet size distribution and departure diameters are controlled by the width of the regions. Condensate water from both the hydrophilic and hydrophobic regions are collected directionally to the open end of the wedge-shaped hydrophilic regions, agreeing with the simulations. Directional droplet transport and controllable departure diameters make the branched gradient surfaces more efficient than smooth surfaces for water collection, which proves that gradient surfaces are potential in water collection, microfluidic devices, anti-fogging and self-cleaning. (paper)

  7. High-Efficiency Fog Collector: Water Unidirectional Transport on Heterogeneous Rough Conical Wires.

    Science.gov (United States)

    Xu, Ting; Lin, Yucai; Zhang, Miaoxin; Shi, Weiwei; Zheng, Yongmei

    2016-12-27

    An artificial periodic roughness-gradient conical copper wire (PCCW) can be fabricated by inspiration from cactus spines and wet spider silks. PCCW can harvest fog on periodic points of the conical surface from air and transports the drops for a long distance without external force, which is attributed to dynamic as-released energy generated from drop deformation in drop coalescence, in addition to both gradients of geometric curve (inducing Laplace pressure) and periodic roughness (inducing surface energy difference). It is found that the ability of fog collection can be related to various tilt-angle wires, thus a fog collector with an array system of PCCWs is further designed to achieve a continuous process of efficient water collection. As a result, the effect of water collection on PCCWs is better than previous results. These findings are significant to develop and design materials with water collection and water transport for promising application in fogwater systems to ease the water crisis.

  8. Lattice Boltzmann simulations of water transport in gas diffusion layer of a polymer electrolyte membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Liang; Cheng, Ping [Ministry of Education Key Laboratory of Power Machinery and Engineering, School of Mechanical Engineering, Shanghai Jiaotong University, DongChuan Road 800, Shanghai 200240 (China)

    2010-06-15

    The effect of wettability on water transport dynamics in gas diffusion layer (GDL) is investigated by simulating water invasion in an initially gas-filled GDL using the multiphase free-energy lattice Boltzmann method (LBM). The results show that wettability plays a significant role on water saturation distribution in two-phase flow in the uniform wetting GDL. For highly hydrophobicity, the water transport falls in the regime of capillary fingering, while for neutral wettability, water transport exhibits the characteristic of stable displacement, although both processes are capillary force dominated flow with same capillary numbers. In addition, the introduction of hydrophilic paths in the GDL leads the water to flow through the hydrophilic pores preferentially. The resulting water saturation distributions show that the saturation in the GDL has little change after water breaks through the GDL, and further confirm that the selective introduction of hydrophilic passages in the GDL would facilitate the removal of liquid water more effectively, thus alleviating the flooding in catalyst layer (CL) and GDL. The LBM approach presented in this study provides an effective tool to investigate water transport phenomenon in the GDL at pore-scale level with wettability distribution taken into consideration. (author)

  9. Transport properties of supercooled confined water

    International Nuclear Information System (INIS)

    Mallamace, F.; Baglioni, P.; Corsaro, C.; Spooren, J.; Stanley, H.E.; Chen, S.-H.

    2011-01-01

    We present an overview of recent experiments performed on water in the deeply supercooled region, a temperature region of fundamental importance in the science of water. We examine data generated by nuclear magnetic resonance, quasi-elastic neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy, and study water confined in nanometer-scale environments. When contained within small pores, water does not crystallize and can be supercooled well below its homogeneous nucleation temperature T H. On this basis, it is possible to carry out a careful analysis of the well-known thermodynamic anomalies of water. Studying the temperature and pressure dependencies of water dynamics, we show that the liquid-liquid phase transition (LLPT) hypothesis represents a reliable model for describing liquid water. In this model, liquid water is a mixture of two different local structures: a low density liquid (LDL) and a high-density liquid (HDL). The LLPT line terminates at a low-T liquid-liquid critical point. We discuss the following experimental findings: 1.) the crossover from non-Arrhenius behavior at high T to Arrhenius behavior at low T in transport parameters; 2.) the breakdown of the Stokes-Einstein relation; 3.) the existence of a Widom line, which is the locus of points corresponding to a maximum correlation length in the P-T phase diagram and which ends in the liquid-liquid critical point; 4.) the direct observation of the LDL phase; and 5.) the minimum in the density at approximately 70 K below the temperature of the density maximum. In our opinion these results strongly support the LLPT hypothesis. All of the basic science and technology community should be impressed by the fact that, although the few ideas (apparently elementary) developed concerning water approximately 27 centuries ago have changed very little up to now, because of the current expansion in our knowledge in this area, they can begin to change in the near future.

  10. Measurement of water transport from saturated pumice aggregates to hardening cement paste

    DEFF Research Database (Denmark)

    Lura, Pietro; Bentz, Dale; Lange, David A.

    2006-01-01

    In internal water curing of High Performance Concrete, it is fundamental to know how and when the water contained in the internal curing agent is released into the hydrating cement paste. In this study, X-ray absorption measurements showed that considerable transport of water from saturated pumice...... the crucial factor to avoid self-desiccation shrinkage at early-age....

  11. The impacts of water stress on phloem transport in Douglas-fir trees

    Science.gov (United States)

    David Woodruff

    2014-01-01

    Despite the critical role that phloem plays in a number of plant functional processes and the potential impact of water stress on phloem structural and phloem sap compositional characteristics, little research has been done to examine how water stress influences phloem transport. The objectives of this study were to develop a more accurate understanding of how water...

  12. Complexity in the validation of ground-water travel time in fractured flow and transport systems

    International Nuclear Information System (INIS)

    Davies, P.B.; Hunter, R.L.; Pickens, J.F.

    1991-01-01

    Ground-water travel time is a widely used concept in site assessment for radioactive waste disposal. While ground-water travel time was originally conceived to provide a simple performance measure for evaluating repository sites, its definition in many flow and transport environments is ambiguous. The U.S. Department of Energy siting guidelines (10 CFR 960) define ground-water travel time as the time required for a unit volume of water to travel between two locations, calculated by dividing travel-path length by the quotient of average ground-water flux and effective porosity. Defining a meaningful effective porosity in a fractured porous material is a significant problem. Although the Waste Isolation Pilot Plant (WIPP) is not subject to specific requirements for ground-water travel time, travel times have been computed under a variety of model assumptions. Recently completed model analyses for WIPP illustrate the difficulties in applying a ground-water travel-time performance measure to flow and transport in fractured, fully saturated flow systems. Computer code used: SWIFT II (flow and transport code). 4 figs., 12 refs

  13. Predictive capabilities of a two-dimensional model in the ground water transport of radionuclides

    International Nuclear Information System (INIS)

    Gureghian, A.B.; Beskid, N.J.; Marmer, G.J.

    1978-01-01

    The discharge of low-level radioactive waste into tailings ponds is a potential source of ground water contamination. The estimation of the radiological hazards related to the ground water transport of radionuclides from tailings retention systems depends on reasonably accurate estimates of the movement of both water and solute. A two-dimensional mathematical model having predictive capability for ground water flow and solute transport has been developed. The flow equation has been solved under steady-state conditions and the mass transport equation under transient conditions. The simultaneous solution of both equations is achieved through the finite element technique using isoparametric elements, based on the Galerkin formulation. However, in contrast to the flow equation solution, the weighting functions used in the solution of the mass transport equation have a non-symmetric form. The predictive capability of the model is demonstrated using an idealized case based on analyses of field data obtained from the sites of operating uranium mills. The pH of the solution, which regulates the variation of the distribution coefficient (K/sub d/) in a particular site, appears to be the most important factor in the assessment of the rate of migration of the elements considered herein

  14. Computational simulation of water transport in PEM fuel cells using an improved membrane model

    International Nuclear Information System (INIS)

    Cao, J.; Djilali, N.

    2000-01-01

    Computational models and simulation tools can provide valuable insight and guidance for design, performance optimization, and cost reduction of fuel cells. In proton-exchange membrane fuel cells it is particularly important to maintain appropriate water content and temperature in the electrolyte membrane. In this paper we describe a mathematical model for the membrane that takes into account the diffusion of water, the pressure variation, and the electro-osmotic drag in the membrane. Applying conservation laws for water and current and using an empirical relationship between electro-osmotic drag and water content, we obtain a transport equation for water molar concentration and derive a new equation for the electric potential that accounts for variable water content and is more accurate than the conventionally employed Laplace's equation does. The model is coupled with a computational fluid dynamics model for diffusive transport in the electrodes and convective transport in the reactant flow channels. Simulations for a two-dimensional cell are performed over nominal current densities ranging form i=0.1 A/cm≅ to 1.2 A/cm≅. The impact and importance of temperature and pressure non-uniformity, and of two-dimensionality are assessed and discussed. (author)

  15. Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Sode, Olaseni; Voth, Gregory A., E-mail: gavoth@uchicago.edu [Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, Computation Institute, The University of Chicago, Chicago, Illinois 60637, USA and Computing, Environment and Life Sciences, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-12-14

    Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A{sup 2−}, a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A{sup 2-} by closing a cavity that could otherwise fill with water near the proximal Fe of the active site.

  16. Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

    International Nuclear Information System (INIS)

    Sode, Olaseni; Voth, Gregory A.

    2014-01-01

    Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A 2− , a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A 2- by closing a cavity that could otherwise fill with water near the proximal Fe of the active site

  17. Use of stable isotopes for estimating water and nitrogen transport in plants

    International Nuclear Information System (INIS)

    Grygoryuk, I.P.; Petrenko, N.I.; Shvedova, O.Yu.; Tkachev, V.I.; Yaroshenko, O.A.

    1998-01-01

    Peculiarities in the response of various wheat cultivars and maize hybrids to water deficiency were studied in laboratory and vegetation experiments. Their resistance to extemal environmental factors was estimated by changes in nitrogen ( 15 N) and water (HDO) accumulation, transport and distribution in plant organs. The water supply was maintained at 60% FWC (control) and was reduced to 30% FWC (experiment) in the absence of plant watering during different stages or with use of polyethylene glycol. Decrease in water potential of medium from -0.05 (control) to -0.5, -0.9 and -1.6 MPa resulted in inhibition of water absorption, transport and distribution in spring wheat organs. After 24-hour stress, root absorption of water of drought-resistant varieties as compared to non-drought resistant ones was more sensitive, during 5, 10 and 15 min intervals after HDO introduction in nutrition medium. Strong depression of water exchange was observed at weaker stress in non-resistant variety. HDO absorption of the low part of the stem at short exposure resembled that of roots. The 24-hour stress revealed the tendency to sharper inhibition of absorption of labelled water in leaves of resistant variety. At a more durable stress the intensity of leaf water-exchange resistant variety was stabilized, while in the non-resistant variety it was reduced considerably. The intensity of HDO and 15 N exchange under stress conditions depended on the lability of regulator mechanism of water transport. Genotypic specificity of N use by wheat and maize plants depending on water supply and inclusion of 15 N in total and protein N was found. The 15 N content in total N in spring wheat cultivars under optimum water supply and under drought made 3.65 to 6.20 and 1.69 to 3.47, respectively. The 15 N content in protein N under the above conditions was 3.03 to 5.96 and 2.36 to 2.93, respectively. At water stress the main mass of labelled N in plant roots and stems was localized, while its intake into

  18. Analysis of coupled proton and water transport in a PEM fuel cell using the binary friction membrane model

    International Nuclear Information System (INIS)

    Carnes, B.; Djilali, N.

    2006-01-01

    Transport of liquid water within a polymer electrolyte membrane (PEM) is critical to the operation of a PEM fuel cell, due to the strong dependence of the membrane transport coefficients on water content. In addition, enhanced predictive abilities are particularly significant in the context of passive air breathing fuel cell designs where lower water contents will prevail in the membrane. We investigate and analyze the numerical predictions of a recently proposed rational model for transport of protons and water in a PEM, when compared to a widely used empirical model. While the performance is similar for a saturated membrane, for PEMs with low water content, the difference in computed current density and membrane water crossover can be substantial. The effects of coupling partially saturated gas diffusion electrodes (GDLs) with the membrane are studied in both a 1D and 2D context. In addition, a simplified 1D analytical membrane water transport model is validated against the complete 1D model predictions. Our numerical results predict a higher current density and more uniform membrane hydration using a dry cathode instead of a dry anode, and illustrate that the strongest 2D effects are for water vapor transport

  19. Geothermal Flux, Basal Melt Rates, and Subglacial Lakes in Central East Antarctica

    Science.gov (United States)

    Carter, S. P.; Blankenship, D. D.; Morse, D. L.

    2002-12-01

    study area. However, analysis of dated internal layers over several bright, flat, "lake-like" reflectors reveals a very different age versus depth relationship in which deeper layers actually thicken with depth. This thickening of deep layers results from ice flowing in from the sides to accommodate significant liquid water production at the base of the ice sheet. This melt is occurring today and can be quantified. With our knowledge of melt rates we can begin to estimate inputs and assess hydrologic parameters for the subglacial lake systems of East Antarctica.

  20. Groundwater-Surface Water Interactions and Downstream Transport of Water, Heat, and Solutes in a Hydropeaked River

    Science.gov (United States)

    Ferencz, S. B.; Cardenas, M. B.; Neilson, B. T.; Watson, J.

    2017-12-01

    A majority of the world's largest river systems are regulated by dams. In addition to being used for water resources management and flood prevention, many large dams are also used for hydroelectric power generation. In the United States, dams account for 7% of domestic electricity, and hydropower accounts for 16% of worldwide electricity production. To help meet electricity demand during peak usage times, hydropower utilities often increase their releases of water during high demand periods. This practice, termed hydropeaking, can cause large transient flow regimes downstream of hydroelectric dams. These transient flow increases can result in order of magnitude daily fluctuations in discharge, and the released water can have different thermal and chemical properties than ambient river water. As hydropeaking releases travel downstream, the temporary rise in stage and increase in discharge can enhance surface water-groundwater (SW-GW) exchange between the river and its alluvial aquifer. This dam-induced SW-GW exchange, combined with hydrodynamic attenuation and heat exchange processes, result in complex responses downstream. The dam-regulated Lower Colorado River downstream of Austin, TX was used as a natural laboratory to observe SW-GW interactions and downstream transport of water, heat, and solutes under hydropeaking conditions. To characterize SW-GW interactions, well transects were installed in the banks of the river to observe exchanges between the river and alluvial aquifer. The well transects were installed at three different distances from the dam (15km, 35km, and 80km). At each well transect conductivity, temperature, and pressure sensors were deployed in the monitoring wells and in the channel. Additional conductivity and temperature sensors were deployed along the study reach to provide a more detailed record of heat and solute transport during hydropeaking releases. The field data spans over two months of daily dam releases that were punctuated by two

  1. Modeling studies of water consumption for transportation fuel options: Hawaii, US-48

    Science.gov (United States)

    King, C. W.; Webber, M. E.

    2011-12-01

    There are now major drivers to move from petroleum transportation: moving to low-carbon transport life cycles for climate change mitigation, fuel diversity to reduce reliance on imported oil, and economic concerns regarding the relatively high price of oil ( $100/barrel) and the resulting impact on discretionary income. Unfortunately many transportation fuel alternatives also have some environmental impacts, particularly with regard to water consumption and biodiversity. In this presentation we will discuss the water and energy sustainability struggle ongoing in Hawai'i on the island of Maui with a brief history and discussion of energy and water modeling scenarios. The vast majority of surface water on Maui is diverted via man-made ditches for irrigation on sugar cane plantations. Maui currently allocates between 250 and 300 million gallons per day (Mgal/d) of irrigation water for sugarcane cultivation each day, and it is likely that the island could support a biofuel-focused sugarcane plantation by shifting production focus from raw sugar to ethanol. However, future water availability is likely to be less than existing water availability because Maui is growing, more water is being reserved for environmental purposes, and precipitation levels are on decline for the past two decades and some expect this trend to continue. While Maui residents cannot control precipitation patterns, they can control the levels of increased requirements for instream flow in Maui's streams. The Hawaii State Commission on Water Resource Management (CWRM) sets instream flow standards, and choosing not to restore instream flow could have what many locals consider negative environmental and cultural impacts that must be weighed against the effects of reducing surface water availability for agriculture. Instream flow standards that reduce legal withdrawals for streams that supply irrigation water would reduce the amount of surface water available for biofuel crop irrigation. Environmental

  2. Water-quality conditions and suspended-sediment transport in the Wilson and Trask Rivers, northwestern Oregon, water years 2012–14

    Science.gov (United States)

    Sobieszczyk, Steven; Bragg, Heather M.; Uhrich, Mark A.

    2015-07-28

    In October 2011, the U.S. Geological Survey began investigating and monitoring water-quality conditions and suspended-sediment transport in the Wilson and Trask Rivers, northwestern Oregon. Water temperature, specific conductance, turbidity, and dissolved oxygen were measured every 15–30 minutes in both streams using real-time instream water-quality monitors. In conjunction with the monitoring effort, suspended-sediment samples were collected and analyzed to model the amount of suspended sediment being transported by each river. Over the course of the 3-year study, which ended in September 2014, nearly 600,000 tons (t) of suspended-sediment material entered Tillamook Bay from these two tributaries. 

  3. Fast water transport in graphene nanofluidic channels

    Science.gov (United States)

    Xie, Quan; Alibakhshi, Mohammad Amin; Jiao, Shuping; Xu, Zhiping; Hempel, Marek; Kong, Jing; Park, Hyung Gyu; Duan, Chuanhua

    2018-01-01

    Superfast water transport discovered in graphitic nanoconduits, including carbon nanotubes and graphene nanochannels, implicates crucial applications in separation processes and energy conversion. Yet lack of complete understanding at the single-conduit level limits development of new carbon nanofluidic structures and devices with desired transport properties for practical applications. Here, we show that the hydraulic resistance and slippage of single graphene nanochannels can be accurately determined using capillary flow and a novel hybrid nanochannel design without estimating the capillary pressure. Our results reveal that the slip length of graphene in the graphene nanochannels is around 16 nm, albeit with a large variation from 0 to 200 nm regardless of the channel height. We corroborate this finding with molecular dynamics simulation results, which indicate that this wide distribution of the slip length is due to the surface charge of graphene as well as the interaction between graphene and its silica substrate.

  4. Whole-tree water transport scales with sapwood capacitance in tropical forest canopy trees.

    Science.gov (United States)

    F.C. Meinzer; S.A. James; G. Goldstein; D. Woodruff

    2003-01-01

    The present study examines the manner in which several whole-tree water transport properties scale with species specific variation in sapwood water storage capacity. The hypothesis that constraints on relationships between sapwood capacitance and other water relations characteristics lead to predictable scaling relationships between intrinsic capacitance and whole-tree...

  5. Sediment transport following water transfer from Yangtze River to Taihu Basin

    Directory of Open Access Journals (Sweden)

    Zheng Gong

    2011-12-01

    Full Text Available To meet the increasing need of fresh water and to improve the water quality of Taihu Lake, water transfer from the Yangtze River was initiated in 2002. This study was performed to investigate the sediment distribution along the river course following water transfer. A rainfall-runoff model was first built to calculate the runoff of the Taihu Basin in 2003. Then, the flow patterns of river networks were simulated using a one-dimensional river network hydrodynamic model. Based on the boundary conditions of the flow in tributaries of the Wangyu River and the water level in Taihu Lake, a one-dimensional hydrodynamic and sediment transport numerical model of the Wangyu River was built to analyze the influences of the inflow rate of the water transfer and the suspended sediment concentration (SSC of inflow on the sediment transport. The results show that the water transfer inflow rate and SSC of inflow have significant effects on the sediment distribution. The higher the inflow rate or SSC of inflow is, the higher the SSC value is at certain cross-sections along the river course of water transfer. Higher inflow rate and SSC of inflow contribute to higher sediment deposition per kilometer and sediment thickness. It is also concluded that a sharp decrease of the inflow velocity at the entrance of the Wangyu River on the river course of water transfer induces intense sedimentation at the cross-section near the Changshu hydro-junction. With an increasing distance from the Changshu hydro-junction, the sediment deposition and sedimentation thickness decrease gradually along the river course.

  6. Water Vapor Transport Over the Tropical Oceans During ENSO as Diagnosed from TRMM and SSM/I Data

    Science.gov (United States)

    Robertson, Franklin R.; Smith, Eric A.; Sohn, Byung-Ju

    2000-01-01

    Traditionally, large-scale water vapor transport [div Q] has been derived directly from circulation statistics in which transport processes are often depicted by mean and eddy motions. Thus detailed and accurate calculations of moisture transport terms over the globe are required. Notably, the lack of systematically spaced conventional measurements of meteorological variables over oceans has hindered understanding of the distribution and transport of water vapor. This motivates the use of indirect calculation methods in which horizontal divergence of water vapor is balanced by the evaporation minus precipitation, assuming the rate of changes of precipitable water and condensates is small over a sufficiently long time period. In order to obtain the water vapor transport, we need evaporation rate minus precipitation (E-P). Focussing on the differences in water vapor transport between El Nino and La Nina periods and their influences on atmospheric circulations, we study January, February, and March of 1998 and 1999 periods which represent El Nino and La Nina respectively. SSM/I-derived precipitation and evaporation rate from SSM/I wind and total precipitable water, in conjunction with NCEP SST and surface air temperature, are used for the calculation of the transport potential function. For the retrieval of evaporation we use a stability-dependent aerodynamic bulk scheme developed by Chou (1993). It was tested against aircraft covariance fluxes measured during cold air outbreaks over the North Atlantic Ocean. Chou et al. (1997) reported that the SSM/I retrieved latent heat flux over the western Pacific warm pool area were found to be comparable with daily mean fluxes of a ship measurements during TOGA/COARE.

  7. Radiotracer methods for effluent transport studies. A possibility of application for coastal sea waters and underground waters in near-sea region; Metody znacznikowe w badaniach transportu zanieczyszczen

    Energy Technology Data Exchange (ETDEWEB)

    Strzelecki, M.; Owczarczyk, A. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

    1994-12-31

    The surface and ground waters are a final receivers of industrial, agriculture and municipal effluents. The observation of their transport and deposition in environmental waters can be the expansion measure for ecological hazard estimation. The tracer methods are one of more convenient tools for studying the number of problems connecting with environmental waters protection. Among them the topics are described in the paper: transport of effluents in big water reservoirs and rivers as well as the effluent transport in aquifers. 9 refs.

  8. CFD Lagrangian Modeling of Water Droplet Transport for ISS Hygiene Activity Application

    Science.gov (United States)

    Son, Chang H.

    2013-01-01

    The goal of this study was to assess the impacts of free water propagation in the Waste and Hygiene Compartment (WHC) installed in Node 3. Free water can be generated inside the WHC in small quantities due to crew hygiene activity. To mitigate potential impact of free water in Node 3 cabin the WHC doorway is enclosed by a waterproof bump-out, Kabin, with openings at the top and bottom. At the overhead side of the rack, there is a screen that prevents large drops of water from exiting. However, as the avionics fan in the WHC causes airflow toward the deck side of the rack, small quantities of free water may exit at the bottom of the Kabin. A Computational Fluid Dynamics (CFD) analysis of Node 3 cabin airflow enable identifying the paths of water transport. To simulate the droplet transport the Lagrangian discrete phase approach was used. Various initial droplet distributions were considered in the study. The droplet diameter was varied in the range of 5-20 mm. The results of the computations showed that most of the drops fall to the rack surface not far from the WHC curtain.

  9. Can Free Water Transport Be Used as a Clinical Parameter for Peritoneal Fibrosis in Long-Term PD Patients?

    Science.gov (United States)

    Krediet, Raymond T; Lopes Barreto, Deirisa; Struijk, Dirk G

    2016-01-01

    Sodium sieving in peritoneal dialysis (PD) occurs in a situation with high osmotically-driven ultrafiltration rates. This dilutional phenomenon is caused by free water transport through the water channel aquaporin-1. It has recently been described that encapsulating peritoneal fibrosis is associated with impaired free water transport, despite normal expression of aquaporin-1. In this review, it will be argued that free water transport can be used for assessment of fibrotic peritoneal alterations, due to the water-binding capacity of collagen. Finally, the consequences for clinical practice will be discussed. Copyright © 2016 International Society for Peritoneal Dialysis.

  10. Mathematical simulation of sediment and contaminant transport in surface waters. Annual report, October 1977--September 1978

    International Nuclear Information System (INIS)

    Onishi, Y.; Arnold, E.M.; Serne, R.J.; Cowan, C.E.; Thompson, F.L.; Mayer, D.W.

    1979-01-01

    Various pathways exist for exposure of humans and biota to radioactive materials released from nuclear facilities. Hydrologic transport (liquid pathway) is one element in the evaluation of the total radiation dose to man. Mathematical models supported by well-planned field data collection programs can be useful tools in assessing the hydrologic transport and ultimate fate of radionuclides. Radionuclides with high distribution coefficients or radionuclides in surface waters with high suspended sediment concentrations are, to a great extent, adsorbed by river and marine sediments. Thus, otherwise dilute contaminants are concentrated. Contaminated sediments may be deposited on the river and ocean beds creating a significant pathway to man. Contaminated bed sediment in turn may become a long-term source of pollution through desorption and resuspension. In order to assess migration and accumulation of radionuclides in surface waters, mathematical models must correctly simulate essential mechanisms of radionuclide transport. The objectives of this study were: (1) to conduct a critical review of (a) radionuclide transport models as well as sediment transport and representative water quality models in rivers, estuaries, oceans, lakes, and reservoirs, and (b) adsorption and desorption mechanisms of radionuclides with sediments in surface waters; (2) to synthesize a mathematical model capable of predicting short- and long-term transport and accumulation of radionuclides in marine environments

  11. Modeling UTLS water vapor: Transport/Chemistry interactions

    International Nuclear Information System (INIS)

    Gulstad, Line

    2005-01-01

    This thesis was initially meant to be a study on the impact on chemistry and climate from UTLS water vapor. However, the complexity of the UTLS water vapor and its recent changes turned out to be a challenge by it self. In the light of this, the overall motivation for the thesis became to study the processes controlling UTLS water vapor and its changes. Water vapor is the most important greenhouse gas, involved in important climate feedback loops. Thus, a good understanding of the chemical and dynamical behavior of water vapor in the atmosphere is crucial for understanding the climate changes in the last century. Additionally, parts of the work was motivated by the development of a coupled climate chemistry model based on the CAM3 model coupled with the Chemical Transport Model Oslo CTM2. The future work will be concentrated on the UTLS water vapor impact on chemistry and climate. We are currently studying long term trends in UTLS water vapor, focusing on identification of the different processes involved in the determination of such trends. The study is based on natural as well as anthropogenic climate forcings. The ongoing work on the development of a coupled climate chemistry model will continue within our group, in collaboration with Prof. Wei-Chyung Wang at the State University of New York, Albany. Valuable contacts with observational groups are established during the work on this thesis. These collaborations will be continued focusing on continuous model validation, as well as identification of trends and new features in UTLS water vapor, and other tracers in this region. (Author)

  12. Radial transport processes as a precursor to particle deposition in drinking water distribution systems.

    Science.gov (United States)

    van Thienen, P; Vreeburg, J H G; Blokker, E J M

    2011-02-01

    Various particle transport mechanisms play a role in the build-up of discoloration potential in drinking water distribution networks. In order to enhance our understanding of and ability to predict this build-up, it is essential to recognize and understand their role. Gravitational settling with drag has primarily been considered in this context. However, since flow in water distribution pipes is nearly always in the turbulent regime, turbulent processes should be considered also. In addition to these, single particle effects and forces may affect radial particle transport. In this work, we present an application of a previously published turbulent particle deposition theory to conditions relevant for drinking water distribution systems. We predict quantitatively under which conditions turbophoresis, including the virtual mass effect, the Saffman lift force, and the Magnus force may contribute significantly to sediment transport in radial direction and compare these results to experimental observations. The contribution of turbophoresis is mostly limited to large particles (>50 μm) in transport mains, and not expected to play a major role in distribution mains. The Saffman lift force may enhance this process to some degree. The Magnus force is not expected to play any significant role in drinking water distribution systems. © 2010 Elsevier Ltd. All rights reserved.

  13. Modeling the transport of hydrogen in the primary coolant of pressurized heavy water reactors

    International Nuclear Information System (INIS)

    Subramanian, H.; Velmurugan, S.; Narasimhan, S.V.; Jain, A.K.; Dash, S.C.

    2008-01-01

    Heavy water (D 2 O) is used in primary heat transport systems of PHWRs. To suppress the radiolysis of heavy water and to control oxygen, hydrogen is added at regular intervals to the primary heat transport system. The added hydrogen finds it way to the heavy water storage tank after passing through the bleed condenser. Owing to the different temperatures and two phase region present in these systems, hydrogen gets redistributed. It is important to know the concentration of dissolved hydrogen in these regions in order to ensure a steady state dissolved hydrogen concentration in the primary system. Different power stations report variations in the frequency and quantity of hydrogen added to achieve the prescribed steady state level. This paper makes an attempt to account for the inventory of hydrogen and model its transport in PHT system. (author)

  14. Control of the Water Transport Activity of Barley HvTIP3;1 Specifically Expressed in Seeds.

    Science.gov (United States)

    Utsugi, Shigeko; Shibasaka, Mineo; Maekawa, Masahiko; Katsuhara, Maki

    2015-09-01

    Tonoplast intrinsic proteins (TIPs) are involved in the transport and storage of water, and control intracellular osmotic pressure by transporting material related to the water potential of cells. In the present study, we focused on HvTIP3;1 during the periods of seed development and desiccation in barley. HvTIP3;1 was specifically expressed in seeds. An immunochemical analysis showed that HvTIP3;1 strongly accumulated in the aleurone layers and outer layers of barley seeds. The water transport activities of HvTIP3;1 and HvTIP1;2, which also accumulated in seeds, were measured in the heterologous expression system of Xenopus oocytes. When they were expressed individually, HvTIP1;2 transported water, whereas HvTIP3;1 did not. However, HvTIP3;1 exhibited water transport activity when co-expressed with HvTIP1;2 in oocytes, and this activity was higher than when HvTIP1;2 was expressed alone. This is the first report to demonstrate that the water permeability of a TIP aquaporin was activated when co-expressed with another TIP. The split-yellow fluorescent protein (YFP) system in onion cells revealed that HvTIP3;1 interacted with HvTIP1;2 to form a heterotetramer in plants. These results suggest that HvTIP3;1 functions as an active water channel to regulate water movement through tissues during the periods of seed development and desiccation. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  15. Dealing with water deficit in Atta ant colonies: large ants scout for water while small ants transport it

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Da-Silva

    2012-07-01

    Leafcutter ants (Atta sexdens rubropilosa (Forel 1908 have an elaborate social organization, complete with caste divisions. Activities carried out by specialist groups contribute to the overall success and survival of the colony when it is confronted with environmental challenges such as dehydration. Ants detect variations in humidity inside the nest and react by activating several types of behavior that enhance water uptake and decrease water loss, but it is not clear whether or not a single caste collects water regardless of the cost of bringing this resource back to the colony. Accordingly, we investigated water collection activities in three colonies of Atta sexdens rubropilosa experimentally exposed to water stress. Specifically, we analyzed whether or not the same ant caste foraged for water, regardless of the absolute energetic cost (distance of transporting this resource back to the colony. Our experimental design offered water sources at 0 m, 1 m and 10 m from the nest. We studied the body size of ants near the water sources from the initial offer of water (time  =  0 to 120 min, and tested for specialization. We observed a reduction in the average size and variance of ants that corroborated the specialization hypothesis. Although the temporal course of specialization changed with distance, the final outcome was similar among distances. Thus, we conclude that, for this species, a specialist (our use of the word “specialist” does not mean exclusive task force is responsible for collecting water, regardless of the cost of transporting water back to the colony.

  16. Moditored unsaturated soil transport processes as a support for large scale soil and water management

    Science.gov (United States)

    Vanclooster, Marnik

    2010-05-01

    The current societal demand for sustainable soil and water management is very large. The drivers of global and climate change exert many pressures on the soil and water ecosystems, endangering appropriate ecosystem functioning. The unsaturated soil transport processes play a key role in soil-water system functioning as it controls the fluxes of water and nutrients from the soil to plants (the pedo-biosphere link), the infiltration flux of precipitated water to groundwater and the evaporative flux, and hence the feed back from the soil to the climate system. Yet, unsaturated soil transport processes are difficult to quantify since they are affected by huge variability of the governing properties at different space-time scales and the intrinsic non-linearity of the transport processes. The incompatibility of the scales between the scale at which processes reasonably can be characterized, the scale at which the theoretical process correctly can be described and the scale at which the soil and water system need to be managed, calls for further development of scaling procedures in unsaturated zone science. It also calls for a better integration of theoretical and modelling approaches to elucidate transport processes at the appropriate scales, compatible with the sustainable soil and water management objective. Moditoring science, i.e the interdisciplinary research domain where modelling and monitoring science are linked, is currently evolving significantly in the unsaturated zone hydrology area. In this presentation, a review of current moditoring strategies/techniques will be given and illustrated for solving large scale soil and water management problems. This will also allow identifying research needs in the interdisciplinary domain of modelling and monitoring and to improve the integration of unsaturated zone science in solving soil and water management issues. A focus will be given on examples of large scale soil and water management problems in Europe.

  17. Simulation of water transport through a lipid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Marrink, S.J.; Berendsen, H.J.C. (Univ. of Groningen (Netherlands))

    1994-04-14

    To obtain insight in the process of water permeation through a lipid membrane we performed molecular dynamics simulations on a phospholipid (DPPC)/water system with atomic detail. Since the actual process of permeation is too slow to be studied directly, we deduced the permeation rate indirectly via computation of the free energy and diffusion rate profiles of a water molecule across the bilayer. We concluded that the permeation of water through a lipid membrane cannot be described adequately by a simple homogeneous solubility-diffusion model. Both the excess free energy and the diffusion rate strongly depend on the position in the membrane, as a result from the inhomogeneous nature of the membrane. The calculated excess free energy profile has a shallow slope and a maximum height of 26 kJ/mol. The diffusion rate is highest in the middle of the membrane where the lipid density is low. In the interfacial region almost all water molecules are bound by the lipid headgroups, and the diffusion turns out to be 1 order of magnitude smaller. The total transport process is essentially determined by the free energy barrier. 78 refs., 12 figs.

  18. Modelling transport of water and solutes in future wetlands in Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Vikstroem, Maria; Gustafsson, Lars-Goeran [DHI Water and Environment AB, Vaexjoe (Sweden)

    2006-03-15

    The Forsmark area consists of a number of natural wetlands. As a part of the evaluation of wetlands in the safety assessment for the area, possible future wetlands are being studied with respect to hydrology and transport mechanisms. A sensitivity analyses is performed to point out the governing parameters for the wetland hydraulics. The analysis of future wetlands is carried out using the hydrological model system Mike SHE. Mike SHE has been used to describe the near-surface hydrology for a regional model area in Forsmark. Three types of areas have been chosen. Today's lake Bolundfjaerden is because of its shallow depth likely to develop into a mire in the future. As it is situated in the downstream part of the regional model area, the runoff to the lake from upstream surface water system is significant. Lake Eckarfjaerden is situated in the upstream part of the catchment at a higher altitude and with a smaller inflow. Lake Puttan is situated above a planned layout of the repository and has a potential to receive discharges from a repository. It also lies in the downstream part of a large discharge area. The topography of the future mires is assumed to be flat, up to today's mean water level in each lake. To transport the surface runoff through the wetland, streams or water courses are assumed to form within the peat. The analyses of future wetlands in the Forsmark area show that the hydraulic conditions that exists today will somewhat alter as the peat is formed. For Bolundsfjaerden, where there during present conditions are weak discharge areas, a recharge area has formed during the summer. This can be explained by the amount of surface water that forms on the surface which increases the head elevation in the upper soil layers. The same holds for Eckarfjaerden, while Puttan after the peat has developed still is a discharge area due to its naturally strong discharge position close to the sea. Different vegetation and development stages for the peat have

  19. Modelling transport of water and solutes in future wetlands in Forsmark

    International Nuclear Information System (INIS)

    Vikstroem, Maria; Gustafsson, Lars-Goeran

    2006-03-01

    The Forsmark area consists of a number of natural wetlands. As a part of the evaluation of wetlands in the safety assessment for the area, possible future wetlands are being studied with respect to hydrology and transport mechanisms. A sensitivity analyses is performed to point out the governing parameters for the wetland hydraulics. The analysis of future wetlands is carried out using the hydrological model system Mike SHE. Mike SHE has been used to describe the near-surface hydrology for a regional model area in Forsmark. Three types of areas have been chosen. Today's lake Bolundfjaerden is because of its shallow depth likely to develop into a mire in the future. As it is situated in the downstream part of the regional model area, the runoff to the lake from upstream surface water system is significant. Lake Eckarfjaerden is situated in the upstream part of the catchment at a higher altitude and with a smaller inflow. Lake Puttan is situated above a planned layout of the repository and has a potential to receive discharges from a repository. It also lies in the downstream part of a large discharge area. The topography of the future mires is assumed to be flat, up to today's mean water level in each lake. To transport the surface runoff through the wetland, streams or water courses are assumed to form within the peat. The analyses of future wetlands in the Forsmark area show that the hydraulic conditions that exists today will somewhat alter as the peat is formed. For Bolundsfjaerden, where there during present conditions are weak discharge areas, a recharge area has formed during the summer. This can be explained by the amount of surface water that forms on the surface which increases the head elevation in the upper soil layers. The same holds for Eckarfjaerden, while Puttan after the peat has developed still is a discharge area due to its naturally strong discharge position close to the sea. Different vegetation and development stages for the peat have been

  20. Application of a soil and ground-water pollutant-transport model

    International Nuclear Information System (INIS)

    Reeves, M.; Duguid, J.O.

    1975-01-01

    A general two-dimensional model was developed for simulation of saturated-unsaturated transport of radionuclides in ground water. This model is being applied to the transport of radionuclides from waste-disposal sites, where field investigations are currently under way to obtain the necessary parameters. A zero-order simulation of a waste-disposal trench is presented. Estimated values of the soil properties have been used since very limited experimental information is available at the present time. However, as more measured values become available from field studies, the simulation will be updated. The end product of this research will be a reliable computer model useful both in predicting future transport of radionuclides from buried waste and in examining control measures if they are shown to be necessary. (U.S.)

  1. Water-mediated interactions enable smooth substrate transport in a bacterial efflux pump.

    Science.gov (United States)

    Vargiu, Attilio Vittorio; Ramaswamy, Venkata Krishnan; Malvacio, Ivana; Malloci, Giuliano; Kleinekathöfer, Ulrich; Ruggerone, Paolo

    2018-04-01

    Efflux pumps of the Resistance-Nodulation-cell Division superfamily confer multi-drug resistance to Gram-negative bacteria. The most-studied polyspecific transporter belonging to this class is the inner-membrane trimeric antiporter AcrB of Escherichia coli. In previous studies, a functional rotation mechanism was proposed for its functioning, according to which the three monomers undergo concerted conformational changes facilitating the extrusion of substrates. However, the molecular determinants and the energetics of this mechanism still remain unknown, so its feasibility must be proven mechanistically. A computational protocol able to mimic the functional rotation mechanism in AcrB was developed. By using multi-bias molecular dynamics simulations we characterized the translocation of the substrate doxorubicin driven by conformational changes of the protein. In addition, we estimated for the first time the free energy profile associated to this process. We provided a molecular view of the process in agreement with experimental data. Moreover, we showed that the conformational changes occurring in AcrB enable the formation of a layer of structured waters on the internal surface of the transport channel. This water layer, in turn, allows for a fairly constant hydration of the substrate, facilitating its diffusion over a smooth free energy profile. Our findings reveal a new molecular mechanism of polyspecific transport whereby water contributes by screening potentially strong substrate-protein interactions. We provided a mechanistic understanding of a fundamental process related to multi-drug transport. Our results can help rationalizing the behavior of other polyspecific transporters and designing compounds avoiding extrusion or inhibitors of efflux pumps. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  2. Modeling particle transport and discoloration risk in drinking water distribution networks

    Directory of Open Access Journals (Sweden)

    J. van Summeren

    2017-10-01

    Full Text Available Discoloration of drinking water is a worldwide phenomenon caused by accumulation and subsequent remobilization of particulate matter in drinking water distribution systems (DWDSs. It contributes a substantial fraction of customer complaints to water utilities. Accurate discoloration risk predictions could improve system operation by allowing for more effective programs on cleaning and prevention actions and field measurements, but are challenged by incomplete understanding on the origins and properties of particles and a complex and not fully understood interplay of processes in distribution networks. In this paper, we assess and describe relevant hydraulic processes that govern particle transport in turbulent pipe flow, including gravitational settling, bed-load transport, and particle entrainment into suspension. We assess which transport mechanisms are dominant for a range of bulk flow velocities, particle diameters, and particle mass densities, which includes common conditions for DWDSs in the Netherlands, the UK, and Australia. Our analysis shows that the theoretically predicted particle settling velocity and threshold shear stresses for incipient particle motion are in the same range as, but more variable than, previous estimates from lab experiments, field measurements, and modeling. The presented material will be used in the future development of a numerical modeling tool to determine and predict the spatial distribution of particulate material and discoloration risk in DWDSs. Our approach is aimed at understanding specific causalities and processes, which can complement data-driven approaches.

  3. RESOLUTION OF THE PROBLEM OF TREATMENT OF WASTE WATER GENERATED BY CAR WASHES AND TRANSPORT ENTERPRISES

    Directory of Open Access Journals (Sweden)

    Gogina Elena Sergeevna

    2012-12-01

    big cities of Russia. At the same time, the quality of the waste water treated by local water treatment stations fails to meet the present-day standard requirements. Moreover, potable water shall not be used for the purpose of washing transport vehicles. Within the recent 10 years, MGSU has developed a number of research projects aimed at the resolution of this problem. The concept developed by the MGSU specialists is to attain the highest quality of treated waste water generated by car washes and transport enterprises using the most advanced technologies of water treatment rather than to design new water treatment plants. Various methods may be applied for this purpose: restructuring of water treatment facilities, advanced feed, updated regulations governing the operation of water treatment plants.

  4. Quantitative characterization of water transport and flooding in the diffusion layers of polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Casalegno, A.; Colombo, L.; Galbiati, S.; Marchesi, R. [Department of Energy, Politecnico di Milano, via Lambruschini 4, 20156 Milano (Italy)

    2010-07-01

    Optimization of water management in polymer electrolyte membrane fuel cells (PEMFC) and in direct methanol fuel cells (DMFC) is a very important factor for the achievement of high performances and long lifetime. A good hydration of the electrolyte membrane is essential for high proton conductivity; on the contrary water in excess may lead to electrode flooding and severe reduction in performances. Many studies on water transport across the gas diffusion layer (GDL) have been carried out to improve these components; anyway efforts in this field are affected by lack of effective experimental methods. The present work reports an experimental investigation with the purpose to determine the global coefficient of water transport across different diffusion layers under real operating conditions. An appropriate and accurate experimental apparatus has been designed and built to test the single GDL under a wide range of operating conditions. Data analysis has allowed quantification of both the water vapor transport across different diffusion layers, and the effects of micro-porous layers; furthermore flooding onset and its consequences on the mass transport coefficient have been characterized by means of suitably defined parameters. (author)

  5. Improving activity transport models for water-cooled nuclear power reactors

    Energy Technology Data Exchange (ETDEWEB)

    Burrill, K.A

    2001-08-01

    Eight current models for describing radioactivity transport and radiation field growth around water-cooled nuclear power reactors have been reviewed and assessed. A frequent failing of the models is the arbitrary nature of the determination of the important processes. Nearly all modelers agree that the kinetics of deposition and release of both dissolved and particulate material must be described. Plant data must be used to guide the selection and development of suitable improved models, with a minimum of empirically-based rate constraints being used. Limiting case modelling based on experimental data is suggested as a way to simplify current models and remove their subjectivity. Improved models must consider the recent change to 'coordinated water chemistry' that appears to produce normal solubility behaviour for dissolved iron throughout the fuel cycle in PWRs, but retrograde solubility remains for dissolved nickel. Profiles are suggested for dissolved iron and nickel concentrations around the heat transport system in CANDU reactors, which operate nominally at constant chemistry, i.e., pH{sub T} constant with time, and which use carbon steel isothermal piping. These diagrams are modified for a CANDU reactor with stainless steel piping, in order to show the changes expected. The significance of these profiles for transport in PWRs is discussed for further model improvement. (author)

  6. Hydrological model for the transport of radioisotope in surface water

    International Nuclear Information System (INIS)

    Adoboah, E.K.

    2011-01-01

    The use of radioisotopes has gained grounds in Ghana as a result of the numerous benefits that could be derived from it. In Ghana, radioisotope materials are used for various purposes in a number of institutions. However, improper disposal of the waste poses threat to the environment. To evaluate the environmental impact of radioisotope pollution, mathematical models play a major role in predicting the pollution level in any medium. This study is concerned with the hydrological model for the transport of radioactive material in the river. The model was composed by employing partial differential equations, describing relevant physical processes evolution (water level, velocities and dissolved substances concentrations) that occurs in water bodies. The mass conservation and momentum laws, state equation and state transport equations are equation system basis. The explicit central difference scheme in space and a forward difference method in time were used for the evaluation of the generalized transport equation, the Advection-Dispersion Equation. A Matlab code was developed to predict the concentration of the radioactive contaminant at any particular time along the river and in a reservoir. The model was able to simulate accurately the various levels of radionuclide concentration changes in the flowing rivers as the flows are augmented by tributary inflows. (au)

  7. Rapid Access Ice Drill: A New Tool for Exploration of the Deep Antarctic Ice Sheets and Subglacial Geology

    Science.gov (United States)

    Goodge, J. W.; Severinghaus, J. P.

    2014-12-01

    The Rapid Access Ice Drill (RAID) will penetrate the Antarctic ice sheets in order to core through deep ice, the glacial bed, and into bedrock below. This new technology will provide a critical first look at the interface between major ice caps and their subglacial geology. Currently in construction, RAID is a mobile drilling system capable of making several long boreholes in a single field season in Antarctica. RAID is interdisciplinary and will allow access to polar paleoclimate records in ice >1 Ma, direct observation at the base of the ice sheets, and recovery of rock cores from the ice-covered East Antarctic craton. RAID uses a diamond rock-coring system as in mineral exploration. Threaded drill-pipe with hardened metal bits will cut through ice using reverse circulation of Estisol for pressure-compensation, maintenance of temperature, and removal of ice cuttings. Near the bottom of the ice sheet, a wireline bottom-hole assembly will enable diamond coring of ice, the glacial bed, and bedrock below. Once complete, boreholes will be kept open with fluid, capped, and made available for future down-hole measurement of thermal gradient, heat flow, ice chronology, and ice deformation. RAID will also sample for extremophile microorganisms. RAID is designed to penetrate up to 3,300 meters of ice and take sample cores in less than 200 hours. This rapid performance will allow completion of a borehole in about 10 days before moving to the next drilling site. RAID is unique because it can provide fast borehole access through thick ice; take short ice cores for paleoclimate study; sample the glacial bed to determine ice-flow conditions; take cores of subglacial bedrock for age dating and crustal history; and create boreholes for use as an observatory in the ice sheets. Together, the rapid drilling capability and mobility of the drilling system, along with ice-penetrating imaging methods, will provide a unique 3D picture of the interior Antarctic ice sheets.

  8. Exospheric transport restrictions on water ice in lunar polar traps

    Science.gov (United States)

    Hodges, R. R., Jr.

    1991-01-01

    There is little doubt that at least 10 exp 17 g of water has accreted on the moon as a result of the reduction of ferric iron at the regolith surface by solar wind protons, the vaporization of chondrites, and perhaps comet impacts. Lacking an efficient escape mechanism, most of this water (or its progeny) is probably on the moon now. If the water were to have migrated to permanently shaded cold traps near the lunar poles, ice deposts with densities greater than 1000 g/sq cm would cover the traps, providing accessible resources. However, exospheric transport considerations suggest that the actual amount of water ice in the cold traps is probably too small to be of practical interest. The alternative is global assimilation of most of the water into the regolith, a process that must account for about 30 micromoles of water per gram of soil.

  9. Water transport in gas diffusion media for PEM fuel cells. Experimental and numerical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Joerg

    2010-08-20

    The water flux in partially saturated hydrophobic carbon fibre paper for polymer electrolyte membrane fuel cell applications is investigated and compared with the frequently used constitutive two-phase flow model based on Darcy's law. Further, the first steps towards a math-based material design for gas diffusion media are explored in this thesis. Two self-developed ex-situ experiments to investigate the liquid water transport are introduced. The first is a newly developed buoyancy-based measurement of the pressuresaturation relationship on thin porous material with an accuracy of 0.5 kPa for the pressure and {+-} 5% for the saturation. The second experiment measures the pressure drop in dependence of flow rates down to magnitudes of {mu}L/s across the partially saturated thin porous material. This flow rate is relevant for the fuel cell application. The liquid water transport through Toray 060 carbon fibre paper, impregnated with 7% and 10% PTFE is investigated at wet and dry boundary conditions. The experiments are also accompanied by analytical and numerical free surface modelling with the consideration of the material morphology and liquid-solid interaction. The imbibing and draining cases of an arrangement of six fibres at varying solid-liquid interaction and boundary conditions are studied with 'Surface Evolver'. In order to evaluate the findings of ex-situ and modelling work for applicability to water transport in fuel cell operation, the technique of nuclear magnetic resonance (NMR) imaging is assessed. The focus is on the visualisation of 2D and 3D water distribution in the operating fuel cell. The compatibility of the NMR experiment with fuel cell operation in relation to material selection, operating temperature, and current density is addressed. NMR imaging is employed for different current densities, stoichiometries, and fuel cell arrangements. The fuel cell arrangements differ by the cathode diffusion medium. Plain, hydrophobic, and

  10. Water transport between CNS compartments: contributions of aquaporins and cotransporters

    DEFF Research Database (Denmark)

    MacAulay, N; Zeuthen, T

    2010-01-01

    or hydrocephalus. The molecular pathways by which water molecules cross the cell membranes of the brain are not well-understood, although the discovery of aquaporin 4 (AQP4) in the brain improved our understanding of some of these transport processes, particularly under pathological conditions. In the present...

  11. Comparison of a modified peptone water transport medium with two ...

    African Journals Online (AJOL)

    A laboratory modified peptone water medium was evaluated alongside Stuart and Amies media for their relative suitability as transport media for aerobic bacteria isolated from wound specimens obtained from Central Hospital, Benin City, Nigeria. The survival rates of isolates from the three media were assessed ...

  12. Optimum design for effective water transport through a double-layered porous hydrogel inspired by plant leaves

    Science.gov (United States)

    Kim, Hyejeong; Kim, Hyeonjeong; Huh, Hyungkyu; Hwang, Hyung Ju; Lee, Sang Joon

    2014-11-01

    Plant leaves are generally known to have optimized morphological structure in response to environmental changes for efficient water usage. However, the advantageous features of plant leaves are not fully utilized in engineering fields yet, since the optimum design in internal structure of plant leaves is unclear. In this study, the tissue organization of the hydraulic pathways inside plant leaves was investigated. Water transport through double-layered porous hydrogel models analogous to mesophyll cells was experimentally observed. In addition, computational experiment and theoretical analysis were applied to the model systems to find the optimal design for efficient water transport. As a result, the models with lower porosity or with pores distributed widely in the structure exhibit efficient mass transport. Our theoretical prediction supports that structural features of plant leaves guarantee sufficient water supply as survival strategy. This study may provide a new framework for investigating the biophysical principles governing the morphological optimization of plant leaves and for designing microfluidic devices to enhance mass transport ability. This study was supported by the National Research Foundation of Korea and funded by the Korean government.

  13. High resolution ice thickness, bed topography, and roughness of a land terminating section of the western Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Lindback, K.; Pettersson, R.; Doyle, S. H.

    above sea level. The bed topography shows an intricate subglacial trough system, resembling the landscape in the proglacial area. We also calculate the hydraulic potential to get a proxy of the subglacial routing of water in the area. To analyse the geomorphological conditions of the bed, we calculated...

  14. Visualization of Fuel Cell Water Transport and Performance Characterization under Freezing Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kandlikar, Satish G. [Rochester Inst. of Technology, Rochester, NY (United States); Lu, Zijie [Rochester Inst. of Technology, Rochester, NY (United States); Rao, Navalgund [Rochester Inst. of Technology, Rochester, NY (United States); Sergi, Jacqueline [Rochester Inst. of Technology, Rochester, NY (United States); Rath, Cody [Rochester Inst. of Technology, Rochester, NY (United States); McDade, Christopher [Rochester Inst. of Technology, Rochester, NY (United States); Trabold, Thomas [General Motors, Honeoye Falls, NY (United States); Owejan, Jon [General Motors, Honeoye Falls, NY (United States); Gagliardo, Jeffrey [General Motors, Honeoye Falls, NY (United States); Allen, Jeffrey [Michigan Technological Univ., Houghton, MI (United States); Yassar, Reza S. [Michigan Technological Univ., Houghton, MI (United States); Medici, Ezequiel [Michigan Technological Univ., Houghton, MI (United States); Herescu, Alexandru [Michigan Technological Univ., Houghton, MI (United States)

    2010-05-30

    In this program, Rochester Institute of Technology (RIT), General Motors (GM) and Michigan Technological University (MTU) have focused on fundamental studies that address water transport, accumulation and mitigation processes in the gas diffusion layer and flow field channels of the bipolar plate. These studies have been conducted with a particular emphasis on understanding the key transport phenomena which control fuel cell operation under freezing conditions.

  15. Functional magnetic resonance microscopy of long- and short-distance water transport in trees

    NARCIS (Netherlands)

    Homan, N.

    2009-01-01

    Due to their long life span, changing climatic conditions are of particular importance for trees. Climate changes will affect the water balance, which can become an important limiting factor for photosynthesis and growth. Long-distance water transport in trees is directly related to the

  16. Modeling the response of Northwest Greenland to enhanced ocean thermal forcing and subglacial discharge

    Science.gov (United States)

    Morlighem, M.; Wood, M.; Seroussi, H. L.; Bondzio, J. H.; Rignot, E. J.

    2017-12-01

    Glacier-front dynamics is an important control on Greenland's ice mass balance. Warm and salty Atlantic water, which is typically found at a depth below 200-300 m, has the potential to trigger ice-front retreats of marine-terminating glaciers, and the corresponding loss in resistive stress leads to glacier acceleration and thinning. It remains unclear, however, which glaciers are currently stable but may retreat in the future, and how far inland and how fast they will retreat. Here, we quantify the sensitivity and vulnerability of marine-terminating glaciers along the Northwest coast of Greenland (from 72.5° to 76°N) to ocean forcing using the Ice Sheet System Model (ISSM), and its new ice front migration capability. We rely on the ice melt parameterization from Rignot et al. 2016, and use ocean temperature and salinity from high-resolution ECCO2 simulations on the continental shelf to constrain the thermal forcing. The ice flow model includes a calving law based on a Von Mises criterion. We investigate the sensitivity of Northwest Greenland to enhanced ocean thermal forcing and subglacial discharge. We find that some glaciers, such as Dietrichson Gletscher or Alison Gletscher, are sensitive to small increases in ocean thermal forcing, while others, such as Illullip Sermia or Qeqertarsuup Sermia, are very difficult to destabilize, even with a quadrupling of the melt. Under the most intense melt experiment, we find that Hayes Gletscher retreats by more than 50 km inland into a deep trough and its velocity increases by a factor of 10 over only 15 years. The model confirms that ice-ocean interactions are the triggering mechanism of glacier retreat, but the bed controls its magnitude. This work was performed at the University of California Irvine under a contract with the National Aeronautics and Space Administration, Cryospheric Sciences Program (#NNX15AD55G), and the National Science Foundation's ARCSS program (#1504230).

  17. The Structure and Transport of Water and Hydrated Ions Within Hydrophobic, Nanoscale Channels

    International Nuclear Information System (INIS)

    Holt, J.K.; Herberg, J.L.; Wu, Y.; Schwegler, E.; Mehta, A.

    2009-01-01

    The purpose of this project includes an experimental and modeling investigation into water and hydrated ion structure and transport at nanomaterials interfaces. This is a topic relevant to understanding the function of many biological systems such as aquaporins that efficiently shuttle water and ion channels that permit selective transport of specific ions across cell membranes. Carbon nanotubes (CNT) are model nanoscale, hydrophobic channels that can be functionalized, making them artificial analogs for these biological channels. This project investigates the microscopic properties of water such as water density distributions and dynamics within CNTs using Nuclear Magnetic Resonance (NMR) and the structure of hydrated ions at CNT interfaces via X-ray Absorption Spectroscopy (XAS). Another component of this work is molecular simulation, which can predict experimental measurables such as the proton relaxation times, chemical shifts, and can compute the electronic structure of CNTs. Some of the fundamental questions this work is addressing are: (1) what is the length scale below which nanoscale effects such as molecular ordering become important, (2) is there a relationship between molecular ordering and transport?, and (3) how do ions interact with CNT interfaces? These are questions of interest to the scientific community, but they also impact the future generation of sensors, filters, and other devices that operate on the nanometer length scale. To enable some of the proposed applications of CNTs as ion filtration media and electrolytic supercapacitors, a detailed knowledge of water and ion structure at CNT interfaces is critical.

  18. Development and optimization of radiographic and tomographic methods for characterization of water transport processes in PEM fuel cell materials

    International Nuclear Information System (INIS)

    Markoetter, Henning

    2013-01-01

    Water transport in polymer electrolyte membrane fuel cells (PEMFC) was non-destructively studied during operation with synchrotron X-ray radiography and tomography. The focus was set on the influence of the three-dimensional morphology of the cell materials on the water distribution and transport. Water management is still one of the mayor issues in PEMFC research. If the fuel cell is too dry, the proton conductivity (of the membrane) decreases leading to a performance loss and, in the worst case, to an irreversible damage of the membrane. On the other hand, the presence of water hinders the gas supply and causes a decrease in the cell performance. For this reason, effective water transport is a prerequisite for successful fuel cell operation. In this work the three-dimensional water transport through the gas diffusion layer (GDL) and its correlated with the 3D morphology of the cell materials has been revealed for the first time. It was shown that water is transported preferably through only a few larger pores which form transport paths of low resistance. This effect is pronounced because of the hydrophobic properties of the employed materials. In addition, water transport was found to be bidirectional, i. e. at appropriate locations a back and forth transport between GDL and flow field channels was observed. Furthermore, liquid water in the GDL was found to agglomerate preferably at the ribs of the flow field. This can be explained by condensation due to a temperature gradient in the cell and by the position, which is sheltered from the gas flow. Larger water accumulations in the gas supply channels were mainly attached to the channel wall opposing the GDL. The gas flow can bypass these agglomerations allowing a continuous gas supply. Moreover, it was shown that randomly distributed cracks in the micro porous layers (MPL) play an important role for the agglomeration of liquid water as they form preferred low resistance transport paths. In this work also

  19. Overexpression of Laccaria bicolor aquaporin JQ585595 alters root water transport properties in ectomycorrhizal white spruce (Picea glauca) seedlings.

    Science.gov (United States)

    Xu, Hao; Kemppainen, Minna; El Kayal, Walid; Lee, Seong Hee; Pardo, Alejandro G; Cooke, Janice E K; Zwiazek, Janusz J

    2015-01-01

    The contribution of hyphae to water transport in ectomycorrhizal (ECM) white spruce (Picea glauca) seedlings was examined by altering expression of a major water-transporting aquaporin in Laccaria bicolor. Picea glauca was inoculated with wild-type (WT), mock transgenic or L. bicolor aquaporin JQ585595-overexpressing (OE) strains and exposed to root temperatures ranging from 5 to 20°C to examine the root water transport properties, physiological responses and plasma membrane intrinsic protein (PIP) expression in colonized plants. Mycorrhization increased shoot water potential, transpiration, net photosynthetic rates, root hydraulic conductivity and root cortical cell hydraulic conductivity in seedlings. At 20°C, OE plants had higher root hydraulic conductivity compared with WT plants and the increases were accompanied by higher expression of P. glauca PIP GQ03401_M18.1 in roots. In contrast to WT L. bicolor, the effects of OE fungi on root and root cortical cell hydraulic conductivities were abolished at 10 and 5°C in the absence of major changes in the examined transcript levels of P. glauca root PIPs. The results provide evidence for the importance of fungal aquaporins in root water transport of mycorrhizal plants. They also demonstrate links between hyphal water transport, root aquaporin expression and root water transport in ECM plants. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  20. Influence of root-water-uptake parameterization on simulated heat transport in a structured forest soil

    Science.gov (United States)

    Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir

    2015-04-01

    Coupled simulations of soil water flow and associated transport of substances have become a useful and increasingly popular tool of subsurface hydrology. Quality of such simulations is directly affected by correctness of its hydraulic part. When near-surface processes under vegetation cover are of interest, appropriate representation of the root water uptake becomes essential. Simulation study of coupled water and heat transport in soil profile under natural conditions was conducted. One-dimensional dual-continuum model (S1D code) with semi-separate flow domains representing the soil matrix and the network of preferential pathways was used. A simple root water uptake model based on water-potential-gradient (WPG) formulation was applied. As demonstrated before [1], the WPG formulation - capable of simulating both the compensatory root water uptake (in situations when reduced uptake from dry layers is compensated by increased uptake from wetter layers), and the root-mediated hydraulic redistribution of soil water - enables simulation of more natural soil moisture distribution throughout the root zone. The potential effect on heat transport in a soil profile is the subject of the present study. [1] Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, 12, 10.2136/vzj2012.0154. The research was supported by the Czech Science Foundation Project No. 14-15201J.

  1. Roles and significance of water conducting features for transport models in performance assessment

    International Nuclear Information System (INIS)

    Carrera, J.; Sanchez-Vila, X.; Medina, A.

    1999-01-01

    The term water conducting features (WCF) refers to zones of high hydraulic conductivity. In the context of waste disposal, it is further implied that they are narrow so that chances of sampling them are low. Yet, they may carry significant amounts of water. Moreover, their relatively small volumetric water content causes solutes to travel fast through them. Water-conducting features are a rather common feature of natural media. The fact that they have become a source of concern in recent years, reflects more the increased level of testing and monitoring than any intrinsic property of low permeability media. Accurate simulations of solute transport require a realistic accounting for water conducting features. Methods are presented to do so and examples are shown to illustrate these methods. Since detailed accounting of WCF's will not be possible in actual performance assessments, efforts should be directed towards typification, so as to identify the essential effects of WCF's on solute transport through different types of rocks. Field evidence suggests that, although individual WCF's may be difficult to characterize, their effects are quite predictable. (author)

  2. Modelling of Transport of Radioactive Substances in the Primary Circuit of Water Cooled Reactors

    International Nuclear Information System (INIS)

    2012-03-01

    Since the beginning of the development of water cooled nuclear power reactors, it has been known that the materials in contact with the water release some of their corrosion products into the water. As a consequence, some of the corrosion products are neutron-activated while in the reactor core and then create a gamma radiation field when deposited outside the core. These radiation fields are hazardous to the inspection, maintenance and operating staff in the power plant and therefore must be minimized. Many methods have been developed to control these radiation fields, such as the proper selection of materials and surface finishing technologies at the design stage, operating and shutdown water chemistry optimization, and the application of different decontamination methods. The need to understand the causes of this radioactivity transport has resulted in many mathematical models to describe the transport, irradiation and deposition of the radioactive corrosion products out of the core. Early models were empirical descriptions of the transport, irradiation and deposition steps, and these models allowed analytical solution of the resulting differential equations. As the mechanisms responsible for radioactivity transport gradually became better understood, more precise models of the mechanisms were made. Computer codes to solve the equations describing these models are necessary. Accurate codes are invaluable design tools for carrying out cost-benefit analysis during materials selection, for estimating shielding thicknesses and for evaluating water chemistry specifications, for example. Such codes are also useful in operating plants to predict radiation fields at specific locations where shielding may be required during a maintenance shutdown, for example, when control of radiation dose to staff is essential. To complement the previous work of the International Atomic Energy Agency (IAEA) to improve the mechanistic understanding of radioactivity transport, a

  3. Analysis of Mechanical Energy Transport on Free-Falling Wedge during Water-Entry Phase

    Directory of Open Access Journals (Sweden)

    Wen-Hua Wang

    2012-01-01

    Full Text Available For better discussing and understanding the physical phenomena and body-fluid interaction of water-entry problem, here mechanical-energy transport (wedge, fluid, and each other of water-entry model for free falling wedge is studied by numerical method based on free surface capturing method and Cartesian cut cell mesh. In this method, incompressible Euler equations for a variable density fluid are numerically calculated by the finite volume method. Then artificial compressibility method, dual-time stepping technique, and Roe's approximate Riemann solver are applied in the numerical scheme. Furthermore, the projection method of momentum equations and exact Riemann solution are used to calculate the fluid pressure on solid boundary. On this basis, during water-entry phase of the free-falling wedge, macroscopic energy conversion of overall body-fluid system and microscopic energy transformation in fluid field are analyzed and discussed. Finally, based on test cases, many useful conclusions about mechanical energy transport for water entry problem are made and presented.

  4. Guidelines to Avoid Biocontamination of Antarctic Subglacial Aquatic Environments: Forward Contamination Concerns, Environmental Management and Scientific Stewardship of Icy analogue environments

    Science.gov (United States)

    Race, M. S.; Hobbie, J.; et al.

    2007-12-01

    For more than a decade, scientists and space mission planners have recognized the importance of collaborative information exchange with the Antarctic research community to address their many shared exploration challenges, from drilling methods, remote sample collection, and data interpretation, to concerns about cross contamination that could adversely impact both the environment and interpretation of scientific data. Another shared concern exists in the regulatory realm; both the Antarctic and outer space environments are subject to separate international treaties that impose regulatory controls and oversight with serious implications for exploration planning. In recent years, both communities have faced the need to adjust their regulatory controls in light of fast-paced advances in scientific understanding of extreme environments, particularly related to potential microbial life. Both communities have sought and received advice from the National Research Council (NRC) through studies that suggested ways to update their respective oversight and regulatory systems while allowing for continued scientific exploration. A recently completed NRC study "Exploration of Antarctic Subglacial Aquatic Environments: Environmental and Scientific Stewardship" provided a suite of recommendations to address1) 'cleanliness' levels necessary for equipment and devices used in exploration of subglacial aquatic environments, as well as 2) the scientific basis for contamination standards, and 3) the steps for defining an overall exploration strategy conducive to sound environmental management and scientific stewardship. This talk will present the findings of the recent multinational NRC study, which is likely to translate into useful information for analogue studies that proceed to test techniques and capabilities for exploring an Europan ocean, other icy celestial locations, and related science targets on Earth. As the science and exploration of subglacial environments grows beyond its

  5. Long-distance heat transport by hot water

    International Nuclear Information System (INIS)

    Munser, H.; Reetz, B.

    1990-01-01

    From the analysis of the centralized heat supply in the GDR energy-economical and ecological indispensable developments of long-distance heat systems in conurbation are derived. The heat extraction from a nuclear power plant combined with long- distance hot-water transport over about 110 kilometres is investigated and presented as a possibility to perspective base load heat demands for the district around Dresden. By help of industrial-economic, hydraulic and thermic evaluations of first design variants of the transit system the acceptance of this ecologic and energetic preferred solution is proved and requirements for its realization are shown

  6. ATMOS Stratospheric Deuterated Water and Implications for Tropospheric-Stratospheric Transport

    Science.gov (United States)

    Moyer, Elisabeth J.; Irion, Fredrick W.; Yung, Yuk L.; Gunson, Michael R.

    1996-01-01

    Measurements of the isotopic composition of stratospheric water by the ATMOS instrument are used to infer the convective history of stratospheric air. The average water vapor entering the stratosphere is found to be highly depleted of deuterium, with delta-D(sub w) of -670 +/- 80 (67% deuterium loss). Model calculations predict, however, that under conditions of thermodynamic equilibrium, dehydration to stratospheric mixing ratios should produce stronger depletion to delta-D(sub w) of -800 to 900 (80-90% deuterium loss). Deuterium enrichment of water vapor in ascending parcels can occur only in conditions of rapid convection; enrichments persisting into the stratosphere require that those conditions continue to near-tropopause altitudes. We conclude that either the predominant source of water vapor to the uppermost troposphere is enriched convective water, most likely evaporated cloud ice, or troposphere-stratosphere transport occurs closely associated with tropical deep convection.

  7. Cross-shelf transport into nearshore waters due to shoaling internal tides in San Pedro Bay, CA

    Science.gov (United States)

    Noble, Marlene A.; Burt Jones,; Peter Hamilton,; Xu, Jingping; George Robertson,; Rosenfeld, Leslie; John Largier,

    2009-01-01

    In the summer of 2001, a coastal ocean measurement program in the southeastern portion of San Pedro Bay, CA, was designed and carried out. One aim of the program was to determine the strength and effectiveness of local cross-shelf transport processes. A particular objective was to assess the ability of semidiurnal internal tidal currents to move suspended material a net distance across the shelf. Hence, a dense array of moorings was deployed across the shelf to monitor the transport patterns associated with fluctuations in currents, temperature and salinity. An associated hydrographic program periodically monitored synoptic changes in the spatial patterns of temperature, salinity, nutrients and bacteria. This set of measurements show that a series of energetic internal tides can, but do not always, transport subthermocline water, dissolved and suspended material from the middle of the shelf into the surfzone. Effective cross-shelf transport occurs only when (1) internal tides at the shelf break are strong and (2) subtidal currents flow strongly downcoast. The subtidal downcoast flow causes isotherms to tilt upward toward the coast, which allows energetic, nonlinear internal tidal currents to carry subthermocline waters into the surfzone. During these events, which may last for several days, the transported water remains in the surfzone until the internal tidal current pulses and/or the downcoast subtidal currents disappear. This nonlinear internal tide cross-shelf transport process was capable of carrying water and the associated suspended or dissolved material from the mid-shelf into the surfzone, but there were no observation of transport from the shelf break into the surfzone. Dissolved nutrients and suspended particulates (such as phytoplankton) transported from the mid-shelf into the nearshore region by nonlinear internal tides may contribute to nearshore algal blooms, including harmful algal blooms that occur off local beaches.

  8. Heat and Water Transport in Soils and Across the Soil-Atmosphere Interface: Comparison of Model Concepts

    DEFF Research Database (Denmark)

    Vanderborght, Jan; Smits, Kathleen; Mosthaf, Klaus

    Evaporation from the soil surface represents a water flow and transport process in a porous medium that is coupled with free air flow and with heat fluxes in the system. We give an overview of different model concepts that are used to describe this process. These range from non-isothermal two......-phase flow two-component transport in the porous medium that is coupled with one-phase flow two-component transport in the free air to isothermal water flow in the porous with upper boundary conditions defined by a potential evaporation flux when available energy and transfer to the free air flow...... models were found. The effect of vapor flow in the porous medium on cumulative evaporation could be evaluated using the desorptivity, Sevap, which represents a weighted average of liquid and vapor diffusivity over the range of soil water contents between the soil surface water content and the initial...

  9. ESKIMO1 disruption in Arabidopsis alters vascular tissue and impairs water transport.

    Directory of Open Access Journals (Sweden)

    Valérie Lefebvre

    Full Text Available Water economy in agricultural practices is an issue that is being addressed through studies aimed at understanding both plant water-use efficiency (WUE, i.e. biomass produced per water consumed, and responses to water shortage. In the model species Arabidopsis thaliana, the ESKIMO1 (ESK1 gene has been described as involved in freezing, cold and salt tolerance as well as in water economy: esk1 mutants have very low evapo-transpiration rates and high water-use efficiency. In order to establish ESK1 function, detailed characterization of esk1 mutants has been carried out. The stress hormone ABA (abscisic acid was present at high levels in esk1 compared to wild type, nevertheless, the weak water loss of esk1 was independent of stomata closure through ABA biosynthesis, as combining mutant in this pathway with esk1 led to additive phenotypes. Measurement of root hydraulic conductivity suggests that the esk1 vegetative apparatus suffers water deficit due to a defect in water transport. ESK1 promoter-driven reporter gene expression was observed in xylem and fibers, the vascular tissue responsible for the transport of water and mineral nutrients from the soil to the shoots, via the roots. Moreover, in cross sections of hypocotyls, roots and stems, esk1 xylem vessels were collapsed. Finally, using Fourier-Transform Infrared (FTIR spectroscopy, severe chemical modifications of xylem cell wall composition were highlighted in the esk1 mutants. Taken together our findings show that ESK1 is necessary for the production of functional xylem vessels, through its implication in the laying down of secondary cell wall components.

  10. Water transport by the Na+/glucose cotransporter under isotonic conditions

    DEFF Research Database (Denmark)

    Zeuthen, T; Meinild, A K; Klaerke, D A

    1997-01-01

    Solute cotransport in the Na+/glucose cotransporter is directly coupled to significant water fluxes. The water fluxes are energized by the downhill fluxes of the other substrates by a mechanism within the protein itself. In the present paper we investigate the Na+/glucose cotransporter expressed ...... of water molecules and the number of Na+ ions transported, equivalent to 390 water molecules per glucose molecule. Unstirred layer effects are ruled out on the basis of experiments on native oocytes incubated with the ionophores gramicidin D or nystatin.......Solute cotransport in the Na+/glucose cotransporter is directly coupled to significant water fluxes. The water fluxes are energized by the downhill fluxes of the other substrates by a mechanism within the protein itself. In the present paper we investigate the Na+/glucose cotransporter expressed...... in Xenopus oocytes. We present a method which allows short-term exposures to sugar under voltage clamp conditions. We demonstrate that water is cotransported with the solutes despite no osmotic differences between the external and intracellular solutions. There is a fixed ratio of 195:1 between the number...

  11. ESTIMATION OF THE WANDA GLACIER (SOUTH SHETLANDS) SEDIMENT EROSION RATE USING NUMERICAL MODELLING

    OpenAIRE

    Kátia Kellem Rosa; Rosemary Vieira; Jefferson Cardia Simões

    2013-01-01

    Glacial sediment yield results from glacial erosion and is influenced by several factors including glacial retreat rate, ice flow velocity and thermal regime. This paper estimates the contemporary subglacial erosion rate and sediment yield of Wanda Glacier (King George Island, South Shetlands). This work also examines basal sediment evacuation mechanisms by runoff and glacial erosion processes during the subglacial transport. This is small temperate glacier that has seen retreating for the l...

  12. Transport of perfluoroalkyl acids in a water-saturated sediment column investigated under near-natural conditions

    International Nuclear Information System (INIS)

    Vierke, Lena; Möller, Axel; Klitzke, Sondra

    2014-01-01

    The aim of this study was to gain an understanding of the transport of C 4–10 perfluoroalkyl carboxylic acids (PFCAs) and C 4,6,8 perfluoroalkyl sulfonic acids (PFSAs) in a water-saturated sediment column representing a riverbank filtration scenario under near-natural conditions. Short-chain PFCAs and PFSAs with up to six C-atoms showed complete tracer-like breakthrough. Longer chain ones were retarded due to sorption to the sediment or due to other processes in the aqueous phase. The study reports the first column derived sediment–water partition coefficients ranging from 0.01 cm 3 g −1 to 0.41 cm 3 g −1 for C 4,6 PFSAs and from 0.0 cm 3 g −1 to 6.5 cm 3 g −1 for C 4,5,6,8,9 PFCAs. The results clearly indicate that short-chain PFCAs and PFSAs may pose a problem if contaminated surface waters are used for drinking water production via riverbank filtration. Highlights: • Transport of per- and polyfluorinated compounds in a riverbank filtration scenario. • Investigations under near-natural conditions with a water-saturated sediment column. • Processes in water and sediment control the transport of analytes. • Short chain PFCAs and PFSAs are not retarded in the water-saturated sediment column. • First column derived sediment–water partition coefficients. -- Quantification of breakthrough of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) under conditions simulating a riverbank filtration scenario

  13. Complexity in the validation of ground-water travel time in fractured flow and transport systems

    International Nuclear Information System (INIS)

    Davies, P.B; Hunter, R.L.; Pickens, J.F.

    1991-02-01

    Ground-water travel time is a widely used concept in site assessment for radioactive waste disposal. While ground-water travel time was originally conceived to provide a simple performance measure for evaluating repository sites, its definition in many flow and transport environments is ambiguous. The US Department of Energy siting guidelines (10 CFR 960) define ground-water travel time as the time required for a unit volume of water to travel between two locations, calculated by dividing travel-path length by the quotient of average ground-water flux and effective porosity. Defining a meaningful effective porosity in a fractured porous material is a significant problem. Although the Waste Isolation Pilot Plant (WIPP) is not subject to specific requirements for ground-water travel time, travel times have been computed under a variety of model assumptions. Recently completed model analyses for WIPP illustrate the difficulties in applying a ground-water travel-time performance measure to flow and transport in fractured, fully saturated flow systems. 12 refs., 4 figs

  14. 75 FR 8412 - Office of New Reactors: Interim Staff Guidance on Assessing Ground Water Flow and Transport of...

    Science.gov (United States)

    2010-02-24

    ... NUCLEAR REGULATORY COMMISSION [NRC-2010-0047] Office of New Reactors: Interim Staff Guidance on Assessing Ground Water Flow and Transport of Accidental Radionuclide Releases; Solicitation of Public... ground water flow and transport of accidental radionuclide releases necessary to demonstrate compliance...

  15. Glacial removal of late Cenozoic subglacially emplaced volcanic edifices by the West Antarctic ice sheet

    Science.gov (United States)

    Behrendt, John C.; Blankenship, D.D.; Damaske, D.; Cooper, A. K.

    1995-01-01

    Local maxima of the horizontal gradient of pseudogravity from closely spaced aeromagnetic surveys over the Ross Sea, northwestern Ross Ice Shelf, and the West Antarctic ice sheet, reveal a linear magnetic rift fabric and numerous subcircular, high-amplitude anomalies. Geophysical data indicate two or three youthful volcanic edifices at widely separated areas beneath the sea and ice cover in the West Antarctic rift system. In contrast, we suggest glacial removal of edifices of volcanic sources of many more anomalies. Magnetic models, controlled by marine seismic reflection and radar ice-sounding data, allow us to infer that glacial removal of the associated late Cenozoic volcanic edifices (probably debris, comprising pillow breccias, and hyaloclastites) has occurred essentially concomitantly with their subglacial eruption. "Removal' of unconsolidated volcanic debris erupted beneath the ice is probably a more appropriate term than "erosion', given its fragmented, ice-contact origin. The exposed volcanoes may have been protected from erosion by the surrounding ice sheet because of more competent rock or high elevation above the ice sheet. -from Authors

  16. European CO2 emission trends: A decomposition analysis for water and aviation transport sectors

    International Nuclear Information System (INIS)

    Andreoni, V.; Galmarini, S.

    2012-01-01

    A decomposition analysis is used to investigate the main factors influencing the CO 2 emissions of European transport activities for the period 2001–2008. The decomposition method developed by Sun has been used to investigate the carbon dioxide emissions intensity, the energy intensity, the structural changes and the economy activity growth effects for the water and the aviation transport sectors. The analysis is based on Eurostat data and results are presented for 14 Member States, Norway and EU27. Results indicate that economic growth has been the main factor behind the carbon dioxide emissions increase in EU27 both for water and aviation transport activities. -- Highlights: ► Decomposition analysis is used to investigate factors that influenced the energy-related CO 2 emissions of European transport. ► Economic growth has been the main factor affecting the energy-related CO 2 emissions increases. ► Investigating the CO 2 emissions drivers is the first step to define energy efficiency policies and emission reduction strategies.

  17. Water and dissolved carbon transport in an eroding soil landscape using column experiments

    DEFF Research Database (Denmark)

    Rieckh, Helene; Gerke, Horst; Glæsner, Nadia

    2014-01-01

    In the hummocky ground moraine soil landscape, a spatial continuum of more or less eroded soils developed from till under intensive agricultural cultivation. Water flow and solute transport are affected by the variable soil structural and pedological developments, which are posing a challenge...... for flux estimation. The objective of this study was to investigate transport of water, dissolved organic (DOC), and particulate carbon (PC) through soil profiles of an eroded Haplic Luvisol and a heavily eroded Haplic Regosol. We studied 5 soil horizons in three replicates each: Ap (0-20 cm) and E (20...... boundary. Breakthrough curves for a pre-applied tracer (Br-) on the soil surface and a tracer applied with irrigation water (3H2O) were modeled analytically using CXTFIT. The heterogeneity of the Luvisol horizons was generally higher than that of the Regosol horizons, which relates to the higher...

  18. 41 CFR 302-10.200 - What costs are allowable when a commercial carrier transports my mobile home overland or over water?

    Science.gov (United States)

    2010-07-01

    ... when a commercial carrier transports my mobile home overland or over water? 302-10.200 Section 302-10... carrier transports my mobile home overland or over water? Your agency will allow the following costs for... State or local law. (b) When transporting over water cost must include, but not limited to the cost of...

  19. Ecology of Subglacial Lake Vostok (Antarctica, Based on Metagenomic/Metatranscriptomic Analyses of Accretion Ice

    Directory of Open Access Journals (Sweden)

    Tom D'Elia

    2013-03-01

    Full Text Available Lake Vostok is the largest of the nearly 400 subglacial Antarctic lakes and has been continuously buried by glacial ice for 15 million years. Extreme cold, heat (from possible hydrothermal activity, pressure (from the overriding glacier and dissolved oxygen (delivered by melting meteoric ice, in addition to limited nutrients and complete darkness, combine to produce one of the most extreme environments on Earth. Metagenomic/metatranscriptomic analyses of ice that accreted over a shallow embayment and over the southern main lake basin indicate the presence of thousands of species of organisms (94% Bacteria, 6% Eukarya, and two Archaea. The predominant bacterial sequences were closest to those from species of Firmicutes, Proteobacteria and Actinobacteria, while the predominant eukaryotic sequences were most similar to those from species of ascomycetous and basidiomycetous Fungi. Based on the sequence data, the lake appears to contain a mixture of autotrophs and heterotrophs capable of performing nitrogen fixation, nitrogen cycling, carbon fixation and nutrient recycling. Sequences closest to those of psychrophiles and thermophiles indicate a cold lake with possible hydrothermal activity. Sequences most similar to those from marine and aquatic species suggest the presence of marine and freshwater regions.

  20. Mechanisms and modeling development of water transport/phase change in catalyst layers of portion exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yexiang [Dept. of Thermal Engineering, Tsinghua University Beijing (China)], email: Yexiang.Xiao@energy.lth.se; Yuan, Jinliang; Sunden, Bengt [Dept. of Energy Sciences, Faculty of Engineering, Lund University (Sweden)], email: Jinliang.yuan@energy.lth.se, email: bengt.sunden@energy.lth.se

    2011-07-01

    Research on proton exchange membrane fuel cells has shown that incorporation of nanosized catalysts can effectively increase active areas and catalyst activity and make a great contribution to development in performance and catalyst utilization. Multiphase transport processes are as significant and complicated as water generation/transfer processes which occur in nano-structured catalyst layers. A review project has been launched aimed at gaining a comprehensive understanding of the mechanisms of water generation or transport phenomena. It covers catalytic reactions and water-phase change within the catalyst layers. The review proceeds in three main stages: Firstly, it characterizes and reconstructs the nano/micro-structured pores and solid-phases; secondly, it emphasises the importance of sensitive and consistent analysis of various water-phase change and transport schemes; and thirdly, it recommends development of microscopic models for multi-phase transport processes in the pores and the solid phases.

  1. Transport of nanoparticles with dispersant through biofilm coated drinking water sand filters.

    Science.gov (United States)

    Li, Zhen; Aly Hassan, Ashraf; Sahle-Demessie, Endalkachew; Sorial, George A

    2013-11-01

    This article characterizes, experimentally and theoretically, the transport and retention of engineered nanoparticles (NP) through sand filters at drinking water treatment plants (DWTPs) under realistic conditions. The transport of four commonly used NPs (ZnO, CeO2, TiO2, and Ag, with bare surfaces and coating agents) through filter beds filled with sands from either acid washed and calcined, freshly acquired filter media, and used filter media from active filter media, were investigated. The study was conducted using water obtained upstream of the sand filter at DWTP. The results have shown that capping agents have a determinant importance in the colloidal stability and transport of NPs through the different filter media. The presence of the biofilm in used filter media increased adsorption of NPs but its effects in retaining capped NPs was less significant. The data was used to build a mathematical model based on the advection-dispersion equation. The model was used to simulate the performance of a scale-up sand filter and the effects on filtration cycle of traditional sand filtration system used in DWTPs. Published by Elsevier Ltd.

  2. Dynamics of the Water Circulations in the Southern South China Sea and Its Seasonal Transports.

    Science.gov (United States)

    Daryabor, Farshid; Ooi, See Hai; Samah, Azizan Abu; Akbari, Abolghasem

    2016-01-01

    A three-dimensional Regional Ocean Modeling System is used to study the seasonal water circulations and transports of the Southern South China Sea. The simulated seasonal water circulations and estimated transports show consistency with observations, e.g., satellite altimeter data set and re-analysis data of the Simple Ocean Data Assimilation. It is found that the seasonal water circulations are mainly driven by the monsoonal wind stress and influenced by the water outflow/inflow and associated currents of the entire South China Sea. The intrusion of the strong current along the East Coast of Peninsular Malaysia and the eddies at different depths in all seasons are due to the conservation of the potential vorticity as the depth increases. Results show that the water circulation patterns in the northern part of the East Coast of Peninsular Malaysia are generally dominated by the geostrophic currents while those in the southern areas are due solely to the wind stress because of negligible Coriolis force there. This study clearly shows that individual surface freshwater flux (evaporation minus precipitation) controls the sea salinity balance in the Southern South China Sea thermohaline circulations. Analysis of climatological data from a high resolution Regional Ocean Modeling System reveals that the complex bathymetry is important not only for water exchange through the Southern South China Sea but also in regulating various transports across the main passages in the Southern South China Sea, namely the Sunda Shelf and the Strait of Malacca. Apart from the above, in comparision with the dynamics of the Sunda Shelf, the Strait of Malacca reflects an equally significant role in the annual transports into the Andaman Sea.

  3. Dynamics of the water circulations in the southern South China Sea and its seasonal transports

    DEFF Research Database (Denmark)

    Daryabor, Farshid; Ooi, See Hai Ooi; Samah, Azizan Abu

    2016-01-01

    -analysis data of the Simple Ocean Data Assimilation. It is found that the seasonal water circulations are mainly driven by the monsoonal wind stress and influenced by the water outflow/inflow and associated currents of the entire South China Sea. The intrusion of the strong current along the East Coast......A three-dimensional Regional Ocean Modeling System is used to study the seasonal water circulations and transports of the Southern South China Sea. The simulated seasonal water circulations and estimated transports show consistency with observations, e.g., satellite altimeter data set and re...... of Peninsular Malaysia and the eddies at different depths in all seasons are due to the conservation of the potential vorticity as the depth increases. Results show that the water circulation patterns in the northern part of the East Coast of Peninsular Malaysia are generally dominated by the geostrophic...

  4. Effects of water content on reactive transport of Sr in Chernobyl sand columns

    International Nuclear Information System (INIS)

    Szenknect, S.; Dewiere, L.; Ardois, C.; Gaudet, J.P.

    2005-01-01

    Full text of publication follows: While transport of non-reactive solutes has been studied extensively in unsaturated porous media, much less is known about the factors that control the transport of sorbing solutes in unsaturated conditions. Three laboratory techniques were used to analyze the transport of Sr in the aeolian sand from Chernobyl Pilot Site [1] in both saturated and unsaturated flow conditions. Batch experiments were performed to study the chemical equilibrium state of the soil/solution system. Stirred flow-through reactor (SFTR) experiments were performed to study the kinetics and reversibility of sorption reactions at the surface of solid particles. Column experiments were also performed in saturated and unsaturated steady flow conditions. Experimental data pointed out a non-linear, instantaneous and reversible sorption process of Sr. A suitable cation-exchange model was used to describe the solute/soil reaction. The former model was coupled with transport models to describe behavior of Sr in saturated [2] and unsaturated flow conditions. Transport properties of sand packed columns have been determined with an inert tracer (HTO). BTCs obtained under saturated conditions exhibit a small amount of dispersion compared to those obtained under unsaturated conditions. Classical advection-dispersion model described successfully saturated tritium breakthrough curves (BTCs), whereas a mobile-immobile model (MIM) was required to described asymmetrical unsaturated BTCs. The MIM assumes that the porous medium contains a mobile water phase in which convective-dispersive transport occurs, and a immobile water phase with which solutes can exchange with a first order kinetic. In our experiments, transport by advection in the mobile phase is the predominant process whatever the flow conditions and mass transfer rate between the mobile and immobile regions is the predominant process for broadening the BTCs. Since dispersion is blurred by mass transfer resistance, the

  5. Nutrient transport in the mammary gland: calcium, trace minerals and water soluble vitamins.

    Science.gov (United States)

    Montalbetti, Nicolas; Dalghi, Marianela G; Albrecht, Christiane; Hediger, Matthias A

    2014-03-01

    Milk nutrients are secreted by epithelial cells in the alveoli of the mammary gland by several complex and highly coordinated systems. Many of these nutrients are transported from the blood to the milk via transcellular pathways that involve the concerted activity of transport proteins on the apical and basolateral membranes of mammary epithelial cells. In this review, we focus on transport mechanisms that contribute to the secretion of calcium, trace minerals and water soluble vitamins into milk with particular focus on the role of transporters of the SLC series as well as calcium transport proteins (ion channels and pumps). Numerous members of the SLC family are involved in the regulation of essential nutrients in the milk, such as the divalent metal transporter-1 (SLC11A2), ferroportin-1 (SLC40A1) and the copper transporter CTR1 (SLC31A1). A deeper understanding of the physiology and pathophysiology of these transporters will be of great value for drug discovery and treatment of breast diseases.

  6. Transport of Astyanax altiparanae Garutti and Britski, 2000 in saline water

    Directory of Open Access Journals (Sweden)

    Ana Lúcia Salaro

    2015-08-01

    Full Text Available Two experiments were performed. The first aimed to assess the tolerance of fingerlings Astyanax altiparanae to water salinity. Fish were exposed to salinity of 0, 3, 6, 9, 12 or 15 g NaCl L-1 for 96 hours. The fish mortality was 0%, in the levels of 0, 3 and 6 g L-1; 75% in the level of 9 g L-1and 100% at 12 and 15 g L-1 of common salt. The second experiment aimed to assess the parameters of water quality, mortality and blood glucose during transport. For this, A. altiparanae were stored in plastic bags at 22, 30 and 37 g of fish L-1 stocking densities and salinity of 0, 3, 6 and 9 g L-1, for. Fish showed similar mortality levels in the different salinities and stocking densities. The increase in fish density reduced the dissolved oxygen levels and salinity decreased the pH. The blood glucose levels were higher in those fish with 0 g L-1 salinity and higher stocking densities. The addition of salt to the water reduces the stress responses of A. altiparanae during transport.

  7. Water transport mechanisms across inorganic membranes in rad waste treatment by electro dialysis. Mecanismos de transporte de agua atraves de membranas inorganicas en tratamiento de desechos radiactivos por electrodialisis

    Energy Technology Data Exchange (ETDEWEB)

    Andalaft, E; Labayru, R [Comision Chilena de Energia Nuclear, Santiago (Chile)

    1992-12-01

    The work described in this paper deals with effects and mechanisms of water transport across an inorganic membrane, as related to some studied on the concentration of caesium, strontium, plutonium and other cations of interest to radioactive waste treatment. Several different water transport mechanisms are analysed and assessed as to their individual contribution towards the total transference of water during electro-dialysis using inorganic membranes. Water transfer assisted by proton jump mechanism, water of hydration transferred along with the ions, water related to thermo-osmotic effect, water transferred by concentration gradient and water transferred electrolytically under zeta potential surface charge drive are some of the different mechanism discussed. (author).

  8. Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips - Part 1: nonuniform infiltration and soil water redistribution

    OpenAIRE

    Munoz Carpena, R.; Lauvernet, C.; Carluer, N.

    2018-01-01

    Vegetation buffers like vegetative filter strips (VFSs) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in floodplains often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and increase surface pollutant transport during a rainfall-runoff event. Simple and robust components of hydrological models are needed to analyze the impacts of WT in the landscape. To si...

  9. NASA Experiment on Tropospheric-Stratospheric Water Vapor Transport in the Intertropical Convergence Zone

    Science.gov (United States)

    Page, William A.

    1982-01-01

    The following six papers report preliminary results obtained from a field experiment designed to study the role of tropical cumulo-nimbus clouds in the transfer of water vapor from the troposphere to the stratosphere over the region of Panama. The measurements were made utilizing special NOAA enhanced IR satellite images, radiosonde-ozonesondes and a NASA U-2 aircraft carrying. nine experiments. The experiments were provided by a group of NASA, NOAA, industry, and university scientists. Measurements included atmospheric humidity, air and cloud top temperatures, atmospheric tracer constituents, cloud particle characteristics and cloud morphology. The aircraft made a total of eleven flights from August 30 through September 18, 1980, from Howard Air Force Base, Panama; the pilots obtained horizontal and vertical profiles in and near convectively active regions and flew around and over cumulo-nimbus towers and through the extended anvils in the stratosphere. Cumulo-nimbus clouds in the tropics appear to play an important role in upward water vapor transport and may represent the principal source influencing the stratospheric water vapor budget. The clouds provide strong vertical circulation in the troposphere, mixing surface air and its trace materials (water vapor, CFM's sulfur compounds, etc.) quickly up to the tropopause. It is usually assumed that large scale mean motions or eddy scale motions transport the trace materials through the tropopause and into the stratosphere where they are further dispersed and react with other stratospheric constituents. The important step between the troposphere and stratosphere for water vapor appears to depend upon the processes occurring at or near the tropopause at the tops of the cumulo-nimbus towers. Several processes have been sugested: (1) The highest towers penetrate the tropopause and carry water in the form of small ice particles directly into the stratosphere. (2) Water vapor from the tops of the cumulonimbus clouds is

  10. Origin and transport of sediments in an alpine glaciated catchment (Bossons glacier, France): a quantification combining hydro-sedimentary data, radio-frequency identification of pebbles, cosmogenic nuclides content and probabilistic methods

    International Nuclear Information System (INIS)

    Guillon, Herve

    2016-01-01

    Among the most efficient agents of erosion, glaciers react dynamically to climate change, leading to a significant adjustment of downstream sediment flux. Present-day global warming raises the question regarding the evolution of the sediment load originating from partially glaciated catchment. The detrital export from such environment results from erosion processes operating within distinct geomorphologic domains: supra-glacial rock-walls, ice-covered substratum and the pro-glacial area, downstream from the glacier. The general intent of this doctoral research is therefore to characterize the origin and transport of sediments in the watersheds of two streams draining Bossons glacier (Mont-Blanc massif, France).For this purpose, the components of the sediment flux coming from supra-glacial, sub-glacial and pro-glacial domains are separated and quantified by innovating methods: i. Using the terrestrial cosmogenic nuclides concentrations as evidence of a supra-glacial transport; ii. Combining meteorological data and hydro-sedimentary data acquired at a high time resolution (2 min) and completed by multi-linear models; iii. Estimating sediment flux by source for 7 years and with a probabilistic method; iv. Associating radio-frequency identification of pebbles in the pro-glacial area with a stochastic transport analysis.Through numerical tools, applying the presented methodologies provides erosion rates of the supra-glacial, sub-glacial and pro-glacial domains, and determines the sediment transfer mechanisms within the catchment.Thus in the terminal part of the glacier, 52±14 to 9±4% of the supra-glacial load is transferred to the sub-glacial drainage network. Moreover, its evolution throughout the melt season leads to the export of the winter sediment production during a limited period. Furthermore, the drainage configuration beneath the glacier and its retreat control the remobilization of a long-term sediment stock. These processes explain the contrast between the

  11. Some analytic diagnostic models for transport processes in estuarine and coastal waters; Algunos modelos analiticos de diagnostico para procesos de transporte en estuarios y aguas costeras

    Energy Technology Data Exchange (ETDEWEB)

    Suarez Antola, R [Industry Energy and Mining Ministry, National Direction of Nuclear Technology, Montevideo (Uruguay)

    2001-03-01

    Advection and dispersion processes in estuarine and coastal waters are briefly reviewed. Beginning from the basic macroscopic equations of transport for a substance diluted or suspended in the considered body of water,several levels of filtering in time and space are described and applied to obtain suitable diagnostic mathematical models both with scale effects and gaussian.The solutions of the aforementioned models,for initial distributions and boundary conditions with enough symmetry,are discussed, as well as their applications to a parameter characterization of the transport properties of the receiving body of water.

  12. Variations in Upper-Level Water Vapor Transport Diagnosed from Climatological Satellite Data

    Science.gov (United States)

    Lerner, Jeffrey A; Jedlovee, Gary J.; Atkinson, Robert J.

    1998-01-01

    GOES-7 VAS measurements during the Pathfinder period (1987-88) have been analysed to reveal seasonal and interannual variations in moisture transport. Long term measurements of quality winds and humidity from satellite estimates show superior benefit in diagnosing middle and upper tropospheric large scale climate variations such as ENSO events and direct circulation systems such as the Hadley Cell. A water Vapor Transport Index (WVTI) has been developed to diagnose preferred regions of strong moisture transport and to gauge the seasonal and interannual intensities detected in the GOES viewing area. Second-order variables that may be derived from GOES winds will be also discussed on the poster.

  13. Moisture harvesting and water transport through specialized micro-structures on the integument of lizards.

    Science.gov (United States)

    Comanns, Philipp; Effertz, Christian; Hischen, Florian; Staudt, Konrad; Böhme, Wolfgang; Baumgartner, Werner

    2011-01-01

    Several lizard species that live in arid areas have developed special abilities to collect water with their bodies' surfaces and to ingest the so collected moisture. This is called rain- or moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even from humid soil. The integument (i.e., the skin plus skin derivatives such as scales) has developed features so that the water spreads and is soaked into a capillary system in between the reptiles' scales. Within this capillary system the water is transported to the mouth where it is ingested. We have investigated three different lizard species which have developed the ability for moisture harvesting independently, viz. the Australian thorny devil (Moloch horridus), the Arabian toadhead agama (Phrynocephalus arabicus) and the Texas horned lizard (Phrynosoma cornutum). All three lizards have a honeycomb like micro ornamentation on the outer surface of the scales and a complex capillary system in between the scales. By investigation of individual scales and by producing and characterising polymer replicas of the reptiles' integuments, we found that the honeycomb like structures render the surface superhydrophilic, most likely by holding a water film physically stable. Furthermore, the condensation of air humidity is improved on this surface by about 100% in comparison to unstructured surfaces. This allows the animals to collect moisture with their entire body surface. The collected water is transported into the capillary system. For Phrynosoma cornutum we found the interesting effect that, in contrast to the other two investigated species, the water flow in the capillary system is not uniform but directed to the mouth. Taken together we found that the micro ornamentation yields a superhydrophilic surface, and the semi-tubular capillaries allow for an efficient passive - and for Phrynosoma directed - transport of water.

  14. Moisture harvesting and water transport through specialized micro-structures on the integument of lizards

    Directory of Open Access Journals (Sweden)

    Philipp Comanns

    2011-04-01

    Full Text Available Several lizard species that live in arid areas have developed special abilities to collect water with their bodies' surfaces and to ingest the so collected moisture. This is called rain- or moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even from humid soil. The integument (i.e., the skin plus skin derivatives such as scales has developed features so that the water spreads and is soaked into a capillary system in between the reptiles' scales. Within this capillary system the water is transported to the mouth where it is ingested. We have investigated three different lizard species which have developed the ability for moisture harvesting independently, viz. the Australian thorny devil (Moloch horridus, the Arabian toadhead agama (Phrynocephalus arabicus and the Texas horned lizard (Phrynosoma cornutum. All three lizards have a honeycomb like micro ornamentation on the outer surface of the scales and a complex capillary system in between the scales. By investigation of individual scales and by producing and characterising polymer replicas of the reptiles' integuments, we found that the honeycomb like structures render the surface superhydrophilic, most likely by holding a water film physically stable. Furthermore, the condensation of air humidity is improved on this surface by about 100% in comparison to unstructured surfaces. This allows the animals to collect moisture with their entire body surface. The collected water is transported into the capillary system. For Phrynosoma cornutum we found the interesting effect that, in contrast to the other two investigated species, the water flow in the capillary system is not uniform but directed to the mouth. Taken together we found that the micro ornamentation yields a superhydrophilic surface, and the semi-tubular capillaries allow for an efficient passive – and for Phrynosoma directed – transport of water.

  15. Moisture harvesting and water transport through specialized micro-structures on the integument of lizards

    Science.gov (United States)

    Comanns, Philipp; Effertz, Christian; Hischen, Florian; Staudt, Konrad; Böhme, Wolfgang

    2011-01-01

    Summary Several lizard species that live in arid areas have developed special abilities to collect water with their bodies' surfaces and to ingest the so collected moisture. This is called rain- or moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even from humid soil. The integument (i.e., the skin plus skin derivatives such as scales) has developed features so that the water spreads and is soaked into a capillary system in between the reptiles' scales. Within this capillary system the water is transported to the mouth where it is ingested. We have investigated three different lizard species which have developed the ability for moisture harvesting independently, viz. the Australian thorny devil (Moloch horridus), the Arabian toadhead agama (Phrynocephalus arabicus) and the Texas horned lizard (Phrynosoma cornutum). All three lizards have a honeycomb like micro ornamentation on the outer surface of the scales and a complex capillary system in between the scales. By investigation of individual scales and by producing and characterising polymer replicas of the reptiles' integuments, we found that the honeycomb like structures render the surface superhydrophilic, most likely by holding a water film physically stable. Furthermore, the condensation of air humidity is improved on this surface by about 100% in comparison to unstructured surfaces. This allows the animals to collect moisture with their entire body surface. The collected water is transported into the capillary system. For Phrynosoma cornutum we found the interesting effect that, in contrast to the other two investigated species, the water flow in the capillary system is not uniform but directed to the mouth. Taken together we found that the micro ornamentation yields a superhydrophilic surface, and the semi-tubular capillaries allow for an efficient passive – and for Phrynosoma directed – transport of water. PMID:21977432

  16. The Effect of Inhomogeneous Compression on Water Transport in the Cathode of a Proton Exchange Membrane Fuel Cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Berning, Torsten; Kær, Søren Knudsen

    2012-01-01

    A three-dimensional, multicomponent, two-fluid model developed in the commercial CFD package CFX 13 (ANSYS Inc.) is used to investigate the effect of porous media compression on water transport in a proton exchange membrane fuel cell (PEMFC). The PEMFC model only consist of the cathode channel, gas....... Furthermore, the presence of irreducible liquid water is taken into account. In order to account for compression, porous media morphology variations are specified based on the gas diffusion layer (GDL) through-plane strain and intrusion which are stated as a function of compression. These morphology...... variations affect gas and liquid water transport, and hence liquid water distribution and the risk of blocking active sites. Hence, water transport is studied under GDL compression in order to investigate the qualitative effects. Two simulation cases are compared; one with and one without compression....

  17. Transport of lincomycin to surface and ground water from manure-amended cropland.

    Science.gov (United States)

    Kuchta, Sandra L; Cessna, Allan J; Elliott, Jane A; Peru, Kerry M; Headley, John V

    2009-01-01

    Livestock manure containing antimicrobials becomes a possible source of these compounds to surface and ground waters when applied to cropland as a nutrient source. The potential for transport of the veterinary antimicrobial lincomycin to surface waters via surface runoff and to leach to ground water was assessed by monitoring manure-amended soil, simulated rainfall runoff, snowmelt runoff, and ground water over a 2-yr period in Saskatchewan, Canada, after fall application of liquid swine manure to cropland. Liquid chromatography tandem mass spectrometry was used to quantify lincomycin in all matrix extracts. Initial concentrations in soil (46.3-117 mug kg(-1)) were not significantly different (p > 0.05) for manure application rates ranging from 60,000 to 95,000 L ha(-1) and had decreased to nondetectable levels by mid-summer the following year. After fall manure application, lincomycin was present in all simulated rainfall runoff (0.07-2.7 mug L(-1)) and all snowmelt runoff (0.038-3.2 mug L(-1)) samples. Concentrations in snowmelt runoff were not significantly different from those in simulated rainfall runoff the previous fall. On average, lincomycin concentrations in ephemeral wetlands dissipated by 50% after 31 d. Concentrations of lincomycin in ground water were generally <0.005 mug L(-1). This study demonstrates that the management practice of using livestock manure from confined animal feeding operations as a plant nutrient source on cropland may result in antimicrobial transport to surface and ground waters.

  18. Formation and interpretation of eskers beneath retreating ice sheets

    Science.gov (United States)

    Creyts, T. T.; Hewitt, I.

    2017-12-01

    The retreat of the ice sheets during the Pleistocene left large and spectacular subglacial features exposed. Understanding these features gives us insight into how the ice sheets retreated, how meltwater influenced retreat, and can help inform our understanding of potential future rates of ice sheet retreat. Among these features, eskers, long sinuous ridges primarily composed of clastic sediments, lack a detailed explanation of how surface melt rates and ice sheet retreat rates influence their growth and spatial distribution. Here, we develop a theory for esker formation based on the initial work of Rothlisberger modified for sediment transport and inclusion of surface meltwater forcing. The primary subglacial ingredients include water flow through subglacial tunnels with the addition of mass balances for sediment transport. We show how eskers when water flow slows below a critical stress for sediment motion. This implies that eskers are deposited in a localized region near the snout of the ice sheet. Our findings suggest that very long eskers form sequentially as the ice front retreats. The position of the esker follows the path of the channel mouth through time, which does not necessarily coincide with the instantaneous route of the feeding channel. However, in most cases, we expect those locations to be similar. The role of surface meltwater and the climatology associated with the forcing is crucial to the lateral spacing of the eskers. We predict that high surface melt rates lead to narrower catchments but that the greater extent of the ablation area means that channels are likely larger. At the same time, for a given channel size (and hence sediment flux), the size of a deposited esker depends on a margin retreat rate. Hence, the size of the eskers is related delicately to the balance between surface melt rates and margin retreat rates. We discuss how our theory can be combined with observed esker distributions to infer the relationship between these two rates

  19. Biofilm bacterial communities in urban drinking water distribution systems transporting waters with different purification strategies.

    Science.gov (United States)

    Wu, Huiting; Zhang, Jingxu; Mi, Zilong; Xie, Shuguang; Chen, Chao; Zhang, Xiaojian

    2015-02-01

    Biofilm formation in drinking water distribution systems (DWDS) has many adverse consequences. Knowledge of microbial community structure of DWDS biofilm can aid in the design of an effective control strategy. However, biofilm bacterial community in real DWDS and the impact of drinking water purification strategy remain unclear. The present study investigated the composition and diversity of biofilm bacterial community in real DWDSs transporting waters with different purification strategies (conventional treatment and integrated treatment). High-throughput Illumina MiSeq sequencing analysis illustrated a large shift in the diversity and structure of biofilm bacterial community in real DWDS. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Nitrospirae, and Cyanobacteria were the major components of biofilm bacterial community. Proteobacteria (mainly Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria) predominated in each DWDS biofilm, but the compositions of the dominant proteobacterial classes and genera and their proportions varied among biofilm samples. Drinking water purification strategy could shape DWDS biofilm bacterial community. Moreover, Pearson's correlation analysis indicated that Actinobacteria was positively correlated with the levels of total alkalinity and dissolved organic carbon in tap water, while Firmicutes had a significant positive correlation with nitrite nitrogen.

  20. Transport of Water, Carbon, and Sediment Through the Yukon River Basin

    Science.gov (United States)

    Brabets, Timothy P.; Schuster, Paul F.

    2008-01-01

    INTRODUCTION In 2001, the U.S. Geological Survey (USGS) began a water-quality study of the Yukon River. The Yukon River Basin (YRB), which encompasses 330,000 square miles in northwestern Canada and central Alaska (fig. 1), is one of the largest and most diverse ecosystems in North America. The Yukon River is more than 1,800 miles long and is one of the last great uncontrolled rivers in the world, and is essential to the eastern Bering Sea and Chukchi Sea ecosystems, providing freshwater runoff, sediments, and nutrients (Brabets and others, 2000). Despite its remoteness, recent studies (Hinzman and others, 2005; Walvoord and Striegl, 2007) indicate the YRB is changing. These changes likely are in response to a warming trend in air temperature of 1.7i??C from 1951 to 2001 (Hartmann and Wendler, 2005). As a result of this warming trend, permafrost is thawing in the YRB, ice breakup occurs earlier on the main stem of the Yukon River and its tributaries, and timing of streamflow and movement of carbon and sediment through the basin is changing (Hinzman and others, 2005; Walvoord and Striegl, 2007). One of the most striking characteristics in the YRB is its seasonality. In the YRB, more than 75 percent of the annual streamflow runoff occurs during a five month period, May through September. This is important because streamflow determines when, where, and how much of a particular constituent will be transported. As an example, more than 95 percent of all sediment transported during an average year also occurs during this period (Brabets and others, 2000). During the other 7 months, streamflow, concentrations of sediment and other water-quality constituents are low and little or no sediment transport occurs in the Yukon River and its tributaries. Streamflow and water-quality data have been collected at more than 50 sites in the YRB (Dornblaser and Halm, 2006; Halm and Dornblaser, 2007). Five sites have been sampled more than 30 times and others have been sampled twice

  1. Modeling the effects of different irrigation water salinity on soil water movement, uptake and multicomponent solute transport

    Science.gov (United States)

    Lekakis, E. H.; Antonopoulos, V. Z.

    2015-11-01

    Simulation models can be important tools for analyzing and managing irrigation, soil salinization or crop production problems. In this study a mathematical model that describes the water movement and mass transport of individual ions (Ca2+, Mg2+ and Na+) and overall soil salinity by means of the soil solution electrical conductivity, is used. The mass transport equations of Ca2+, Mg2+ and Na+ have been incorporated as part of the integrated model WANISIM and the soil salinity was computed as the sum of individual ions. The model was calibrated and validated against field data, collected during a three year experiment in plots of maize, irrigated with three different irrigation water qualities, at Thessaloniki area in Northern Greece. The model was also used to evaluate salinization and sodification hazards by the use of irrigation water with increasing electrical conductivity of 0.8, 3.2 and 6.4 dS m-1, while maintaining a ratio of Ca2+:Mg2+:Na+ equal to 3:3:2. The qualitative and quantitative procedures for results evaluation showed that there was good agreement between the simulated and measured values of the water content, overall salinity and the concentration of individual soluble cations, at two soil layers (0-35 and 35-75 cm). Nutrient uptake was also taken into account. Locally available irrigation water (ECiw = 0.8 dS m-1) did not cause soil salinization or sodification. On the other hand, irrigation water with ECiw equal to 3.2 and 6.4 dS m-1 caused severe soil salinization, but not sodification. The rainfall water during the winter seasons was not sufficient to leach salts below the soil profile of 110 cm. The modified version of model WANISIM is able to predict the effects of irrigation with saline waters on soil and plant growth and it is suitable for irrigation management in areas with scarce and low quality water resources.

  2. Use of orthonormal polynomials to fit energy spectrum data for water transported through membrane

    International Nuclear Information System (INIS)

    Bogdanova, N.; Todorova, L.

    2001-01-01

    A new application of our approach with orthonormal polynomials to curve fitting is given when both variables have errors. We approximate and describe data of a new effect due to change of water energy spectrum as a result of water transport in a porous membrane

  3. Interfacial transport phenomena and stability in liquid-metal/water systems: scaling considerations

    International Nuclear Information System (INIS)

    Abdulla, S.; Liu, X.; Anderson, M.; Bonazza, R.; Corradini, M.; Cho, D.

    2001-01-01

    One concept being considered for steam generation in innovative nuclear reactor applications, involves water coming into direct contact with a circulating molten metal. The vigorous agitation of the two fluids, the direct liquid-liquid contact and the consequent large interfacial area give rise to very high heat transfer coefficients and rapid steam generation. For an optimum design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability. In this paper we describe current results from the first year of this research that studies the transport phenomena involved with the injection of water into molten metals (e.g., lead alloys). In particular, this work discusses scaling considerations related to direct contact heat exchange, our experimental plans for investigation and a test plan for the important experimental parameters; i.e., the water and liquid metal mass flow rates, the liquid metal pool temperature and the ambient pressure of the direct contact heat exchanger. Past experimental work and initial scaling results suggest that our experiments can directly represent the proper liquid metal pool temperature and the water subcooling. The experimental variation in water and liquid metal flow rates and system pressure (1-10 bar), although smaller than the current conceptual system designs, is sufficient to verify the expected scale effects to demonstrate the phenomena. (authors)

  4. Climate Change Intensification of Horizontal Water Vapor Transport in CMIP5

    Science.gov (United States)

    Lavers, D. A.; Ralph, F. M.; Waliser, D. E.; Gershunov, A.; Dettinger, M. D.

    2015-12-01

    The global water cycle is hypothesized to intensify with a warming Earth's atmosphere. To determine associated hydrological changes, most previous research has used precipitation scenarios without considering changes to the horizontal water vapor transport (IVT). As few studies have analyzed the IVT, and given that many extreme precipitation and flood events are driven by intense water vapor transport, it is the aim of this study to investigate projected changes to global IVT. Furthermore, this approach can identify climatological changes to the IVT between water source and sink regions. Using 22 global circulation models from the Climate Model Intercomparison Project Phase 5 (CMIP5) we evaluate, globally, the mean, standard deviation, and the 95th percentile of IVT from the historical simulations (1979-2005) and two emissions scenarios (2073-2099); representative concentration pathways (RCP4.5 and RCP8.5). This analysis is undertaken for December, January, and February (Boreal winter); and for June, July, and August (Austral winter). The CMIP5 historical multi-model mean has good agreement with the fields from the ECMWF ERA-Interim reanalysis, which provides confidence in the models' signal. In the future, under more extreme emissions (RCP8.5), multi-model mean IVT increases by 30-40% in the North Pacific and North Atlantic storm tracks and in the equatorial Pacific Ocean trade winds. The Arctic region has the largest relative IVT increase especially in Boreal winter. Analysis of low-altitude moisture and winds suggest that these projected changes are mainly due to higher atmospheric water vapor content.

  5. Stable isotope reactive transport modeling in water-rock interactions during CO2 injection

    Science.gov (United States)

    Hidalgo, Juan J.; Lagneau, Vincent; Agrinier, Pierre

    2010-05-01

    Stable isotopes can be of great usefulness in the characterization and monitoring of CO2 sequestration sites. Stable isotopes can be used to track the migration of the CO2 plume and identify leakage sources. Moreover, they provide unique information about the chemical reactions that take place on the CO2-water-rock system. However, there is a lack of appropriate tools that help modelers to incorporate stable isotope information into the flow and transport models used in CO2 sequestration problems. In this work, we present a numerical tool for modeling the transport of stable isotopes in groundwater reactive systems. The code is an extension of the groundwater single-phase flow and reactive transport code HYTEC [2]. HYTEC's transport module was modified to include element isotopes as separate species. This way, it is able to track isotope composition of the system by computing the mixing between the background water and the injected solution accounting for the dependency of diffusion on the isotope mass. The chemical module and database have been expanded to included isotopic exchange with minerals and the isotope fractionation associated with chemical reactions and mineral dissolution or precipitation. The performance of the code is illustrated through a series of column synthetic models. The code is also used to model the aqueous phase CO2 injection test carried out at the Lamont-Doherty Earth Observatory site (Palisades, New York, USA) [1]. References [1] N. Assayag, J. Matter, M. Ader, D. Goldberg, and P. Agrinier. Water-rock interactions during a CO2 injection field-test: Implications on host rock dissolution and alteration effects. Chemical Geology, 265(1-2):227-235, July 2009. [2] Jan van der Lee, Laurent De Windt, Vincent Lagneau, and Patrick Goblet. Module-oriented modeling of reactive transport with HYTEC. Computers & Geosciences, 29(3):265-275, April 2003.

  6. Management-oriented sensitivity analysis for pesticide transport in watershed-scale water quality modeling using SWAT.

    Science.gov (United States)

    Luo, Yuzhou; Zhang, Minghua

    2009-12-01

    The Soil and Water Assessment Tool (SWAT) was calibrated for hydrology conditions in an agricultural watershed of Orestimba Creek, California, and applied to simulate fate and transport of two organophosphate pesticides chlorpyrifos and diazinon. The model showed capability in evaluating pesticide fate and transport processes in agricultural fields and instream network. Management-oriented sensitivity analysis was conducted by applied stochastic SWAT simulations for pesticide distribution. Results of sensitivity analysis identified the governing processes in pesticide outputs as surface runoff, soil erosion, and sedimentation in the study area. By incorporating sensitive parameters in pesticide transport simulation, effects of structural best management practices (BMPs) in improving surface water quality were demonstrated by SWAT modeling. This study also recommends conservation practices designed to reduce field yield and in-stream transport capacity of sediment, such as filter strip, grassed waterway, crop residue management, and tailwater pond to be implemented in the Orestimba Creek watershed.

  7. Subglacial Lake Vostok (Antarctica accretion ice contains a diverse set of sequences from aquatic, marine and sediment-inhabiting bacteria and eukarya.

    Directory of Open Access Journals (Sweden)

    Yury M Shtarkman

    Full Text Available Lake Vostok, the 7(th largest (by volume and 4(th deepest lake on Earth, is covered by more than 3,700 m of ice, making it the largest subglacial lake known. The combination of cold, heat (from possible hydrothermal activity, pressure (from the overriding glacier, limited nutrients and complete darkness presents extreme challenges to life. Here, we report metagenomic/metatranscriptomic sequence analyses from four accretion ice sections from the Vostok 5G ice core. Two sections accreted in the vicinity of an embayment on the southwestern end of the lake, and the other two represented part of the southern main basin. We obtained 3,507 unique gene sequences from concentrates of 500 ml of 0.22 µm-filtered accretion ice meltwater. Taxonomic classifications (to genus and/or species were possible for 1,623 of the sequences. Species determinations in combination with mRNA gene sequence results allowed deduction of the metabolic pathways represented in the accretion ice and, by extension, in the lake. Approximately 94% of the sequences were from Bacteria and 6% were from Eukarya. Only two sequences were from Archaea. In general, the taxa were similar to organisms previously described from lakes, brackish water, marine environments, soil, glaciers, ice, lake sediments, deep-sea sediments, deep-sea thermal vents, animals and plants. Sequences from aerobic, anaerobic, psychrophilic, thermophilic, halophilic, alkaliphilic, acidophilic, desiccation-resistant, autotrophic and heterotrophic organisms were present, including a number from multicellular eukaryotes.

  8. Water activated doping and transport in multilayered germanane crystals

    International Nuclear Information System (INIS)

    Young, Justin R; Johnston-Halperin, Ezekiel; Chitara, Basant; Cultrara, Nicholas D; Arguilla, Maxx Q; Jiang, Shishi; Fan, Fan; Goldberger, Joshua E

    2016-01-01

    The synthesis of germanane (GeH) has opened the door for covalently functionalizable 2D materials in electronics. Herein, we demonstrate that GeH can be electronically doped by incorporating stoichiometric equivalents of phosphorus dopant atoms into the CaGe 2 precursor. The electronic properties of these doped materials show significant atmospheric sensitivity, and we observe a reduction in resistance by up to three orders of magnitude when doped samples are measured in water-containing atmospheres. This variation in resistance is a result of water activation of the phosphorus dopants. Transport measurements in different contact geometries show a significant anisotropy between in-plane and out-of-plane resistances, with a much larger out-of-plane resistance. These measurements along with finite element modeling results predict that the current distribution in top-contacted crystals is restricted to only the topmost, water activated crystal layers. Taken together, these results pave the way for future electronic and optoelectronic applications utilizing group IV graphane analogues. (paper)

  9. Modeling ground water flow and radioactive transport in a fractured aquifer

    International Nuclear Information System (INIS)

    Pohll, G.; Hassan, A.E.; Chapman, J.B.; Papelis, C.; Andricevic, R.

    1999-01-01

    Three-dimensional numerical modeling is used to characterize ground water flow and contaminant transport at the Shoal nuclear test site in north-central Nevada. The fractured rock aquifer at the site is modeled using an equivalent porous medium approach. Field data are used to characterize the fracture system into classes: large, medium, and no/small fracture zones. Hydraulic conductivities are assigned based on discrete interval measurements. Contaminants from the Shoal test are assumed to all be located within the cavity. Several challenging issues are addressed in this study. Radionuclides are apportioned between surface deposits and volume deposits in nuclear melt glass, based on their volatility and previous observations. Surface-deposited radionuclides are released hydraulically after equilibration of the cavity with the surrounding ground water system, and as a function of ground water flow through the higher-porosity cavity into the low-porosity surrounding aquifer. Processes that are modeled include the release functions, retardation, radioactive decay, prompt injection, and in growth of daughter products. Prompt injection of radionuclides away from the cavity is found to increase the arrival of mass at the control plane but is not found to significantly impact calculated concentrations due to increased spreading. Behavior of the other radionuclides is affected by the slow chemical release and retardation behavior. The transport calculations are sensitive to many flow and transport parameters. Most important are the heterogeneity of the flow field and effective porosity. The effect of porosity in radioactive decay is crucial and has not been adequately addressed in the literature. For reactive solutes, retardation and the glass dissolution rate are also critical

  10. Transport and sorption of volatile organic compounds and water vapor in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tsair-Fuh [Univ. of California, Berkeley, CA (United States)

    1995-07-01

    To gain insight on the controlling mechanisms for VOC transport in porous media, the relations among sorbent properties, sorption equilibrium and intraparticle diffusion processes were studied at the level of individual sorbent particles and laboratory columns for soil and activated carbon systems. Transport and sorption of VOCs and water vapor were first elucidated within individual dry soil mineral grains. Soil properties, sorption capacity, and sorption rates were measured for 3 test soils; results suggest that the soil grains are porous, while the sorption isotherms are nonlinear and adsorption-desorption rates are slow and asymmetric. An intragranular pore diffusion model coupled with the nonlinear Freundlich isotherm was developed to describe the sorption kinetic curves. Transport of benzene and water vapor within peat was studied; partitioning and sorption kinetics were determined with an electrobalance. A dual diffusion model was developed. Transport of benzene in dry and moist soil columns was studied, followed by gaseous transport and sorption in activated carbon. The pore diffusion model provides good fits to sorption kinetics for VOCs to soil and VOC to granular activated carbon and activated carbon fibers. Results of this research indicate that: Intraparticle diffusion along with a nonlinea sorption isotherm are responsible for the slow, asymmetric sorption-desorption. Diffusion models are able to describe results for soil and activated carbon systems; when combined with mass transfer equations, they predict column breakthrough curves for several systems. Although the conditions are simplified, the mechanisms should provide insight on complex systems involving transport and sorption of vapors in porous media.

  11. Prolonged river water pollution due to variable-density flow and solute transport in the riverbed

    Science.gov (United States)

    Jin, Guangqiu; Tang, Hongwu; Li, Ling; Barry, D. A.

    2015-04-01

    A laboratory experiment and numerical modeling were used to examine effects of density gradients on hyporheic flow and solute transport under the condition of a solute pulse input to a river with regular bed forms. Relatively low-density gradients due to an initial salt pulse concentration of 1.55 kg m-3 applied in the experiment were found to modulate significantly the pore-water flow and solute transport in the riverbed. Such density gradients increased downward flow and solute transport in the riverbed by factors up to 1.6. This resulted in a 12.2% increase in the total salt transfer from the water column to the riverbed over the salt pulse period. As the solute pulse passed, the effect of the density gradients reversed, slowing down the release of the solute back to the river water by a factor of 3.7. Numerical modeling indicated that these density effects intensified as salt concentrations in the water column increased. Simulations further showed that the density gradients might even lead to unstable flow and result in solute fingers in the bed of large bed forms. The slow release of solute from the bed back to the river led to a long tail of solute concentration in the river water. These findings have implications for assessment of impact of pollution events on river systems, in particular, long-term effects on both the river water and riverbed due to the hyporheic exchange.

  12. Far-reaching transport of Pearl River plume water by upwelling jet in the northeastern South China Sea

    Science.gov (United States)

    Chen, Zhaoyun; Pan, Jiayi; Jiang, Yuwu; Lin, Hui

    2017-09-01

    Satellite images from the Moderate Resolution Imaging Spectroradiometer (MODIS) show that there was a belt of turbid water appearing along an upwelling front near the Chinese coast of Guangdong, and indicate that the turbid water of the Pearl River plume water could be transported to a far-reaching area east of the Taiwan Bank. Numerical modeling results are consistent with the satellite observations, and reveal that a strong jet exists at the upwelling front with a speed as high as 0.8 m s- 1, which acts as a pathway for transporting the high-turbidity plume water. The dynamical analysis suggests that geostrophic equilibrium dominates in the upwelling front and plume areas, and the baroclinicity of the upwelling front resulting from the horizontal density gradient is responsible for the generation of the strong jet, which enhances the far-reaching transport of the terrigenous nutrient-rich water of the Pearl River plume. Model sensitivity analyses also confirm that this jet persists as long as the upwelling front exists, even when the wind subsides and becomes insignificant. Further idealized numerical model experiments indicate that the formation and persistence of the upwelling front jet depend on the forcing strength of the upwelling-favorable wind. The formation time of the jet varies from 15 to 158 h as the stress of the upwelling-favorable wind changes from 0.2 to 0.01 N m- 2. With the persistent transport of the nutrient-rich plume water, biophysical activities can be promoted significantly in the far-reaching destination area of the oligotrophic water.

  13. Capillary transport of water through textile-reinforced concrete applied in repairing and/or strengthening cracked RC structures

    International Nuclear Information System (INIS)

    Lieboldt, M.; Mechtcherine, V.

    2013-01-01

    The use of textile-reinforced concrete (TRC) has great potential for innovative solutions in repairing, protecting, and strengthening concrete and RC structures. The article at hand reports on an investigation on composite concrete specimens made of cracked ordinary concrete as substrate and textile-reinforced concrete (TRC) as a cover layer for its strengthening and repair. The TRC cover layer was assessed with regard to its effectiveness as a protective layer against the ingress of water through capillary action. Since in real applications such TRC layers may be cracked or presumed to be so, thereby activating the load-carrying function of the textile reinforcement, the TRC layer was cracked for purposes of this study. The water transport in the cracked ordinary concrete specimens without the TRC layer was used as a reference. Gravimetric measurements and neutron radiography served as the testing techniques. In ordinary concrete quick and deep ingress of water through relatively wide macro-cracks of approximately 100 μm width, followed by transport through the capillary pore system, caused saturation of large areas in a rather short time. TRC applied to the RC surface reduced the ingress of water to a large extent. Its small crack widths of 15 to 20 μm changed suction behaviour fundamentally. In the cracked substrate of ordinary concrete, capillary suction was prevented, and transport through the pore system of the matrix became the prevailing transport mechanism of capillary action. Not only was the mechanism altered, but the transport of water deep into inner regions was markedly retarded as well

  14. Virus-induced plasma membrane aquaporin PsPIP2;1 silencing inhibits plant water transport of Pisum sativum.

    Science.gov (United States)

    Song, Juanjuan; Ye, Guoliang; Qian, Zhengjiang; Ye, Qing

    2016-12-01

    Aquaporins (AQPs) are known to facilitate water transport across cell membranes, but the role of a single AQP in regulating plant water transport, particularly in plants other than Arabidopsis remains largely unexplored. In the present study, a virus-induced gene silencing (VIGS) technique was employed to suppress the expression of a specific plasma membrane aquaporin PsPIP2;1 of Pea plants (Pisum sativum), and subsequent effects of the gene suppression on root hydraulic conductivity (Lp r ), leaf hydraulic conductivity (K leaf ), root cell hydraulic conductivity (Lp rc ), and leaf cell hydraulic conductivity (Lp lc ) were investigated, using hydroponically grown Pea plants. Compared with control plants, VIGS-PsPIP2;1 plants displayed a significant suppression of PsPIP2;1 in both roots and leaves, while the expression of other four PIP isoforms (PsPIP1;1, PsPIP1;2, PsPIP2;2, and PsPIP2;3) that were simultaneously monitored were not altered. As a consequence, significant declines in water transport of VIGS-PsPIP2;1 plants were observed at both organ and cell levels, i.e., as compared to control plants, Lp r and K leaf were reduced by 29 %, and Lp rc and Lp lc were reduced by 20 and 29 %, respectively. Our results demonstrate that PsPIP2;1 alone contributes substantially to root and leaf water transport in Pea plants, and highlight VIGS a useful tool for investigating the role of a single AQP in regulating plant water transport.

  15. Management-oriented sensitivity analysis for pesticide transport in watershed-scale water quality modeling using SWAT

    International Nuclear Information System (INIS)

    Luo Yuzhou; Zhang Minghua

    2009-01-01

    The Soil and Water Assessment Tool (SWAT) was calibrated for hydrology conditions in an agricultural watershed of Orestimba Creek, California, and applied to simulate fate and transport of two organophosphate pesticides chlorpyrifos and diazinon. The model showed capability in evaluating pesticide fate and transport processes in agricultural fields and instream network. Management-oriented sensitivity analysis was conducted by applied stochastic SWAT simulations for pesticide distribution. Results of sensitivity analysis identified the governing processes in pesticide outputs as surface runoff, soil erosion, and sedimentation in the study area. By incorporating sensitive parameters in pesticide transport simulation, effects of structural best management practices (BMPs) in improving surface water quality were demonstrated by SWAT modeling. This study also recommends conservation practices designed to reduce field yield and in-stream transport capacity of sediment, such as filter strip, grassed waterway, crop residue management, and tailwater pond to be implemented in the Orestimba Creek watershed. - Selected structural BMPs are recommended for reducing loads of OP pesticides.

  16. Management-oriented sensitivity analysis for pesticide transport in watershed-scale water quality modeling using SWAT

    Energy Technology Data Exchange (ETDEWEB)

    Luo Yuzhou [University of California, Davis, CA 95616 (United States); Wenzhou Medical College, Wenzhou 325035 (China); Zhang Minghua, E-mail: mhzhang@ucdavis.ed [University of California, Davis, CA 95616 (United States); Wenzhou Medical College, Wenzhou 325035 (China)

    2009-12-15

    The Soil and Water Assessment Tool (SWAT) was calibrated for hydrology conditions in an agricultural watershed of Orestimba Creek, California, and applied to simulate fate and transport of two organophosphate pesticides chlorpyrifos and diazinon. The model showed capability in evaluating pesticide fate and transport processes in agricultural fields and instream network. Management-oriented sensitivity analysis was conducted by applied stochastic SWAT simulations for pesticide distribution. Results of sensitivity analysis identified the governing processes in pesticide outputs as surface runoff, soil erosion, and sedimentation in the study area. By incorporating sensitive parameters in pesticide transport simulation, effects of structural best management practices (BMPs) in improving surface water quality were demonstrated by SWAT modeling. This study also recommends conservation practices designed to reduce field yield and in-stream transport capacity of sediment, such as filter strip, grassed waterway, crop residue management, and tailwater pond to be implemented in the Orestimba Creek watershed. - Selected structural BMPs are recommended for reducing loads of OP pesticides.

  17. Numerical modeling of coupled water flow and heat transport in soil and snow

    Science.gov (United States)

    Thijs J. Kelleners; Jeremy Koonce; Rose Shillito; Jelle Dijkema; Markus Berli; Michael H. Young; John M. Frank; William Massman

    2016-01-01

    A one-dimensional vertical numerical model for coupled water flow and heat transport in soil and snow was modified to include all three phases of water: vapor, liquid, and ice. The top boundary condition in the model is driven by incoming precipitation and the surface energy balance. The model was applied to three different terrestrial systems: A warm desert bare...

  18. Transport and transfer rates in the waters of the continental shelf. Annual report

    International Nuclear Information System (INIS)

    Biscaye, P.E.

    1980-09-01

    The goal of govern project is to understand and quantify the processes that the transport and dispersal of energy-related pollutants introduced to the waters of the continental shelf and slope. The report is divided into sections dealing with processes associated with suspended solids; processes associated with sediments sinks for radionuclides and other pollutants; and spreading of water characteristics and species in solution

  19. Modeling Coupled Water and Heat Transport in the Root Zone of Winter Wheat under Non-Isothermal Conditions

    Directory of Open Access Journals (Sweden)

    Rong Ren

    2017-04-01

    Full Text Available Temperature is an integral part of soil quality in terms of moisture content; coupling between water and heat can render a soil fertile, and plays a role in water conservation. Although it is widely recognized that both water and heat transport are fundamental factors in the quantification of soil mass and energy balance, their computation is still limited in most models or practical applications in the root zone under non-isothermal conditions. This research was conducted to: (a implement a fully coupled mathematical model that contains the full coupled process of soil water and heat transport with plants focused on the influence of temperature gradient on soil water redistribution and on the influence of change in soil water movement on soil heat flux transport; (b verify the mathematical model with detailed field monitoring data; and (c analyze the accuracy of the model. Results show the high accuracy of the model in predicting the actual changes in soil water content and temperature as a function of time and soil depth. Moreover, the model can accurately reflect changes in soil moisture and heat transfer in different periods. With only a few empirical parameters, the proposed model will serve as guide in the field of surface irrigation.

  20. Changes in urinary excretion of water and sodium transporters during amiloride and bendroflumethiazide treatment

    DEFF Research Database (Denmark)

    Jensen, Janni M; Mose, Frank H; Kulik, Anna-Ewa O

    2015-01-01

    AIM: To quantify changes in urinary excretion of aquaporin2 water channels (u-AQP2), the sodium-potassium-chloride co-transporter (u-NKCC2) and the epithelial sodium channels (u-ENaC) during treatment with bendroflumethiazide (BFTZ), amiloride and placebo. METHODS: In a randomized, double....... General linear model with repeated measures or related samples Friedman's two-way analysis was used to compare differences. Post hoc Bonferroni correction was used for multiple comparisons of post infusion periods to baseline within each treatment group. RESULTS: At baseline there were no differences in u...... by the constant infusion clearance technique with (51)Cr-EDTA as reference substance. To estimate the changes in water transport via AQP2 and sodium transport via NKCC2 and ENaC, u-NKCC2, the gamma fraction of ENaC (u-ENaCγ), and u-AQP2 were measured at baseline and after infusion with 3% hypertonic saline. U...

  1. A mass conservative numerical solution of vertical water flow and mass transport equations in unsaturated porous media

    International Nuclear Information System (INIS)

    Lim, S.C.; Lee, K.J.

    1993-01-01

    The Galerkin finite element method is used to solve the problem of one-dimensional, vertical flow of water and mass transport of conservative-nonconservative solutes in unsaturated porous media. Numerical approximations based on different forms of the governing equation, although they are equivalent in continuous forms, can result in remarkably different solutions in an unsaturated flow problem. Solutions given by a simple Galerkin method based on the h-based Richards equation yield a large mass balance error and an underestimation of the infiltration depth. With the employment of the ROMV (restoration of main variable) concept in the discretization step, the mass conservative numerical solution algorithm for water flow has been derived. The resulting computational schemes for water flow and mass transport are applied to sandy soil. The ROMV method shows good mass conservation in water flow analysis, whereas it seems to have a minor effect on mass transport. However, it may relax the time-step size restriction and so ensure an improved calculation output. (author)

  2. Evolution and Transport of Water in the Upper Regolith of Mars

    Science.gov (United States)

    Hudson, T. L.; Aharonson, O.; Schorghofer, N.; Hecht, M. H.; Bridges, N. T.; Green, J. R.

    2003-01-01

    Long standing theoretical predictions [1-3], as well as recent spacecraft observations [4] indicate that large quantities of ice is present in the high latitudes upper decimeters to meters of the Martian regolith. At shallower depths and warmer locations small amounts of H2O, either adsorbed or free, may be present transiently. An understanding of the evolution of water based on theoretical and experimental considerations of the processes operating at the Martian environment is required. In particular, the porosity, diffusivity, and permeability of soils and their effect on water vapor transport under Mars-like conditions have been estimated, but experimental validation of such models is lacking. Goal: Three related mechanisms may affect water transport in the upper Martian regolith. 1) diffusion along a concentration gradient under isobaric conditions, 2) diffusion along a thermal gradient, which may give rise to a concentration gradient as ice sublimes or molecules desorb from the regolith, and 3) hydraulic flow, or mass motion in response to a pressure gradient. Our combined theoretical and experimental investigation seeks to disentangle these mechanisms and determine which process(es) are dominant in the upper regolith over various timescales. A detailed one-dimensional model of the upper regolith is being created which incorporates water adsorption/ desorption, condensation, porosity, diffusivity, and permeability effects. Certain factors such as diffusivity are difficult to determine theoretically due to the wide range of intrinsic grain properties such as particle sizes, shapes, packing densities, and emergent properties such as tortuosity. An experiment is being designed which will allow us to more accurately determine diffusivity, permeability, and water desorption isotherms for regolith simulants.

  3. Impacts of Cropland Changes on Water Balance, Sediment and Nutrient Transport in Eden River, UK

    Science.gov (United States)

    Huang, Yumei; Quinn, Paul; Liang, Qiuhua; Adams, Russell

    2017-04-01

    Water is the key to food and human life. Farming is the main part of economic and society in Eden, with approximately 2000 farms which covers 95% of under crops. However, with the growth of farming practice and global climate changes, Eden has presented great challenges and bringing uncertainty in the water quality caused by the agricultural diffuse pollution. This expected to reduce negative impacts of the water diffuse pollution from agriculture in Eden. Therefore, there is a high need to ensure effective water resource management to enhance water quality, to address the flow pathways and sediment transport in different farming practice and cropland changes. Hence we need to understand nutrient and the hydrological flow pathways from soil to Hillslope to channel. The aim of this research is to evaluate the impacts of different cropland changes on water balance, sediment and nutrient transport. By using the hydrological models Soil and Water Assessment Tool (SWAT) and the Catchment Runoff Attenuation Flux Tool (CRAFT), it can show the sediment and nutrient export from the load for each flow pathways (overland flow, soil water flow and ground water flow). We will show results from a small research catchment (10km2) area to the whole of Eden (800km2) at a daily time step.

  4. The Coupled Mars Dust and Water Cycles: Understanding How Clouds Affect the Vertical Distribution and Meridional Transport of Dust and Water.

    Science.gov (United States)

    Kahre, M. A.

    2015-01-01

    The dust and water cycles are crucial to the current Martian climate, and they are coupled through cloud formation. Dust strongly impacts the thermal structure of the atmosphere and thus greatly affects atmospheric circulation, while clouds provide radiative forcing and control the hemispheric exchange of water through the modification of the vertical distributions of water and dust. Recent improvements in the quality and sophistication of both observations and climate models allow for a more comprehensive understanding of how the interaction between the dust and water cycles (through cloud formation) affects the dust and water cycles individually. We focus here on the effects of clouds on the vertical distribution of dust and water, and how those vertical distributions control the net meridional transport of water. For this study, we utilize observations of temperature, dust and water ice from the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO) combined with the NASA ARC Mars Global Climate Model (MGCM). We demonstrate that the magnitude and nature of the net meridional transport of water between the northern and southern hemispheres during NH summer is sensitive to the vertical structure of the simulated aphelion cloud belt. We further examine how clouds influence the atmospheric thermal structure and thus the vertical structure of the cloud belt. Our goal is to identify and understand the importance of radiative/dynamic feedbacks due to the physical processes involved with cloud formation and evolution on the current climate of Mars.

  5. Mineralogy controls on reactive transport of Marcellus Shale waters.

    Science.gov (United States)

    Cai, Zhang; Wen, Hang; Komarneni, Sridhar; Li, Li

    2018-07-15

    Produced or flowback waters from Marcellus Shale gas extraction (MSWs) typically are highly saline and contain chemicals including trace metals, which pose significant concerns on water quality. The natural attenuation of MSW chemicals in groundwater is poorly understood due to the complex interactions between aquifer minerals and MSWs, limiting our capabilities to monitor and predict. Here we combine flow-through experiments and process-based reactive transport modeling to understand mechanisms and quantify the retention of MSW chemicals in a quartz (Qtz) column, a calcite-rich (Cal) column, and a clay-rich (Vrm, vermiculite) column. These columns were used to represent sand, carbonate, and clay-rich aquifers. Results show that the types and extent of water-rock interactions differ significantly across columns. Although it is generally known that clay-rich media retard chemicals and that quartz media minimize water-rock interactions, results here have revealed insights that differ from previous thoughts. We found that the reaction mechanisms are much more complex than merely sorption and mineral precipitation. In clay rich media, trace metals participate in both ion exchange and mineral precipitation. In fact, the majority of metals (~50-90%) is retained in the solid via mineral precipitation, which is surprising because we typically expect the dominance of sorption in clay-rich aquifers. In the Cal column, trace metals are retained not only through precipitation but also solid solution partitioning, leading to a total of 75-99% retention. Even in the Qtz column, trace metals are retained at unexpectedly high percentages (~20-70%) due to precipitation. The reactive transport model developed here quantitatively differentiates the relative importance of individual processes, and bridges a limited number of experiments to a wide range of natural conditions. This is particularly useful where relatively limited knowledge and data prevent the prediction of complex rock

  6. The Mars Dust and Water Cycles: Investigating the Influence of Clouds on the Vertical Distribution and Meridional Transport of Dust and Water

    Science.gov (United States)

    Kahre, Melinda A.; Haberle, Robert M.; Hollingsworth, Jeffery L.; Brecht, Amanda S.; Urata, Richard A.

    2015-11-01

    The dust and water cycles are critical to the current Martian climate, and they interact with each other through cloud formation. Dust modulates the thermal structure of the atmosphere and thus greatly influences atmospheric circulation. Clouds provide radiative forcing and control the net hemispheric transport of water through the alteration of the vertical distributions of water and dust. Recent advancements in the quality and sophistication of both climate models and observations enable an increased understanding of how the coupling between the dust and water cycles (through cloud formation) impacts the dust and water cycles. We focus here on the effects of clouds on the vertical distributions of dust and water and how those vertical distributions control the net meridional transport of water. We utilize observations of temperature, dust and water ice from the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO) and the NASA ARC Mars Global Climate Model (MGCM) to show that the magnitude and nature of the hemispheric exchange of water during NH summer is sensitive to the vertical structure of the simulated aphelion cloud belt. Further, we investigate how clouds influence atmospheric temperatures and thus the vertical structure of the cloud belt. Our goal is to isolate and understand the importance of radiative/dynamic feedbacks due to the physical processes involved with cloud formation and evolution on the current climate of Mars.

  7. The Mars Dust and Water Cycles: Investigating the Influence of Clouds on the Vertical Distribution and Meridional Transport of Dust and Water.

    Science.gov (United States)

    Kahre, M. A.; Haberle, R. M.; Hollingsworth, J. L.; Brecht, A. S.; Urata, R.

    2015-01-01

    The dust and water cycles are critical to the current Martian climate, and they interact with each other through cloud formation. Dust modulates the thermal structure of the atmosphere and thus greatly influences atmospheric circulation. Clouds provide radiative forcing and control the net hemispheric transport of water through the alteration of the vertical distributions of water and dust. Recent advancements in the quality and sophistication of both climate models and observations enable an increased understanding of how the coupling between the dust and water cycles (through cloud formation) impacts the dust and water cycles. We focus here on the effects of clouds on the vertical distributions of dust and water and how those vertical distributions control the net meridional transport of water. We utilize observations of temperature, dust and water ice from the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO) and the NASA ARC Mars Global Climate Model (MGCM) to show that the magnitude and nature of the hemispheric exchange of water during NH summer is sensitive to the vertical structure of the simulated aphelion cloud belt. Further, we investigate how clouds influence atmospheric temperatures and thus the vertical structure of the cloud belt. Our goal is to isolate and understand the importance of radiative/dynamic feedbacks due to the physical processes involved with cloud formation and evolution on the current climate of Mars.

  8. Effects of heat and water transport on the performance of polymer electrolyte membrane fuel cell under high current density operation

    International Nuclear Information System (INIS)

    Tabuchi, Yuichiro; Shiomi, Takeshi; Aoki, Osamu; Kubo, Norio; Shinohara, Kazuhiko

    2010-01-01

    Key challenges to the acceptance of polymer electrolyte membrane fuel cells (PEMFCs) for automobiles are the cost reduction and improvement in its power density for compactness. In order to get the solution, the further improvement in a fuel cell performance is required. In particular, under higher current density operation, water and heat transport in PEMFCs has considerable effects on the cell performance. In this study, the impact of heat and water transport on the cell performance under high current density was investigated by experimental evaluation of liquid water distribution and numerical validation. Liquid water distribution in MEA between rib and channel area is evaluated by neutron radiography. In order to neglect the effect of liquid water in gas channels and reactant species concentration distribution in the flow direction, the differential cell was used in this study. Experimental results suggested that liquid water under the channel was dramatically changed with rib/channel width. From the numerical study, it is found that the change of liquid water distribution was significantly affected by temperature distribution in MEA between rib and channel area. In addition, not only heat transport but also water transport through the membrane also significantly affected the cell performance under high current density operation.

  9. Water uptake and transport in lianas and co-occurring trees of a seasonally dry tropical forest.

    Science.gov (United States)

    José Luis Andrade; Frederick C. Meinzer; Guillermo Goldstein; Stefan A. Schnitzer

    2005-01-01

    Water uptake and transport were studied in eight liana species in a seasonally dry tropical forest on Barro Colorado Island, Panama. Stable hydrogen isotope composition (δD) of xylem and soil water, soil volumetric water content (θv), and basal sap flow were measured during the 1997 and...

  10. Biofuel scenarios in a water perspective: the global blue and green water footprint of road transport in 2030

    NARCIS (Netherlands)

    van Lienden, A.R.; Gerbens-Leenes, Winnie; Hoekstra, Arjen Ysbert; van der Meer, Theodorus H.

    2010-01-01

    The trend towards substitution of conventional transport fuels by biofuels requires additional water. The EU aims In the last two centuries, fossil fuels have been our major source of energy. However, issues concerning energy security and the quality of the environment have given an impulse to the

  11. Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030

    NARCIS (Netherlands)

    Gerbens-Leenes, Winnie; van Lienden, A.R.; Hoekstra, Arjen Ysbert; van der Meer, Theodorus H.

    2012-01-01

    Concerns over energy security and climate change stimulate developments towards renewable energy. Transport is expected to switch from fossil fuel use to the use of fuel mixtures with a larger fraction of biofuels, e.g. bio-ethanol and biodiesel. Growing biomass for biofuels requires water, a scarce

  12. Climate change and the impact of increased rainfall variability on sediment transport and catchment scale water quality

    Science.gov (United States)

    Hancock, G. R.; Willgoose, G. R.; Cohen, S.

    2009-12-01

    Recently there has been recognition that changing climate will affect rainfall and storm patterns with research directed to examine how the global hydrological cycle will respond to climate change. This study investigates the effect of different rainfall patterns on erosion and resultant water quality for a well studied tropical monsoonal catchment that is undisturbed by Europeans in the Northern Territory, Australia. Water quality has a large affect on a range of aquatic flora and fauna and a significant change in sediment could have impacts on the aquatic ecosystems. There have been several studies of the effect of climate change on rainfall patterns in the study area with projections indicating a significant increase in storm activity. Therefore it is important that the impact of this variability be assessed in terms of catchment hydrology, sediment transport and water quality. Here a numerical model of erosion and hydrology (CAESAR) is used to assess several different rainfall scenarios over a 1000 year modelled period. The results show that that increased rainfall amount and intensity increases sediment transport rates but predicted water quality was variable and non-linear but within the range of measured field data for the catchment and region. Therefore an assessment of sediment transport and water quality is a significant and complex issue that requires further understandings of the role of biophysical feedbacks such as vegetation as well as the role of humans in managing landscapes (i.e. controlled and uncontrolled fire). The study provides a robust methodology for assessing the impact of enhanced climate variability on sediment transport and water quality.

  13. Hydrological balance and water transport processes of partially sealed soils

    Science.gov (United States)

    Timm, Anne; Wessolek, Gerd

    2017-04-01

    With increased urbanisation, soil sealing and its drastic effects on hydrological processes have received a lot of attention. Based on safety concerns, there has been a clear focus on urban drainage and prevention of urban floods caused by storm water events. For this reason, any kind of sealing is often seen as impermeable runoff generator that prevents infiltration and evaporation. While many hydrological models, especially storm water models, have been developed, there are only a handful of empirical studies actually measuring the hydrological balance of (partially) sealed surfaces. These challenge the general assumption of negligible infiltration and evaporation and show that these processes take place even for severe sealing such as asphalt. Depending on the material, infiltration from partially sealed surfaces can be equal to that of vegetated ones. Therefore, more detailed knowledge is needed to improve our understanding and models. In Berlin, two partially sealed weighable lysimeters were equipped with multiple temperature and soil moisture sensors in order to study their hydrological balance, as well as water and heat transport processes within the soil profile. This combination of methods affirms previous observations and offers new insights into altered hydrological processes of partially sealed surfaces at a small temporal scale. It could be verified that not all precipitation is transformed into runoff. Even for a relatively high sealing degree of concrete slabs with narrow seams, evaporation and infiltration may exceed runoff. Due to the lack of plant roots, the hydrological balance is mostly governed by precipitation events and evaporation generally occurs directly after rainfall. However, both surfaces allow for upward water transport from the upper underlying soil layers, sometimes resulting in relatively low evaporation rates on days without precipitation. The individual response of the surfaces differs considerably, which illustrates how

  14. Redesigning transport equipment – comparative analysis of energy expenditure (power and water in refrigerators

    Directory of Open Access Journals (Sweden)

    Lisiane Ilha Librelotto

    2015-12-01

    Full Text Available Sustainability is defined as an approach that integrates social, economic and environmental concerns (SEE. This philosophy carries several implications for daily factory work, where culturally, the economic issue is considered most important. This paper provides a case study at a meat and bone-meal (MBM factory, and the preliminary studies of the adaptation of this factory to the SEE philosophy, focusing initially on economic aspect, and its relationship with the two other aspects. It also shows how the design of a conveyor belt - used to transport entrails and feathers from the slaughter site to the byproducts production site - could improve the consumption of power and water resources at the factory studied. Currently, this transport is accomplished manually (for feathers and by pneumatic conveying (for entrails. As a result, it was found that a change in the transport processes to align with the SEE philosophy would allow an 18% reduction of water use.

  15. Circumpolar Deep Water transport and current structure at the Amundsen Sea shelf break

    Science.gov (United States)

    Assmann, Karen M.; Wåhlin, Anna K.; Heywood, Karen J.; Jenkins, Adrian; Kim, Tae Wan; Lee, Sang Hoon

    2017-04-01

    The West Antarctic Ice Sheet has been losing mass at an increasing rate over the past decades. Ocean heat transport to the ice-ocean interface has been identified as an important contributor to this mass loss and the role it plays in ice sheet stability makes it crucial to understand its drivers in order to make accurate future projections of global sea level. While processes closer to the ice-ocean interface modulate this heat transport, its ultimate source is located in the deep basin off the continental shelf as a core of relatively warm, salty water underlying a colder, fresher shallow surface layer. To reach the marine terminating glaciers and the base of floating ice shelves, this warm, salty water mass must cross the bathymetric obstacle of the shelf break. Glacial troughs that intersect the Amundsen shelf break and deepen southwards towards the ice shelf fronts have been shown to play an important role in transporting warm, salty Circumpolar Deep Water (CDW) towards the ice shelves. North of the shelf break, circulation in the Amundsen Sea occupies an intermediate regime between the eastward Antarctic Circumpolar Current that impinges on the shelf break in the Bellingshausen Sea and the westward southern limb of the Ross Gyre that follows the shelf break in the Ross Sea. Hydrographic and mooring observations and numerical model results at the mouth of the central shelf break trough leading to Pine Island and Thwaites Glaciers show a westward wind-driven shelf break current overlying an eastward undercurrent that turns onto the shelf in the trough. It is thought that the existence of the latter feature facilitates the on-shelf transport of CDW. A less clearly defined shelf break depression further west acts as the main pathway for CDW to Dotson and eastern Getz Ice shelves. Model results indicate that a similar eastward undercurrent exists here driving the on-shelf transport of CDW. Two moorings on the upper slope east of the trough entrance show a

  16. Transport of North Pacific 137Cs labeled waters to the south-eastern Atlantic Ocean

    Science.gov (United States)

    Sanchez-Cabeza, J. A.; Levy, I.; Gastaud, J.; Eriksson, M.; Osvath, I.; Aoyama, M.; Povinec, P. P.; Komura, K.

    2011-04-01

    During the reoccupation of the WOCE transect A10 at 30°S by the BEAGLE2003 cruise, the SHOTS project partners collected a large number of samples for the analysis of isotopic tracers. 137Cs was mostly deposited on the oceans surface during the late 1950s and early 1960s, after the atmospheric detonation of large nuclear devices, which mostly occurred in the Northern Hemisphere. The development of advanced radioanalytical and counting techniques allowed to obtain, for the first time in this region, a zonal section of 137Cs water concentrations, where little information existed before, thus constituting an important benchmark for further studies. 137Cs concentrations in the upper waters (0-1000 m) of the south-eastern Atlantic Ocean are similar to those observed in the south-western Indian Ocean, suggesting transport of 137Cs labeled waters by the Agulhas current to the Benguela Current region. In contrast, bomb radiocarbon data do not show this feature, indicating the usefulness of 137Cs as a radiotracer of water mass transport from the Indian to the South Atlantic Ocean.

  17. A Thermomechanical Transport Approach and Application in Soil-Water System of Polluted Mining Areas considering the Three-Phase Coupling

    Directory of Open Access Journals (Sweden)

    Xuan Guo

    2016-01-01

    Full Text Available The thermomechanical transport approach includes the process of diffusing or the condition of being diffused, absorption/desorption, swell/shrink, equilibrium/nonequilibrium, and thermomechanical transport of contaminant in three phases of polluted mining soil which are discussed. The thermomechanical transport model of the contaminants transport in polluted soil is established, and its basic equations are given. Based on that, the distribution regularities of the contaminant seepage in water-soil system are discussed in detail and the sensitivities of parameters are analyzed. The study shows that the parameter has important influence on the contamination distribution and transportation in polluted soil-water system. The influence degree is also related to the action of seepage force directly.

  18. Dynamics of glycerine and water transport across human skin from binary mixtures.

    Science.gov (United States)

    Ventura, S A; Kasting, G B

    2017-04-01

    Skin transport properties of glycerine and water from binary mixtures contacting human skin were determined to better understand the mechanism of skin moisturization by aqueous glycerine formulations. Steady-state permeation for 3 H 2 O and 14 C-glycerine across split-thickness human skin in vitro and desorption dynamics of the same permeants in isolated human stratum corneum (HSC) were experimentally determined under near equilibrium conditions. These data were compared to a priori values developed in the context of a thermodynamic model for binary mixtures of glycerine and water and a previously determined water sorption isotherm for HSC. This allowed the estimation of diffusion and partition coefficients for each permeant in the HSC, as well as HSC thickness, as a function of composition of the contacting solution. These data may be used to estimate water retention and associated HSC swelling related to the absorption and slow release of glycerine from the skin. It took 6+ days for glycerine to completely desorb from HSC immersed in glycerine/water binary solutions. Desorption of both 3 H 2 O and 14 C-glycerine from HSC was slower in pure water than from binary mixtures, a result that is largely explained by the greater swelling of HSC in water. Parametric relationships were developed for water and glycerine intradiffusivities in HSC as functions of HSC water content, and a mutual diffusion coefficient was estimated by analogy with glycerine/water binary solutions. The intradiffusivity of 14 C-glycerine in HSC as inferred from sorption/desorption experiments was shown to be approximately 10-fold less than that inferred from permeation experiments, whereas the corresponding values for 3 H 2 O were comparable. These studies confirm that glycerine enters HSC in substantial quantities and has a long residence time therein. The coupling between bulk water and glycerine transport projected from binary solution data suggests the net effect of glycerine is to slow water

  19. Liquid Water Transport in the Reactant Channels of Proton Exchange Membrane Fuel Cells

    Science.gov (United States)

    Banerjee, Rupak

    Water management has been identified as a critical issue in the development of PEM fuel cells for automotive applications. Water is present inside the PEM fuel cell in three phases, i.e. liquid phase, vapor phase and mist phase. Liquid water in the reactant channels causes flooding of the cell and blocks the transport of reactants to the reaction sites at the catalyst layer. Understanding the behavior of liquid water in the reactant channels would allow us to devise improved strategies for removing liquid water from the reactant channels. In situ fuel cell tests have been performed to identify and diagnose operating conditions which result in the flooding of the fuel cell. A relationship has been identified between the liquid water present in the reactant channels and the cell performance. A novel diagnostic technique has been established which utilizes the pressure drop multiplier in the reactant channels to predict the flooding of the cell or the drying-out of the membrane. An ex-situ study has been undertaken to quantify the liquid water present in the reactant channels. A new parameter, the Area Coverage Ratio (ACR), has been defined to identify the interfacial area of the reactant channel which is blocked for reactant transport by the presence of liquid water. A parametric study has been conducted to study the effect of changing temperature and the inlet relative humidity on the ACR. The ACR decreases with increase in current density as the gas flow rates increase, removing water more efficiently. With increase in temperature, the ACR decreases rapidly, such that by 60°C, there is no significant ACR to be reported. Inlet relative humidity of the gases does change the saturation of the gases in the channel, but did not show any significant effect on the ACR. Automotive powertrains, which is the target for this work, are continuously faced with transient changes. Water management under transient operating conditions is significantly more challenging and has not

  20. Water characteristics and transport of the Antarctic circumpolar current in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Mathew, B.

    Geostrophic velocities are computed across meridians 37 degrees E and 105 degrees E using hydrographic data. The estimated mass transport is represented on a temperature - salinity diagram. The characteristics of the water within the Antarctic...

  1. Tectonic and erosion-driven uplift in the Gamburtsev Subglacial Mountains of East Antarctica

    Science.gov (United States)

    Ferraccioli, Fausto; Jordan, Tom; Watts, Tony; Bell, Robin; Jamieson, Stewart; Finn, Carol; Damaske, Detlef

    2014-05-01

    Understanding the mechanisms leading to intraplate mountain building remains a significant challenge in Earth Sciences compared to ranges formed along plate margins. The most enigmatic intraplate mountain range on Earth is the Gamburtsev Subglacial Mountains (GSM) located in the middle of the Precambrian East Antarctic Craton. During the International Polar Year, the AGAP project acquired 120,000 line km of new airborne geophysical data (Bell et al., 2011, Science) and seismological observations (Hansen et al., 2010, EPSL) across central East Antarctica. Models derived from these datasets provide new geophysical perspectives on crustal architecture and possible uplift mechanisms for the enigmatic GSM (Ferraccioli et al., 2011, Nature). The geophysical data define a 2,500-km-long Paleozoic to Mesozoic rift system in East Antarctica surrounding the GSM. A thick high-density lower crustal root is partially preserved beneath the range and has been interpreted as formed during the Proterozoic assembly of East Antarctica. Rifting could have triggered phase/density changes at deep crustal levels, perhaps restoring some of the latent root buoyancy, as well as causing rift-flank uplift. Permian rifting is well-established in the adjacent Lambert Rift, and was followed by Cretaceous strike-slip faulting and transtension associated with Gondwana break-up; this phase may have provided a more recent tectonic trigger for the initial uplift of the modern GSM. The Cretaceous rift-flank uplift model for the Gamburtsevs is appealing because it relates the initiation of intraplate mountain-building to large-scale geodynamic processes that led to the separation of Greater India from East Antarctica. It is also consistent with several geological and geophysical interpretations within the Lambert Rift. However, recent detrital thermochrology results from Oligocene-Quaternary sediments in Prydz Bay (Tochlin et al., 2012, G3) argue against the requirement for major Cretaceous rift

  2. Design and operational parameters of transportable supercritical water oxidation waste destruction unit

    International Nuclear Information System (INIS)

    McFarland, R.D.; Brewer, G.R.; Rofer, C.K.

    1991-12-01

    Supercritical water oxidation (SCWO) is the destruction of hazardous waste by oxidation in the presence of water at temperatures and pressures above its critical point. A 1 gal/h SCWO waste destruction unit (WDU) has been designed, built, and operated at Los Alamos National Laboratory. This unit is transportable and is intended to demonstrate the SCWO technology on wastes at Department of Energy sites. This report describes the design of the WDU and the preliminary testing phase leading to demonstration

  3. Radiobiological application of simulation of low-energy electron transport in liquid water

    International Nuclear Information System (INIS)

    Eudaldo Puell, Teresa.

    1979-01-01

    A Monte-Carlo transport simulation method, so-called event-after-event method provide results about trajectories of low-energy electrons, slowing-down in liquid water. A radiosensitive target model constituted by water cylindrical volumes, like the ones which surround the DNA molecule, is taken into consideration. The results characterizing the primary physical stage of radiation action, such as, space ionization distributions, interionization distance distributions ..., are obtained in some configurations constituted by single or several targets, in order to approach the biological reality [fr

  4. Modeling of Dense Water Production and Salt Transport from Alaskan Coastal Polynyas

    Science.gov (United States)

    Signorini, Sergio R.; Cavalieri, Donald J.

    2000-01-01

    The main significance of this paper is that a realistic, three-dimensional, high-resolution primitive equation model has been developed to study the effects of dense water formation in Arctic coastal polynyas. The model includes realistic ambient stratification, realistic bottom topography, and is forced by time-variant surface heat flux, surface salt flux, and time-dependent coastal flow. The salt and heat fluxes, and the surface ice drift, are derived from satellite observations (SSM/I and NSCAT sensors). The model is used to study the stratification, salt transport, and circulation in the vicinity of Barrow Canyon during the 1996/97 winter season. The coastal flow (Alaska coastal current), which is an extension of the Bering Sea throughflow, is formulated in the model using the wind-transport regression. The results show that for the 1996/97 winter the northeastward coastal current exports 13% to 26% of the salt produced by coastal polynyas upstream of Barrow Canyon in 20 to 30 days. The salt export occurs more rapidly during less persistent polynyas. The inclusion of ice-water stress in the model makes the coastal current slightly weaker and much wider due to the combined effects of surface drag and offshore Ekman transport.

  5. Development of computer code on sodium-water reaction products transport

    International Nuclear Information System (INIS)

    Arikawa, H.; Yoshioka, N.; Suemori, M.; Nishida, K.

    1988-01-01

    The LMFBR concept eliminating the secondary sodium system has been considered to be one of the most promissing concepts for offering cost reductions. In this reactor concept, the evaluation of effects on reactor core by the sodium-water reaction products (SWRPs) during sodium-water reaction at primary steam generator becomes one of the major safety issues. In this study, the calculation code was developed as the first step of the processes of establishing the evaluation method for SWRP effects. The calculation code, called SPROUT, simulates the SWRPs transport and distribution in primary sodium system using the system geometry, thermal hydraulic data and sodium-water reacting conditions as input. This code principally models SWRPs behavior. The paper contain the modelings for SWRPs behaviors, with solution, precipation, deposition and so on, and the results and discussions of the demonstration calculation for a typical FBR plant eliminating the secondary sodium system

  6. Evaluating the effects of variable water chemistry on bacterial transport during infiltration.

    Science.gov (United States)

    Zhang, Haibo; Nordin, Nahjan Amer; Olson, Mira S

    2013-07-01

    Bacterial infiltration through the subsurface has been studied experimentally under different conditions of interest and is dependent on a variety of physical, chemical and biological factors. However, most bacterial transport studies fail to adequately represent the complex processes occurring in natural systems. Bacteria are frequently detected in stormwater runoff, and may present risk of microbial contamination during stormwater recharge into groundwater. Mixing of stormwater runoff with groundwater during infiltration results in changes in local solution chemistry, which may lead to changes in both bacterial and collector surface properties and subsequent bacterial attachment rates. This study focuses on quantifying changes in bacterial transport behavior under variable solution chemistry, and on comparing the influences of chemical variability and physical variability on bacterial attachment rates. Bacterial attachment rate at the soil-water interface was predicted analytically using a combined rate equation, which varies temporally and spatially with respect to changes in solution chemistry. Two-phase Monte Carlo analysis was conducted and an overall input-output correlation coefficient was calculated to quantitatively describe the importance of physiochemical variation on the estimates of attachment rate. Among physical variables, soil particle size has the highest correlation coefficient, followed by porosity of the soil media, bacterial size and flow velocity. Among chemical variables, ionic strength has the highest correlation coefficient. A semi-reactive microbial transport model was developed within HP1 (HYDRUS1D-PHREEQC) and applied to column transport experiments with constant and variable solution chemistries. Bacterial attachment rates varied from 9.10×10(-3)min(-1) to 3.71×10(-3)min(-1) due to mixing of synthetic stormwater (SSW) with artificial groundwater (AGW), while bacterial attachment remained constant at 9.10×10(-3)min(-1) in a constant

  7. Control of unidirectional transport of single-file water molecules through carbon nanotubes in an electric field.

    Science.gov (United States)

    Su, Jiaye; Guo, Hongxia

    2011-01-25

    The transport of water molecules through nanopores is not only crucial to biological activities but also useful for designing novel nanofluidic devices. Despite considerable effort and progress that has been made, a controllable and unidirectional water flow is still difficult to achieve and the underlying mechanism is far from being understood. In this paper, using molecular dynamics simulations, we systematically investigate the effects of an external electric field on the transport of single-file water molecules through a carbon nanotube (CNT). We find that the orientation of water molecules inside the CNT can be well-tuned by the electric field and is strongly coupled to the water flux. This orientation-induced water flux is energetically due to the asymmetrical water-water interaction along the CNT axis. The wavelike water density profiles are disturbed under strong field strengths. The frequency of flipping for the water dipoles will decrease as the field strength is increased, and the flipping events vanish completely for the relatively large field strengths. Most importantly, a critical field strength E(c) related to the water flux is found. The water flux is increased as E is increased for E ≤ E(c), while it is almost unchanged for E > E(c). Thus, the electric field offers a level of governing for unidirectional water flow, which may have some biological applications and provides a route for designing efficient nanopumps.

  8. Dual-Functional Superhydrophobic Textiles with Asymmetric Roll-Down/Pinned States for Water Droplet Transportation and Oil-Water Separation.

    Science.gov (United States)

    Su, Xiaojing; Li, Hongqiang; Lai, Xuejun; Zhang, Lin; Liao, Xiaofeng; Wang, Jing; Chen, Zhonghua; He, Jie; Zeng, Xingrong

    2018-01-31

    Superhydrophobic surfaces with tunable adhesion from lotus-leaf to rose-petal states have generated much attention for their potential applications in self-cleaning, anti-icing, oil-water separation, microdroplet transportation, and microfluidic devices. Herein we report a facile magnetic-field-manipulation strategy to fabricate dual-functional superhydrophobic textiles with asymmetric roll-down/pinned states on the two surfaces of the textile simultaneously. Upon exposure to a static magnetic field, fluoroalkylsilane-modified iron oxide (F-Fe 3 O 4 ) nanoparticles in polydimethylsiloxane (PDMS) moved along the magnetic field to construct discrepant hierarchical structures and roughnesses on the two sides of the textile. The positive surface (closer to the magnet, or P-surface) showed a water contact angle up to 165°, and the opposite surface (or O-surface) had a water contact angle of 152.5°. The P-surface where water droplets easily slid off with a sliding angle of 7.5° appeared in the "roll-down" state as Cassie mode, while the O-surface was in the "pinned" state as Wenzel mode, where water droplets firmly adhered even at vertical (90°) and inverted (180°) angles. The surface morphology and wetting mode were adjustable by varying the ratios of F-Fe 3 O 4 nanoparticles and PDMS. By taking advantage of the asymmetric adhesion behaviors, the as-fabricated superhydrophobic textile was successfully applied in no-loss microdroplet transportation and oil-water separation. Our method is simple and cost-effective. The fabricated textile has the characteristics of superhydrophobicity, magnetic responsiveness, excellent chemical stability, adjustable surface morphology, and controllable adhesion. Our findings conceivably stand out as a new tool to fabricate functional superhydrophobic materials with asymmetric surface properties for various potential applications.

  9. The establishment of Atlantic Water transport as a topographically trapped slope current off Scotland

    Directory of Open Access Journals (Sweden)

    Qin Zhou

    2013-05-01

    Full Text Available Atlantic Water, with its origin in the western Atlantic, enters the Nordic Seas partly as a barotropic current following the continental slope. This water mass is carried across the Atlantic by the baroclinic North Atlantic Current (NAC. When the NAC meets the continental slope at the east side of the Atlantic, some of the transport is converted to barotropic transport over the slope before continuing northward. Here, we show that this baroclinic to barotropic conversion is in agreement with geostrophic theory. Historical observations show that the transport of the slope current increases significantly from the Rockall Channel (RC to the Faroe–Shetland Channel (FSC. Geostrophy predicts that with a northward decreasing buoyancy, baroclinic currents from the west will be transferred into northward topographically steered barotropic flow. We use hydrographic data from two sections crossing the continental slope, one located in the RC and another in the FSC, to estimate baroclinic and barotropic transport changes over the slope, within the framework of geostrophic dynamics. Our results indicate that ~1 Sv of the cross-slope baroclinic flow is mainly converted to northward barotropic transport above the 200–500m isobaths, which is consistent with observed transport changes between the RC and the FSC. Similar processes are also likely to occur further south, along the eastern Atlantic margin. This shows that AW within the slope current in the FSC is derived from both the eastern and the western Atlantic, in agreement with earlier studies of AW inflow to the Nordic Seas.

  10. DNA-labeled micro- and nanoparticles: a new approach to study contaminant transport in the subsurface

    Science.gov (United States)

    McNew, C.; Wang, C.; Kocis, T. N.; Murphy, N. P.; Dahlke, H. E.

    2017-12-01

    Though our understanding of contaminant behavior in the subsurface has improved, our ability to measure and predict complex contaminant transport pathways at hillslope to watershed scales is still lacking. By utilizing bio-molecular nanotechnology developed for nano-medicines and drug delivery, we are able to produce DNA-labeled micro- and nanoparticles for use in a myriad of environmental systems. Control of the fabrication procedure allows us to produce particles of custom size, charge, and surface functionality to mimic the transport properties of the particulate contaminant or colloid of interest. The use of custom sequenced DNA allows for the fabrication of an enormous number of unique particle labels (approximately 1.61 x 1060 unique sequences) and the ability to discern between varied spatial and temporal applications, or the transport effect of varied particle size, charge, or surface properties. To date, this technology has been utilized to study contaminant transport from lab to field scales, including surface and open channel flow applications, transport in porous media, soil retention, and even subglacial flow pathways. Here, we present the technology for production and detection of the DNA-labeled particles along with the results from a current hillslope study at the Sierra Foothills Research and Extension Center (SFREC). This field study utilizes spatial and temporal variations in DNA-labeled particle applications to identify subsurface pollutant transport pathways through the four distinct soil horizons present at the SFREC site. Results from this and previous studies highlight the tremendous potential of the DNA-labeled particle technology for studying contaminant transport through the subsurface.

  11. [Monitoring of water and salt transport in silt and sandy soil during the leaching process].

    Science.gov (United States)

    Fu, Teng-Fei; Jia, Yong-Gang; Guo, Lei; Liu, Xiao-Lei

    2012-11-01

    Water and salt transport in soil and its mechanism is the key point of the saline soil research. The dynamic rule of water and transport in soil during the leaching process is the theoretical basis of formation, flush, drainage and improvement of saline soil. In this study, a vertical infiltration experiment was conducted to monitor the variation in the resistivity of silt and sandy soil during the leaching process by the self-designed automatic monitoring device. The experimental results showed that the peaks in the resistivity of the two soils went down and faded away in the course of leaching. It took about 30 minutes for sandy soil to reach the water-salt balance, whereas the silt took about 70 minutes. With the increasing leaching times, the desalination depth remained basically the same, being 35 cm for sandy soil and 10 cm for the silt from the top to bottom of soil column. Therefore, 3 and 7 leaching processes were required respectively for the complete desalination of the soil column. The temporal and spatial resolution of this monitoring device can be adjusted according to the practical demand. This device can not only achieve the remote, in situ and dynamic monitoring data of water and salt transport, but also provide an effective method in monitoring, assessment and early warning of salinization.

  12. Rapid Water Transport by Long-Lasting Modon Eddy Pairs in the Southern Midlatitude Oceans

    Science.gov (United States)

    Hughes, Chris W.; Miller, Peter I.

    2017-12-01

    Water in the ocean is generally carried with the mean flow, mixed by eddies, or transported westward by coherent eddies at speeds close to the long baroclinic Rossby wave speed. Modons (dipole eddy pairs) are a theoretically predicted exception to this behavior, which can carry water to the east or west at speeds much larger than the Rossby wave speed, leading to unusual transports of heat, nutrients, and carbon. We provide the first observational evidence of such rapidly moving modons propagating over large distances. These modons are found in the midlatitude oceans around Australia, with one also seen in the South Atlantic west of the Agulhas region. They can travel at more than 10 times the Rossby wave speed of 1-2 cm s-1 and typically persist for about 6 months carrying their unusual water mass properties with them, before splitting into individual vortices, which can persist for many months longer.

  13. Water and sediment transport modeling of a large temporary river basin in Greece.

    Science.gov (United States)

    Gamvroudis, C; Nikolaidis, N P; Tzoraki, O; Papadoulakis, V; Karalemas, N

    2015-03-01

    The objective of this research was to study the spatial distribution of runoff and sediment transport in a large Mediterranean watershed (Evrotas River Basin) consisting of temporary flow tributaries and high mountain areas and springs by focusing on the collection and use of a variety of data to constrain the model parameters and characterize hydrologic and geophysical processes at various scales. Both monthly and daily discharge data (2004-2011) and monthly sediment concentration data (2010-2011) from an extended monitoring network of 8 sites were used to calibrate and validate the Soil and Water Assessment Tool (SWAT) model. In addition flow desiccation maps showing wet and dry aquatic states obtained during a dry year were used to calibrate the simulation of low flows. Annual measurements of sediment accumulation in two reaches were used to further calibrate the sediment simulation. Model simulation of hydrology and sediment transport was in good agreement with field observations as indicated by a variety of statistical measures used to evaluate the goodness of fit. A water balance was constructed using a 12 year long (2000-2011) simulation. The average precipitation of the basin for this period was estimated to be 903 mm yr(-1). The actual evapotranspiration was 46.9% (424 mm yr(-1)), and the total water yield was 13.4% (121 mm yr(-1)). The remaining 33.4% (302 mm yr(-1)) was the amount of water that was lost through the deep groundwater of Taygetos and Parnonas Mountains to areas outside the watershed and for drinking water demands (6.3%). The results suggest that the catchment has on average significant water surplus to cover drinking water and irrigation demands. However, the situation is different during the dry years, where the majority of the reaches (85% of the river network are perennial and temporary) completely dry up as a result of the limited rainfall and the substantial water abstraction for irrigation purposes. There is a large variability in the

  14. Predation and transport of persistent pathogens in GAC and slow sand filters: a threat to drinking water safety?

    Science.gov (United States)

    Bichai, Françoise; Dullemont, Yolanda; Hijnen, Wim; Barbeau, Benoit

    2014-11-01

    Zooplankton has been shown to transport internalized pathogens throughout engineered drinking water systems. In this study, experimental measurements from GAC and SSF filtration tests using high influent concentrations of Cryptosporidium (1.3 × 10(6) and 3.3 × 10(4) oocysts L(-1)) and Giardia (4.8 × 10(4) cysts L(-1)) are presented and compared. A predation and transport conceptual model was developed to extrapolate these results to environmental conditions of typical (oo)cyst concentrations in surface water in order to predict concentrations of internalized (oo)cysts in filtered water. Pilot test results were used to estimate transport and survival ratios of internalized (oo)cysts following predation by rotifers in the filter beds. Preliminary indications of lower transport and survival ratios in SSF were found as compared with GAC filters. A probability of infection due to internalized (oo)cysts in filtered water was calculated under likeliest environmental conditions and under a worst-case scenario. Estimated risks under the likeliest environmental scenario were found to fall below the tolerable risk target of 10(-4) infections per person per year. A discussion is presented on the health significance of persistent pathogens that are internalized by zooplankton during granular filtration processes and released into treated water. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. The Role of Subsurface Properties on Transport of Water and Trace Gases: 1D Simulations at Selected Mars Landing Sites.

    Science.gov (United States)

    Karatekin, O.; Gloesener, E.; Dehant, V. M. A.

    2017-12-01

    In this work, water ice stability and water vapour transport through porous martian subsurface are studied using a 1D diffusive model. The role of adsorption on water transfer in martian conditions is investigated as well as the range of parameters that have the largest effect on gas transport. In addition, adsorption kinetics is considered to examine its influence on the water vapor exchange between the subsurface and the atmosphere. As methane has been detected in the martian atmosphere, the subsurface model is then used to study methane diffusion in the CH4/CO2/H2O system from variable depths under the surface. The results of subsurface gas transport at selected locations/landing sites are shown and implications for present/future observations are discussed.

  16. On the development and benchmarking of an approach to model gas transport in fractured media with immobile water storage

    Science.gov (United States)

    Harp, D. R.; Ortiz, J. P.; Pandey, S.; Karra, S.; Viswanathan, H. S.; Stauffer, P. H.; Anderson, D. N.; Bradley, C. R.

    2017-12-01

    In unsaturated fractured media, the rate of gas transport is much greater than liquid transport in many applications (e.g., soil vapor extraction operations, methane leaks from hydraulic fracking, shallow CO2 transport from geologic sequestration operations, and later-time radionuclide gas transport from underground nuclear explosions). However, the relatively immobile pore water can inhibit or promote gas transport for soluble constituents by providing storage. In scenarios with constant pressure gradients, the gas transport will be retarded. In scenarios with reversing pressure gradients (i.e. barometric pressure variations) pore water storage can enhance gas transport by providing a ratcheting mechanism. Recognizing the computational efficiency that can be gained using a single-phase model and the necessity of considering pore water storage, we develop a Richard's solution approach that includes kinetic dissolution/volatilization of constituents. Henry's Law governs the equilibrium gaseous/aqueous phase partitioning in the approach. The approach is implemented in a development branch of the PFLOTRAN simulator. We verify the approach with analytical solutions of: (1) 1D gas diffusion, (2) 1D gas advection, (3) sinusoidal barometric pumping of a fracture, and (4) gas transport along a fracture with uniform flow and diffusive walls. We demonstrate the retardation of gas transport in cases with constant pressure gradients and the enhancement of gas transport with reversing pressure gradients. The figure presents the verification of our approach to the analytical solution of barometric pumping of a fracture from Nilson et al (1991) where the x-axis "Horizontal axis" is the distance into the matrix block from the fracture.

  17. The composite water and solute transport of barley (Hordeum vulgare) roots: effect of suberized barriers.

    Science.gov (United States)

    Ranathunge, Kosala; Kim, Yangmin X; Wassmann, Friedrich; Kreszies, Tino; Zeisler, Viktoria; Schreiber, Lukas

    2017-03-01

    Roots have complex anatomical structures, and certain localized cell layers develop suberized apoplastic barriers. The size and tightness of these barriers depend on the growth conditions and on the age of the root. Such complex anatomical structures result in a composite water and solute transport in roots. Development of apoplastic barriers along barley seminal roots was detected using various staining methods, and the suberin amounts in the apical and basal zones were analysed using gas chromatography-mass spectometry (GC-MS). The hydraulic conductivity of roots ( Lp r ) and of cortical cells ( Lp c ) was measured using root and cell pressure probes. When grown in hydroponics, barley roots did not form an exodermis, even at their basal zones. However, they developed an endodermis. Endodermal Casparian bands first appeared as 'dots' as early as at 20 mm from the apex, whereas a patchy suberin lamellae appeared at 60 mm. The endodermal suberin accounted for the total suberin of the roots. The absolute amount in the basal zone was significantly higher than in the apical zone, which was inversely proportional to the Lp r . Comparison of Lp r and Lp c suggested that cell to cell pathways dominate for water transport in roots. However, the calculation of Lp r from Lp c showed that at least 26 % of water transport occurs through the apoplast. Roots had different solute permeabilities ( P sr ) and reflection coefficients ( σ sr ) for the solutes used. The σ sr was below unity for the solutes, which have virtually zero permeability for semi-permeable membranes. Suberized endodermis significantly reduces Lp r of seminal roots. The water and solute transport across barley roots is composite in nature and they do not behave like ideal osmometers. The composite transport model should be extended by adding components arranged in series (cortex, endodermis) in addition to the currently included components arranged in parallel (apoplastic, cell to cell pathways). © The

  18. Analysis of the Sodium Recirculation Theory of Solute Coupled Water Transport in Small Intestine

    DEFF Research Database (Denmark)

    Larsen, E. H.; Sørensen, Jens Nørkær; Sørensen, J. B.

    2002-01-01

    Our previous mathematical model of solute-coupled water transport through the intestinal epithelium is extended for dealing with electrolytes rather than electroneutral solutes. A 3Na+-2K+ pump in the lateral membranes provides the energy-requiring step for driving transjunctional and translateral......, computations predict that the concentration differences between lis and bathing solutions are small for all three ions. Nevertheless, the diffusion fluxes of the ions out of lis significantly exceed their mass transports. It is concluded that isotonic transport requires recirculation of all three ions....... The computed sodium recirculation flux that is required for isotonic transport corresponds to that estimated in experiments on toad small intestine. This result is shown to be robust and independent of whether the apical entrance mechanism for the sodium ion is a channel, a SGLT1 transporter driving inward...

  19. The Association of Cryptosporidium parvum With Suspended Sediments: Implications for Transport in Surface Waters

    Science.gov (United States)

    Searcy, K. E.; Packman, A. I.; Atwill, E. R.; Harter, T.

    2003-12-01

    Understanding the transport and fate of microorganisms in surface waters is of vital concern in protecting the integrity and safety of municipal water supply systems. The human pathogen Cryptosporidium parvum is a particular public health interest, as it is ubiquitous in the surface waters of the United States, it can persist for long periods in the environment, and it is difficult to disinfect in water treatment plants. Due to its small size (5 um), low specific gravity (1.05 g/cm3), and negative surface charge, C. parvum oocysts are generally considered to move through watersheds from their source to drinking water reservoirs with little attenuation. However, the transport of the oocysts in surface waters may be mediated by interactions with suspended sediments. Batch experiments were conducted to determine the extent of C. parvum oocyst attachment to several inorganic and organic sediments under varying water chemical conditions, and settling column experiments were performed to demonstrate how these associations influence the effective settling velocity of C. parvum oocysts. Results from these experiments showed that C. parvum oocysts do associate with inorganic and organic sediments and often settle at the rate of the suspended sediment. The size and surface charge of the host suspended sediment influenced the extent of oocyst attachment as oocysts preferentially associated with particles greater than 3 um, and fewer oocysts associated with particles having a highly negative surface charge. Background water chemical conditions including ionic strength, ion composition, and pH did not have a significant effect on oocyst attachment to suspended sediments.

  20. Transport Canada : navigable water protection technical paper on boating safety at dams

    Energy Technology Data Exchange (ETDEWEB)

    Putt, B [Transport Canada, Sarnia, ON (Canada); Di Censo, V M [Transport Canada, Ottawa, ON (Canada)

    2009-07-01

    The Navigable Waters Protection Act (NWPA) was designed to ensure a balance between public rights of navigation and the need to build bridges, dams, and other structures. This paper discussed an owner's guide to navigation safety around water control structures. Developed by Transport Canada, the guide was intended to help owners of water control structures address boating safety matters and assist owners in making applications under the NWPA. The guide was prepared to address amendments made to the NWPA in 2009 as well as to assist owners in identifying potential hazards and interactions by the boating public at water control structures. The guide included information related to signage; navigation aids; barriers and booms; warning alerts and alarms; portage and access around structures; and application requirements. It was concluded that the guide will also provide a summary of legislation that may affect owners of water control structures.

  1. Analysing the mechanisms of soil water and vapour transport in the desert vadose zone of the extremely arid region of northern China

    Science.gov (United States)

    Du, Chaoyang; Yu, Jingjie; Wang, Ping; Zhang, Yichi

    2018-03-01

    The transport of water and vapour in the desert vadose zone plays a critical role in the overall water and energy balances of near-surface environments in arid regions. However, field measurements in extremely dry environments face many difficulties and challenges, so few studies have examined water and vapour transport processes in the desert vadose zone. The main objective of this study is to analyse the mechanisms of soil water and vapour transport in the desert vadose zone (depth of ∼350 cm) by using measured and modelled data in an extremely arid environment. The field experiments are implemented in an area of the Gobi desert in northwestern China to measure the soil properties, daily soil moisture and temperature, daily water-table depth and temperature, and daily meteorological records from DOYs (Days of Year) 114-212 in 2014 (growing season). The Hydrus-1D model, which simulates the coupled transport of water, vapour and heat in the vadose zone, is employed to simulate the layered soil moisture and temperature regimes and analyse the transport processes of soil water and vapour. The measured results show that the soil water and temperatures near the land surface have visible daily fluctuations across the entire soil profile. Thermal vapour movement is the most important component of the total water flux and the soil temperature gradient is the major driving factor that affects vapour transport in the desert vadose zone. The most active water and heat exchange occurs in the upper soil layer (depths of 0-25 cm). The matric potential change from the precipitation mainly re-draws the spatio-temporal distribution of the isothermal liquid water in the soil near the land surface. The matric potential has little effect on the isothermal vapour and thermal liquid water flux. These findings offer new insights into the liquid water and vapour movement processes in the extremely arid environment.

  2. Impact analysis and testing of tritiated heavy water transportation packages including hydrodynamic effects

    International Nuclear Information System (INIS)

    Sauve, R.G.; Tulk, J.D.; Gavin, M.E.

    1989-01-01

    Ontario Hydro has recently designed a new Type B(M) Tritiated Heavy Water Transportation Package (THWTP) for the road transportation of tritiated heavy water from its operating nuclear stations to the Tritium Removal Facility in Ontario. These packages must demonstrate the ability to withstand severe shock and impact scenarios such as those prescribed by IAEA standards. The package, shown in figure 1, comprises an inner container filled with tritiated heavy water, and a 19 lb/ft 3 polyurethane foam-filled overpack. The overpack is of sandwich construction with 304L stainless steel liners and 10.5 inch thick nominal foam walls. The outer shell is 0.75 inch thick and the inner shell is 0.25 inch thick. The primary containment boundary consists of the overpack inner liner, the containment lid and outer containment seals in the lid region. The total weight of the container including the 12,000 lb. payload is 36,700 lb. The objective of the present study is to evaluate the hydrodynamic effect of the tritiated heavy water payload on the structural integrity of the THWTP during a flat end drop from a height of 9 m. The study consisted of three phases: (i) developing an analytical model to simulate the hydrodynamic effects of the heavy water payload during impact; (ii) performing an impact analysis for a 9 m flat end drop of the THWTP including fluid structure interaction; (iii) verification of the analytical models by experiment

  3. Quantification of the Intracellular Life Time of Water Molecules to Measure Transport Rates of Human Aquaglyceroporins.

    Science.gov (United States)

    Palmgren, Madelene; Hernebring, Malin; Eriksson, Stefanie; Elbing, Karin; Geijer, Cecilia; Lasič, Samo; Dahl, Peter; Hansen, Jesper S; Topgaard, Daniel; Lindkvist-Petersson, Karin

    2017-12-01

    Orthodox aquaporins are transmembrane channel proteins that facilitate rapid diffusion of water, while aquaglyceroporins facilitate the diffusion of small uncharged molecules such as glycerol and arsenic trioxide. Aquaglyceroporins play important roles in human physiology, in particular for glycerol metabolism and arsenic detoxification. We have developed a unique system applying the strain of the yeast Pichia pastoris, where the endogenous aquaporins/aquaglyceroporins have been removed and human aquaglyceroporins AQP3, AQP7, and AQP9 are recombinantly expressed enabling comparative permeability measurements between the expressed proteins. Using a newly established Nuclear Magnetic Resonance approach based on measurement of the intracellular life time of water, we propose that human aquaglyceroporins are poor facilitators of water and that the water transport efficiency is similar to that of passive diffusion across native cell membranes. This is distinctly different from glycerol and arsenic trioxide, where high glycerol transport efficiency was recorded.

  4. Beta-adrenergic activation of solute coupled water uptake by toad skin epithelium results in near-isosmotic transport

    DEFF Research Database (Denmark)

    Nielsen, Robert; Larsen, Erik Hviid

    2007-01-01

    (V) with a [Na+] of the transported fluid of 130+/-24 mM ([Na+]Ringer's solution = 117.4 mM). Addition of bumetanide to the inside solution reduced J(V). Water was transported uphill and J(V) reversed at an excess outside osmotic concentration, deltaC(S,rev) = 28.9+/-3.9 mOsm, amiloride decreased delta......C(S,rev) to 7.5+/-1.5 mOsm. It is concluded that water uptake is accomplished by osmotic coupling in the lateral intercellular space (lis), and hypothesized that a small fraction of the Na+ flux pumped into lis is recirculated via basolateral NKCC transporters.......Transepithelial potential (V(T)), conductance (G(T)), and water flow (J(V)) were measured simultaneously with good time resolution (min) in isolated toad (Bufo bufo) skin epithelium with Ringer on both sides. Inside application of 5 microM isoproterenol resulted in the fast increase in G(T) from 1...

  5. Experimental elucidation on rate-determining process of water transport in polymer electrolyte fuel cell membrane by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Takita, Shinpei; Tsushima, Shohji; Hirai, Shuichiro; Kubo, Norio; Aotani, Koichiro

    2007-01-01

    We examined rate-determining process of water transport in polymer electrolyte membrane (PEM) used in fuel cells by using magnetic resonance imaging (MRI). We measured transversal water content distributions of the membrane by MRI and through-plane mass flux of water by hygrometers. Through place water flux has taken place in the membrane when relative humidify of supplied gas is not equal in both side of the membrane. MRI results revealed that diffusion coefficient of water in the membrane increases with water content of membrane, λ, whilst it shows intensive peak at λ=3-4. Diffusion resistance and mass transfer resistance involving evaporation and condensation on the interface are almost in the same order and thus water transport process in the membrane is determined by either concentration diffusion or mass transfer, depending on water content of membrane. (author)

  6. Fish larval transport in the coastal waters through ecological modelling

    Digital Repository Service at National Institute of Oceanography (India)

    George, G.

    are as follows: (i) to find out the influence of environmental parameters on the biology of the given ecosystem (ii) to track larval transport and biological abundance in relation to environmental vari- ables (iii) to compare biological abundance and fish larval... include the following investigations: (i) analysis of satellite chlorophyll data along the southwest coastal waters of India to derive a biological calender for sardine (ii) tracking the larval survival and establish a link between food and sardine inter...

  7. Evaluation of water transport behavior in sodium fire experiment-II

    Energy Technology Data Exchange (ETDEWEB)

    Nakagiri, Toshio [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center

    2000-02-01

    Evaluation of water transport behavior in Sodium Fire-II (Run-D4) was performed. Results of other experiments performed in Oarai-Engineering Center were considered in the evaluation, and the results of the evaluation were compared with the calculated results of ASSCOPS code. The main conclusions are described below. (1) It was estimated that aerosol hydrates were not formed in the test cell in the experiment, because of high gas temperatures (200degC - 300degC), but water vapor absorption by the formation of aerosol hydrates and water vapor condensation were occurred in humility measure line, because of low gas temperature (20degC - 40degC). Therefore, it was considered appropriate that measured water vapor concentration in the humidity measure line was different from the real concentration in the test cell. (2) Water vapor concentration in the test cell was assumed to be about 35,000 ppm during sodium leak, and reached to about 70,000 ppm because of water release from heated concrete (over 100degC) walls after 190 min from sodium leak started. The assumed value of about 35,000 ppm during sodium leak almost agree with assumed value from the quantity of aerosol in the humidity measure line, but no support for the value of about 70,000 ppm after 190 min could be found. Therefore, water release rate from heated concrete walls can change with their temperature history. (author)

  8. Anthropogenic contamination of a phreatic drinking water winning: 3-dimensional reactive transport modelling

    NARCIS (Netherlands)

    Griffioen, J.|info:eu-repo/dai/nl/091129265; van der Grift, B.|info:eu-repo/dai/nl/373433484; Maas, D.; van den Brink, C.|info:eu-repo/dai/nl/187443416; Zaadnoordijk, J. W.

    2003-01-01

    Groundwater is contaminated at the regional scale by agricultural activities and atmospheric deposition. A 3-D transport model was set-up for a phreatic drinking water winning, where the groundwater composition was monitored accurately. The winning is situated at an area with unconsolidated

  9. PHAST--a program for simulating ground-water flow, solute transport, and multicomponent geochemical reactions

    Science.gov (United States)

    Parkhurst, David L.; Kipp, Kenneth L.; Engesgaard, Peter; Charlton, Scott R.

    2004-01-01

    The computer program PHAST simulates multi-component, reactive solute transport in three-dimensional saturated ground-water flow systems. PHAST is a versatile ground-water flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. PHAST is applicable to the study of natural and contaminated ground-water systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock-water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, density-dependent flow, or waters with high ionic strengths. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux, and leaky conditions, as well as the special cases of rivers and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, gases, surface complexation sites, ion exchange sites, and solid solutions; and (3) kinetic reactions with rates that are a function of solution composition. The aqueous model (elements, chemical reactions, and equilibrium constants), minerals, gases, exchangers, surfaces, and rate expressions may be defined or modified by the user. A number of options are available to save results of simulations to output files. The data may be saved in three formats: a format suitable for viewing with a text editor; a

  10. Criticality benchmark guide for light-water-reactor fuel in transportation and storage packages

    International Nuclear Information System (INIS)

    Lichtenwalter, J.J.; Bowman, S.M.; DeHart, M.D.; Hopper, C.M.

    1997-03-01

    This report is designed as a guide for performing criticality benchmark calculations for light-water-reactor (LWR) fuel applications. The guide provides documentation of 180 criticality experiments with geometries, materials, and neutron interaction characteristics representative of transportation packages containing LWR fuel or uranium oxide pellets or powder. These experiments should benefit the U.S. Nuclear Regulatory Commission (NRC) staff and licensees in validation of computational methods used in LWR fuel storage and transportation concerns. The experiments are classified by key parameters such as enrichment, water/fuel volume, hydrogen-to-fissile ratio (H/X), and lattice pitch. Groups of experiments with common features such as separator plates, shielding walls, and soluble boron are also identified. In addition, a sample validation using these experiments and a statistical analysis of the results are provided. Recommendations for selecting suitable experiments and determination of calculational bias and uncertainty are presented as part of this benchmark guide

  11. Core 2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2

    Energy Technology Data Exchange (ETDEWEB)

    Samper, J.; Juncosa, R.; Delgado, J.; Montenegro, L. [Universidad de A Coruna (Spain)

    2000-07-01

    Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)

  12. Core2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2

    International Nuclear Information System (INIS)

    Samper, J.; Juncosa, R.; Delgado, J.; Montenegro, L.

    2000-01-01

    Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)

  13. Core 2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2

    Energy Technology Data Exchange (ETDEWEB)

    Samper, J; Juncosa, R; Delgado, J; Montenegro, L [Universidad de A Coruna (Spain)

    2000-07-01

    Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)

  14. Monte Carlo electron-photon transport using GPUs as an accelerator: Results for a water-aluminum-water phantom

    Energy Technology Data Exchange (ETDEWEB)

    Su, L.; Du, X.; Liu, T.; Xu, X. G. [Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2013-07-01

    An electron-photon coupled Monte Carlo code ARCHER - Accelerated Radiation-transport Computations in Heterogeneous Environments - is being developed at Rensselaer Polytechnic Institute as a software test bed for emerging heterogeneous high performance computers that utilize accelerators such as GPUs. In this paper, the preliminary results of code development and testing are presented. The electron transport in media was modeled using the class-II condensed history method. The electron energy considered ranges from a few hundred keV to 30 MeV. Moller scattering and bremsstrahlung processes above a preset energy were explicitly modeled. Energy loss below that threshold was accounted for using the Continuously Slowing Down Approximation (CSDA). Photon transport was dealt with using the delta tracking method. Photoelectric effect, Compton scattering and pair production were modeled. Voxelised geometry was supported. A serial ARHCHER-CPU was first written in C++. The code was then ported to the GPU platform using CUDA C. The hardware involved a desktop PC with an Intel Xeon X5660 CPU and six NVIDIA Tesla M2090 GPUs. ARHCHER was tested for a case of 20 MeV electron beam incident perpendicularly on a water-aluminum-water phantom. The depth and lateral dose profiles were found to agree with results obtained from well tested MC codes. Using six GPU cards, 6x10{sup 6} histories of electrons were simulated within 2 seconds. In comparison, the same case running the EGSnrc and MCNPX codes required 1645 seconds and 9213 seconds, respectively, on a CPU with a single core used. (authors)

  15. Hydrology in Lichens: How Biological Architecture is Used to Regulate Water Access to Support Drought Resilience and Nutrient Transport

    Science.gov (United States)

    Ten Veldhuis, M. C.; Dismukes, G. C.; Ananyev, G.

    2017-12-01

    Lichens are Nature's masters at controlling water and air flux within a symbiotic organism comprised of an algal photobiont and its fungal host. Here we investigated the equilibrium partitioning and kinetic transport of water between the symbionts in the lichen flavoparmelia species. Lichens have developed a unique strategy to recover after deep dehydration, that otherwise would kill the majority of free living phototrophs. By measuring both kinetics of water content and chlorophyll fluorescence emission (indicative of algal charge separation and water oxidation) during dehydration, we identified 3 distinct temporal stages and mapped these to physical zones by confocal microscopy using a combination of hydro-philic/-phobic dyes. Below a critical level of water content, controlled by the greater hydrophilicity of fungal tissues, algal photosynthesis rapidly turns off. We show that the distinct stages in dehydration mirror the 3D architecture of lichen tissue (the thallus). We provide evidence that control of water distribution is achieved by capillary forces within ordered zones of physical space possessing different hydro-phobic/-philic characteristics. This strategy ensures that photosynthetic capacity is protected from and can quickly recover after desiccation. The fungal host controls the onset and extent of photosynthesis in the enslaved alga, presumably to ensure transport of algal derived sugars and oxygen (O2) to the fungal host only when sufficient water exists for transport. Lichen architecture provides Nature's solution to gas-water transport that is self-regulated by humidity. It offers novel lessons for designing practical devices such as fuel cell membranes and dialysis membranes. Supported by the US Dept of Energy, Basic Energy Sciences, Physical Biosciences Division.

  16. PATTERNS UTILIZED IN THE SIMULATION OF UNDERGROUND WATER FLOW AND THE TRANSPORTATION OF POLLUTANTS IN THE BAHLUI DRAINAGE BASIN

    Directory of Open Access Journals (Sweden)

    Ionut Minea

    2012-03-01

    Full Text Available ABSTRACT. – Patterns utilized in the simulation of underground water flow and the transportation of pollutants in the Bahlui drainage basin. In the actual context of accelerate economic development, the excessive exploatation of water resources from the underground and the contamination of these with different water pollutants has become a major problem which has enetered the attention of many researchers. For the evaluation of an underground water flow and pollutants transport sistem we have chosen the package of programs MODFLOW which includes a whole series of applications,such as MOC3D, MT3D, MT3DMS, PEST, UCODE, PMPATH, which allow simulations and multiple recalibrations of the capacity of recharging of the aquifers, the flowing of the water towards wells and drillings the transport of a pollutant agent in the underground or the evaluation of the exchange of water between the hidrographic network and aquifers. The sistem targets both the evaluation of the modelation of the underground flowing and the simulation of a punctual polluation of the canvas of groundwater scenery, in the meadow of the river Bahlui, west from Letcani village.

  17. Water transport by Na+-coupled cotransporters of glucose (SGLT1) and of iodide (NIS). The dependence of substrate size studied at high resolution

    DEFF Research Database (Denmark)

    Zeuthen, Thomas; Belhage, Bo; Zeuthen, Emil

    2005-01-01

    and osmosis at the membrane with diffusion in the cytoplasm. The combination of high resolution measurements and precise modelling showed that water transport across the membrane can be explained by cotransport of water in the membrane proteins and that intracellular unstirred layers effects are minute.......The relation between substrate and water transport was studied in Na+-coupled cotransporters of glucose (SGLT1) and of iodide (NIS) expressed in Xenopus oocytes. The water transport was monitored from changes in oocyte volume at a resolution of 20 pl, more than one order of magnitude better than...... previous investigations. The rate of cotransport was monitored as the clamp current obtained from two-electrode voltage clamp. The high resolution data demonstrated a fixed ratio between the turn-over of the cotransporter and the rate of water transport. This applied to experiments in which the rate...

  18. Transport of jundiá Rhamdia quelen juveniles at different loading densities: water quality and blood parameters

    Directory of Open Access Journals (Sweden)

    Paulo César Falanghe Carneiro

    Full Text Available Fish transportation is a common practice on fish farms and is considered to be a stressor that could negatively affect fish health. The objective of this study was to evaluate several physiological responses of stress in jundiá caused by transport at different loading densities. Jundiá juveniles were placed in plastic bags on a mechanical transport simulator for four hours at four different loading densities (75, 150, 250 and 350 g L-1 and then transferred to sixteen 80-L plastic boxes for 96 hours after transport. Water samples were collected before and after transport to measure dissolved oxygen, temperature, pH and ammonia levels. Blood samples were taken at departure and arrival, as well as at 24 and 96 hours after transport to monitor cortisol, glucose, ammonia, chloride and hematocrit levels. Water ammonia levels were found to increase gradually as loading densities increased. Plasma ammonia was higher after transport in fish from all treatments. Compared to initial values, substantial increases in plasma cortisol and ammonia levels were detected mainly in those fish submitted to the highest loading density. Blood glucose appeared to be positively influenced by the increase of transport densities. No statistical differences were observed in any of the other blood parameters. The costs in fish culture, as in other animal production systems, must be minimized and fish producers depend on optimal techniques to ensure better profit. Therefore, based on fish survival and the physiological indicators determined in the present study, especially during recovery, the best density at which to transport jundiá in plastic bags for four hours is about 350 g/L.

  19. Solute transport in coupled inland-coastal water systems. General conceptualisation and application to Forsmark

    International Nuclear Information System (INIS)

    Jarsjoe, Jerker; Destouni, Georgia; Persson, Klas; Prieto, Carmen

    2007-12-01

    We formulate a general theoretical conceptualisation of solute transport from inland sources to downstream recipients, considering main recipient load contributions from all different nutrient and pollutant sources that may exist within any catchment. Since the conceptualisation is model independent, its main hydrological factors and mass delivery factors can be quantified on the basis of inputs to and outputs from any considered analytical or numerical model. Some of the conceptually considered source contribution and transport pathway combinations are however commonly neglected in catchment-scale solute transport and attenuation modelling, in particular those related to subsurface sources, diffuse sources at the land surface and direct groundwater transport into the recipient. The conceptual framework provides a possible tool for clarification of underlying and often implicit model assumptions, which can be useful for e.g. inter-model comparisons. In order to further clarify and explain research questions that may be of particular importance for transport pathways from deep groundwater surrounding a repository, we concretise and interpret some selected transport scenarios for model conditions in the Forsmark area. Possible uncertainties in coastal discharge predictions, related to uncertain spatial variation of evapotranspiration within the catchment, were shown to be small for the relatively large, focused surface water discharges from land to sea, because local differences were averaged out along the length of the main water flow paths. In contrast, local flux values within the diffuse groundwater flow field from land to sea are more uncertain, although estimates of mean values and total sums of submarine groundwater discharge (SGD) along some considerable coastline length may be robust. The present results show that 80% to 90% of the total coastal discharge of Forsmark occurred through focused flows in visible streams, whereas the remaining 10% to 20% was

  20. Sublimation and transport of water from the north residual polar cap on Mars

    Science.gov (United States)

    Haberle, Robert M.; Jakosky, Bruce M.

    1990-01-01

    The possible role of the north residual cap in the current Martian water cycle was examined using models to assess the ability of the cap to supply water to the atmosphere and the ability of the atmospheric circulation to transport it out of the polar regions to low northern latitudes. Results indicate that rather extreme circumstances would be required for the cap to provide all of the observed increase in atmospheric water, such as a combination of high surface winds, low cap emissivities, or substantial evaporation from dark material. But even if these conditions could be met, the high-latitude circulation is too localized in scale to move much water vapor out of the polar environment. Both the present calculations and the data from the Viking's Mars Atmospheric Water Detection Experiment show that about two thirds of the water appearing in the Martian northern hemisphere during summer must be supplied by other sources. It is suggested that the additional source is water desorbing from the nonpolar regolith.

  1. The function of 7D-cadherins: a mathematical model predicts physiological importance for water transport through simple epithelia

    Directory of Open Access Journals (Sweden)

    Walcher Sebastian

    2011-06-01

    Full Text Available Abstract Background 7D-cadherins like LI-cadherin are cell adhesion molecules and represent exceptional members of the cadherin superfamily. Although LI-cadherin was shown to act as a functional Ca2+-dependent adhesion molecule, linking neighboring cells together, and to be dysregulated in a variety of diseases, the physiological role is still enigmatic. Interestingly 7D-cadherins occur only in the lateral plasma membranes of cells from epithelia of water transporting tissues like the gut, the liver or the kidney. Furthermore LI-cadherin was shown to exhibit a highly cooperative Ca2+-dependency of the binding activity. Thus it is tempting to assume that LI-cadherin regulates the water transport through the epithelium in a passive fashion by changing its binding activity in dependence on the extracellular Ca2+. Results We developed a simple mathematical model describing the epithelial lining of a lumen with a content of variable osmolarity covering an interstitium of constant osmolarity. The width of the lateral intercellular cleft was found to influence the water transport significantly. In the case of hypertonic luminal content a narrow cleft is necessary to further increase concentration of the luminal content. If the cleft is too wide, the water flux will change direction and water is transported into the lumen. Electron microscopic images show that in fact areas of the gut can be found where the lateral intercellular cleft is narrow throughout the lateral cell border whereas in other areas the lateral intercellular cleft is widened. Conclusions Our simple model clearly predicts that changes of the width of the lateral intercellular cleft can regulate the direction and efficiency of water transport through a simple epithelium. In a narrow cleft the cells can increase the concentration of osmotic active substances easily by active transport whereas if the cleft is wide, friction is reduced but the cells can hardly build up high osmotic

  2. Methane transport and emissions from soil as affected by water table and vascular plants.

    Science.gov (United States)

    Bhullar, Gurbir S; Iravani, Majid; Edwards, Peter J; Olde Venterink, Harry

    2013-09-08

    The important greenhouse gas (GHG) methane is produced naturally in anaerobic wetland soils. By affecting the production, oxidation and transport of methane to the atmosphere, plants have a major influence upon the quantities emitted by wetlands. Different species and functional plant groups have been shown to affect these processes differently, but our knowledge about how these effects are influenced by abiotic factors such as water regime and temperature remains limited. Here we present a mesocosm experiment comparing eight plant species for their effects on internal transport and overall emissions of methane under contrasting hydrological conditions. To quantify how much methane was transported internally through plants (the chimney effect), we blocked diffusion from the soil surface with an agar seal. We found that graminoids caused higher methane emissions than forbs, although the emissions from mesocosms with different species were either lower than or comparable to those from control mesocosms with no plant (i.e. bare soil). Species with a relatively greater root volume and a larger biomass exhibited a larger chimney effect, though overall methane emissions were negatively related to plant biomass. Emissions were also reduced by lowering the water table. We conclude that plant species (and functional groups) vary in the degree to which they transport methane to the atmosphere. However, a plant with a high capacity to transport methane does not necessarily emit more methane, as it may also cause more rhizosphere oxidation of methane. A shift in plant species composition from graminoids to forbs and/or from low to high productive species may lead to reduction of methane emissions.

  3. Evaluation of the radiological risk resulting from road transportation of tritiated water

    International Nuclear Information System (INIS)

    Menossi, C.A.; Segado, R.; Reyes, R.

    1983-01-01

    A probability model for the evaluation of the individual radiological risk resulting from road transportation of tritiated water in 200-liter drums is presented. In order to evaluate such risk, an evaluation must be made of the probability for an individual to be involved in the consequences of a radiological transport accident, to incur a given dose and to suffer deleterious effects resulting from the dose incurred. With the purpose of quantifying the importance of accidents, a severity level classification was adopted as a function of the fraction of liquid volume spilled as a result of the accident. Considering the above-mentioned severity classification and the transported volume, the volume and the spill area are implied, while the soil characteristics are taken into account. By evaluating the spill characteristics, the average meteorological conditions in the area under analysis and the activity concentration of the transported liquid, the activity concentration values for tritium in air may be estimated, thus allowing calculation of the effective dose equivalent to be incurred by the individual who is most exposed to the consequences of an associated event. As a result of the summarized analysis above, a value of the individual risk per unit of activity concentration is obtained for tritium and for a given volume of transported liquid. 8 references

  4. A New Scheme for Considering Soil Water-Heat Transport Coupling Based on Community Land Model: Model Description and Preliminary Validation

    Science.gov (United States)

    Wang, Chenghai; Yang, Kai

    2018-04-01

    Land surface models (LSMs) have developed significantly over the past few decades, with the result that most LSMs can generally reproduce the characteristics of the land surface. However, LSMs fail to reproduce some details of soil water and heat transport during seasonal transition periods because they neglect the effects of interactions between water movement and heat transfer in the soil. Such effects are critical for a complete understanding of water-heat transport within a soil thermohydraulic regime. In this study, a fully coupled water-heat transport scheme (FCS) is incorporated into the Community Land Model (version 4.5) to replaces its original isothermal scheme, which is more complete in theory. Observational data from five sites are used to validate the performance of the FCS. The simulation results at both single-point and global scale show that the FCS improved the simulation of soil moisture and temperature. FCS better reproduced the characteristics of drier and colder surface layers in arid regions by considering the diffusion of soil water vapor, which is a nonnegligible process in soil, especially for soil surface layers, while its effects in cold regions are generally inverse. It also accounted for the sensible heat fluxes caused by liquid water flow, which can contribute to heat transfer in both surface and deep layers. The FCS affects the estimation of surface sensible heat (SH) and latent heat (LH) and provides the details of soil heat and water transportation, which benefits to understand the inner physical process of soil water-heat migration.

  5. The role of the complete Coriolis force in cross-equatorial transport of the Antarctic Bottom Water

    Science.gov (United States)

    Stewart, Andrew; Dellar, Paul

    2010-05-01

    We investigate the equatorial crossing of the Antarctic Bottom Water using a shallow water model that includes the complete Coriolis force. Most theoretical models of the atmosphere and ocean neglect the component of the Coriolis force associated with the horizontal component of the Earth's rotation vector, the so-called traditional approximation. This approximation is typically justified on the basis that ratio of the ocean depth to the Rossby radius of deformation is negligibly small, H-Rd ≪ 1. However, the steep topography and weak stratification in the abyssal ocean magnify the role of the non-traditional component of the Coriolis force. This is most pronounced in equatorial regions, where the traditional component of the Coriolis force is weakest and the non-traditional component is strongest. The inclusion of the complete Coriolis force gives rise to a range of very long sub-inertial waves, whose frequencies lie below the inertial frequency, in the two-layer shallow water equations. These waves have a dramatically different structure to their traditional counterparts, particularly when the stratification is weak. We focus on the flow of the Antarctic Bottom Water from the Brazil Basin in the western South Atlantic to the Guiana Basin in the western North Atlantic. In this region, the current traverses a deep channel directed westwards and very slightly northwards across the equator. Previous attempts to model this flow have struggled to explain why the cross-equatorial transport is so high, with around 2.0-2.2 Sv exiting at the northern end of the channel. We present analytical and numerical solutions of the non-traditional shallow water equations for the cross-equatorial flow of the Antarctic Bottom Water. We obtain analytical solutions by considering the steady-state flow of a single layer of shallow water through a northwesterly channel with a simple geometry. We assume zero potential vorticity, as it may be shown that fluid whose potential vorticity q

  6. Chemical mass transport between fluid fine tailings and the overlying water cover of an oil sands end pit lake

    Science.gov (United States)

    Dompierre, Kathryn A.; Barbour, S. Lee; North, Rebecca L.; Carey, Sean K.; Lindsay, Matthew B. J.

    2017-06-01

    Fluid fine tailings (FFT) are a principal by-product of the bitumen extraction process at oil sands mines. Base Mine Lake (BML)—the first full-scale demonstration oil sands end pit lake (EPL)—contains approximately 1.9 × 108 m3 of FFT stored under a water cover within a decommissioned mine pit. Chemical mass transfer from the FFT to the water cover can occur via two key processes: (1) advection-dispersion driven by tailings settlement; and (2) FFT disturbance due to fluid movement in the water cover. Dissolved chloride (Cl) was used to evaluate the water cover mass balance and to track mass transport within the underlying FFT based on field sampling and numerical modeling. Results indicated that FFT was the dominant Cl source to the water cover and that the FFT is exhibiting a transient advection-dispersion mass transport regime with intermittent disturbance near the FFT-water interface. The advective pore water flux was estimated by the mass balance to be 0.002 m3 m-2 d-1, which represents 0.73 m of FFT settlement per year. However, the FFT pore water Cl concentrations and corresponding mass transport simulations indicated that advection rates and disturbance depths vary between sample locations. The disturbance depth was estimated to vary with location between 0.75 and 0.95 m. This investigation provides valuable insight for assessing the geochemical evolution of the water cover and performance of EPLs as an oil sands reclamation strategy.

  7. Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees

    Science.gov (United States)

    Apgaua, Deborah M. G.; Ishida, Françoise Y.; Tng, David Y. P.; Laidlaw, Melinda J.; Santos, Rubens M.; Rumman, Rizwana; Eamus, Derek; Holtum, Joseph A. M.; Laurance, Susan G. W.

    2015-01-01

    Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees). We characterised the species’ hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios. PMID:26087009

  8. Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees.

    Directory of Open Access Journals (Sweden)

    Deborah M G Apgaua

    Full Text Available Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees. We characterised the species' hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios.

  9. Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees.

    Science.gov (United States)

    Apgaua, Deborah M G; Ishida, Françoise Y; Tng, David Y P; Laidlaw, Melinda J; Santos, Rubens M; Rumman, Rizwana; Eamus, Derek; Holtum, Joseph A M; Laurance, Susan G W

    2015-01-01

    Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees). We characterised the species' hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios.

  10. Letter from A & R Transport about Section 308 of the Clean Water Act Discharge of Perfluorinated Compounds

    Science.gov (United States)

    January 16, 2009 letter from Kenneth E. Pate, VP of Safety and Risk Management of A & R Transport, Inc. to EPA Clean Water Enforcement Branch, about an Information Request about the Section 308 of the Clean Water Act, discharge of pefluorinated compounds.

  11. A suggested revision to the specific activity limit for tritiated water transported as LSA-II

    International Nuclear Information System (INIS)

    Nandakumar, A.N.

    2003-01-01

    Tritiated water of specific activity not greater than 0.8 TBq L -1 is classified as LSA-II. This paper demonstrates by some simple calculations that the dose that may result from an accident involving tritiated water of this specific activity is very low and suggests that even if the specific activity limit of tritiated water which may be transported as LSA-II is raised above 0.8 TBq kg -1 , the resulting dose in accident conditions would not be unacceptable. (author)

  12. Effects of coal gangue content on water movement and solute transport in a China loess plateau soil

    Energy Technology Data Exchange (ETDEWEB)

    Beibei, Zhou; Quanjiu, Wang [Institute of Water Resources and Hydro-electric Engineering, Xi' an University of Technology, Xi' an (China); State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A and F University, Yangling, Shaanxi (China); Ming' an, Shao; Mingxia, Wen [State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A and F University, Yangling, Shaanxi (China); College of Resources and Environment, Northwest A and F University, Yangling, Shaanxi (China); Horton, Robert [Department of Agronomy, Iowa State University, Ames, Iowa (United States)

    2010-11-15

    The mining industry has grown strongly in China in recent decades, resulting in large amounts of coal gangues, which cause water and soil pollution, soil erosion, and various other environmental problems. They are often used in reclamation projects in attempts to restore land damaged by mining, hence they are frequently present (in widely varying proportions) in the topsoil in areas around mines. Their presence can strongly affect key soil variables, including its bulk density, structure, water retention, water movement, and solute transport rates. In the study presented here, the effects of gangue contents on infiltration, saturated hydraulic conductivity, and solute transport parameters of a Chinese Loess plateau soil were examined. The results show that infiltration rates and saturated hydraulic conductivity decreased with increasing gangue content. The Peck-Watson equation modeled these relationships well, but Bouwer-Rice equations provided poorer matches with the acquired data. Cumulative infiltration over time was described well by both the Philip equation and Kostiakov equation. Both the simplified convection-dispersion equation and a two-region model described the solute transport processes well. In addition, the dispersion increased, while both the Peclet number and mobile water fraction decreased, with increases in gangue contents. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Solute transport in coupled inland-coastal water systems. General conceptualisation and application to Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Jarsjoe, Jerker; Destouni, Georgia; Persson, Klas; Prieto, Carmen (Dept. of Physical Geography, Quaternary Geology, Stockholm Univ., Stockholm (Sweden))

    2007-12-15

    We formulate a general theoretical conceptualisation of solute transport from inland sources to downstream recipients, considering main recipient load contributions from all different nutrient and pollutant sources that may exist within any catchment. Since the conceptualisation is model independent, its main hydrological factors and mass delivery factors can be quantified on the basis of inputs to and outputs from any considered analytical or numerical model. Some of the conceptually considered source contribution and transport pathway combinations are however commonly neglected in catchment-scale solute transport and attenuation modelling, in particular those related to subsurface sources, diffuse sources at the land surface and direct groundwater transport into the recipient. The conceptual framework provides a possible tool for clarification of underlying and often implicit model assumptions, which can be useful for e.g. inter-model comparisons. In order to further clarify and explain research questions that may be of particular importance for transport pathways from deep groundwater surrounding a repository, we concretise and interpret some selected transport scenarios for model conditions in the Forsmark area. Possible uncertainties in coastal discharge predictions, related to uncertain spatial variation of evapotranspiration within the catchment, were shown to be small for the relatively large, focused surface water discharges from land to sea, because local differences were averaged out along the length of the main water flow paths. In contrast, local flux values within the diffuse groundwater flow field from land to sea are more uncertain, although estimates of mean values and total sums of submarine groundwater discharge (SGD) along some considerable coastline length may be robust. The present results show that 80% to 90% of the total coastal discharge of Forsmark occurred through focused flows in visible streams, whereas the remaining 10% to 20% was

  14. Terminal zone glacial sediment transfer at a temperate overdeepened glacier system

    Science.gov (United States)

    Swift, D. A.; Cook, S. J.; Graham, D. J.; Midgley, N. G.; Fallick, A. E.; Storrar, R.; Toubes Rodrigo, M.; Evans, D. J. A.

    2018-01-01

    Continuity of sediment transfer through glacial systems is essential to maintain subglacial bedrock erosion, yet transfer at temperate glaciers with overdeepened beds, where subglacial fluvial sediment transport should be greatly limited by adverse slopes, remains poorly understood. Complex multiple transfer processes in temperate overdeepened systems has been indicated by the presence of large frontal moraine systems, supraglacial debris of mixed transport origin, thick basal ice sequences, and englacial thrusts and eskers. At Svínafellsjökull, thrusts comprising decimetre-thick debris-rich bands of stratified facies ice of basal origin, with a coarser size distribution and higher clast content than that observed in basal ice layers, contribute substantially to the transfer of subglacial material in the terminal zone. Entrainment and transfer of material occurs by simple shear along the upper surface of bands and by strain-induced deformation of stratified and firnified glacier ice below. Thrust material includes rounded and well-rounded clasts that are also striated, indicating that fluvial bedload is deposited as subglacial channels approach the overdeepening and then entrained along thrusts. Substantial transfer also occurs within basal ice, with facies type and debris content dependent on the hydrological connectedness of the adverse slope. A process model of transfer at glaciers with terminal overdeepenings is proposed, in which the geometry of the overdeepening influences spatial patterns of ice deformation, hydrology, and basal ice formation. We conclude that the significance of thrusting in maintaining sediment transfer continuity has likely been overlooked by glacier sediment budgets and glacial landscape evolution studies.

  15. [Prokaryotic community of subglacial bottom sediments of Antarctic Lake Untersee: detection by cultural and direct microscopic techniques].

    Science.gov (United States)

    Muliukin, A L; Demkina, E V; Manucharova, N A; Akimov, V N; Andersen, D; McKay, C; Gal'chenko, V F

    2014-01-01

    The heterotrophic mesophilic component was studied in microbial communities of the samples of frozen regolith collected from the glacier near Lake Untersee collected in 2011 during the joint Russian-American expedition to central Dronning Maud Land (Eastern Antarctica). Cultural techniques revealed high bacterial numbers in the samples. For enumeration of viable cells, the most probable numbers (MPN) method proved more efficient than plating on agar media. Fluorescent in situ hybridization with the relevant oligonucleotide probes revealed members of the groups Eubacteria (Actinobacteria, Firmicutes) and Archaea. Application of the methods of cell resuscitation, such as the use of diluted media and prevention of oxidative stress, did not result in a significant increase in the numbers of viable cells retrieved form subglacial sediment samples. Our previous investigations demonstrated the necessity for special procedures for efficient reactivation of the cells from microbial communities of preserved fossil soil and permafrost samples collected in the Arctic zone. The differences in response to the special resuscitation procedures may reflect the differences in the physiological and morphological state of bacterial cells in microbial communities subject to continuous or periodic low temperatures and dehydration.

  16. Fate and Transport of Nutrients in Groundwater and Surface Water in an Urban Slum Catchment Kampala, Uganda

    NARCIS (Netherlands)

    Nyenje, P.

    2014-01-01

    This study investigates the generation, transport and fate of sanitation-related nutrients in groundwater and surface water in an urban slum area in sub-Saharan Africa. In excess, nutrients can cause eutrophication of downstream water bodies. The study argues that nitrogen-containing rains and

  17. Transport and transfer rates in the waters of the continental shelf. Annual report

    International Nuclear Information System (INIS)

    Biscaye, P.E.; Broecker, W.S.; Feely, H.W.; Gerard, R.D.

    1976-04-01

    The report is to the Energy Research and Development Administration on accomplishments of the Lamont-Doherty Geological Observatory geochemistry and physical oceanography groups during the 1975-1976 funding period on grant E(11-1)2185. Goals are to obtain detailed, quantitative knowledge of the rates of mixing within coastal waters of the New York Bight and across the continental slope and the exchange of water masses and species transported within them between shelf and Atlantic Ocean waters. The research is aimed at understanding the chemical, physical, and biological processes which control the origin, dispersal, and fate of particulate matter and trace metals, and to ultimately model the impact of energy related pollutants on the continental shelf

  18. Holocene climate and fjord glaciations in Northeast Greenland: implications for IRD deposition in the North Atlantic

    DEFF Research Database (Denmark)

    Reeh, Niels

    2004-01-01

    been released by intensive sub-glacial melting during the long stay of the ice-islands in coastal waters. The Holocene glacial geological record from Northeast Greenland is compared to the record of ice rafted debris (IRD) from North Atlantic deep-sea sediment cores. The comparison shows that transport...... by icebergs in the form of basal debris is unlikely to be the dominant transport mechanism of IRD to deposition sites in the North Atlantic during the Holocene. The ice rafted debris is more likely to be carried at the surface of sea- (or glacier) ice. This supports the result of previous studies by other...... workers that changes of atmospheric and ocean-surface circulation and temperature are the likely causes of Holocene cycles in IRD concentration in North Atlantic deep-sea sediments....

  19. Coordination and transport of water and carbohydrates in the coupled soil-root-xylem-phloem leaf system

    Science.gov (United States)

    Katul, Gabriel; Huang, Cheng-Wei

    2017-04-01

    In response to varying environmental conditions, stomatal pores act as biological valves that dynamically adjust their size thereby determining the rate of CO2 assimilation and water loss (i.e., transpiration) to the atmosphere. Although the significance of this biotic control on gas exchange is rarely disputed, representing parsimoniously all the underlying mechanisms responsible for stomatal kinetics remain a subject of some debate. It has been conjectured that stomatal control in seed plants (i.e., angiosperm and gymnosperm) represents a compromise between biochemical demand for CO2 and prevention of excessive water loss. This view has been amended at the whole-plant level, where xylem hydraulics and sucrose transport efficiency in phloem appear to impose additional constraints on gas exchange. If such additional constraints impact stomatal opening and closure, then seed plants may have evolved coordinated photosynthetic-hydraulic-sugar transporting machinery that confers some competitive advantages in fluctuating environmental conditions. Thus, a stomatal optimization model that explicitly considers xylem hydraulics and maximum sucrose transport is developed to explore this coordination in the leaf-xylem-phloem system. The model is then applied to progressive drought conditions. The main findings from the model calculations are that (1) the predicted stomatal conductance from the conventional stomatal optimization theory at the leaf and the newly proposed models converge, suggesting a tight coordination in the leaf-xylem-phloem system; (2) stomatal control is mainly limited by the water supply function of the soil-xylem hydraulic system especially when the water flux through the transpiration stream is significantly larger than water exchange between xylem and phloem; (3) thus, xylem limitation imposed on the supply function can be used to differentiate species with different water use strategy across the spectrum of isohydric to anisohydric behavior.

  20. Simulations of Ground-Water Flow, Transport, Age, and Particle Tracking near York, Nebraska, for a Study of Transport of Anthropogenic and Natural Contaminants (TANC) to Public-Supply Wells

    Science.gov (United States)

    Clark, Brian R.; Landon, Matthew K.; Kauffman, Leon J.; Hornberger, George Z.

    2008-01-01

    Contamination of public-supply wells has resulted in public-health threats and negative economic effects for communities that must treat contaminated water or find alternative water supplies. To investigate factors controlling vulnerability of public-supply wells to anthropogenic and natural contaminants using consistent and systematic data collected in a variety of principal aquifer settings in the United States, a study of Transport of Anthropogenic and Natural Contaminants to public-supply wells was begun in 2001 as part of the U.S. Geological Survey National Water-Quality Assessment Program. The area simulated by the ground-water flow model described in this report was selected for a study of processes influencing contaminant distribution and transport along the direction of ground-water flow towards a public-supply well in southeastern York, Nebraska. Ground-water flow is simulated for a 60-year period from September 1, 1944, to August 31, 2004. Steady-state conditions are simulated prior to September 1, 1944, and represent conditions prior to use of ground water for irrigation. Irrigation, municipal, and industrial wells were simulated using the Multi-Node Well package of the modular three-dimensional ground-water flow model code, MODFLOW-2000, which allows simulation of flow and solutes through wells that are simulated in multiple nodes or layers. Ground-water flow, age, and transport of selected tracers were simulated using the Ground-Water Transport process of MODFLOW-2000. Simulated ground-water age was compared to interpreted ground-water age in six monitoring wells in the unconfined aquifer. The tracer chlorofluorocarbon-11 was simulated directly using Ground-Water Transport for comparison with concentrations measured in six monitoring wells and one public supply well screened in the upper confined aquifer. Three alternative model simulations indicate that simulation results are highly sensitive to the distribution of multilayer well bores where leakage

  1. Evaluation of potential sources and transport mechanisms of fecal indicator bacteria to beach water, Murphy Park Beach, Door County, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Corsi, Steven R.; McDermott, Colleen; Kleinheinz, Gregory; Fogarty, Lisa R.; Haack, Sheridan K.; Johnson, Heather E.

    2013-01-01

    Fecal Indicator Bacteria (FIB) concentrations in beach water have been used for many years as a criterion for closing beaches due to potential health concerns. Yet, current understanding of sources and transport mechanisms that drive FIB occurrence remains insufficient for accurate prediction of closures at many beaches. Murphy Park Beach, a relatively pristine beach on Green Bay in Door County, Wis., was selected for a study to evaluate FIB sources and transport mechanisms. Although the relatively pristine nature of the beach yielded no detection of pathogenic bacterial genes and relatively low FIB concentrations during the study period compared with other Great Lakes Beaches, its selection limited the number of confounding FIB sources and associated transport mechanisms. The primary sources of FIB appear to be internal to the beach rather than external sources such as rivers, storm sewer outfalls, and industrial discharges. Three potential FIB sources were identified: sand, swash-zone groundwater, and Cladophora mats. Modest correlations between FIB concentrations in these potential source reservoirs and FIB concentrations at the beach from the same day illustrate the importance of understanding transport mechanisms between FIB sources and the water column. One likely mechanism for transport and dispersion of FIB from sand and Cladophora sources appears to be agitation of Cladophora mats and erosion of beach sand due to storm activity, as inferred from storm indicators including turbidity, wave height, current speed, wind speed, sky visibility, 24-hour precipitation, and suspended particulate concentration. FIB concentrations in beach water had a statistically significant relation (p-value ‹0.05) with the magnitude of these storm indicators. In addition, transport of FIB in swash-zone groundwater into beach water appears to be driven by groundwater recharge associated with multiday precipitation and corresponding increased swash-zone groundwater discharge at

  2. Mathematical modelling of water and gas transport in layered soil covers for coal ash deposits

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, A; Lindgren, M [Kemakta Consultants Co, Stockholm (SE)

    1990-12-17

    In the present work the dry deposition alternative is investigated. In particular the design of soil covers is treated theoretically using mathematical models. The soil cover should primarily act as a barrier against infiltrating water. This is done by having soil cover materials with low permeabilities and sloping covers thereby diverting the infiltrating water in the lateral direction. An important design aspect is that overflow should be avoided since this may cause erosional problems. Thus the design of the cover should allow for lateral water flow within the cover. In the present work we use the computer code TRUST for calculating the flow rates and the moisture contents in two layer covers (till on top of clay) for varying conditions. The calculations so far show that the hydraulic conductivity of the clay layer should be smaller than 10{sup -8} m/s. However, for the simulated longer covers (50 m) a lower hydraulic conductivity gives overflow indicating that better lateral drainage must be provided for. This can be done by increasing the thickness or hydraulic conductivity of the till layer. Simulations for different slopes give little impact, while the hydraulic conductivity of the clay layer is of major importance. Gas transport through the soil cover may be of importance if the waste contains pyrite. In the presence of oxygen and water, pyrite is oxidized producing sulphuric acid. The lowered pH will accelerate the leaching of several heavy metals. The transport rate of gas through a porous material is very sensitive to the water content, decreasing rapidly with increasing water content. In the present work a model, where the unsaturated conditions are accounted for, is outlined. A previously developed method for calculating oxygen transport and oxidation rate of pyrite in connection with mine wastes is generalized from 1D to 2D. A sample calculation illustrates the feasibility of the method. (au) (43 refs.).

  3. Forms of trace arsenic, cesium, cadmium, and lead transported into river water for the irrigation of Japanese paddy rice fields

    Science.gov (United States)

    Nakaya, Shinji; Chi, Hai; Muroda, Kengo; Masuda, Harue

    2018-06-01

    In this study, we focus on the behavior of geogenic, toxic trace elements, particularly As, Cs, Cd, and Pb, during their transportation in two rivers for irrigation commonly used in monsoon Asia; one river originates from an active volcano, Mt. Asama, and the other originates from a currently inactive volcano, Yatsugatake Mountains in Nagano, Japan. These rivers were investigated to understand the role of river water as a pollutant of rice and other aquatic plants (via irrigation) and aquatic animals. The results indicated that the behavior of toxic trace elements in river water are likely controlled by their interactions with particulate Fe, Al, and Ti compounds. The majority of Pb and Cd is transported as particulate matter with Fe, Al, and Ti, while the majority of As is transported in the dissolved form, predominantly as arsenate, with low abundance of particulate matter. Cs is transported either as the dissolved form or as particulate matter in both rivers. The investigated elements are transported in the rivers as particulate and dissolved forms, and the ratio of these forms is controlled by the pH and presence of particulate Fe, Al, and Ti phases in the river water. With respect to Cs in both rivers, the parameter governing the concentration and transportation of Cs, in the bimodal form (i.e., particulate and dissolved forms), through the river possibly shifts from sorption to pH by particulate Fe-Al-Ti, according to the abrupt increase in the concentration of Cs in the river. The chemical attraction of particulate Fe-Al-Ti for Cs is weaker than that for Pb and Cd, indicating that the lower electronegativity of Cs weakens the chemical attraction on a colloid for the competitive sorption with the other trace elements. The different relationships between As and Fe in the river and in the irrigation water and soil water, as well as those in paddy rice, suggested that As in paddy rice is not directly derived from As in the irrigation water from the river under

  4. Economics of radioactive material transportation in the light-water reactor nuclear fuel cycle

    International Nuclear Information System (INIS)

    Dupree, S.A.; O'Malley, L.C.

    1980-10-01

    This report presents estimates of certain transportation costs, in 1979 dollars, associated with Light-Water Reactor (LWR) once-through and recycle fuel cycles. Shipment of fuel, high-level waste and low-level waste was considered. Costs were estimated for existing or planned transportation systems and for recommended alternate systems, based on the assumption of mature fuel cycles. The annual radioactive material transportation costs required to support a nominal 1000-MW(e) LWR in a once-through cycle in which spent fuel is shipped to terminal storage or disposal were found to be approx. $490,000. Analogous costs for an average reactor operating in a fuel cycle with uranium and plutonim recycle were determined to be approx. $770,000. These results assume that certain recommended design changes will occur in radioactive material shipping systems as a mature fuel cycle evolves

  5. Using a simple model for water and nitrogen transport in soil in the practical works of Horticulture

    Directory of Open Access Journals (Sweden)

    A. Lidón

    2017-08-01

    Full Text Available Simulation models for the transport of water and nitrogen in the soil are useful tools for evaluating the consequences  of  different  crop  management  practices  without  waiting  until  the  end  of  the  crop  cycle.  Particularly,  simple compartmental models for the transport of water and nitrogen are based on the solution of mass balance equations for  the  water  and  a  system  of  ordinary  differential  equations  for  the  nitrogen  cycle.  In this work, these models are used to evaluate different possible scenarios of irrigation and nitrogen fertilization in a cauliflower crop, as a practical work for the students of Horticulture course. The results show that different irrigation and fertilization strategies lead to different results for the nitrate leaching, water drainage and nitrogen uptake.

  6. Transportation cost of nuclear off-peak power for hydrogen production based on water electrolysis

    International Nuclear Information System (INIS)

    Shimizu, Saburo; Ueno, Shuichi

    2004-01-01

    The paper describes transportation cost of the nuclear off-peak power for a hydrogen production based on water electrolysis in Japan. The power could be obtainable by substituting hydropower and/or fossil fueled power supplying peak and middle demands with nuclear power. The transportation cost of the off-peak power was evaluated to be 1.42 yen/kWh when an electrolyser receives the off-peak power from a 6kV distribution wire. Marked reduction of the cost was caused by the increase of the capacity factor. (author)

  7. Modeling Water Exchange and Contaminant Transport through a Baltic Coastal Region

    International Nuclear Information System (INIS)

    Engqvist, Anders; Doeoes, Kristofer; Andrejev, Oleg

    2006-01-01

    The water exchange of the Baltic coastal zone is characterized by its seasonally varying regimes. In the safety assessment of a potential repository for spent nuclear fuel, it is important to assess the consequences of a hypothetical leak of radionuclides through the seabed into a waterborne transport phase. In particular, estimates of the associated residence times in the near-shore coastal zone are of interest. There are several methods to quantify such measures, of which three are presented here. Using the coastal location of Forsmark (Sweden) as an example, methods based on passive tracers, particle trajectories, and the average age distribution of exogenous water parcels are compared for a representative one-year cycle. Tracer-based methods can simulate diffusivity more realistically than the other methods. Trajectory-based methods can handle Lagrangian dispersion processes due to advection but neglect diffusion on the sub-grid scale. The method based on the concept of average age (AvA) of exogenous water can include all such sources simultaneously not only boundary water bodies but also various (fresh)water discharges. Due to the inclusion of sub-grid diffusion this method gives a smoother measure of the water renewal. It is shown that backward in time trajectories and AvA-times are basically equipollent methods, yielding correlated results within the limits set by the diffusivity

  8. A computerized coal-water slurry transportation model

    Energy Technology Data Exchange (ETDEWEB)

    Ljubicic, B.R.; Trostad, B. [Univ. of North Dakota, Grand Forks, ND (United States); Bukurov, Z.; Cvijanovic, P. [Univ. of Novi Sad (Yugoslavia)

    1995-12-01

    Coal-water fuel (CWF) technology has been developed to the point where full-scale commercialization is just a matter of gaining sufficient market confidence in the price stability of alternate fossil fuels. In order to generalize alternative fuel cost estimates for the desired combinations of processing and/or transportation, a great deal of flexibility is required owing to the understood lack of precision in many of the newly emerging coal technologies. Previously, decisions regarding the sequential and spatial arrangement of the various process steps were made strictly on the basis of experience, simplified analysis, and intuition. Over the last decade, computer modeling has progressed from empirically based correlation to that of intricate mechanistic analysis. Nomograms, charts, tables, and many simple rules of thumb have been made obsolete by the availability of complex computer models. Given the ability to view results graphically in real or near real time, the engineer can immediately verify, from a practical standpoint, whether the initial assumptions and inputs were indeed valid. If the feasibility of a project is being determined in the context of a lack of specific data, the ability to provide a dynamic software-based solution is crucial. Furthermore, the resulting model can be used to establish preliminary operating procedures, test control logic, and train plant/process operators. Presented in this paper is a computerized model capable of estimating the delivered cost of CWF. The model uses coal-specific values, process and transport requirements, terrain factors, and input costs to determine the final operating configuration, bill of materials, and, ultimately, the capital, operating, and unit costs.

  9. Modeling of water flow and solute transport in unsaturated heterogeneous fields

    International Nuclear Information System (INIS)

    Bresler, E.; Dagan, G.

    1982-01-01

    A comprehensive model which considers dispersive solute transport, nonsteady moisture flow regimes and complex boundary conditions is described. The main assumptions are: vertical flow; spatial variability which is associated with the saturated hydraulic conductivity K/sub s/ occurs in the horizontal plane, but is constant in the profile, and has a lognormal probability distribution function (PDF); deterministic recharge and solute concentration are applied during infiltration; the soil is at uniform water content and salt concentration prior to infiltration. The problem is to solve, for arbitrary K/sub s/, the Richards' equation of flow simultaneously with the diffusion-convection equation for salt transport, with the boundary and initial conditions appropriate to infiltration-redistribution. Once this is achieved, the expectation and variance of various quantities of interest (solute concentration, moisture content) are obtained by using the statistical averaging procedure and the given PDF of K/sub s/. Since the solution of Richards' equation for the infiltration-redistribution cycle is extremely difficult (for a given K/sub s/), an approxiate solution is derived by using the concept of piston flow type wetting fronts. Similarly, accurate numerical solutions are used as input for the same statistical averaging procedure. The stochastic model is applied to two spatially variable soils by using both accurate numerical solutions and the simplified water and salt transport models. A comparison between the results shows that the approximate simplified models lead to quite accurate values of the expectations and variances of the flow variables for the entire field. It is suggested that in spatially variable fields, stochastic modeling represents the actual flow phenomena realistically, and provides the main statistical moments by using simplified flow models which can be used with confidence in applications

  10. Effects of water stress on photosynthetic electron transport, photophosphorylation, and metabolite levels of Xanthium strumarium mesophyll cells.

    Science.gov (United States)

    Sharkey, T D; Badger, M R

    1982-12-01

    Several component processes of photosynthesis were measured in osmotically stressed mesophyll cells of Xanthium strumarium L. The ribulose-1,5-bisphosphate regeneration capacity was reduced by water stress. Photophoshorylation was sensitive to water stress but photosynthetic electron transport was unaffected by water potentials down to-40 bar (-4 MPa). The concentrations of several intermediates of the photosynthetic carbon-reduction cycle remained relatively constant and did not indicate that ATP supply was limiting photosynthesis in the water-stressed cells.

  11. A mechanism for overdeepenings of glacial valleys and fjords

    OpenAIRE

    Herman F.; Beaud F.; Champagnac J.-D.; Lemieux J.-M.; Sternai P.

    2011-01-01

    Most glacial erosion models assume that erosion rates are proportional to ice sliding velocity. While recent studies have shown that water plays a major role in modulating sliding velocities the impact it might have on erosion rates is still unclear. Here we incorporate subglacial hydrology into a glacial erosion model that is based on a sliding rule. Our results explicitly highlight that adding subglacial hydrology has profound impacts on the temporal and spatial patterns of glacial erosion....

  12. Inelastic cross-sections for electron transport in liquid water: a comparison of dielectric models

    International Nuclear Information System (INIS)

    Emfietzoglou, D.

    2003-01-01

    Various methodologies for constructing inelastic cross-sections for low-energy (<10 keV) electron transport in liquid water are presented and compared. They are all based on an optical-data model which provides the dependence on energy loss, and a dispersion algorithm which incorporates the momentum-transfer dependence. A Drude dielectric model was used to analytically represent the optical data. Various dispersion schemes were examined: the Bethe approximation, the δ-oscillator models of Ashley and Liljequist, and two forms of Ritchie's extended-Drude model. They all have been used in Monte-Carlo (MC) codes for analog electron transport in the condensed phase. Results in the form of differential and total inelastic cross-sections are presented. Where possible, comparisons with results of other studies are made. It was found that, despite the application of general constraints (e.g. sum rules), the optical model has a notable influence on the single-collision energy loss spectrum. In addition, both the shape and peak position of the total and differential cross-section distributions depend strongly on the dispersion model adopted. The work is particularly relevant to the development of event-by-event MC transport codes for liquid water, as well as, to the calculations of stopping-powers below the range of applicability of Bethe's formula

  13. Investigation of tritium transport by the water courses from the territory of Krasnoyarsk MCC

    International Nuclear Information System (INIS)

    Nosov, A.V.; Martynova, A.M.; Shabanov, V.F.; Savitskij, Yu.V.; Shishlov, A.E.; Revenko, Yu.A.

    2001-01-01

    The problem of the Enisej river contamination as a result of tritium transport from the territory of the Krasnoyarsk Mining and Chemical Complex is discussed. The results of investigations realized for the Complex sewerage waters and streams running out from its territory and flowing into the Enisej river within the controlled area are analyzed. The investigations include hydrometric measurements of water flow rate, dosimetric measurements of of water stream profiles and sampling of water, bottom sediments, tidal soils, as well as hydrobionts for radioisotope and chemical analysis. Maximum tritium concentration revealed amounts to 125 Bq/l which is not dangerous from ecological viewpoint. The conclusion on necessity of the tritium monitoring in the zone affected by the Krasnoyarsk Mining and Chemical Complex is made [ru

  14. The Modelling Analysis of the Response of Convective Transport of Energy and Water to Multiscale Surface Heterogeneity over Tibetan Plateau

    Science.gov (United States)

    SUN, G.; Hu, Z.; Ma, Y.; Ma, W.

    2017-12-01

    The land-atmospheric interactions over a heterogeneous surface is a tricky issue for accurately understanding the energy-water exchanges between land surface and atmosphere. We investigate the vertical transport of energy and water over a heterogeneous land surface in Tibetan Plateau during the evolution of the convective boundary layer using large eddy simulation (WRF_LES). The surface heterogeneity is created according to remote sensing images from high spatial resolution LandSat ETM+ images. The PBL characteristics over a heterogeneous surface are analyzed in terms of secondary circulations under different background wind conditions based on the horizontal and vertical distribution and evolution of wind. The characteristics of vertical transport of energy and heat over a heterogeneous surface are analyzed in terms of the horizontal distribution as well as temporal evolution of sensible and latent heat fluxes at different heights under different wind conditions on basis of the simulated results from WRF_LES. The characteristics of the heat and water transported into the free atmosphere from surface are also analyzed and quantified according to the simulated results from WRF_LES. The convective transport of energy and water are analyzed according to horizontal and vertical distributions of potential temperature and vapor under different background wind conditions. With the analysis based on the WRF_LES simulation, the performance of PBL schemes of mesoscale simulation (WRF_meso) is evaluated. The comparison between horizontal distribution of vertical fluxes and domain-averaged vertical fluxes of the energy and water in the free atmosphere is used to evaluate the performance of PBL schemes of WRF_meso in the simulation of vertical exchange of energy and water. This is an important variable because only the energy and water transported into free atmosphere is able to influence the regional and even global climate. This work would will be of great significance not

  15. An Assessment of Transport Property Estimation Methods for Ammonia–Water Mixtures and Their Influence on Heat Exchanger Size

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Modi, Anish; Jensen, Jonas Kjær

    2015-01-01

    Transport properties of fluids are indispensable for heat exchanger design. The methods for estimating the transport properties of ammonia–water mixtures are not well established in the literature. The few existent methods are developed from none or limited, sometimes inconsistent experimental...... of ammonia–water mixtures. Firstly, the different methods are introduced and compared at various temperatures and pressures. Secondly, their individual influence on the required heat exchanger size (surface area) is investigated. For this purpose, two case studies related to the use of the Kalina cycle...... the interpolative methods in contrast to the corresponding state methods. Nevertheless, all possible mixture transport property combinations used herein resulted in a heat exchanger size within 4.3 % difference for the flue-gas heat recovery boiler, and within 12.3 % difference for the oil-based boiler....

  16. Experimental characterization of the water transport properties of PEM fuel cells diffusion media

    Science.gov (United States)

    Ramos-Alvarado, Bladimir; Sole, Joshua D.; Hernandez-Guerrero, Abel; Ellis, Michael W.

    2012-11-01

    A full experimental characterization of the liquid water transport properties of Toray TGP-090 paper is carried out in this work. Porosity, capillary pressure curves (capillary pressure-saturation relationships), absolute permeability, and relative permeability are obtained via experimental procedures. Porosity was determined using two methods, both aimed to obtain the solid volume of the network of fibers comprising the carbon paper. Capillary pressure curves were obtained using a gas displacement porosimeter where liquid water is injected using a syringe pump and the capillary pressure is recorded using a differential pressure transducer. Absolute and relative permeability were also measured with an apparatus designed at Virginia Tech. Absolute permeability was calculated at different flow rates using nitrogen. On the other hand, relative permeability was a more complicated task to carry out giving the complexity (two-phase flow condition) of this property. All of the water transport properties of Toray TGP-090 were studied under the effects of wet-proofing (PTFE treatment) and compression. Some observations were that wet-proofing reduces the porosity of the raw material, increases the hydrophobicity (Pc-S curves), and reduces the permeability of the material. Similar effects were observed for compression, where compressed material exhibited trends similar to those of wet-proofing effects. The results presented here will allow a more accurate modeling of PEMFCs, providing an experimentally verified alternative to the assumptions frequently employed.

  17. Transport and transformation of pharmaceuticals and other contaminants of emerging concern from wastewater discharge through surface water to drinking water intake and treatment

    Science.gov (United States)

    The ubiquitous presence of pharmaceuticals, hormones, and other contaminants of emerging concern (CECs) in surface-water resources have necessitated research that better elucidates pathways of transport and transformation for these compounds from their discharged wastewater, thro...

  18. Modeling Groundwater-Surface Water Interaction and Contaminant Transport of Chlorinated Solvent Contaminated Site

    Science.gov (United States)

    Yimer Ebrahim, Girma; Jonoski, Andreja; van Griensven, Ann; Dujardin, Juliette; Baetelaan, Okke; Bronders, Jan

    2010-05-01

    Chlorinated-solvent form one of the largest groups of environmental chemicals. Their use and misuse in industry have lead to a large entry of these chemicals into the environment, resulting in widespread dissemination and oftentimes environmental contamination. Chlorinated solvent contamination of groundwater resources has been widely reported. For instance, there has been much interest in the assessment of these contaminant levels and their evolutions with time in the groundwater body below the Vilvoorde-Machelen industrial area (Belgium). The long industrial history of the area has lead to complex patterns of pollution from multiple sources and the site has been polluted to the extent that individual plumes are not definable any more. Understanding of groundwater/surface water interaction is a critical component for determining the fate of contaminant both in streams and ground water due to the fact that groundwater and surface water are in continuous dynamic interaction in the hydrologic cycle. The interaction has practical consequences in the quantity and quality of water in either system in the sense that depletion and/or contamination of one of the system will eventually affect the other one. The transition zone between a stream and its adjacent aquifer referred to as the hyporheic zone plays a critical role in governing contaminant exchange and transformation during water exchange between the two water bodies. The hyporheic zone of Zenne River ( the main receptor ) is further complicated due to the fact that the river banks are artificially trained with sheet piles along its reach extending some 12 m below the surface. This study demonstrates the use of MODFLOW, a widely used modular three-dimensional block-centred finite difference, saturated flow model for simulating the flow and direction of movement of groundwater through aquifer and stream-aquifer interaction and the use of transport model RT3D, a three-dimensional multi-species reactive transport model

  19. Surface Water Transport for the F/H Area Seepage Basins Groundwater Program

    International Nuclear Information System (INIS)

    Chen, Kuo-Fu.

    1995-01-01

    The contribution of the F- and H-Area Seepage Basins (FHSBs) tritium releases to the tritium concentration in the Savannah River are presented in this report. WASP5 was used to simulate surface water transport for tritium releases from the FHSBs. The WASP5 model was qualified with the 1993 tritium measurements at US Highway 301. The tritium concentrations in Fourmile Branch and the Savannah River were calculated for tritium releases from FHSBs. The calculated tritium concentrations above normal environmental background in the Savannah River, resulting from FHSBs releases, drop from 1.25 pCi/ml (<10% of EPA Drinking Water Guide) in 1995 to 0.0056 pCi/ml in 2045

  20. Expressional Changes of Water Transport-related Molecules in the Efferent Ductules and Initial Segment of Mouse Treated with Bisphenol A-Containing Drinking Water for Two Generations.

    Science.gov (United States)

    Han, Su-Yong; Lee, Ki-Ho

    2013-09-01

    Bisphenol A (BPA) is an estrogenic endocrine disrupter. However, depending on a way of treatment, the harmful effects of BPA have not been confirmed. Also, trans-generational effects of BPA on male reproduction are still controversial. Because the reabsorption of testicular fluid in the efferent ductules (ED) and initial segment (IS) is important for sperm maturation, the present study was designed to determine trans-generational effect of BPA administrated orally on expression of water transport-related molecules in the mouse ED and IS. Ethanol-dissolved BPA was diluted in water to be 100 ng (low), 10 μg (medium), and 1 mg/Ml water (high). BPA-containing water was provided for two generations. Expression of ion transporters and water channels in the ED and IS were measured by relative real-time PCR analysis. In the ED, BPA treatment caused expressional increases of carbonic anhydrase II, cystic fibrosis transmembrane regulator, Na(+)/K(+) ATPase α1 subunit, and aquaporin (AQP) 1. No change of Na(+)/H(+) exchange (NHE) 3 expression was detected. BPA treatment at medium dose resulted in an increase of AQP9 expression. In the IS, the highest expressional levels of all molecules tested were observed in medium-dose BPA treatment. Generally, high-dose BPA treatment resulted in a decrease or no change of gene expression. Fluctuation of NHE3 gene expression by BPA treatment at different concentrations was detected. These findings suggest that trans-generational exposure to BPA, even at low dose, could affect gene expression of water-transport related molecules. However, such effects of BPA would be differentially occurred in the ED and IS.

  1. The Annual Glaciohydrology Cycle in the Ablation Zone of the Greenland Ice Sheet: Part 1. Hydrology Model

    Science.gov (United States)

    Colgan, William; Rajaram, Harihar; Anderson, Robert; Steffen. Konrad; Phillips, Thomas; Zwally, H. Jay; Abdalati, Waleed

    2012-01-01

    We apply a novel one-dimensional glacier hydrology model that calculates hydraulic head to the tidewater-terminating Sermeq Avannarleq flowline of the Greenland ice sheet. Within a plausible parameter space, the model achieves a quasi-steady-state annual cycle in which hydraulic head oscillates close to flotation throughout the ablation zone. Flotation is briefly achieved during the summer melt season along a approx.17 km stretch of the approx.50 km of flowline within the ablation zone. Beneath the majority of the flowline, subglacial conduit storage closes (i.e. obtains minimum radius) during the winter and opens (i.e. obtains maximum radius) during the summer. Along certain stretches of the flowline, the model predicts that subglacial conduit storage remains open throughout the year. A calculated mean glacier water residence time of approx.2.2 years implies that significant amounts of water are stored in the glacier throughout the year. We interpret this residence time as being indicative of the timescale over which the glacier hydrologic system is capable of adjusting to external surface meltwater forcings. Based on in situ ice velocity observations, we suggest that the summer speed-up event generally corresponds to conditions of increasing hydraulic head during inefficient subglacial drainage. Conversely, the slowdown during fall generally corresponds to conditions of decreasing hydraulic head during efficient subglacial drainage.

  2. Air and Water Transportation Occupations. Reprinted from the Occupational Outlook Handbook, 1978-79 Edition.

    Science.gov (United States)

    Bureau of Labor Statistics (DOL), Washington, DC.

    Focusing on air and water transportation occupations, this document is one in a series of forty-one reprints from the Occupational Outlook Handbook providing current information and employment projections for individual occupations and industries through 1985. The specific occupations covered in this document include civil aviation workers, air…

  3. Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349

    International Nuclear Information System (INIS)

    Bostick, Kent; Daniel, Anamary; Tachiev, Georgio; Malek-Mohammadi, Siamak

    2013-01-01

    In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The model also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude

  4. Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349

    Energy Technology Data Exchange (ETDEWEB)

    Bostick, Kent; Daniel, Anamary [Professional Project Services, Inc., Bethel Valley Road, Oak Ridge, TN, 37922 (United States); Tachiev, Georgio [Florida International University, Applied Research Center 10555 W. Flagler St., EC 2100 Miami Florida 33174 (United States); Malek-Mohammadi, Siamak [Bradley University, 413A Jobst Hall, Preoria, IL 61625 (United States)

    2013-07-01

    In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The model also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude

  5. Greenland's 20th Century retreat illuminated - great spatial variability with strong connections to subglacial topography and fjord bathymetry

    Science.gov (United States)

    Bjork, A. A.; Kjeldsen, K. K.; Boeckel, M. V.; Korsgaard, N. J.; Fenty, I. G.; Khan, S. A.; Mouginot, J.; Morlighem, M.; Rignot, E. J.; Dowdeswell, J. A.; Kjaer, K. H.

    2017-12-01

    Mass loss acceleration from the Greenland Ice Sheet is a dominant contributor in recent global sea-level rise, and has been for several decades. While ice sheet wide mass loss has recently been documented from the end of the Little Ice Age (c. 1900 CE) to the 1980s, the detailed changes during this period remain poorly known. In this study, we map glacier margins of Greenland's 310 largest outlet glaciers in order to get the full picture of the 20th Century mass loss. We take advantage of the rich history of aerial photography over Greenland and combine photos from archives in Denmark, Norway, United Kingdom, and United States. We supplement the historical aerial photographs with declassified US spy satellite imagery and recent satellite imagery to document glacial retreat and advance on a decadal scale. With recent advances in bathymetry mapping and subglacial topography mapping, we are able to show that spatial differences in retreat throughout the last 100 years are largely controlled by the underlying topography. Our study further highlights hotspots of past rapid mass loss in Greenland, and discusses implications for periods of regional stability and advance.

  6. Nanoscale Titanium Dioxide (nTiO2) Transport in Water-Saturated Natural Sediments: Influence of Soil Organic Matter and Fe/Al Oxyhydroxides

    Science.gov (United States)

    Fisher-Power, L.; Cheng, T.

    2017-12-01

    Transport of engineered nanoparticles (ENP) in subsurface environments has important implications to water quality and soil contamination. Although extensive research has been conducted to understand the effects of water chemistry on ENP transport, less attention has been paid to influences from the transport medium/matrix. The objective of this research is to investigate the effects of natural organic matter (NOM) and Fe/Al oxyhydroxides in a natural sediment on ENP transport. A sediment was collected and separated into four portions, one of which was unmodified, and the others treated to remove specific components (organic matter, Fe/Al oxyhydroxides, or both organic matter and Fe/Al oxyhydroxides). Transport of nanoscale titanium dioxide (nTiO2) in columns packed with quartz sand and each of the four types of the sediment under water-saturated conditions was studied. Our results showed that nTiO2 transport was strongly influenced by pH and sediment composition. When influent pH = 5, nTiO2 transport in all the sediments was low, as positively-charged nTiO2 was attracted to negatively charged NOM, quartz, and other minerals. nTiO2 transport was slightly enhanced in columns packed with untreated sediment or Fe/Al oxyhydroxides removed sediment due to dissolved organic matter generated by the partial dissolution of NOM, which adsorbed onto nTiO2 surface and reversed its zeta potential to negative. When influent pH = 9, nTiO2 transport was generally high since negatively-charged nTiO2 was repelled by negatively charged transport medium. However, in columns packed with the organic matter removed sediment or the Fe/Al oxyhydroxides removed sediment, nTiO2 transport was low. This was attributable to pH buffering by the sediment, which decreased pore water pH in the column, resulting in zeta potential change and electrostatic attraction between Fe/Al oxyhydroxides and nTiO2. This research demonstrates that electrostatic forces between nTiO2 and mineral/organic components

  7. Transport of uranium in water and soil: colloidal-isotopic combined approach

    International Nuclear Information System (INIS)

    Harguindeguy, Stephanie

    2013-01-01

    Mechanisms of interaction between uranium and colloids were studied by samples taken from a site of interest for the 'French Nuclear Agency' (CEA). The mobilization of uranium from soils was apprehended by static and dynamic leaching experiments. The transfer and transport have been studied by considering pond waters and drain waters. Results confirm that anthropogenic uranium is more mobile than natural uranium. However mechanisms of mobilization and distribution of uranium, does not differ depending on its origin. The colloidal fraction plays an important role on the migration in soil and the transfer into water by representing from 10 to 90 % uranium depending on samples. The colloidal fractions of uranium are in a continuum of size up to about 200 nm hydrodynamic diameter. They are mainly composed of organic material, iron and aluminum. Along the drain, from the upstream to the downstream of the site, rearrangement of colloidal associations between uranium and organic material occurs in disfavor of colloidal associations between uranium and iron, the proportion of colloidal uranium bound to aluminum remains unchanged. (author) [fr

  8. Modeling the Influence of Variable Tributary Inflow on Circulation and Contaminant Transport in a Water Supply Reservoir

    Science.gov (United States)

    Nguyen, L. H.; Wildman, R.

    2012-12-01

    This study characterizes quantitatively the flow and mixing regimes of a water supply reservoir, while also conducting numerical tracer experiments on different operation scenarios. We investigate the effects of weather events on water quality via storm water inflows. Our study site the Kensico Reservoir, New York, the penultimate reservoir of New York City's water supply, is never filtered and thus dependent on stringent watershed protection. This reservoir must meet federal drinking water standards under changing conditions such as increased suburban, commercial, and highway developments that are much higher than the rest of the watershed. Impacts from these sources on water quality are magnified by minor tributary flows subject to contaminants from development projects as other tributaries providing >99% of water to this reservoir are exceedingly clean due to management practices upstream. These threats, coupled with possible changes in the frequency/intensity of weather events due to climate change, increase the potential for contaminants to enter the reservoir and drinking water intakes. This situation provides us with the unique ability to study the effects of weather events on water quality via insignificant storm water inflows, without influence from the major tributaries due to their pristine water quality characteristics. The concentration of contaminants at the drinking water intake depends partially on transport from their point of entry in the reservoir. Thus, it is crucial to understand water circulation in this reservoir and to estimate residence times and water ages at different locations and under different hydrologic scenarios. We described water age, residence time, thermal structure, and flow dynamics of tributary plumes in Kensico Reservoir during a 22-year simulation period using a two-dimensional hydrodynamic and water quality model (CE-QUAL-W2). Our estimates of water age can reach a maximum of ~300 days in deep-reservoir-cells, with

  9. Study on lead transportation in air-water-paddy system with 210Pb as tracer

    International Nuclear Information System (INIS)

    Li Shuding; Zhang Hairong; Ma Xuejun

    1987-08-01

    With 210 PbCl 2 as tracer, a research into lead sources in brown rice, lead distribution in soil and rice, lead chemical forms in soil and their change with time, availability of soil for rice and effect of soil pH on the Pb adsorption was carried out in air-water-paddy system near cities and towns located upper and middle reaches of Liaohe River, northeastern China. Test soil was light acid meadow brown soil. The Pb proportions in rice grain derived from the soil, airborne dust and irrigation water and the transportation pathway to brown rice were investigated. Transportation coefficients of Pb in the system were determined by tracer experiment. It was indicated that the Pb concentration in rice root, the Pb concentration and its distribution in the soil are main factors effecting Pb transportation to rice. Based on the simulation test, mathematical model for computing soil environmental capacity of Pb in the system is put forward. The soil environmental capacity of Pb computed is 1600 - 1700 ppm, i.e. 3.6 - 3.8 t/ha. The computed result was in agreement with the observed. The mathematical model was also used to compute soil enviromental capacity of those heavy metal corresponding respectively with 203 Hg, 115+115m Cd, 65 Zn, 51 Cr, 65 Ni, 60 Co etc

  10. Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins

    Science.gov (United States)

    Coupe, R.H.; Kalkhoff, S.J.; Capel, P.D.; Gregoire, C.

    2012-01-01

    Background: Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used widely throughout the world in the production of many crops and is heavily used on soybeans, corn and cotton. Glyphosate is used in almost all agricultural areas of the United States, and the agricultural use of glyphosate has increased from less than 10 000 Mg in 1992 to more than 80 000 Mg in 2007. The greatest intensity of glyphosate use is in the midwestern United States, where applications are predominantly to genetically modified corn and soybeans. In spite of the increase in usage across the United States, the characterization of the transport of glyphosate and its degradate aminomethylphosphonic acid (AMPA) on a watershed scale is lacking. Results: Glyphosate and AMPA were frequently detected in the surface waters of four agricultural basins. The frequency and magnitude of detections varied across basins, and the load, as a percentage of use, ranged from 0.009 to 0.86% and could be related to three general characteristics: source strength, rainfall runoff and flow route. Conclusions: Glyphosate use in a watershed results in some occurrence in surface water; however, the watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff and a flow route that does not include transport through the soil. ?? 2011 Society of Chemical Industry.

  11. Modified finite element transport model, FETRA, for sediment and radionuclide migration in open coastal waters

    International Nuclear Information System (INIS)

    Onishi, Y.; Arnold, E.M.; Mayer, D.W.

    1979-08-01

    The finite element model, FETRA, simulates transport of sediment and radionuclides (and other contaminants, such as heavy metals, pesticides, and other toxic substances) in surface water bodies. The model is an unsteady, two-dimensional (longitudinal and lateral) model which consists of the following three submodels coupled to include sediment-contaminant interactions: (1) sediment transport submodel, (2) dissolved contaminant transport submodel, and (3) particulate contaminant (contaminant adsorbed by sediment) transport submodel. Under the current phase of the study, FETRA was modified to include sediment-wave interaction in order to extend the applicability of the model to coastal zones and large lakes (e.g., the Great Lakes) where wave actions can be one of the dominant mechanisms to transport sediment and toxic contaminant. FETRA was further modified to handle both linear and quadratic approximations to velocity and depth distributions in order to be compatible with various finite element hydrodynamic models (e.g., RMA II and CAFE) which supply hydrodynamic input data to FETRA. The next step is to apply FETRA to coastal zones to simulate transport of sediment and radionuclides with their interactions in order to test and verify the model under marine and large lacustrine environments

  12. Water flow and solute transport in floating fen root mats

    Science.gov (United States)

    Stofberg, Sija F.; EATM van der Zee, Sjoerd

    2015-04-01

    be very similar and likely functionally related. Our experimental field data were used for modelling water flow and solute transport in floating fens, using HYDRUS 2D. Fluctuations of surface water and root mat, as well as geometry and unsaturated zone parameters can have a major influence on groundwater fluctuations and the exchange between rain and surface water and the water in the root mats. In combination with the duration of salt pulses in surface water, and sensitivity of fen plants to salinity (Stofberg et al. 2014, submitted), risks for rare plants can be anticipated.

  13. Water transport through the intestinal epithelial barrier under different osmotic conditions is dependent on LI-cadherin trans-interaction.

    Science.gov (United States)

    Weth, Agnes; Dippl, Carsten; Striedner, Yasmin; Tiemann-Boege, Irene; Vereshchaga, Yana; Golenhofen, Nikola; Bartelt-Kirbach, Britta; Baumgartner, Werner

    2017-04-03

    In the intestine water has to be reabsorbed from the chymus across the intestinal epithelium. The osmolarity within the lumen is subjected to high variations meaning that water transport often has to take place against osmotic gradients. It has been hypothesized that LI-cadherin is important in this process by keeping the intercellular cleft narrow facilitating the buildup of an osmotic gradient allowing water reabsorption. LI-cadherin is exceptional among the cadherin superfamily with respect to its localization along the lateral plasma membrane of epithelial cells being excluded from adherens junction. Furthermore it has 7 but not 5 extracellular cadherin repeats (EC1-EC7) and a small cytosolic domain. In this study we identified the peptide VAALD as an inhibitor of LI-cadherin trans-interaction by modeling the structure of LI-cadherin and comparison with the known adhesive interfaces of E-cadherin. This inhibitory peptide was used to measure LI-cadherin dependency of water transport through a monolayer of epithelial CACO2 cells under various osmotic conditions. If LI-cadherin trans-interaction was inhibited by use of the peptide, water transport from the luminal to the basolateral side was impaired and even reversed in the case of hypertonic conditions whereas no effect could be observed at isotonic conditions. These data are in line with a recently published model predicting LI-cadherin to keep the width of the lateral intercellular cleft small. In this narrow cleft a high osmolarity can be achieved due to ion pumps yielding a standing osmotic gradient allowing water absorption from the gut even if the faeces is highly hypertonic.

  14. The Water Vapor Source and Transport Characteristic of Rainy Seasons in Eastern China Base on Lagrangian Method

    Science.gov (United States)

    Shi, Y.; Jiang, Z.; Liu, Z.; Li, L.

    2017-12-01

    The Hybrid Single-Particle Lagrangian Integrated Trajectory platform is employed in this studyto simulate trajectories of air parcels in the different rainy seasons in East China from 1961 to 2010,with the purpose of investigating general and specific characteristics of moisture sources and the eventual relationship withprecipitation in each rainy season.The moisture transport andsource-sink characteristics of different rainy seasons have evident differences. The results show that the frontal pre-rainy season is mainly influenced bywinter monsoon system, and the precipitation is strongly affected by water vapor from Pacific Ocean (PO) and East China (EC). Afterthe onset of South China Sea Summer Monsoon (SCSMS), the moisture from Pacific Ocean decreases and from Indian Ocean monsoon area increases. Afterwards, with the northward of the rain belt, the parcels from Southwest region (South China Sea (SCS), Indian Ocean (IO) andIndo-China Peninsula and Indian Peninsula(IP)) decrease and from North region (EC, Eurasia (EA) and PO) increase. Besides, most of the land areas are water vapor sink region and most of sea areas are water vapor source region. Before the onset of SCSMS, EC and PO are two main water vapor source areas.After the onset of SCSMS, the source from PO decreasesand Indian monsoon area becomes the main vapor source region. IP is the main water vapor sink area for all four rainy seasons.As for moisture circulation characteristics, the results of vertical structure of water vapor transport indicate that the maximum water vapor transport in west and east boundaries is located in mid-troposphere and in south and north boundaries is at low-troposphere. The spatiotemporal analysis of moisture trajectory based onmultivariate empirical orthogonal function (MVEOF) indicates that the first mode has close relationship with the precipitation in North China and PDO pattern; the second mode is closely related with the precipitation in Yangtze-Huaihe river basin and

  15. Dynamics of leaf gas exchange, xylem and phloem transport, water potential and carbohydrate concentration in a realistic 3-D model tree crown.

    Science.gov (United States)

    Nikinmaa, Eero; Sievänen, Risto; Hölttä, Teemu

    2014-09-01

    Tree models simulate productivity using general gas exchange responses and structural relationships, but they rarely check whether leaf gas exchange and resulting water and assimilate transport and driving pressure gradients remain within acceptable physical boundaries. This study presents an implementation of the cohesion-tension theory of xylem transport and the Münch hypothesis of phloem transport in a realistic 3-D tree structure and assesses the gas exchange and transport dynamics. A mechanistic model of xylem and phloem transport was used, together with a tested leaf assimilation and transpiration model in a realistic tree architecture to simulate leaf gas exchange and water and carbohydrate transport within an 8-year-old Scots pine tree. The model solved the dynamics of the amounts of water and sucrose solute in the xylem, cambium and phloem using a fine-grained mesh with a system of coupled ordinary differential equations. The simulations predicted the observed patterns of pressure gradients and sugar concentration. Diurnal variation of environmental conditions influenced tree-level gradients in turgor pressure and sugar concentration, which are important drivers of carbon allocation. The results and between-shoot variation were sensitive to structural and functional parameters such as tree-level scaling of conduit size and phloem unloading. Linking whole-tree-level water and assimilate transport, gas exchange and sink activity opens a new avenue for plant studies, as features that are difficult to measure can be studied dynamically with the model. Tree-level responses to local and external conditions can be tested, thus making the approach described here a good test-bench for studies of whole-tree physiology.

  16. Transport of Escherichia Coli and solutes during waste water infiltration in an urban alluvial aquifer

    NARCIS (Netherlands)

    Foppen, J.W.A.; van Herwerden, M.; Kebtie, M.; Noman, A.; Schrijven, J.F.; Stuijfzand, P.J.; Uhlenbrook, S.

    2008-01-01

    Recharge of waste water in an unconsolidated poorly sorted alluvial aquifer is a complex process, both physically and hydrochemically. The aim of this paper is to analyse and conceptualise vertical transport mechanisms taking place in an urban area of extensive wastewater infiltration by analysing

  17. Numerical modeling of water-vapor transport during pre-storm and COHMEX

    Science.gov (United States)

    Djuric, Dusan

    1986-01-01

    Initial conditions are designed for numerical simulation of mesocale processes in the atmosphere using the Limited Area Mesoscale Prediction System (LAMPS) model. These initial conditions represent an idealized baroclinic wave in which the transport of water vapor can be simulated. The constructed atmosphere has two homogeneous air masses, polar front, polar jet stream and a stratosphere. All these simulate the basic structure of the earth's atmosphere. The hydrostatic and geostrophic balances make it possible to evaluate mutually consistent fields of wind and of the height of isobaric surfaces.

  18. An ATP-binding cassette subfamily G full transporter is essential for the retention of leaf water in both wild barley and rice.

    Science.gov (United States)

    Chen, Guoxiong; Komatsuda, Takao; Ma, Jian Feng; Nawrath, Christiane; Pourkheirandish, Mohammad; Tagiri, Akemi; Hu, Yin-Gang; Sameri, Mohammad; Li, Xinrong; Zhao, Xin; Liu, Yubing; Li, Chao; Ma, Xiaoying; Wang, Aidong; Nair, Sudha; Wang, Ning; Miyao, Akio; Sakuma, Shun; Yamaji, Naoki; Zheng, Xiuting; Nevo, Eviatar

    2011-07-26

    Land plants have developed a cuticle preventing uncontrolled water loss. Here we report that an ATP-binding cassette (ABC) subfamily G (ABCG) full transporter is required for leaf water conservation in both wild barley and rice. A spontaneous mutation, eibi1.b, in wild barley has a low capacity to retain leaf water, a phenotype associated with reduced cutin deposition and a thin cuticle. Map-based cloning revealed that Eibi1 encodes an HvABCG31 full transporter. The gene was highly expressed in the elongation zone of a growing leaf (the site of cutin synthesis), and its gene product also was localized in developing, but not in mature tissue. A de novo wild barley mutant named "eibi1.c," along with two transposon insertion lines of rice mutated in the ortholog of HvABCG31 also were unable to restrict water loss from detached leaves. HvABCG31 is hypothesized to function as a transporter involved in cutin formation. Homologs of HvABCG31 were found in green algae, moss, and lycopods, indicating that this full transporter is highly conserved in the evolution of land plants.

  19. Transport and Retention of Carboxymethylcellulose-Modified Carbon Nanotube-Magnetite Nanohybrids in Water-Saturated Porous Media

    Science.gov (United States)

    Wang, D.; Su, C.

    2017-12-01

    Carbon-metal oxide nanohybrids (NHs) are increasingly recognized as the next-generation, promising group of nanomaterials for solving emerging environmental issues and challenges. This research, for the first time, systematically explored the transport and retention of the multifunctional carbon nanotube-magnetite (CNT-Fe3O4) NHs in water-saturated porous media under environmentally relevant physicochemical conditions. An environment-benign macromolecule, carboxymethylcellulose (CMC), was employed to stabilize the NHs. Classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and colloid transport model were used to describe the transport and retention of the NHs. Our results showed that transport of the magnetic CNT-Fe3O4 NHs was lower than that of the parent CNT due to greater aggregation (induced by magnetic attraction) during transport. The DLVO theory well-interpreted the NHs' transport; and secondary minimum played dominant roles in NHs' retention. A novel transport feature, an initial low and following sharp peaks occurred frequently in the NHs' breakthrough curves; and the magnitude and location of both transport peaks varied with different experimental conditions due to the interplay between variability of the fluid viscosity and aggregation-dispersion nature of the NHs. Very promisingly, the estimated maximum transport distance of NHs using the Tufenkji-Elimelech equation ranged between 0.38-46 m, supporting the feasibility of employing the magnetically recyclable CNT-Fe3O4 NHs for in-situ nanoremediation of contaminated soils, sediment aquifers, and groundwater.

  20. Hollow Nanospheres with Fluorous Interiors for Transport of Molecular Oxygen in Water

    KAUST Repository

    Vu, Khanh B.

    2016-08-11

    A dispersion system for saturated fluorocarbon (SFC) liquids based on permeable hollow nanospheres with fluorous interiors is described. The nanospheres are well dispersible in water and are capable of immediate uptake of SFCs. The nanosphere shells are gas-permeable and feature reactive functional groups for easy modification of the exterior. These features make the SFC-filled nanospheres promising vehicles for respiratory oxygen storage and transport. Uptake of molecular oxygen into nanosphere-stabilized SFC dispersions is demonstrated.