WorldWideScience

Sample records for understanding water transport

  1. Fundamentals of Melt-Water Interfacial Transport Phenomena: Improved Understanding for Innovative Safety Technologies in ALWRs

    Energy Technology Data Exchange (ETDEWEB)

    M. Anderson; M. Corradini; K.Y. Bank; R. Bonazza; D. Cho

    2005-04-26

    The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core-melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The goal of this work is to provide the fundamental understanding needed for melt-water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability. The work considers the ex-vessel coolability phenomena in two stages. The first stage is the melt quenching process and is being addressed by Argonne National Lab and University of Wisconsin in modified test facilities. Given a quenched melt in the form of solidified debris, the second stage is to characterize the long-term debris cooling process and is being addressed by Korean Maritime University in via test and analyses. We then address the appropriate scaling and design methodologies for reactor applications.

  2. Fundamentals of Melt-Water Interfacial Transport Phenomena: Improved Understanding for Innovative Safety Technologies in ALWRs

    International Nuclear Information System (INIS)

    Anderson, M.; Corradini, M.; Bank, K.Y.; Bonazza, R.; Cho, D.

    2005-01-01

    The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core-melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The goal of this work is to provide the fundamental understanding needed for melt-water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability. The work considers the ex-vessel coolability phenomena in two stages. The first stage is the melt quenching process and is being addressed by Argonne National Lab and University of Wisconsin in modified test facilities. Given a quenched melt in the form of solidified debris, the second stage is to characterize the long-term debris cooling process and is being addressed by Korean Maritime University in via test and analyses. We then address the appropriate scaling and design methodologies for reactor applications

  3. Understanding the role of pore size homogeneity in the water transport through graphene layers.

    Science.gov (United States)

    Su, Jiaye; Zhao, Yunzhen; Fang, Chang

    2018-03-16

    Graphene is a versatile 2D material and attracts increasing attentions from a broad scientific community, including novel nanofluidic devices. In this work, we use molecular dynamics simulations to study the pressure driven water transport through graphene layers, focusing on the pore size homogeneity, realized by the arrangement of two pore sizes. For a given layer number, we find the water flux exhibits an excellent linear behavior with the pressure, in agreement with the prediction of Hagen-Poiseuille equation. Interestingly, the flux for concentrated pore size distribution is around twice larger than that of uniform distribution. More surprisingly, under a given pressure, the water flux changes in an opposite way for these two distributions, where the flux ratio almost increases linearly with the layer number. For the largest layer number, more distributions suggest the same conclusion that higher water flux can be attained for more concentrated pore size distributions. Similar differences for the water translocation time and occupancy are also identified. The major reason for these results should be clearly due to hydrogen bond and density profile distributions. Our results are helpful to delineate the exquisite role of pore size homogeneity, and should have great implications for the design of high flux nanofluidic devices and inversely the detection of pore structures. © 2018 IOP Publishing Ltd.

  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. 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...

  6. 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…

  7. Predicting major subsurface transport pathways as a key to understand spatial dynamics of reactive nitrogen in stream water

    DEFF Research Database (Denmark)

    Kraft, P.; Dalgaard, Tommy; Schelde, Kirsten

    Process based modelling of nitrogen turnover and transport is mainly focused on the plot and field scale. However, scaling up to the landscape level with sufficient topographic gradient and conductivities, Nr is relocated in the landscape through surface runoff, interflow as well as lateral groun...... due to the hydrogeological conditions is likely and indicated by spatially differing concentrations of Nr in the stream water under comparable land use practices....

  8. Using quantitative topographic analysis to understand the role of water on transport and deposition processes on crater walls

    Science.gov (United States)

    Palucis, Marisa Christina

    that crisscrossed on the lower slopes. We hypothesize that the fine material, likely generated in the impact, and deposited with the coarse debris on the lower portion of the crater wall, is key to this bulking up process as flows cut across the deposits. Fluvial processes following the debris flow gullies extended alluvial deposits to the crater floor and contributed to lake infilling. Cosmogenic dating confirms that most of the modification of the crater walls occurred before the early Holocene. To account for the 75 distinct deposits currently lying on the crater floor, debris flow frequency would be about 1 event every 17 years, assuming debris flow activity terminated ˜10,000 years ago. Assuming a water-to-rock ratio of 0.2 at the time of transport, it would have taken ˜100,000 m3 of water to transport the ˜500,000 m3 of debris flow deposits on the crater floor. Given the 4.5 km2 size of the crater, this extensive erosion would require less than 0.02 m of total runoff, or the equivalent of just 0.001 mm/year over a 40,000 year period. This insignificant amount of water was likely packaged into short-lived storm or snow-melt events when debris flows were generated. Much more runoff did occur, as evidenced by the lake and fluvial deposits, as well as the likely cool, wet conditions of the late Pleistocene. This suggests only a small fraction of the total runoff is needed to do considerable geomorphic evolution, producing strongly gully-scared crater walls. Currently, only minor fluvial modification of the gully networks occurs. (Abstract shortened by UMI.).

  9. Water transport in brain:

    DEFF Research Database (Denmark)

    MacAulay, Nanna; Hamann, Steffan; Zeuthen, Thomas

    2004-01-01

    It is generally accepted that cotransporters transport water in addition to their normal substrates, although the precise mechanism is debated; both active and passive modes of transport have been suggested. The magnitude of the water flux mediated by cotransporters may well be significant: both...... the number of cotransporters per cell and the unit water permeability are high. For example, the Na(+)-glutamate cotransporter (EAAT1) has a unit water permeability one tenth of that of aquaporin (AQP) 1. Cotransporters are widely distributed in the brain and participate in several vital functions: inorganic......(+)-lactate cotransporters. We have previously determined water transport capacities for these cotransporters in model systems (Xenopus oocytes, cell cultures, and in vitro preparations), and will discuss their role in water homeostasis of the astroglial cell under both normo- and pathophysiologal situations. Astroglia...

  10. 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.

  11. Using quantitative topographic analysis to understand the role of water on transport and deposition processes on crater walls

    OpenAIRE

    Palucis, Marisa

    2014-01-01

    The amount of water runoff need to evolve landscapes is rarely assessed. Empirical studies correlate erosion rate to runoff or mean annual precipitation, but rarely is the full history of a landscape known such that it is possible to assess how much water was required to produce it. While this may not seem to be of primary importance on Earth where water is commonly plentiful, on Mars the amount of water to drive landscape evolution is a key question. Here we tackle this question through a se...

  12. Networks of Interacting Processes: Relationships Between Drivers and Deltaic Variables to Understand Water and Sediment Transport in Wax Lake Delta, Coastal Louisiana

    Science.gov (United States)

    Sendrowski, A.; Passalacqua, P.; Wagner, W.; Mohrig, D. C.; Meselhe, E. A.; Sadid, K. M.; Castañeda-Moya, E.; Twilley, R.

    2017-12-01

    Studying distributary channel networks in river deltaic systems provides important insight into deltaic functioning and evolution. This view of networks highlights the physical connection along channels and can also encompass the structural link between channels and deltaic islands (termed structural connectivity). An alternate view of the deltaic network is one composed of interacting processes, such as relationships between external drivers (e.g., river discharge, tides, and wind) and internal deltaic response variables (e.g., water level and sediment concentration). This network, also referred to as process connectivity, is dynamic across space and time, often comprises nonlinear relationships, and contributes to the development of complex channel networks and ecologically rich island platforms. The importance of process connectivity has been acknowledged, however, few studies have directly quantified these network interactions. In this work, we quantify process connections in Wax Lake Delta (WLD), coastal Louisiana. WLD is a naturally prograding delta that serves as an analogue for river diversion projects, thus it provides an excellent setting for understanding the influence of river discharge, tides, and wind on water and sediment in a delta. Time series of water level and sediment concentration were collected in three channels from November 2013 to February 2014, while water level and turbidity were collected on an island from April 2014 to August 2015. Additionally, a model run on WLD bathymetry generated two years of sediment concentration time series in multiple channels. River discharge, tide, and wind measurements were collected from the USGS and NOAA, respectively. We analyze this data with information theory (IT), a set of statistics that measure uncertainty in signals and communication between signals. Using IT, the timescale, strength, and direction of network links are quantified by measuring the synchronization and direct influence from one

  13. 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.

  14. 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...

  15. Modelling Ballast Water Transport

    Digital Repository Service at National Institute of Oceanography (India)

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

    water in the marine environment. The bathymetry of the region has been taken from the CMAP data and augmented by data from hydrographic charts and bathymetry data available at NIO Data Center, Goa. Tides along the open boundary were generated...

  16. 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...... review we introduce another family of transport proteins as water transporters, namely the cotransporters and the glucose uniport GLUT1. In direct contrast to the aquaporins, these proteins have an inherent ability to transport water against an osmotic gradient. Some of them may also function as water...

  17. Isotope Hydrology: Understanding and Managing Water Resources

    International Nuclear Information System (INIS)

    Madsen, Michael

    2013-01-01

    Development is intricately linked to water whether concerning issues of health, food and agriculture, sanitation, the environment, industry, or energy. The IAEA, through its Water Resources Programme provides its Member States with science-based information and technical skills to improve understanding and management of their water resources

  18. K9 water searches: scent and scent transport considerations.

    Science.gov (United States)

    Osterkamp, Tom

    2011-07-01

    Increased use of water search dogs for detecting submerged bodies has created the need for a better understanding of scent emanating from the bodies and how it transits the water to the dog's nose. A review of recent literature identifies likely scent sources, potential scent transport processes, and research needs. Scent sources include gases in bubbles or dissolved in the water, liquids as buoyant plumes and droplets or dissolved in the water, and solids consisting of buoyant particulates with secretions, bacteria, and body fluids. Potential transport processes through the water include buoyancy, entrainment, and turbulence. Transport processes from the water surface into the air include volatilization and evaporation enhanced by bubble bursting, breaking waves, splashing, and wind spray. Implications for the use of water search dogs are examined. Observations of submerged, decomposing bodies are needed to quantify the physical and chemical characteristics of the scent and scent transport processes. © 2011 American Academy of Forensic Sciences.

  19. Understanding the transport and fate of multiple pollutants: development and testing of a coupled surface-groundwater flow and water quality model

    Science.gov (United States)

    Sinha, Sumit; Wade, Andrew

    2017-04-01

    The problem of river pollutant diversity, especially in the south-east of UK, is typically associated with sediment, nutrients and micro-organic chemicals such as pesticides. The pollution problem is further exacerbated by climate change and population growth. Given this policy makers and environmental regulators need catchment scale water quantity and quality model that could be potentially used to assess multiple pollutants in catchments with a large groundwater contribution. The research presented here details development of a spatially explicit, coupled surface- groundwater model and its application in an exemplar lowland catchment in the south-east of UK with extensive surface and groundwater datasets available. More specifically, the fully distributed mesoscale hydrological model (mHM) is coupled with MODFLOW in the Enborne catchment (150 km2). Simulations are conducted on daily time step with spatial resolution of 1 km2 grid cell between 1970 and 2010. The spatially explicit nature of the modelling framework is being used to explore aquifer recharge and water and solute residence times to ultimately explore the lags between changes to pollutant loadings, the introduction of small-scale pollution control measures and the within stream response.

  20. 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

    2018-03-01

    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.

  1. 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

  2. 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...

  3. Toward an Improved Understanding of the Global Fresh Water Budget

    Science.gov (United States)

    Hildebrand, Peter H.

    2005-01-01

    The major components of the global fresh water cycle include the evaporation from the land and ocean surfaces, precipitation onto the Ocean and land surfaces, the net atmospheric transport of water from oceanic areas over land, and the return flow of water from the land back into the ocean. The additional components of oceanic water transport are few, principally, the mixing of fresh water through the oceanic boundary layer, transport by ocean currents, and sea ice processes. On land the situation is considerably more complex, and includes the deposition of rain and snow on land; water flow in runoff; infiltration of water into the soil and groundwater; storage of water in soil, lakes and streams, and groundwater; polar and glacial ice; and use of water in vegetation and human activities. Knowledge of the key terms in the fresh water flux budget is poor. Some components of the budget, e.g. precipitation, runoff, storage, are measured with variable accuracy across the globe. We are just now obtaining precise measurements of the major components of global fresh water storage in global ice and ground water. The easily accessible fresh water sources in rivers, lakes and snow runoff are only adequately measured in the more affluent portions of the world. presents proposals are suggesting methods of making global measurements of these quantities from space. At the same time, knowledge of the global fresh water resources under the effects of climate change is of increasing importance and the human population grows. This paper provides an overview of the state of knowledge of the global fresh water budget, evaluating the accuracy of various global water budget measuring and modeling techniques. We review the measurement capabilities of satellite instruments as compared with field validation studies and modeling approaches. Based on these analyses, and on the goal of improved knowledge of the global fresh water budget under the effects of climate change, we suggest

  4. Understanding Transportation Choice of Families with Small Children in Oslo

    OpenAIRE

    Miller, Scott Thomas

    2011-01-01

    This qualitative study took place in the Oslo area and focused on the transportation mode choices of parents with children in day care. Understanding why parents choose a certain mode of transport was the main objective of this research. Answers to the question of why were looked at in the context of theories stemming from urban planning, sociology, psychology amongst others. The findings show that while geographical distances did have the largest impact on how people travelled around work h...

  5. 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)...

  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 from the GOES-8 satellite spanning the 1987-1988 El Nino...

  7. Manganese: Recent advances in understanding its transport and neurotoxicity

    International Nuclear Information System (INIS)

    Aschner, Michael; Guilarte, Tomas R.; Schneider, Jay S.; Zheng Wei

    2007-01-01

    The present review is based on presentations from the meeting of the Society of Toxicology in San Diego, CA (March 2006). It addresses recent developments in the understanding of the transport of manganese (Mn) into the central nervous system (CNS), as well as brain imaging and neurocognitive studies in non-human primates aimed at improving our understanding of the mechanisms of Mn neurotoxicity. Finally, we discuss potential therapeutic modalities for treating Mn intoxication in humans

  8. 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 ...

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

    Indian Academy of Sciences (India)

    Abstract. 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 ...

  10. 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

  11. 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

  12. 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.

  13. Understanding the dynamics of citrus water use

    CSIR Research Space (South Africa)

    Taylor

    2012-12-01

    Full Text Available The quantification of water use of citrus orchards is important in order to prevent stress developing in the orchard and to avoid wasting precious water resources. Measurement of citrus orchard water use is not possible under all environ...

  14. Coupled water transport by rat proximal tubule.

    Science.gov (United States)

    Green, R; Giebisch, G; Unwin, R; Weinstein, A M

    1991-12-01

    Simultaneous microperfusion of proximal tubules and peritubular capillaries in kidneys of rats anesthetized with Inactin was used to examine water reabsorption by this epithelium. Osmolality of the luminal solution was varied with changes in NaCl concentration and by the addition of raffinose. Capillary perfusates contained either low (2 g/dl) or high (16 g/dl) concentrations of albumin. We used low-bicarbonate perfusates for both lumen and capillary so that we might apply the nonequilibrium thermodynamic model of transport for a single solute (NaCl) to interpret our observations. Linear regression with the volume flux equation Jv = -Lp delta II - Lp sigma delta C + Jav (where Jv is volume flux, Lp is hydraulic conductance, delta II is oncotic force, sigma is osmotic reflection coefficient, delta C is salt concentration difference, and Jav is the component of Jv not attributed to transepithelial hydrostatic or osmotic forces) revealed a tubule water permeability (Pf = 0.11 +/- 0.01 cm/s) and a sigma (0.74 +/- 0.08) in agreement with previous determinations. These transport parameters were unaffected by changes in peritubular protein. We also found that Jav was substantial, approximately three-fourths of the rate of isotonic transport under these perfusion conditions. Further, this component of water transport nearly doubled with the transition from low- to high-protein peritubular capillary perfusion. When expressed as a capacity for water reabsorption against an osmotic gradient, the salt concentration differences required to null volume flux were 13.2 +/- 2.4 and 29.4 +/- 4.0 mosmol/kgH2O under low and high peritubular protein. Our data suggest that this protein effect is, most likely, an increase in solute transport by the tubule epithelial cells.

  15. Pentobarbital inhibits glucose uptake, but not water transport by glucose transporter type 3.

    Science.gov (United States)

    Tomioka, Shigemasa; Kaneko, Miyuki; Nakajo, Nobuyoshi

    2012-08-01

    To understand the mechanisms underlying the neuroprotective efficacy of barbiturates, the effect of pentobarbital on glucose uptake and water transport was determined in Xenopus oocytes expressing glucose transporter type 3 (GLUT3). Pentobarbital induced a 50% concentration-dependent inhibition in glucose uptake, but exerted no effect on water transport by GLUT3. Eadie-Hofstee analysis showed that pentobarbital decreased Vmax significantly, but not Km of GLUT3 for 2-deoxy-D-glucose. Although the protein kinase C (PKC) activator significantly decreased glucose uptake by GLUT3, no additive or synergistic interactions were observed between the PKC activator and pentobarbital. Our results suggest that pentobarbital may play an important role in neuroprotection by inhibition of glucose uptake by GLUT3 by a mechanism involving PKC.

  16. Understanding water's anomalies with locally favored structures

    OpenAIRE

    Russo, John; Tanaka, Hajime

    2013-01-01

    Water is a complex structured liquid of hydrogen-bonded molecules that displays a surprising array of unusual properties, also known as water anomalies, the most famous being the density maximum at about $4^\\circ$C. The origin of these anomalies is still a matter of debate, and so far a quantitative description of water's phase behavior starting from the molecular arrangements is still missing. Here we provide a simple physical description from microscopic data obtained through computer simul...

  17. Electronic transport in partially ionized water plasmas

    Science.gov (United States)

    French, Martin; Redmer, Ronald

    2017-09-01

    We use ab initio simulations based on density functional theory to calculate the electrical and thermal conductivities of electrons in partially ionized water plasmas at densities above 0.1 g/cm3. The resulting conductivity data are then fitted to analytic expressions for convenient application. For low densities, we develop a simple and fully analytic model for electronic transport in low-density plasmas in the chemical picture using the relaxation-time approximation. In doing so, we derive a useful analytic expression for electronic transport cross sections with neutral particles, based on a model potential. In the regime of thermal ionization, electrical conductivities from the analytic model agree with the ab initio data within a factor of 2. Larger deviations are observed for the thermal conductivity, and their origin is discussed. Our results are relevant for modeling the interior and evolution of water-rich planets as well as for technical plasma applications.

  18. Understanding and managing disaster evacuation on a transportation network.

    Science.gov (United States)

    Lambert, James H; Parlak, Ayse I; Zhou, Qian; Miller, John S; Fontaine, Michael D; Guterbock, Thomas M; Clements, Janet L; Thekdi, Shital A

    2013-01-01

    Uncertain population behaviors in a regional emergency could potentially harm the performance of the region's transportation system and subsequent evacuation effort. The integration of behavioral survey data with travel demand modeling enables an assessment of transportation system performance and the identification of operational and public health countermeasures. This paper analyzes transportation system demand and system performance for emergency management in three disaster scenarios. A two-step methodology first estimates the number of trips evacuating the region, thereby capturing behavioral aspects in a scientifically defensible manner based on survey results, and second, assigns these trips to a regional highway network, using geographic information systems software, thereby making the methodology transferable to other locations. Performance measures are generated for each scenario including maps of volume-to-capacity ratios, geographic contours of evacuation time from the center of the region, and link-specific metrics such as weighted average speed and traffic volume. The methods are demonstrated on a 600 segment transportation network in Washington, DC (USA) and are applied to three scenarios involving attacks from radiological dispersion devices (e.g., dirty bombs). The results suggests that: (1) a single detonation would degrade transportation system performance two to three times more than that which occurs during a typical weekday afternoon peak hour, (2) volume on several critical arterials within the network would exceed capacity in the represented scenarios, and (3) resulting travel times to reach intended destinations imply that un-aided evacuation is impractical. These results assist decisions made by two categories of emergency responders: (1) transportation managers who provide traveler information and who make operational adjustments to improve the network (e.g., signal retiming) and (2) public health officials who maintain shelters, food and

  19. 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

  20. Understanding water's anomalies with locally favoured structures.

    Science.gov (United States)

    Russo, John; Tanaka, Hajime

    2014-04-02

    Water is a complex liquid that displays a surprising array of unusual properties, the most famous being the density maximum at about 4 °C. The origin of these anomalies is still a matter of debate, and so far a quantitative description of water's phase behaviour starting from the molecular arrangements is still missing. Here we report a study of the microscopic structural features of water as obtained from computer simulations. We identify locally favoured structures having a high degree of translational order in the second shell, and a two-state model is used to describe the behaviour of liquid water over a wide region of the phase diagram. Furthermore, we show that locally favoured structures not only have translational order in the second shell but also contain five-membered rings of hydrogen-bonded molecules. This suggests their mixed character: the former helps crystallization, whereas the latter causes frustration against crystallization.

  1. Water Breaking: Understand This Sign of Labor

    Science.gov (United States)

    Healthy Lifestyle Labor and delivery, postpartum care Water breaking worries? Prepare yourself for childbirth by getting the facts about this important sign of labor. By Mayo Clinic Staff If you're ...

  2. 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...

  3. Transport Models for Inland and Coastal Waters

    Science.gov (United States)

    Hamilton, Peter

    This proceedings volume originates from a symposium held at Berkeley, California, in August 1980. The purpose of the symposium was to assess the ability of models to predict surface water flow and the transport of dissolved substances in natural systems. The authors were invited, after an initial call for papers, by a Scientific Committee of the International Association for Hydraulic Research.In this context, predictive modeling is limited to hydrodynamic and transport models as applied to rivers, estuaries, shallow coastal waters, lakes, and reservoirs. This is a large subject, though evidently not the whole story on predictive techniques applied to natural water bodies, and many different models are described with applications to a wide variety of natural systems. There is relatively little overlap of material between chapters. It is noteworthy that 21 out of 24 authors of the chapters are affiliated with institutions outside the United States, and many of these are from large European hydraulic laboratories. A number of the chapters summarize numerical modeling studies undertaken by these institutions and so provide the U.S. reader with valuable references to the European open literature and laboratory technical reports. The latter are not usually readily available in the United States. This bias reflects a greater willingness of European engineers to employ sophisticated hydrodynamic numerical models as tools for the solution of engineering and environmental problems of natural water bodies.

  4. Innovative Approaches to Understanding Transportation/Societal Interactions. Volume 2 : Study Design Reports

    Science.gov (United States)

    1981-10-01

    In 1979, the Transportation Systems Center (TSC), under sponsorship of the Urban Mass Transportation Administration (UMTA), began a program of research directed toward improving the understanding of the role of transportation in society, in particula...

  5. 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.

  6. The evolution of water transport in plants: an integrated approach.

    Science.gov (United States)

    Pittermann, J

    2010-03-01

    This review examines the evolution of the plant vascular system from its beginnings in the green algae to modern arborescent plants, highlighting the recent advances in developmental, organismal, geochemical and climatological research that have contributed to our understanding of the evolution of xylem. Hydraulic trade-offs in vascular structure-function are discussed in the context of canopy support and drought and freeze-thaw stress resistance. This qualitative and quantitative neontological approach to palaeobotany may be useful for interpreting the water-transport efficiencies and hydraulic limits in fossil plants. Large variations in atmospheric carbon dioxide levels are recorded in leaf stomatal densities, and may have had profound impacts on the water conservation strategies of ancient plants. A hypothesis that links vascular function with stomatal density is presented and examined in the context of the evolution of wood and/or vessels. A discussion of the broader impacts of plant transport on hydrology and climate concludes this review.

  7. Case Studies in Understanding Transport Sensitive Industries (TSI)

    DEFF Research Database (Denmark)

    Holzweber, Markus; Serin, Göran Folke

    be affordable and should also help to protect the environment. Businesses and consumer rely on round the clock transport and logistic solutions. Transport Sensitive Industries (TSI) are pushing hard to achieve every day transport and logistic solutions, using all the resources available to transportation...

  8. 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...

  9. Stochastic water demand modelling for a better understanding of hydraulics in water distribution networks

    NARCIS (Netherlands)

    Blokker, E.J.M.

    2010-01-01

    In the water distribution network water quality process take place influenced by de flow velocity and residence time of the water in the network. In order to understand how the water quality changes in the water distribution network, a good understanding of hydraulics is required. Specifically in

  10. Mechanistic understanding of cellular level of water in plant-based food material

    Science.gov (United States)

    Khan, Md. Imran H.; Kumar, C.; Karim, M. A.

    2017-06-01

    Understanding of water distribution in plant-based food material is crucial for developing an accurate heat and mass transfer drying model. Generally, in plant-based food tissue, water is distributed in three different spaces namely, intercellular water, intracellular water, and cell wall water. For hygroscopic material, these three types of water transport should be considered for actual understanding of heat and mass transfer during drying. However, there is limited study dedicated to the investigation of the moisture distribution in a different cellular environment in the plant-based food material. Therefore, the aim of the present study was to investigate the proportion of intercellular water, intracellular water, and cell wall water inside the plant-based food material. During this study, experiments were performed for two different plant-based food tissues namely, eggplant and potato tissue using 1H-NMR-T2 relaxometry. Various types of water component were calculated by using multicomponent fits of the T2 relaxation curves. The experimental result showed that in potato tissue 80-82% water exist in intracellular space; 10-13% water in intercellular space and only 4-6% water exist in the cell wall space. In eggplant tissue, 90-93% water in intracellular space, 4-6% water exists in intercellular space and the remaining percentage of water is recognized as cell wall water. The investigated results quantify different types of water in plant-based food tissue. The highest proportion of water exists in intracellular spaces. Therefore, it is necessary to include different transport mechanism for intracellular, intercellular and cell wall water during modelling of heat and mass transfer during drying.

  11. 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 ...

  12. 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

  13. How LeuT shapes our understanding of the mechanisms of sodium-coupled neurotransmitter transporters.

    Science.gov (United States)

    Penmatsa, Aravind; Gouaux, Eric

    2014-03-01

    Neurotransmitter transporters are ion-coupled symporters that drive the uptake of neurotransmitters from neural synapses. In the past decade, the structure of a bacterial amino acid transporter, leucine transporter (LeuT), has given valuable insights into the understanding of architecture and mechanism of mammalian neurotransmitter transporters. Different conformations of LeuT, including a substrate-free state, inward-open state, and competitive and non-competitive inhibitor-bound states, have revealed a mechanistic framework for the transport and transport inhibition of neurotransmitters. The current review integrates our understanding of the mechanistic and pharmacological properties of eukaryotic neurotransmitter transporters obtained through structural snapshots of LeuT.

  14. 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.

  15. 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

  16. Drug release from hydrogel: a new understanding of transport phenomena.

    Science.gov (United States)

    Perale, G; Rossi, F; Santoro, M; Marchetti, P; Mele, A; Castiglione, F; Raffa, E; Masi, M

    2011-06-01

    In tissue engineering, i.e., in combined advanced technologies to replace damaged or missing parts of living tissues, emerging strategies strongly point toward the use of hydrogels also for their ability of being vehicles for local controlled drug delivery. The investigation of drug release mechanisms in such matrices thus plays a key role in the design of smart system but literature is still very controversial on theoretical interpretations and understanding of available data. In this framework we used the new HRMAS-NMR DOSY technique to study the diffusive motions of sodium fluorescein, a drug mimetic small chromophoric molecule, loaded in a promising hydrogel developed for tissue engineering. While fluorescein behavior in water was as expected, also showing aggregation from mid concentrations, data collected within hydrogel samples surprisingly showed no aggregation and diffusion coefficients were always higher with respect to aqueous solution. Furthermore, the promotion of diffusion increased along with fluorescein concentration. The proportion of this effect was directly linked to hydrogel mesh size, thus carrying intrinsic novelty, but also complexity, and suggesting that not only strictly hydrodynamic effects should be considered but also electrostatic interactions between polymer chains and drug molecules might be key players in avoiding fluorescein aggregation and also affecting diffusivity.

  17. A new approach for understanding ion transport in glasses; example ...

    Indian Academy of Sciences (India)

    Mechanism of ion transport in glasses continues to be incompletely understood. Several of the theoretical ... All important observations in d.c. and a.c. transport in glasses are found consistent with this model. Keywords. Diborate glass ...... In the process it is su- pposed to move through the crowded environment by mecha- ...

  18. Water Transport and the Evolution of CM Parent Bodies

    Science.gov (United States)

    Coker, R.; Cohen, B.

    2014-01-01

    Extraterrestrial water-bearing minerals are of great importance both for understanding the formation and evolution of the solar system and for supporting future human activities in space. Asteroids are the primary source of meteorites, many of which show evidence of an early heating episode and varying degrees of aqueous alteration. The origin and characterization of hydrated minerals (minerals containing H2O or OH) among both the main-belt and near-earth asteroids is important for understanding a wide range of solar system formation and evolutionary processes, as well as for planning for human exploration. Current hypotheses postulate asteroids began as mixtures of water ice and anhydrous silicates. A heating event early in solar system history was then responsible for melting the ice and driving aqueous alteration. The link between asteroids and meteorites is forged by reflectance spectra, which show 3-µm bands indicative of bound OH or H2O on the C-class asteroids, which are believed to be the parent bodies of the carbonaceous chondrites in our collections. The conditions at which aqueous alteration occurred in the parent bodies of carbonaceous chondrites are thought to be well-constrained: at 0-25 C for less than 15 Myr after asteroid formation. In previous models, many scenarios exhibit peak temperatures of the rock and co-existing liquid water in more than 75 percent of the asteroid's volume rising to 150 C and higher, due to the exothermic hydration reactions triggering a thermal runaway effect. However, even in a high porosity, water-saturated asteroid very limited liquid water flow is predicted (distances of 100's nm at most). This contradiction has yet to be resolved. Still, it may be possible for water to become liquid even in the near-surface environment, for a long enough time to drive aqueous alteration before vaporizing or freezing then subliming. Thus, we are using physics- and chemistry-based models that include thermal and fluid transport as well

  19. Understanding the Occurrence and Transport of Current-use Pesticides in the San Francisco Estuary Watershed

    Directory of Open Access Journals (Sweden)

    Kathryn Kuivila

    2008-10-01

    Full Text Available The occurrence and potential effects of current-use pesticides are of concern in the San Francisco Estuary watershed but our understanding of the spatial and temporal distribution of contamination is limited. This paper summarizes almost two decades of historical data and uses it to describe our current knowledge of the processes controlling the occurrence of current-use pesticides in the watershed. Monitoring studies analyze fewer than half of the pesticides applied in the watershed and most of our knowledge is about inputs of dissolved pesticides in the upper watershed. The four major seasonal patterns of riverine inputs of pesticides to the estuary can be identified by usage and transport mechanism. Dormant spray insecticides applied to orchards and herbicides applied to a variety of crops are transported by rainfall during the winter. Alfalfa pesticides are detected following rainfall and irrigation return flow in the spring, and rice pesticides are detected following release of rice field water in the summer. Irrigation return flows transport a variety of herbicides during the summer. In addition, pesticides applied on Delta islands can cause elevated pesticide concentrations in localized areas. Although not as well characterized, urban creeks appear to have their own patterns of insecticide concentrations causing toxicity throughout most of the year. Current-use pesticides have also been detected on suspended and bed sediments throughout the watershed but limited data make it difficult to determine occurrence patterns. Data gaps include the lack of analysis of many pesticides (or degradates, changing pesticide use, limited information on pesticide transport within the Delta, and an incomplete understanding of the transport and persistence of sediment-associated pesticides. Future monitoring programs should be designed to address these data gaps.

  20. Understanding and predicting trends in urban freight transport

    OpenAIRE

    Mrazovic, Petar; Eravci, Bahaeddin; Larriba-Pey, Josep Lluis; Ferhatosmanoglu, Hakan; Matskin, Mihhail

    2017-01-01

    Among different components of urban mobility, urban freight transport is usually considered as the least sustainable. Limited traffic infrastructures and increasing demands in dense urban regions lead to frequent delivery runs with smaller freight vehicles. This increases the traffic in urban areas and has negative impacts upon the quality of life in urban populations. Data driven optimizations are essential to better utilize existing urban transport infrastructures and to reduce the negative...

  1. 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

  2. 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 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....... 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...

  3. Understanding the LCA and ISO water footprint: A response to ...

    Science.gov (United States)

    Water footprinting has emerged as an important approach to assess water use related effects from consumption of goods and services. Assessment methods are proposed by two different communities, the Water Footprint Network (WFN) and the Life Cycle Assessment (LCA) community. The proposed methods are broadly similar and encompass both the computation of water use and its impacts, but differ in communication of a water footprint result. In this paper, we explain the role and goal of LCA and ISO-compatible water footprinting and resolve the six issues raised by Hoekstra (2016) in “A critique on the water-scarcity weighted water footprint in LCA”. By clarifying the concerns, we identify both the overlapping goals in the WFN and LCA water footprint assessments and discrepancies between them. The main differing perspective between the WFN and LCA-based approach seems to relate to the fact that LCA aims to account for environmental impacts, while the WFN aims to account for water productivity of global fresh water as a limited resource. We conclude that there is potential to use synergies in research for the two approaches and highlight the need for proper declaration of the methods applied. This paper advances efforts to understand ways to accurately capture use of water in life cycle analysis in other contexts. As the paper indicates, there is a discussion about whether quantities of water should be weighted by some local stress factor. This paper attempts to brid

  4. 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.

  5. Molecular mechanisms of water transport in the eye

    DEFF Research Database (Denmark)

    Hamann, Steffen

    2002-01-01

    in a general model for water transport in ocular epithelia. Some water-transporting membranes contain aquaporins, others do not. The ultrastructure is also variable among the cell layers and cannot be fitted into a general model. On the other hand, the direction of cotransport in symporters complies...

  6. Simultaneous transport of water and solutes under transient ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 117; Issue 4. Simultaneous transport of water and solutes under transient unsaturated flow conditions – A case study ... Keywords. Hydraulic conductivity; infiltration; leaching; Malaprabha; modeling; permeability; salinity; solute transport; SWIM model; water flow.

  7. Case Studies in Understanding Transport Sensitive Industries (TSI)

    DEFF Research Database (Denmark)

    Holzweber, Markus; Serin, Göran Folke

    The mega trends of modern mobility are increasing the pressure on capacity, time and costs. Globalization, urbanization, demographic, and change in consumerism represent the biggest challenges to transport and logistics today. More and more goods have to be brought to their destination. Goods must...

  8. Toward understanding the ecological impact of transportation corridors

    Science.gov (United States)

    Victoria J. Bennett; Winston P. Smith; Matthew G. Betts

    2011-01-01

    Transportation corridors (notably roads) affect wildlife habitat, populations, and entire ecosystems. Considerable effort has been expended to quantify direct effects of roads on wildlife populations and ecological communities and processes. Much less effort has been expended toward quantifying indirect effects. In this report, we provide a comprehensive review of road...

  9. 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.

  10. Recent advances in the understanding of the interaction of antidepressant drugs with serotonin and norepinephrine transporters

    DEFF Research Database (Denmark)

    Andersen, Jacob; Kristensen, Anders Skov; Bang-Andersen, Benny

    2009-01-01

    and amphetamine. Seminal advances in the understanding of the structure and function of this transporter family have recently been accomplished by structural studies of a bacterial transporter, as well as medicinal chemistry and pharmacological studies of mammalian transporters. This feature article focuses...

  11. Structure and Water Transport in Nafion Nanocomposite Membranes

    Science.gov (United States)

    Davis, Eric; Page, Kirt

    2014-03-01

    Perfluorinated ionomers, specifically Nafion, are the most widely used ion exchange membranes for vanadium redox flow battery applications, where an understanding of the relationship between membrane structure and transport of water/ions is critical to battery performance. In this study, the structure of Nafion/SiO2 nanocomposite membranes, synthesized using sol-gel chemistry, as well as cast directly from Nafion/SiO2 nanoparticle dispersions, was measured using both small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS). Through contrast match studies of the SiO2 nanoparticles, direct information on the change in the structure of the Nafion membranes and the ion-transport channels within was obtained, where differences in membrane structure was observed between the solution-cast membranes and the membranes synthesized using sol-gel chemistry. Additionally, water sorption and diffusion in these Nafion/SiO2 nanocomposite membranes were measured using in situ time-resolved Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and dynamic vapor sorption (DVS).

  12. 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.

  13. Understanding hopping transport and thermoelectric properties of conducting polymers

    Science.gov (United States)

    Ihnatsenka, S.; Crispin, X.; Zozoulenko, I. V.

    2015-07-01

    We calculate the conductivity σ and the Seebeck coefficient S for the phonon-assisted hopping transport in conducting polymers poly(3,4-ethylenedioxythiophene) or PEDOT, experimentally studied by Bubnova et al. [J. Am. Chem. Soc. 134, 16456 (2012)], 10.1021/ja305188r. We use the Monte Carlo technique as well as the semianalytical approach based on the transport energy concept. We demonstrate that both approaches show a good qualitative agreement for the concentration dependence of σ and S . At the same time, we find that the semianalytical approach is not in a position to describe the temperature dependence of the conductivity. We find that both Gaussian and exponential density of states (DOS) reproduce rather well the experimental data for the concentration dependence of σ and S giving similar fitting parameters of the theory. The obtained parameters correspond to a hopping model of localized quasiparticles extending over 2-3 monomer units with typical jumps over a distance of 3-4 units. The energetic disorder (broadening of the DOS) is estimated to be 0.1 eV. Using the Monte Carlo calculation we reproduce the activation behavior of the conductivity with the calculated activation energy close to the experimentally observed one. We find that for a low carrier concentration a number of free carriers contributing to the transport deviates strongly from the measured oxidation level. Possible reasons for this behavior are discussed. We also study the effect of the dimensionality on the charge transport by calculating the Seebeck coefficient and the conductivity for the cases of three-, two-, and one-dimensional motion.

  14. Understanding catchment dynamics through a Space-Society-Water trialectic

    Science.gov (United States)

    Sutherland, Catherine; Jewitt, Graham; Risko, Susan; Hay, Ducan; Stuart-Hill, Sabine; Browne, Michelle

    2017-04-01

    Can healthy catchments be utilized to secure water for the benefit of society? This is a complex question as it requires an understanding of the connections and relations between biophysical, social, political, economic and governance dimensions over space and time in the catchment and must interrogate whether there is 'value' in investing in the catchment natural or ecological infrastructure (EI), how this should be done, where the most valuable EI is located, and whether an investment in EI will generate co-benefits socially, environmentally and economically. Here, we adopt a social ecological relations rather than systems approach to explore these interactions through development of a space-society-water trialectic. Trialectic thinking is challenging as it requires new epistemologies and it challenges conventional modes of thought. It is not ordered or fixed, but rather is constantly evolving, revealing the dynamic relations between the elements under exploration. The construction of knowledge, through detailed scientific research and social learning, which contributes to the understanding and achievement of sustainable water supply, water related resilient economic growth, greater social equity and justice in relation to water and the reduction of environmental risk is illustrated through research in the uMngeni Catchment, South Africa. Using four case studies as a basis, we construct the catchment level society-water-space trialectic as a way of connecting, assembling and comparing the understanding and knowledge that has been produced. The relations in the three elements of the trialectic are constructed through identifying, understanding and analysing the actors, discourses, knowledge, biophysical materialities, issues and spatial connections in the case studies. Together these relations, or multiple trajectories, are assembled to form the society-water-space trialectic, which illuminates the dominant relations in the catchment and hence reveal the leverage

  15. 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

  16. Vapor Transport Modeling of Continental Water Isotope Gradients

    Science.gov (United States)

    Ritch, A. J.; Caves, J. K.; Ibarra, D. E.; Winnick, M. J.; Chamberlain, C. P.

    2015-12-01

    Stable isotopes have been widely used to reconstruct past climatic conditions and topographic histories of mountain belts. However, many studies do not account for the influences of evapotranspiration and vapor recycling on downstream meteoric water isotopic compositions. Here we present a case study of the modern Sierra Nevada and Basin and Range to illustrate the value of using process-based models across larger spatial scales to reconstruct the conditions driving local- to regional-scale water isotopic compositions. We use a one-dimensional reactive vapor transport model, driven by the National Centers for Environmental Prediction (NCEP) high-resolution North American Regional Reanalysis (NARR) dataset, to simulate the isotopic composition of modern meteoric waters (δ18O and δD) along storm tracks across the Sierra Nevada and Basin and Range. Storm track pathways are generated using NOAA's Air Resources Laboratory's Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. In addition, we couple the vapor transport model with a soil moisture model to simulate depth profiles of the oxygen isotopic composition of authigenic carbonate along our storm tracks. We show that, given reasonable estimates of the modern partitioning between evaporation and transpiration, our model output is in agreement with modern isotopic data both from compilations of published meteoric water samples and from newly collected soil carbonate samples along a transect across the northern Sierra Nevada and Basin and Range (~38-42° N). These results demonstrate that our modeling approach can be used to analyze the relative contributions of climate and topography to observed isotopic gradients. Future studies can apply this modeling framework to isotopes preserved in the geologic record to provide a quantitative means of understanding the paleoclimatic influences on spatial isotopic distributions.

  17. 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....

  18. Understanding the dynamics of water availability and use in China

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R.P.; Conrad, S.H.; Jeppesen, D.M.; Engi, E.

    1997-07-01

    This report presents the preliminary results of an analysis of China`s water resources, part of an effort undertaken by the National Intelligence Council Medea scientists to improve the understanding of future food production and consumption in the People`s Republic of China. A dynamic water model was developed to simulate the hydrological budgetary processes in five river drainage basins located in northeastern, central, and southern China: the Chang Jiang (Yangtse River), Huanghe (Yellow River), Haihe, Huaihe, and Liaohe. The model was designed to assess the effects of changes in urban, industrial, and agricultural water use requirements on the availability of water in each basin and to develop estimates of the water surpluses and/or deficits in China through the year 2025. The model imposes a sustainable yield constraint, that is, groundwater extraction is not allowed to exceed the sustainable yield; if the available water does not meet the total water use requirements, a deficit results. An agronomic model was also developed to generate projections of the water required to service China`s agricultural sector and compare China`s projected grain production with projected grain consumption requirements to estimate any grain surplus and/or deficit. In future refinements, the agronomic model will interface directly with the water model to provide for the exchange of information on projected water use requirements and available water. The preliminary results indicate that the Chang Jiang basin will have a substantial surplus of water through 2025 and that the Haihe basin is in an ongoing situation. The agricultural water use requirements based on grain production indicate that an agricultural water deficit in the Haihe basin begins before the onset of the modeling period (1980) and steadily worsens through 2025. This assumption is confirmed by reports that groundwater mining is already under way in the most intensely cultivated and populated areas of northern China.

  19. 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.

  20. Towards an understanding of flows in avalanche transport phenomena

    Science.gov (United States)

    Jin, Suying; Ramadan, Nikolas; van Compernolle, Bart; Poulos, Matt J.; Morales, George J.

    2017-10-01

    Recent heat transport experiments conducted in the Large Plasma Device (LAPD) at UCLA, studying avalanche phenomena at steep cross-magnetic field pressure gradients, suggest that flows play a critical role in the evolution of transport phenomena, motivating further characterization. A ring shaped electron beam source injects sub-ionization energy electrons along the strong background magnetic field within a larger quiescent plasma, creating a hollow, high pressure filament. Two distinct regimes are observed as the density decays; the first characterized by multiple small avalanches producing sudden relaxations of the pressure profile which then recovers under continued heating, and the second signaled by a permanent collapse of the density profile after a global avalanche event, then dominated by drift-Alfven waves. The source is modified from previous experiments to gain active control of the flows by controlling the bias between the emitting ring and surrounding carbon masks. The results of flow measurements obtained using a Mach probe and Langmuir/emissive probe are here presented and compared. An analytical model for the behavior of the electron beam source is also in development. Sponsored by NSF Grant 1619505 and by DOE/NSF at BaPSF.

  1. Scientific Models Help Students Understand the Water Cycle

    Science.gov (United States)

    Forbes, Cory; Vo, Tina; Zangori, Laura; Schwarz, Christina

    2015-01-01

    The water cycle is a large, complex system that encompasses ideas across the K-12 science curriculum. By the time students leave fifth grade, they should understand "that a system is a group of related parts that make up a whole and can carry out functions its individual parts cannot" and be able to describe both components and processes…

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

    African Journals Online (AJOL)

    The objective was to evaluate the effect of sunlight, transport and storage vessels on drinking water quality in rural Ghana with the aim of reducing the high demand for fuel wood in the household treatment of water. Well water was exposed for 6h to direct natural sunlight in aluminium, iron, and plastic receptacles and ...

  3. Science to support the understanding of Ohio's water resources

    Science.gov (United States)

    Shaffer, Kimberly; Kula, Stephanie; Bambach, Phil; Runkle, Donna

    2012-01-01

    Ohio’s water resources support a complex web of human activities and nature—clean and abundant water is needed for drinking, recreation, farming, and industry, as well as for fish and wildlife needs. The distribution of rainfall can cause floods and droughts, which affects streamflow, groundwater, water availability, water quality, recreation, and aquatic habitats. Ohio is bordered by the Ohio River and Lake Erie and has over 44,000 miles of streams and more than 60,000 lakes and ponds (State of Ohio, 1994). Nearly all the rural population obtain drinking water from groundwater sources. The U.S. Geological Survey (USGS) works in cooperation with local, State, and other Federal agencies, as well as universities, to furnish decisionmakers, policymakers, USGS scientists, and the general public with reliable scientific information and tools to assist them in management, stewardship, and use of Ohio’s natural resources. The diversity of scientific expertise among USGS personnel enables them to carry out large- and small-scale multidisciplinary studies. The USGS is unique among government organizations because it has neither regulatory nor developmental authority—its sole product is reliable, impartial, credible, relevant, and timely scientific information, equally accessible and available to everyone. The USGS Ohio Water Science Center provides reliable hydrologic and water-related ecological information to aid in the understanding of use and management of the Nation’s water resources, in general, and Ohio’s water resources, in particular. This fact sheet provides an overview of current (2012) or recently completed USGS studies and data activities pertaining to water resources in Ohio. More information regarding projects of the USGS Ohio Water Science Center is available at http://oh.water.usgs.gov/.

  4. 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.

  5. 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.

  6. 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.

  7. Transport Properties of Water and Sodium Dodecyl Sulfate (Postprint)

    Science.gov (United States)

    2013-08-01

    applicability and on the molecular system to be studied [34,46]. Bulk liquid properties using rigid water models are extensively studied and available...intended to be used to simulate bulk liquid water. In order to investigate the transport properties of the MP2f water model, we computed the diffusion... Monde , M., 2012, “Enhancement of Nucleate Pool Boiling Heat Transfer in Ammonia/Water Mixtures With a Surface-Active Agent,” Int. J. Heat Mass Transfer

  8. 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

  9. Water transport in the gas diffusion layer of a polymer electrolyte fuel cell : Dynamic Pore-Network Modeling

    NARCIS (Netherlands)

    Qin, C.

    2015-01-01

    The pore-scale modeling is a powerful tool for increasing our understanding of water transport in the fibrous gas diffusion layer (GDL) of a polymer electrolyte fuel cell (PEFC). In this work, a new dynamic pore-network model for air-water flow in the GDL is developed. It incorporates water vapor

  10. Water footprint of U.S. transportation fuels.

    Science.gov (United States)

    Scown, Corinne D; Horvath, Arpad; McKone, Thomas E

    2011-04-01

    In the modern global economy, water and energy are fundamentally connected. Water already plays a major role in electricity generation and, with biofuels and electricity poised to gain a significant share of the transportation fuel market, water will become significantly more important for transportation energy as well. This research provides insight into the potential changes in water use resulting from increased biofuel or electricity production for transportation energy, as well as the greenhouse gas and freshwater implications. It is shown that when characterizing the water impact of transportation energy, incorporating indirect water use and defensible allocation techniques have a major impact on the final results, with anywhere between an 82% increase and a 250% decrease in the water footprint if evaporative losses from hydroelectric power are excluded. The greenhouse gas impact results indicate that placing cellulosic biorefineries in areas where water must be supplied using alternative means, such as desalination, wastewater recycling, or importation can increase the fuel's total greenhouse gas footprint by up to 47%. The results also show that the production of ethanol and petroleum fuels burden already overpumped aquifers, whereas electricity production is far less dependent on groundwater.

  11. 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.…

  12. Deep update with new water transport cost model

    International Nuclear Information System (INIS)

    Khamis, I.; Ibrahim, A.H.A.D.; Suleiman, S.

    2007-01-01

    DEEP 3.11 is a new version of DEEP which is capable to calculate the water transport cost in any place, with acceptable accuracy. The user needs only to specify water flow or the capacity, pipeline length and elevation of sites against sea level or difference in elevation of the beginning and end of the pipeline routs

  13. 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).

  14. Cellular water distribution, transport, and its investigation methods for plant-based food material.

    Science.gov (United States)

    Khan, Md Imran H; Karim, M A

    2017-09-01

    Heterogeneous and hygroscopic characteristics of plant-based food material make it complex in structure, and therefore water distribution in its different cellular environments is very complex. There are three different cellular environments, namely the intercellular environment, the intracellular environment, and the cell wall environment inside the food structure. According to the bonding strength, intracellular water is defined as loosely bound water, cell wall water is categorized as strongly bound water, and intercellular water is known as free water (FW). During food drying, optimization of the heat and mass transfer process is crucial for the energy efficiency of the process and the quality of the product. For optimizing heat and mass transfer during food processing, understanding these three types of waters (strongly bound, loosely bound, and free water) in plant-based food material is essential. However, there are few studies that investigate cellular level water distribution and transport. As there is no direct method for determining the cellular level water distributions, various indirect methods have been applied to investigate the cellular level water distribution, and there is, as yet, no consensus on the appropriate method for measuring cellular level water in plant-based food material. Therefore, the main aim of this paper is to present a comprehensive review on the available methods to investigate the cellular level water, the characteristics of water at different cellular levels and its transport mechanism during drying. The effect of bound water transport on quality of food product is also discussed. This review article presents a comparative study of different methods that can be applied to investigate cellular water such as nuclear magnetic resonance (NMR), bioelectric impedance analysis (BIA), differential scanning calorimetry (DSC), and dilatometry. The article closes with a discussion of current challenges to investigating cellular water

  15. Integrating the social sciences to understand human-water dynamics

    Science.gov (United States)

    Carr, G.; Kuil, L., Jr.

    2017-12-01

    Many interesting and exciting socio-hydrological models have been developed in recent years. Such models often aim to capture the dynamic interplay between people and water for a variety of hydrological settings. As such, peoples' behaviours and decisions are brought into the models as drivers of and/or respondents to the hydrological system. To develop and run such models over a sufficiently long time duration to observe how the water-human system evolves the human component is often simplified according to one or two key behaviours, characteristics or decisions (e.g. a decision to move away from a drought or flood area; a decision to pump groundwater, or a decision to plant a less water demanding crop). To simplify the social component, socio-hydrological modellers often pull knowledge and understanding from existing social science theories. This requires them to negotiate complex territory, where social theories may be underdeveloped, contested, dynamically evolving, or case specific and difficult to generalise or upscale. A key question is therefore, how can this process be supported so that the resulting socio-hydrological models adequately describe the system and lead to meaningful understanding of how and why it behaves as it does? Collaborative interdisciplinary research teams that bring together social and natural scientists are likely to be critical. Joint development of the model framework requires specific attention to clarification to expose all underlying assumptions, constructive discussion and negotiation to reach agreement on the modelled system and its boundaries. Mutual benefits to social scientists can be highlighted, i.e. socio-hydrological work can provide insights for further exploring and testing social theories. Collaborative work will also help ensure underlying social theory is made explicit, and may identify ways to include and compare multiple theories. As socio-hydrology progresses towards supporting policy development, approaches that

  16. Transport and transfer rates in the waters of the continental shelf. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    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. (ACR)

  17. Kinetics of proton transport in water

    DEFF Research Database (Denmark)

    Kornyshev, A.A.; Kuznetsov, A.M.; Spohr, E.

    2003-01-01

    +), (ii) proton transfer from hydronium to a neighboring water molecule, and (iii) structural diffusion of the Zundel complex (H5O2+), the processes all controlled by orientational fluctuations or hydrogen bond breaking in neighboring hydration shells. Spontaneous conversion of excess proton states...

  18. Advancing the understanding of plasma transport in mid-size stellarators

    Science.gov (United States)

    Hidalgo, Carlos; Talmadge, Joseph; Ramisch, Mirko; TJ-II, the; HXS; TJ-K Teams

    2017-01-01

    The tokamak and the stellarator are the two main candidate concepts for magnetically confining fusion plasmas. The flexibility of the mid-size stellarator devices together with their unique diagnostic capabilities make them ideally suited to study the relation between magnetic topology, electric fields and transport. This paper addresses advances in the understanding of plasma transport in mid-size stellarators with an emphasis on the physics of flows, transport control, impurity and particle transport and fast particles. The results described here emphasize an improved physics understanding of phenomena in stellarators that complements the empirical approach. Experiments in mid-size stellarators support the development of advanced plasma scenarios in Wendelstein 7-X (W7-X) and, in concert with better physics understanding in tokamaks, may ultimately lead to an advance in the prediction of burning plasma behaviour.

  19. Advances in Understanding Global Water Cycle with Advent of Global Precipitation Measurement (GPM) Mission

    Science.gov (United States)

    Smith, Eric A.; Starr, David (Technical Monitor)

    2002-01-01

    Within this decade the internationally organized Global Precipitation Measurement (GPM) Mission will take an important step in creating a global precipitation observing system from space. One perspective for understanding the nature of GPM is that it will be a hierarchical system of datastreams beginning with very high caliber combined dual frequency radar/passive microwave (PMW) rain-radiometer retrievals, to high caliber PMW rain-radiometer only retrievals, and then on to blends of the former datastreams with additional lower-caliber PMW-based and IR-based rain retrievals. Within the context of the now emerging global water & energy cycle (GWEC) programs of a number of research agencies throughout the world, GPM serves as a centerpiece space mission for improving our understanding of the global water cycle from a global measurement perspective. One of the salient problems within our current understanding of the global water and energy cycle is determining whether a change in the rate of the water cycle is accompanying changes in climate, e.g., climate warming. As there are a number of ways in which to define a rate-change of the global water cycle, it is not entirely clear as to what constitutes such a determination. This paper presents an overview of the GPM Mission and how its observations can be used within the framework of the oceanic and continental water budget equations to determine whether a given perturbation in precipitation is indicative of an actual rate change in the global water cycle, consistent with required responses in water storage and/or water flux transport processes, or whether it is the natural variability of a fixed rate cycle.

  20. Advances In Understanding Global Water Cycle With Advent of GPM Mission

    Science.gov (United States)

    Smith, Eric A.

    2002-01-01

    During the coming decade, the internationally organized Global Precipitation Measurement (GPM) Mission will take an important step in creating a global precipitation observing system from space based on an international fleet of satellites operated as a constellation. One perspective for understanding the nature of GPM is that it will be a hierarchical system of datastreams beginning with very high caliber combined dual frequency radar/passive microwave (PMW) rain-radiometer retrievals, to high caliber PMW rain-radiometer only retrievals, and then on to blends of the former datastreams with additional lower-caliber PMW-based and IR-based rain retrievals. Within the context of the now emerging global water & energy cycle (GWEC) programs of a number of research agencies throughout the world, GPM serves as a centerpiece space mission for improving our understanding of the Earth's water cycle from a global measurement perspective and on down to regional scales and below. One of the salient problems within our current understanding of the global water and energy cycle is determining whether a change in the rate of the water cycle is accompanying changes in climate, e.g., climate warming. As there are a number of ways in which to define a rate-change of the global water cycle, it is not entirely clear as to what constitutes such a determination. This paper first presents an overview of the GPM Mission and how its overriding scientific objectives for climate, weather, and hydrology flow from the anticipated improvements that are being planned for the constellation-based measuring system. Next, the paper shows how the GPM observations can be used within the framework of the oceanic and continental water budget equations to determine whether a given perturbation in precipitation is indicative of an actual rate change in the water cycle, consistent with required responses in water storage and/or water flux transport processes, or whether it is simply part of the natural

  1. 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

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

    Science.gov (United States)

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

    2008-07-01

    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 relation between each transport route and the osmotic gradient. The 4-h standard peritoneal permeability analyses of 80 stable PD patients were studied. Small pore transport (SPT) was calculated based on the transported amount of sodium. FWT was calculated by subtracting SPT from transcapillary ultrafiltration (TCUF). Water transport rates were determined. The osmotic gradient was calculated. The slope of the relation between FWT rate and osmotic gradient (slope(FWT)), and the elimination constant (K(e)) of the exponential relation between SPT rate and osmotic gradient (K(SPT)) were calculated for every patient. The FWT rate was related to the osmotic gradient (P = 0.001). A similar correlation was also found between the SPT rate and osmotic gradient when fitted exponentially (P = 0.005). The rates of FWT decreased significantly between each time point during the whole dwell. The SPT rates decreased significantly within the first half of the dwell and levelled off thereafter. No correlations were found between the slope(FWT), K(SPT) and PD duration. The slope(FWT) of the relationship between the FWT and the osmotic gradient is an indirect measurement of the amount of functioning water channels. Similarly, the K(SPT) value represents the number of functioning small pores. The absence of a relationship of these parameters with the duration of PD suggests opposing mechanisms, for instance a lower number of functioning pores in combination with an increased vascular surface area. Conclusion. The curves of the relationship between FWR, SPT and OG support the assumption that FWR is much more dependent on the OG than SPT. Non-osmotic determinants are likely to be important in small pore fluid

  3. Effect of hydrophilic defects on water transport in MFI zeolites.

    Science.gov (United States)

    Humplik, Thomas; Raj, Rishi; Maroo, Shalabh C; Laoui, Tahar; Wang, Evelyn N

    2014-06-10

    The subnanometer pore structure of zeolites and other microporous materials has been proposed to act as a molecular sieve for various water separation technologies. However, due to the increased interaction between the solid and water in these nanoconfined spaces, it is unclear which type of interface, be it hydrophilic or hydrophobic, offers an advantageous medium for enhancing transport properties. In this work, we probe the role of hydrophilic defects on the transport of water inside the microporous hydrophobic MFI zeolite pore structure via combined sorption and high-pressure infiltration experiments. While the inclusion of defects was observed to increase the amount of water within the zeolite pore network by up to 7 times at the saturation pressure, the diffusivity of this infiltrated water was lowered by up to 2 orders of magnitude in comparison to that of water within the nearly defect-free hydrophobic MFI zeolite. Subsequently, the permeability of water within the more defective MFI zeolite was an order of magnitude lower than that of the nearly defect-free zeolite. The results from these experiments suggest that the intrinsic hydrophobic pore structure of MFI zeolites can facilitate faster water transport due to the decreased attraction between the water and the defect-free surface. While the strong attraction of water to the defects allows for water to infiltrate the porous network at lower pressures, the results suggest that this strong attraction decreases the mobility of the infiltrated water. The insights gained from this study can be utilized to improve the design of future membranes for water desalination and other separation techniques.

  4. Measuring and understanding soil water repellency through novel interdisciplinary approaches

    Science.gov (United States)

    Balshaw, Helen; Douglas, Peter; Doerr, Stefan; Davies, Matthew

    2017-04-01

    Food security and production is one of the key global issues faced by society. It has become evermore essential to work the land efficiently, through better soil management and agronomy whilst protecting the environment from air and water pollution. The failure of soil to absorb water - soil water repellency - can lead to major environmental problems such as increased overland flow and soil erosion, poor uptake of agricultural chemicals and increased risk of groundwater pollution due to the rapid transfer of contaminants and nutrient leaching through uneven wetting and preferential flow pathways. Understanding the causes of soil hydrophobicity is essential for the development of effective methods for its amelioration, supporting environmental stability and food security. Organic compounds deposited on soil mineral or aggregate surfaces have long been recognised as a major factor in causing soil water repellency. It is widely accepted that the main groups of compounds responsible are long-chain acids, alkanes and other organic compounds with hydrophobic properties. However, when reapplied to sands and soils, the degree of water repellency induced by these compounds and mixtures varied widely with compound type, amount and mixture, in a seemingly unpredictable way. Our research to date involves two new approaches for studying soil wetting. 1) We challenge the theoretical basis of current ideas on the measured water/soil contact angle measurements. Much past and current discussion involves Wenzel and Cassie-Baxter models to explain anomalously high contact angles for organics on soils, however here we propose that these anomalously high measured contact angles are a consequence of the measurement of a water drop on an irregular non-planar surface rather than the thermodynamic factors of the Cassie-Baxter and Wenzel models. In our analysis we have successfully used a much simpler geometric approach for non-flat surfaces such as soil. 2) Fluorescent and phosphorescent

  5. 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)

  6. Modeling water transport in liquid feed direct methanol fuel cells

    Science.gov (United States)

    Liu, Wenpeng; Wang, Chao-Yang

    Proper water management in direct methanol fuel cells (DMFCs) is very critical and complicated because of many interacting physicochemical phenomena. Among these, the liquid saturation in the cathode side is believed to have a very strong effect on water crossover through the membrane, a key parameter to determine water balance between the anode and cathode. In this paper, based on an interfacial liquid coverage model implemented in a three-dimensional (3D) two-phase DMFC model, the liquid saturation variations in the cathode are examined in detail and their effects on the net water transport coefficient through the membrane discussed.

  7. 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)

  8. Moisture transport through water-impermeable concrete elements

    International Nuclear Information System (INIS)

    Rahn, Axel C.; Friedrich, Matthias; Rieger, Stephan

    2005-01-01

    Frequently during planning construction elements made of water-impermeable concrete it is disregarded that they are a matter of design, not of material. The article comments on different ways of moisture transport in water-impermeable concrete elements and explains the state of the knowledge. It goes into the German guideline ''WU-Richtlinie'' published by the German Committee of Reinforced Concrete (DAfStb) and discusses the consideration of moisture transport for the specification of the guideline requirements. Additional possible measures to be taken in cases of high-quality classification of design utilization in accordance with the guideline are described. (Abstract Copyright [2005], Wiley Periodicals, Inc.) [de

  9. 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.

  10. Water Resources System Archetypes: Towards a Holistic Understanding of Persistent Water Resources Problems

    Science.gov (United States)

    Mirchi, A.; Watkins, D. W.; Madani, K.

    2011-12-01

    Water resources modeling, a well-established tool in water resources planning and management practice, facilitates understanding of the physical and socio-economic processes impacting the wellbeing of humans and ecosystems. While watershed models continue to become more holistic, there is a need for appropriate frameworks and tools for integrated conceptualization of problems to provide reliable qualitative and quantitative bases for policy selection. In recent decades, water resources professionals have become increasingly cognizant of important feedback relationships within water resources systems. We contend that a systems thinking paradigm is required to facilitate characterization of the closed-loop nature of these feedbacks. Furthermore, a close look at different water resources issues reveals that, while many water resources problems are essentially very similar in nature, they continuously appear in different geographical locations. In the systems thinking literature, a number of generic system structures known as system archetypes have been identified to describe common patterns of problematic behavior within systems. In this research, we identify some main system archetypes governing water resources systems, demonstrating their benefits for holistic understanding of various classes of persistent water resources problems. Using the eutrophication problem of Lake Allegan, Michigan, as a case study, we illustrate how the diagnostic tools of system dynamics modeling can facilitate identification of problematic feedbacks within water resources systems and provide insights for sustainable development.

  11. From nose to brain: understanding transport capacity and transport rate of drugs.

    Science.gov (United States)

    Wu, Hongbing; Hu, Kaili; Jiang, Xinguo

    2008-10-01

    The unique relationship between nasal cavity and cranial cavity tissues in anatomy and physiology makes intranasal delivery to the brain feasible. An intranasal delivery provides some drugs with short channels to bypass the blood-brain barrier (BBB), especially for those with fairly low brain concentrations after a routine delivery, thus greatly enhancing the therapeutic effect on brain diseases. In the past two decades, a good number of encouraging outcomes have been reported in the treatment of diseases of the brain or central nervous system (CNS) through nasal administration. In spite of the significant merit of bypassing the BBB, direct nose-to-brain delivery still bears the problems of low efficiency and volume for capacity due to the limited volume of the nasal cavity, the small area ratio of olfactory mucosa to nasal mucosa and the limitations of low dose and short retention time of drug absorption. It is crucial that selective distribution and retention time of drugs or preparations on olfactory mucosa should be enhanced so as to increase the direct delivery efficiency. In this article, we first briefly review the nose-to-brain transport pathways, before detailing the impacts on them, followed by a comprehensive summary of effective methods, including formulation modification, agglutinant-mediated transport and a brain-homing, peptide-mediated delivery based on phage display screening technique, with a view to providing a theoretic reference for elevating the therapeutic effects on brain diseases.

  12. 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

  13. Organic matter linked radionuclide transport in Boom clay - Phenomenological understanding and abstraction to PA

    International Nuclear Information System (INIS)

    Maes, N.; Bruggeman, C.; Liu, D.J.; Salah, S.; Van Laer, L.; Wang, L.; Weetjens, E.; Govaerts, J.; Marivoet, J.; Brassinnes, S.

    2012-01-01

    Document available in extended abstract form only. In the frame of the Belgian research program on long term management of high-level and/or long-lived radioactive wastes coordinated by ONDRAF/NIRAS, plastic clays (i.e., Boom Clay and Ypresian clays) are investigated for their potential to host a deep geological disposal repository for radioactive waste because of, among others, their ability to significantly retard radionuclide releases to the biosphere. The Boom Clay is characterised by the presence of a relatively high amount of dissolved organic matter (DOM, humic substances) which show a strong interaction with a suite of radionuclides (RN) like lanthanides, actinides and transition metals. This interaction with DOM leads in general to an increased mobility of the radionuclide as the OM can act as a colloidal carrier for the radionuclide. Therefore, the quantification and the understanding of the underlying processes are needed for the demonstration of confidence in the host formation to act as a suitable barrier. However, this is not an easy task, given the multitude of processes involved: complexation/colloid formation, sorption, kinetics, filtration, -. In this presentation, we will provide an overview of the research work that leads to a straightforward reactive transport model capturing fairly well the experimental observations. The model can be considered as an intermediate model providing a good basis for further safety abstraction on the one hand and the way to a more detailed phenomenological understanding on the other hand. The research is focussed on the underlying processes that govern speciation, sorption and transport. These underlying processes are investigated in a bottom-up approach, from simple systems to more complex systems. Interpretation is done using thermodynamic based models. Whereas the contribution of Bruggeman et al. focusses mainly on (batch) sorption studies (of trivalent RN), this presentation will provide more details on the

  14. Water magnetization and phosphorus transport parameters in the soil

    OpenAIRE

    Generoso, Tarcila N.; Martinez, Mauro A.; Rocha, Genelício C.; Hamakawa, Paulo J.

    2017-01-01

    ABSTRACT There are scientific studies describing changes in properties of the water when subjected to the action of a magnetic field, which may favor the availability of some nutrients in the soil solution. Some nutrients, although they are essential to the process of crop development, can be sources of pollution for watercourses and soil. The aim of this study was to evaluate the effect of water magnetization on transport parameters of the phosphate ion in a Red Latosol (RL) and in a Quartza...

  15. Mechanisms and regulation of water transport across the peritoneal membrane

    OpenAIRE

    Morelle, Johann

    2016-01-01

    Peritoneal dialysis represents the major home-based dialysis modality for patients with end-stage renal disease. The capacity of the peritoneal membrane to transport water in response to an osmotic gradient contributes to the efficiency of the technique. Previous studies have demonstrated that aquaporin water channels are expressed in the endothelium lining peritoneal microvessels and mediate ultrafiltration during peritoneal dialysis. The investigations presented in this work provide novel i...

  16. Water Diplomacy: A Synthesis of Water Information and Understanding to Create Actionable Knowledge

    Science.gov (United States)

    Gao, Y.; Islam, S.

    2010-12-01

    Water issues are complex because they cross multiple boundaries and involve various stakeholders with competing needs. The origin of many water issues is a dynamic consequence of competition and feedback among variables in the natural, societal and political domains. When viewed as a limited resource, water lends itself to destructive conflicts over its division; knowledge of water, however, can transform a finite water quantity into a flexible resource. To generate such a transformative knowledge base for water, we need a framework to synthesize explicit (scientific information) and tacit (contextual understanding) water knowledge. Such a framework must build on scientific objectivity and be cognizant of contextual differences inherent to water issues. An example of such an approach is qualitative reasoning (QR) that was developed by the artificial intelligence community to provide non-numerical descriptions of systems and their qualitative and quantitative behavior while preserving important behavioral properties and qualitative distinctions. Using the Apalachicola-Chattahoochee-Flint River Basin (ACF Basin) as an example we will illustrate the use of QR to model and analyze water conflicts in the context of a coupled Natural and Societal Domain (NSD) framework. Two QR models related to the ACF water dispute will be compared and contrasted. Our results suggest that QR models within a NSD framework can provide ways to resolve complex water problems through negotiated solutions.

  17. Do Estimates of Water Productivity Enhance Understanding of Farm-Level Water Management?

    Directory of Open Access Journals (Sweden)

    Dennis Wichelns

    2014-03-01

    Full Text Available Estimates of water productivity are appearing with increasing frequency in the literature pertaining to agronomy, water management, and water policy. Some authors report such estimates as one of the outcome variables of experiment station studies, while others calculate water productivities when comparing regional crop production information. Many authors suggest or imply that higher values of water productivity are needed to ensure that future food production goals are achieved. Yet maximizing water productivity might not be consistent with farm-level goals or with societal objectives regarding water allocation and management. Farmers in both rainfed and irrigated settings must address a complex set of issues pertaining to risk, uncertainty, prices, and opportunity costs, when selecting activities and determining optimal strategies. It is not clear that farmers in either setting will or should choose to maximize water productivity. Upon examining water productivity, both conceptually and empirically, using published versions of crop production functions, I conclude that estimates of water productivity contain too little information to enhance understanding of farm-level water management.

  18. Understanding the behavior of floodplains as human-water systems

    Science.gov (United States)

    Di Baldassarre, G.; Brandimarte, L.

    2012-12-01

    Floodplains are among the most valuable ecosystems for supporting biodiversity and providing services to the environment. Moreover, they are home of approximately one-sixth of the world population as they offer favorable conditions for economic development. As a result, flood disasters currently affect more than 100 million people a year. Sadly, flood losses and fatalities are expected to increase further in many countries because of population growth as well as changes in land use and climate. Given the relevance of floodplain systems, a number of social scientists have examined how the frequency and severity of flooding often determine whether human development in floodplains is desirable or not. Meanwhile, many earth scientists have investigated the impact of human activities (e.g. land-use changes, urbanization, river training) on the frequency and magnitude of floods. In fact, as human activities change the frequency of flooding, the frequency of flooding affects human developments in floodplain areas. Yet, these dynamic interactions between floods and societies and the associated feedback mechanisms remain largely unexplored and poorly understood. As a result, we typically consider humans as external forcing (or boundary condition) without representing the feedback loops and our prediction of future trajectories are therefore extremely limited. This presentation shows a first attempt to understand the behavior of floodplains as coupled human-water systems. In particular, we analyzed a number of long time series of hydrological and population data in the Po River Basin (Italy) to explore the feedback mechanisms, reciprocal effects, surprises, and threshold mechanisms, taking place in floodplain systems. The outcomes of the study enable a better understanding of how the occurrences of floods shape human developments while, at the same time, human activities shape the magnitude and frequency of floods. The presentation also discusses the opportunities offered by

  19. 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.

  20. 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.

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

    African Journals Online (AJOL)

    STORAGESEVER

    2010-06-07

    Jun 7, 2010 ... 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.

  2. 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…

  3. 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 ...

  4. 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…

  5. 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).

  6. 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

  7. Simultaneous transport of water and solutes under transient ...

    Indian Academy of Sciences (India)

    Simultaneous transport of water and solutes under transient unsaturated flow conditions – A case study. B K Purandara. ∗. , N Varadarajan and B Venkatesh. National Institute of Hydrology, Hard Rock Regional Center, Belgaum 590 001, Karnataka, India. ∗ e-mail: purandarabk@yahoo.com. The imbalance between ...

  8. 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...

  9. Wind driven vertical transport in a vegetated, wetland water column with air-water gas exchange

    Science.gov (United States)

    Poindexter, C.; Variano, E. A.

    2010-12-01

    Flow around arrays of cylinders at low and intermediate Reynolds numbers has been studied numerically, analytically and experimentally. Early results demonstrated that at flow around randomly oriented cylinders exhibits reduced turbulent length scales and reduced diffusivity when compared to similarly forced, unimpeded flows (Nepf 1999). While horizontal dispersion in flows through cylinder arrays has received considerable research attention, the case of vertical dispersion of reactive constituents has not. This case is relevant to the vertical transfer of dissolved gases in wetlands with emergent vegetation. We present results showing that the presence of vegetation can significantly enhance vertical transport, including gas transfer across the air-water interface. Specifically, we study a wind-sheared air-water interface in which randomly arrayed cylinders represent emergent vegetation. Wind is one of several processes that may govern physical dispersion of dissolved gases in wetlands. Wind represents the dominant force for gas transfer across the air-water interface in the ocean. Empirical relationships between wind and the gas transfer coefficient, k, have been used to estimate spatial variability of CO2 exchange across the worlds’ oceans. Because wetlands with emergent vegetation are different from oceans, different model of wind effects is needed. We investigated the vertical transport of dissolved oxygen in a scaled wetland model built inside a laboratory tank equipped with an open-ended wind tunnel. Plastic tubing immersed in water to a depth of approximately 40 cm represented emergent vegetation of cylindrical form such as hard-stem bulrush (Schoenoplectus acutus). After partially removing the oxygen from the tank water via reaction with sodium sulfite, we used an optical probe to measure dissolved oxygen at mid-depth as the tank water re-equilibrated with the air above. We used dissolved oxygen time-series for a range of mean wind speeds to estimate the

  10. Techniques to better understand complex epikarst hydrogeology and contaminant transport in telogenetic karst settings

    Science.gov (United States)

    The movement of autogenic recharge through the shallow epikarstic zone in soil-mantled karst aquifers is important in understanding recharge areas and rates, groundwater storage, and contaminant transport processes. The groundwater flow in agricultural karst areas, such as Kentucky’s Pennyroyal Plat...

  11. An Active Learning Exercise to Facilitate Understanding of Nephron Function: Anatomy and Physiology of Renal Transporters

    Science.gov (United States)

    Dirks-Naylor, Amie J.

    2016-01-01

    Renal transport is a central mechanism underlying electrolyte homeostasis, acid base balance and other essential functions of the kidneys in human physiology. Thus, knowledge of the anatomy and physiology of the nephron is essential for the understanding of kidney function in health and disease. However, students find this content difficult to…

  12. Quantized Water Transport: Ideal Desalination through Graphyne-4 Membrane

    Science.gov (United States)

    Zhu, Chongqin; Li, Hui; Zeng, Xiao Cheng; Wang, E. G.; Meng, Sheng

    2013-01-01

    Graphyne sheet exhibits promising potential for nanoscale desalination to achieve both high water permeability and salt rejection rate. Extensive molecular dynamics simulations on pore-size effects suggest that γ-graphyne-4, with 4 acetylene bonds between two adjacent phenyl rings, has the best performance with 100% salt rejection and an unprecedented water permeability, to our knowledge, of ~13 L/cm2/day/MPa, 3 orders of magnitude higher than prevailing commercial membranes based on reverse osmosis, and ~10 times higher than the state-of-the-art nanoporous graphene. Strikingly, water permeability across graphyne exhibits unexpected nonlinear dependence on the pore size. This counter-intuitive behavior is attributed to the quantized nature of water flow at the nanoscale, which has wide implications in controlling nanoscale water transport and designing highly effective membranes. PMID:24196437

  13. Understanding and Control of Transport in Advanced Tokamak Regimes in DIII-D

    International Nuclear Information System (INIS)

    C.M. Greenfield; J.C. DeBoo; T.C. Luce; B.W. Stallard; E.J. Synakowski; L.R. Baylor; K.H. Burrell; T.A. Casper; E.J. Doyle; D.R. Ernst; J.R. Ferron; P. Gohil; R.J. Groebner; L.L. Lao; M. Makowski; G.R. McKee; M. Murakami; C.C. Petty; R.I. Pinsker; P.A. Politzer; R. Prater; C.L. Rettig; T.L. Rhodes; B.W. Rice; G.L. Schmidt; G.M. Staebler; E.J. Strait; D.M. Thomas; M.R. Wade

    1999-01-01

    Transport phenomena are studied in Advanced Tokamak (AT) regimes in the DIII-D tokamak [Plasma Physics and Controlled Nuclear Fusion Research, 1986 (International Atomics Energy Agency, Vienna, 1987), Vol. I, p. 159], with the goal of developing understanding and control during each of three phases: Formation of the internal transport barrier (ITB) with counter neutral beam injection takes place when the heating power exceeds a threshold value of about 9 MW, contrasting to CO-NBI injection, where P threshold N H 89 = 9 for 16 confinement times has been accomplished in a discharge combining an ELMing H-mode edge and an ITB, and exhibiting ion thermal transport down to 2-3 times neoclassical. The microinstabilities usually associated with ion thermal transport are predicted stable, implying that another mechanism limits performance. High frequency MHD activity is identified as the probable cause

  14. Enhancing our Understanding of the Arctic Atmospheric Hydrological Cycle using Observations from an International Arctic Water Vapor Isotope Network

    Science.gov (United States)

    Masson-Delmotte, V.; Steen-Larsen, H. C.; Werner, M.

    2014-12-01

    Due to the role of water vapor and clouds in positive feedback mechanisms, water vapor is a key player in the future of Arctic climate. Ecosystems and human societies are vulnerable to climate change through even minor changes in precipitation patterns, including the occurrence of extreme events. It is therefore essential to monitor, understand and model correctly the mechanisms of transport of moisture, at the regional scale. Water isotopes - the relative abundance of heavy and light water in the atmosphere - hold the key to understanding the physical processes influencing future Arctic climate. Water isotope observations in the atmosphere are a modern analog to the Rosetta Stone for understanding the processes involved in evaporation, moisture transport, cloud formation and to track moisture origin. Indeed, technological progress now allows continuous, in situ or remote sensing monitoring of water isotopic composition. In parallel, a growing number of atmospheric circulation models are equipped with the explicit modeling of water stable isotopes, allowing evaluation at the process scale. We present here data obtained through national or bi-national initiatives from stations onboard an icebreaker and land based stations in Greenland, Iceland, Svalbard, and Siberia - together forming an emerging international Arctic water vapor isotope network. Using water tagging and back trajectories we show water vapor of Arctic origin to have a high d-excess fingerprint. This show the potential of using water vapor isotopes as tracer for changes in the Arctic hydrological cycle. Using the network of monitoring stations we quantify using the isotopes advection of air masses and the key processes affecting the water vapor en-route between stations. We have successfully used the obtained atmospheric water vapor isotope observations to benchmark isotope-enabled general circulation models. This comparison allows us to address key processes of the atmospheric hydrological cycle for

  15. 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.

  16. Current Understanding of Interactions between Nanoparticles and ABC Transporters in Cancer Cells.

    Science.gov (United States)

    Yin, Jian; Deng, Xudong; Zhang, Jie; Lin, Jun

    2018-03-14

    Adenosine triphosphate-binding cassette (ABC) transporters-mediated multidrug resistance (MDR) remains as a obstacle for effective cancer therapy. Nanoparticles (NPs)-based delivery systems are promising to overcome MDR, but only a few of them have been accepted for clinical treatment, due to characteristics such as insufficient transportation and potential toxicity. In this respect, mounting attention has been attracted towards interactions between NPs and ABC transporters, which hold a key role in the treatment of multidrug-resistant cancer and NP toxicity. In this review article, current knowledge on the involvement of ABC transporters in MDR and their inhibitors is provided. More importantly, recent literatures about the interactions between NPs and ABC transporters are summarized here. Organic and inorganic NPs inhibit the function of ABC transporters based on distinct mechanisms. The effects of organic NPs are caused by several excipients like surfactants, polymers, lipids and cyclodextrin, whereas inorganic NPs act as substrates of ABC transporters and competitively inhibit the efflux of drugs. Based on these interesting phenomena, a more thorough understanding of the specific mechanisms is necessary and essential in the hope to develop more efficient NPs to overcome MDR and decrease environmental toxicity of NPs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  17. Solute transport modelling in a coupled water and heat flow system applied to cold regions hydrogeology

    Science.gov (United States)

    Frampton, Andrew; Destouni, Georgia

    2016-04-01

    In cold regions, flow in the unsaturated zone is highly dynamic with seasonal variability and changes in temperature, moisture, and heat and water fluxes, all of which affect ground freeze-thaw processes and influence transport of inert and reactive waterborne substances. In arctic permafrost environments, near-surface groundwater flow is further restricted to a relatively shallow and seasonally variable active layer, confined by perennially frozen ground below. The active layer is typically partially saturated with ice, liquid water and air, and is strongly dependent on seasonal temperature fluctuations, thermal forcing and infiltration patterns. Here there is a need for improved understanding of the mechanisms controlling subsurface solute transport in the partially saturated active layer zone. Studying solute transport in cold regions is relevant to improve the understanding of how natural and anthropogenic pollution may change as activities in arctic and sub-arctic regions increase. It is also particularly relevant for understanding how dissolved carbon is transported in coupled surface and subsurface hydrological systems under climate change, in order to better understand the permafrost-hydrological-carbon climate feedback. In this contribution subsurface solute transport under surface warming and degrading permafrost conditions is studied using a physically based model of coupled cryotic and hydrogeological flow processes combined with a particle tracking method. Changes in subsurface water flows and solute transport travel times are analysed for different modelled geological configurations during a 100-year warming period. Results show that for all simulated cases, the minimum and mean travel times increase non-linearly with warming irrespective of geological configuration and heterogeneity structure. The travel time changes are shown to depend on combined warming effects of increase in pathway length due to deepening of the active layer, reduced transport

  18. 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.

  19. Understanding and managing the food-energy-water nexus - opportunities for water resources research

    Science.gov (United States)

    Cai, Ximing; Wallington, Kevin; Shafiee-Jood, Majid; Marston, Landon

    2018-01-01

    Studies on the food, energy, and water (FEW) nexus lay a shared foundation for researchers, policy makers, practitioners, and stakeholders to understand and manage linked production, utilization, and security of FEW systems. The FEW nexus paradigm provides the water community specific channels to move forward in interdisciplinary research where integrated water resources management (IWRM) has fallen short. Here, we help water researchers identify, articulate, utilize, and extend our disciplinary strengths within the broader FEW communities, while informing scientists in the food and energy domains about our unique skillset. This paper explores the relevance of existing and ongoing scholarship within the water community, as well as current research needs, for understanding FEW processes and systems and implementing FEW solutions through innovations in technologies, infrastructures, and policies. Following the historical efforts in IWRM, hydrologists, water resources engineers, economists, and policy analysts are provided opportunities for interdisciplinary studies among themselves and in collaboration with energy and food communities, united by a common path to achieve sustainability development goals.

  20. Reassessing the stable water isotope record in understanding past climate

    International Nuclear Information System (INIS)

    Noone, D.; Simmonds, I.

    1999-01-01

    Full text: The impact of atmospheric circulation on the stable water isotope record has been examined using an atmospheric general circulation model to reassess the validity of using isotopes to reconstruct Earth's climate history. Global temperature changes are classically estimated from the variations in (polar) isotopic values assuming a simple linear relationship. Such a relationship can be justified from first order theoretical considerations given that the isotopic fractionation at the deposition (ice core) site is temperature dependent. However, it is found that the history of a given air mass is more important that local processes because of the net effect of condensation events active along the transport pathway from the source region. Modulations in the hemispheric flow are seen to be crucial to Antarctic precipitation and the isotopic signal. Similarly, both transient and stationary disturbances influence the pathways of the air masses associated with Antarctic precipitation. During different climate regimes, such as that of the Last Glacial Maximum, the properties of these types of disturbances may not be assumed to be the same. As such, we may not assume that the condensation histories are the same as under different climate conditions. Therefore, the veracity of the linear climate reconstructions becomes questionable. Notwithstanding this result, the types of changes to the circulation regime that are expected generally correspond to changes in the global temperature. This fortunate result does not disallow the use of regressional reconstruction, however, the uncertainties associated with these circulation changes are of the same magnitude as the differences suggested by conventional linear regression in climate reconstruction. This indicates that interpretation of ice core data must be accompanied by detailed examination of the atmospheric processes and quantification of the impacts of their changes. Copyright (1999) Geological Society of Australia

  1. Neutron imaging of root water uptake, transport and hydraulic redistribution

    Science.gov (United States)

    Warren, J.; Bilheux, H.; Kang, M.; Voisin, S.; Cheng, C.; Horita, J.; Perfect, E.

    2012-12-01

    Knowledge of plant water fluxes is critical for assessing mechanistic processes linked to biogeochemical cycles, yet resolving root water transport dynamics has been a particularly daunting task. Our objectives were to demonstrate the ability to non-invasively monitor individual root functionality and water fluxes within 1-3-week old Zea mays L. (maize) and Panicum virgatum L. (switchgrass) seedlings using neutron imaging. Seedlings were propagated in a growth chamber adjacent to the HFIR CG1 Beam Line at Oak Ridge National Laboratory in cylindrical or plate-like aluminum chambers containing sand. Seedlings were maintained under fairly dry conditions, with water added only to replace daily evapotranspiration. Plants were placed into the high flux cold neutron beam line and injections of H2O or deuterium oxide (D2O) were tracked through the soil and root systems by collecting consecutive CCD radiographs through time. Water fluxes within the root systems were manipulated by cycling on a growth lamp that altered foliar demand for water and thus internal water potential driving forces. 2D and 3D neutron radiography readily illuminated root structure, root growth, and relative plant and soil water content. 2D pulse-chase irrigation experiments with H2O and D2O, which have different neutron cross sections and thus differences in resulting image contrast, successfully allowed observation of uptake and mass flow of water within the root system. After irrigation there was rapid root water uptake from the newly wetted soil, followed by progressive hydraulic redistribution of water through the root systems to roots terminating in dry soil. Water flux within individual roots responded differentially to foliar illumination based on internal water potential gradients. Using 2D radiography, absolute fluxes of H2O or D2O through the system could not be easily determined since neutron attenuation through the sample was dependent on unknown and dynamic magnitudes of both D and H

  2. Structural basis of water-specific transport through the AQP1 water channel

    Science.gov (United States)

    Sui, Haixin; Han, Bong-Gyoon; Lee, John K.; Walian, Peter; Jap, Bing K.

    2001-12-01

    Water channels facilitate the rapid transport of water across cell membranes in response to osmotic gradients. These channels are believed to be involved in many physiological processes that include renal water conservation, neuro-homeostasis, digestion, regulation of body temperature and reproduction. Members of the water channel superfamily have been found in a range of cell types from bacteria to human. In mammals, there are currently 10 families of water channels, referred to as aquaporins (AQP): AQP0-AQP9. Here we report the structure of the aquaporin 1 (AQP1) water channel to 2.2Å resolution. The channel consists of three topological elements, an extracellular and a cytoplasmic vestibule connected by an extended narrow pore or selectivity filter. Within the selectivity filter, four bound waters are localized along three hydrophilic nodes, which punctuate an otherwise extremely hydrophobic pore segment. This unusual combination of a long hydrophobic pore and a minimal number of solute binding sites facilitates rapid water transport. Residues of the constriction region, in particular histidine 182, which is conserved among all known water-specific channels, are critical in establishing water specificity. Our analysis of the AQP1 pore also indicates that the transport of protons through this channel is highly energetically unfavourable.

  3. Understanding residential water-use behaviour in urban South Africa

    CSIR Research Space (South Africa)

    Jacobs-Mata, Inga M

    2018-01-01

    Full Text Available South Africa’s water supply is under great pressure as demand continues to rise. Demand mitigation strategies implemented by the Department of Water and Sanitation (DWS), water boards and local authorities, and a few water awareness initiatives...

  4. Understanding Dissolved and Colloidal Metal Transport and Transformation - Pathways for Aquatic Toxicity

    Science.gov (United States)

    Kimball, B. A.; Besser, J. M.

    2004-05-01

    Hundreds of miles of streams in the western United States are affected by the release of metals from weathering of mineralized bedrock and mine wastes. In many cases, historical mining has accelerated these weathering processes and increased concentrations of metals in affected streams. Copper and zinc are two metals that affect aquatic health in such streams. Aquatic toxicity from copper and zinc is thought to be related principally to their dissolved concentrations. But there are alternative pathways that may lead to toxicity. Movement of many metals associated with mine drainage is affected by iron colloidal solids. The initial precipitation of iron hydroxides results in nanometer-sized colloids that subsequently aggregate to form a continuum of particle sizes from about one nanometer to greater than one micrometer. This behavior makes the popular or legal definition of dissolved metals at 0.45 micrometers meaningless in streams affected by mine drainage. Ultrafiltration, using tangential-flow across 10,000-Dalton membranes, provides a means to understand dissolved and colloidal metal concentrations. When ultrafiltration is combined with methods to determine mass loading, it is possible to quantify sources and chemical reactions affecting metals. For example, results from a mass-loading study in Mineral Creek, Colorado, indicate that copper and zinc are contributed to the stream from both mined and unmined sources. As the pH of Mineral Creek changes in response to both neutral and acidic inflows, copper was repeatedly transferred between dissolved and colloidal phases through sorption reactions. When the colloidal phase was dominant, the total load of copper consistently decreased because the colloids are entrained by algae on cobbles and strained by the streambed during hyporheic exchange. Zinc load also decreased during transport, but this was a result of the physical process of water exchange with the hyporheic zone, and not a result of colloidal

  5. Computational and experimental platform for understanding and optimizing water flux and salt rejection in nanoporous membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Rempe, Susan B.

    2010-09-01

    Affordable clean water is both a global and a national security issue as lack of it can cause death, disease, and international tension. Furthermore, efficient water filtration reduces the demand for energy, another national issue. The best current solution to clean water lies in reverse osmosis (RO) membranes that remove salts from water with applied pressure, but widely used polymeric membrane technology is energy intensive and produces water depleted in useful electrolytes. Furthermore incremental improvements, based on engineering solutions rather than new materials, have yielded only modest gains in performance over the last 25 years. We have pursued a creative and innovative new approach to membrane design and development for cheap desalination membranes by approaching the problem at the molecular level of pore design. Our inspiration comes from natural biological channels, which permit faster water transport than current reverse osmosis membranes and selectively pass healthy ions. Aiming for an order-of-magnitude improvement over mature polymer technology carries significant inherent risks. The success of our fundamental research effort lies in our exploiting, extending, and integrating recent advances by our team in theory, modeling, nano-fabrication and platform development. A combined theoretical and experimental platform has been developed to understand the interplay between water flux and ion rejection in precisely-defined nano-channels. Our innovative functionalization of solid state nanoporous membranes with organic protein-mimetic polymers achieves 3-fold improvement in water flux over commercial RO membranes and has yielded a pending patent and industrial interest. Our success has generated useful contributions to energy storage, nanoscience, and membrane technology research and development important for national health and prosperity.

  6. 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).

  7. 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.

  8. Mercuric Chloride Effects on Root Water Transport in Aspen Seedlings.

    Science.gov (United States)

    Wan; Zwiazek

    1999-11-01

    HgCl(2) (0.1 mM) reduced pressure-induced water flux and root hydraulic conductivity in the roots of 1-year-old aspen (Populus tremuloides Michx.) seedlings by about 50%. The inhibition was reversed with 50 mM mercaptoethanol. Mercurial treatment reduced the activation energy of water transport in the roots from 10.82 +/- 0.700 kcal mol(-1) to 6.67 +/- 0.193 kcal mol(-1) when measured over the 4 degrees C to 25 degrees C temperature range. An increase in rhodamine B concentration in the xylem sap of mercury-treated roots suggested a decrease in the symplastic transport of water. However, the apoplastic pathway in both control and mercury-treated roots constituted only a small fraction of the total root water transport. Electrical conductivity and osmotic potentials of the expressed xylem sap suggested that 0.1 mM HgCl(2) and temperature changes over the 4 degrees C to 25 degrees C range did not induce cell membrane leakage. The 0.1 mM HgCl(2) solution applied as a root drench severely reduced stomatal conductance in intact plants, and this reduction was partly reversed by 50 mM mercaptoethanol. In excised shoots, 0.1 mM HgCl(2) did not affect stomatal conductance, suggesting that the signal that triggered stomatal closure originated in the roots. We suggest that mercury-sensitive processes in aspen roots play a significant role in regulating plant water balance by their effects on root hydraulic conductivity.

  9. How More Data About Direct and Virtual Water Use Could Help People Understand Their Water Footprints and Save More Water

    Science.gov (United States)

    Madel, R.; Olson-Sawyer, K.; Hanlon, P.; Rabin, K.

    2017-12-01

    their water use behaviors rather than a true calculation of how much water they use in a day. More data about water use (especially for food and agriculture since this is overwhelmingly the biggest use) at a consumer scale in the US would be advantageous to create more accurate estimates of personal water use and help people understand how to most effectively conserve water.

  10. Understanding peri-urban water management in India | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    14 juil. 2014 ... Access to water is a major concern in India, where rapid urbanization and the unpredictable effects of a changing climate are aggravating water tensions. In the southern city of Bangalore, one of India's largest urban areas, older water supply reservoirs are almost dry while artificial lakes within the city are ...

  11. Grounding Water: Building Conceptual Understanding through Multimodal Assessment

    Science.gov (United States)

    Schwartz, Kerry L.; Thomas-Hilburn, Holly; Haverland, Arin

    2011-01-01

    The world's population is growing by about 80 million people a year, implying an estimated increased freshwater demand of about 64 billion cubic meters annually (World Water Assessment Programme, 2009, Water in a Changing World: United Nations World Water Development Report 3, Chap. 1, p. 3-21). Groundwater depletion, which reduces the amount of…

  12. Understanding peri-urban water management in India | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2014-07-14

    Jul 14, 2014 ... Access to water is a major concern in India, where rapid urbanization and the unpredictable effects of a changing climate are aggravating water tensions. In the southern city of Bangalore, one of India's largest urban areas, older water supply reservoirs are almost dry while artificial lakes within the city are ...

  13. Understanding the transport properties of metabolites: case studies and considerations for drug development.

    Science.gov (United States)

    Zamek-Gliszczynski, Maciej J; Chu, Xiaoyan; Polli, Joseph W; Paine, Mary F; Galetin, Aleksandra

    2014-04-01

    Recent analyses demonstrated that metabolites are unlikely to contribute significantly to clinical inhibition of cytochrome P450 (P450)-mediated drug metabolism, and that only ∼2% of this type of drug interaction could not be predicted from the parent drug alone. Due to generally increased polarity and decreased permeability, metabolites are less likely to interact with P450s, but their disposition is instead more likely to involve transporters. This commentary presents case studies illustrating the potential importance of transporters as determinants of metabolite disposition, and as sites of drug interactions, which may alter drug efficacy and safety. Many of these examples are hydrophilic phase II conjugates involved in enterohepatic cycling, where modulation of transporter-dependent disposition may alter pharmacokinetics/pharmacodynamics. The case studies suggest that characterization of metabolite disposition, toxicology, and pharmacology should not focus solely on metabolites with appreciable systemic exposure, but should take into consideration major excretory metabolites. A more thorough understanding of metabolite (phase I and II; circulating and excreted) transport properties during drug development may provide an improved understanding of complex drug-drug interactions (DDIs) that can alter drug and/or metabolite systemic and intracellular exposure. Knowledge and capability gaps remain in clinical translation of in vitro and animal data regarding metabolite disposition. To this end, useful experimental and modeling approaches are highlighted. Application of these tools may lead to a better understanding of metabolite victim and perpetrator DDI potential, and ultimately the establishment of approaches for prediction of pharmacodynamic and toxicodynamic consequences of metabolite transport modulation.

  14. Scotland's Water Map: Understanding water sector links to support decision making for the Hydro Nation Agenda

    Science.gov (United States)

    Falconer, Ruth E.; Gilmour, Daniel; Duffy, Alison; Isaacs, John; Stojanovic, Vladeta; O'Keeffe, Juliette; Blackwood, David

    2015-04-01

    The value of Scotland's water and sewerage market is projected to grow to £1.24bn by 2016/17. Developing future opportunities must take place alongside maintaining current service provision; however the demand on water and waste water services is constantly evolving. An integrated approach to water management requires an understanding of complex interactions that exist between key actors in the sector to allow water management strategies to exploit inter-sectorial links. Successful integrated analysis of the water sector in Scotland will support management activities key to responding to the Hydro Nation themes of 1) Governance and international development 2) Environmental protection 3) Economic opportunities 4) Research development. In order to deliver on these objectives an approach is required to capture and communicate the scope and scale of the water sector and its interconnectedness. The methodology required to determine scope, scale and interconnectedness of water sector involved the identification and application of an appropriate range of techniques from the Information and Knowledge Management disciplines combined with the Information Visualisation field. Scope and scale of the water sector was identified by a desk based study and this data was visualized using a geographic map. Sector interconnectedness was determined by interviewing key actors. The interviews identified the stakeholders associated with information flows, and the purpose of the information transfer through Reporting/Managing (R/M), Influence and Information sharing (I) or Control (C) activities. Primary information flows were also scored with respect to importance against the 4 key Hydro Nation agenda themes. Many organisations were identified who interact within Scotland's water sector including the Scottish Government and Ministers, the Regulators (WICS, DWQR, SEPA), Scottish Water (core and non-core functions), plus many other stakeholders ranging from research institutions to

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-06-15

    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.

  16. Role of Oxygen Functionalities in Graphene Oxide Architectural Laminate Subnanometer Spacing and Water Transport.

    Science.gov (United States)

    Amadei, Carlo Alberto; Montessori, Andrea; Kadow, Julian P; Succi, Sauro; Vecitis, Chad D

    2017-04-18

    Active research in nanotechnology contemplates the use of nanomaterials for environmental engineering applications. However, a primary challenge is understanding the effects of nanomaterial properties on industrial device performance and translating unique nanoscale properties to the macroscale. One emerging example consists of graphene oxide (GO) membranes for separation processes. Thus, here we investigate how individual GO properties can impact GO membrane characteristics and water permeability. GO chemistry and morphology were controlled with easy-to-implement photoreduction and sonication techniques and were quantitatively correlated, offering a valuable tool for accelerating characterization. Chemical GO modification allows for fine control of GO oxidation state, allowing control of GO architectural laminate (GOAL) spacing and permeability. Water permeability was measured for eight GOALs characterized by different GOAL chemistry and morphology and indicates that GOAL nanochannel height dictates water transport. The experimental outputs were corroborated with mesoscale water transport simulations of relatively large domains (thousands of square nanometers) and indicate a no-slip Darcy-like behavior inside the GOAL nanochannels. The experimental and simulation evidence presented in this study helps create a clearer picture of water transport in GOAL and can be used to rationally design more effective and efficient GO membranes.

  17. 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

  18. Water transport confined in graphene oxide channels through the rarefied effect.

    Science.gov (United States)

    Chen, Bo; Jiang, Haifeng; Liu, Xiang; Hu, Xuejiao

    2018-02-21

    Understanding the mechanism of water transport inside an interlayer between graphene-based plates has tremendous value for theoretical studies and industrial applications. The fluid flow confined in nano-scaled spaces experiences a slip velocity near the wall, which is significantly different to that of bulk water. Here we propose a model combining classic hydrodynamics with kinetic theory to depict the dependency of the slip effect on the oxide concentration of valley plates. The influence of oxidized graphene on water flow is a comprehensive result of a slipped boundary, and depends on both the diffuse reflection coefficient of the wall, and the shrunken effective passageway caused by the electrostatic interactions between the oxidized surface and the water molecules. The former effect enhances the water flow, which reduces with increasing oxide concentration, while the latter effect inhibits water flow. We examine the diffuse reflection coefficient and the shrunken effective passageway at different oxide concentrations of the GO sheets by molecular dynamics simulations, and we quantitively predict the flux relationship at various concentrations. This work provides a molecular insight into transport processes of confined water and a useful guideline for the design of perfect graphene-derived membranes for desalination.

  19. 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

    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...

  20. Variation in material transport and water chemistry along a large ephemeral river in the Namib Desert

    Science.gov (United States)

    Jacobson, P.J.; Jacobson, K.M.; Angermeier, P.L.; Cherry, D.S.

    2000-01-01

    1. The chemical characteristics of floodwaters in ephemeral rivers are little known, particularly with regard to their organic loads. These rivers typically exhibit a pronounced downstream hydrological decay but few studies have documented its effect on chemical characteristics and material transport. To develop a better understanding of the dynamics of floods and associated material transport in large ephemeral rivers, floods of the ephemeral Kuiseb River in south-western Africa were tracked and repeatedly sampled at multiple points along the river's lower 220 km. 2. We quantified the composition and transport of solute and sediment loads in relation to longitudinal hydrological patterns associated with downstream hydrological decay. Source and sink areas for transported materials were identified, and the composition and transport dynamics of the organic matter load were compared to those described from more mesic systems. 3. Concentrations of sediments and solutes transported by floods in the Kuiseb River tended to increase downstream in association with pronounced hydrological decay. The contribution of particulate organic matter to total organic load is among the highest recorded, despite our observation of unusually high levels of dissolved organic matter. Hydrological decay resulted in deposition of all transported material within the lower Kuiseb River, with no discharge of water or materials to the Atlantic Ocean. 4. Our results suggest that longitudinal variation in surface flow and associated patterns of material transport renders the lower Kuiseb River a sink for materials transported from upstream. The downstream transport and deposition of large amounts of labile organic matter provides an important carbon supplement to heterotrophic communities within the river's lower reaches.

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

    Science.gov (United States)

    van Summeren, Joost; Blokker, Mirjam

    2017-10-01

    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.

  2. Hydrogen/deuterium substitution methods: understanding water structure in solution

    International Nuclear Information System (INIS)

    Soper, A.K.

    1993-01-01

    The hydrogen/deuterium substitution method has been used for different applications, such as the short range order between water molecules in a number of different environments (aqueous solutions of organic molecules), or to study the partial structure factors of water at high pressure and temperature. The absolute accuracy that can be obtained remains uncertain, but important qualitative information can be obtained on the local organization of water in aqueous solution. Some recent results with pure water, methanol and dimethyl sulphoxide (DMSO) solutions are presented. It is shown that the short range water structure is not greatly affected by most solutes except at high concentrations and when the solute species has its own distinctive interaction with water (such as a dissolved small ion). 3 figs., 14 refs

  3. 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)

  4. Advances in Understanding Sorption and Transport Processes Affecting the Fate of Environmental Pollutants in the Subsurface

    Science.gov (United States)

    Karapanagioti, H. K.; Werner, D.; Werth, C.

    2012-04-01

    The results of a call for a special issue that is now in press by the Journal of Contaminant Hydrology will be presented. This special issue is edited by the authors and is entitled "Sorption and Transport Processes Affecting the Fate of Environmental Pollutants in the Subsurface". A short abstract of each paper will be presented along with the most interesting results. Nine papers were accepted. Pollutants studied include: biocolloids, metals (arsenic, chromium, nickel), organic compounds such as hydrocarbons, chlorinated hydrocarbons, micropollutants (PAHs, PCBs), pesticides (glyphosate, 2,4-D). Findings presented in the papers include a modified batch reactor system to study equilibrium-reactive transport problems of metals. Column studies along with theoretical approximations evaluate the combined effects of grain size and pore water velocity on the transport in water saturated porous media of three biocolloids. A polluted sediment remediation method is evaluated considering site-specific conditions through monitoring results and modelling. A field study points to glogging and also sorption as mechanisms affecting the effectiveness of sub-surface flow constructed wetlands. A new isotherm model combining modified traditionally used isotherms is proposed that can be used to simulate pH-dependent metal adsorption. Linear free energy relationships (LFERs) demonstrate ability to predict slight isotope shifts into the groundwater due to sorption. Possible modifications that improve the reliability of kinetic models and parameter values during the evaluation of experiments that assess the sorption of pesticides on soils are tested. Challenges in selecting groundwater pollutant fate and transport models that account for the effect of grain-scale sorption rate limitations are evaluated based on experimental results and are discussed based on the Damköhler number. Finally, a thorough review paper presents the impact of mineral micropores on the transport and fate of

  5. Development of the living thing transportation systems worksheet on learning cycle model to increase student understanding

    Science.gov (United States)

    Rachmawati, E.; Nurohman, S.; Widowati, A.

    2018-01-01

    This study aims to know: 1) the feasibility LKPD review of aspects of the didactic requirements, construction requirements, technical requirements and compliance with the Learning Cycle. 2) Increase understanding of learners with Learning Model Learning Cycle in SMP N 1 Wates in the form LKPD. 3) The response of learners and educators SMP N 1 Wates to quality LKPD Transportation Systems Beings. This study is an R & D with the 4D model (Define, Design, Develop and Disseminate). Data were analyzed using qualitative analysis and quantitative analysis. Qualitative analysis in the form of advice description and assessment scores from all validates that was converted to a scale of 4. While the analysis of quantitative data by calculating the percentage of materializing learning and achievement using the standard gain an increased understanding and calculation of the KKM completeness evaluation value as an indicator of the achievement of students understanding. the results of this study yield LKPD IPA model learning Cycle theme Transportation Systems Beings obtain 108.5 total scores of a maximum score of 128 including the excellent category (A). LKPD IPA developed able to demonstrate an improved understanding of learners and the response of learners was very good to this quality LKPD IPA.

  6. Water challenges of the future; how scientific understanding can help

    Science.gov (United States)

    Young, G.

    2012-04-01

    Demands for water resources are diverse and are increasing as human populations grow and become more concentrated in urban areas and as economies develop. Water is essential for many uses including the basic human needs of food and the maintenance of good health, for many industries and the creation of electrical energy and as vital for the sustenance of the natural ecosystems on which all life is dependent. At the same time threats from water - floods, droughts - are increasing with these extreme events becoming more common and more intense in many regions of the world and as more people locate in flood- and drought-prone regions. In general, the challenges for water managers are thus becoming greater; managers not only are having to make increasingly difficult decisions regarding allocation of water resources between competing uses as demand outstrips supply, but they also have to take measures to protect societies from the ravages of extreme events. The intensity of the challenges facing water managers is not uniform throughout the world - many nations in the less developed world experiencing far greater problems than most highly developed nations - but the trend towards greater challenges is clear. Decision-makers, whether at the international, national, provincial or local level benefit from reliable information on water resources. They need information on the availability in quantity and quality of water from a variety of sources - surface waters, aquifers or from artificial sources such as re-cycling of wastewater and desalination techniques. Managers also need reliable predictions on water availability for the various uses to which water is put - such predictions are needed on time scales from weeks to decades to inform decision-making. Predictions are also needed on the probabilities of occurrence of extreme events. Thus hydrological scientists developing predictive models and working within a fast-changing world have much to contribute to the needs of

  7. Ground-water transport model selection and evaluation guidelines

    International Nuclear Information System (INIS)

    Simmons, C.S.; Cole, C.R.

    1983-01-01

    Guidelines are being developed to assist potential users with selecting appropriate computer codes for ground-water contaminant transport modeling. The guidelines are meant to assist managers with selecting appropriate predictive models for evaluating either arid or humid low-level radioactive waste burial sites. Evaluation test cases in the form of analytical solutions to fundamental equations and experimental data sets have been identified and recommended to ensure adequate code selection, based on accurate simulation of relevant physical processes. The recommended evaluation procedures will consider certain technical issues related to the present limitations in transport modeling capabilities. A code-selection plan will depend on identifying problem objectives, determining the extent of collectible site-specific data, and developing a site-specific conceptual model for the involved hydrology. Code selection will be predicated on steps for developing an appropriate systems model. This paper will review the progress in developing those guidelines. 12 references

  8. Water magnetization and phosphorus transport parameters in the soil

    Directory of Open Access Journals (Sweden)

    Tarcila N. Generoso

    Full Text Available ABSTRACT There are scientific studies describing changes in properties of the water when subjected to the action of a magnetic field, which may favor the availability of some nutrients in the soil solution. Some nutrients, although they are essential to the process of crop development, can be sources of pollution for watercourses and soil. The aim of this study was to evaluate the effect of water magnetization on transport parameters of the phosphate ion in a Red Latosol (RL and in a Quartzarenic Neosol (QN. Saturated leaching columns were connected to bottles containing KH2PO4 solutions. In RL, there were significant differences in phosphorus (P transport parameters, related to the retardation factor (R and distribution coefficient (Kd. For the others, Peclet number (Pe, dispersive-diffusion coefficient (D and dispersivity (λ, there were no significant differences in the comparison between the treatments with magnetized and non-magnetized water. In QN, there were statistical differences in R and Kd. For the other parameters, Pe, D and λ, there were no statistical differences between treatments.

  9. Interstitial Fibrosis Restricts Osmotic Water Transport in Encapsulating Peritoneal Sclerosis

    Science.gov (United States)

    Morelle, Johann; Sow, Amadou; Hautem, Nicolas; Bouzin, Caroline; Crott, Ralph

    2015-01-01

    Encapsulating peritoneal sclerosis (EPS) is a rare but severe complication of peritoneal dialysis (PD) characterized by extensive fibrosis of the peritoneum. Changes in peritoneal water transport may precede EPS, but the mechanisms and potential predictive value of that transport defect are unknown. Among 234 patients with ESRD who initiated PD at our institution over a 20-year period, 7 subsequently developed EPS. We evaluated changes in peritoneal transport over time on PD in these 7 patients and in 28 matched controls using 3.86% glucose peritoneal equilibration tests. Compared with long-term PD controls, patients with EPS showed early loss of ultrafiltration capacity and sodium sieving before the onset of overt EPS. Multivariate analysis revealed that loss of sodium sieving was the most powerful predictor of EPS. Compared with long-term PD control and uremic peritoneum, EPS peritoneum showed thicker submesothelial fibrosis, with increased collagen density and a greater amount of thick collagen fibers. Reduced osmotic conductance strongly correlated with the degree of peritoneal fibrosis, but not with vasculopathy. Peritoneal fibrosis was paralleled by an excessive upregulation of vascular endothelial growth factor and endothelial nitric oxide synthase, but the expression of endothelial aquaporin-1 water channels was unaltered. Our findings suggest that an early and disproportionate reduction in osmotic conductance during the course of PD is an independent predictor of EPS. This functional change is linked to specific alterations of the collagen matrix in the peritoneal membrane of patients with EPS, thereby validating the serial three-pore membrane/fiber matrix and distributed models of peritoneal transport. PMID:25636412

  10. Global Model Comparison with NOAA Observed Surface Ozone to Understand Transport in the Arctic

    Science.gov (United States)

    Petropavlovskikh, I. V.; McClure-Begley, A.; Tummon, F.; Tilmes, S.; Yudina, A.; Crepinsek, S.; Uttal, T.

    2016-12-01

    The Arctic region is rapidly gaining interest and support for scientific studies to help understand and characterize the processes, sources, and chemical composition of the Arctic environment. In order to understand the Arctic climate system and the changes that are occurring, it is imperative to know the behavior and impact of atmospheric constituents. As a secondary pollutant which impacts the oxidation capacity and radiative forcing of the atmosphere, ozone is an imperative species to characterize. Global atmospheric models help to confirm and understand the influence of long-distance transport on local ozone conditions. This analysis highlights the winter season when ozone conditions are not being driven by photochemical influence, and transport is the prevalent means of ozone variation. In order to ensure adequate representation of ozone conditions and source regions, model comparison verifies the ability of models to represent the behavior of ozone at the surface. Ozone mixing ratios observed from Barrow, Alaska and Summit, Greenland, are critical observations to provide fundamental knowledge of the behavior and trends of ground-level ozone in the Arctic. The observed surface ozone and wind data are compared against two different global climate-chemistry models to assess the ability for models to simulate surface ozone in the arctic region. The CCM SOCOL (Modeling tools for studies of Solar Climate Ozone Links) and Community Earth System Model (CESM1) CAM4-chem are compared to observational measurements. Comparisons between the model and observations are used as the first step in understanding of the long-range transport contribution to ozone variability in the boundary layer of the Arctic environment. An improvement in agreement between observations and chemistry-climate hind cast is found when the model is forced with reanalysis wind conditions.

  11. 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.

  12. 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.

  13. 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.

  14. Sustainable urban water management: understanding and fostering champions of change.

    Science.gov (United States)

    Taylor, A C

    2009-01-01

    This paper highlights and discusses ten characteristic attributes of emergent leaders (also known as 'champions') who worked as influential change agents within publicly managed, Australian water agencies to encourage more sustainable forms of urban water management. These attributes relate to: the 'openness to experience' personality characteristic; career mobility and work history demographics; personal and position power; strategic social networks; the culture of their organisations; and five distinguishing leadership behaviours (e.g. persisting under adversity). Guided by the findings of an international literature review, the author conducted a multiple case study involving six water agencies. This research identified attributes of these leaders that were typically strong and/or distinguishing compared to relevant control groups, as well as influential contextual factors. While it is widely acknowledged that these leaders play a critical role in the delivery of sustainable urban water management, there has been a paucity of context-sensitive research involving them. The research project highlighted in this paper is a response to this situation and has led to the development of a suite of 39 practical, evidence-based strategies to build leadership capacity throughout water agencies. Such capacity is one of the elements needed to drive the transition to more 'water sensitive cities'.

  15. Molecular-dynamics of water transport through membranes - water from solvent to solute

    NARCIS (Netherlands)

    BERENDSEN, HJC; MARRINK, SJ

    1993-01-01

    An application of Molecular Dynamics computer simulation (MD) to the process of transport of water through a lipid bilayer membrane is described. The permeation process is far too slow to be modeled by straightforward MD. In stead the inverse of the permeability coefficient is expressed as an

  16. Peristaltic transport of copper-water nanofluid saturating porous medium

    Science.gov (United States)

    Abbasi, F. M.; Hayat, T.; Ahmad, B.

    2015-03-01

    Prime goal of present study is to model the problem for peristaltic transport of copper-water nanofluid in an asymmetric channel. The fluid fills porous space. Analysis is carried out in the presence of mixed conviction, viscous dissipation and heat generation/absorption. Long wavelength and low Reynolds number approximations are utilized in problem formulation. Numerical computations are presented for the axial velocity, pressure gradient, streamlines, temperature and heat transfer rate at the boundary. Graphical analysis is carried out to examine the effects of sundry parameters on flow quantities of interest. Results revealed that the axial velocity of copper-water nanofluid decreases with an increase in the nanoparticle volume fraction. Copper nanoparticles prove effective coolant since they sufficiently reduce the fluid temperature and show increase in the heat transfer between the fluid and solid boundary. Moreover temperature of the fluid decreases by increasing the permeability of porous medium.

  17. Transport and transfer rates in the waters of the Continental Shelf. Annual report

    International Nuclear Information System (INIS)

    Biscaye, P.E.

    1978-07-01

    The present contract year has been one of transition from an emphasis on field work and sample gathering to the predominance of sample and data analysis and the formulation of testable hypotheses concerning specific processes in the New York Bight. We have begun to understand the seasonal transition in the role of phytoplankton vs. grazing zooplankton in forming the particles on which some reactive pollutants are removed. Using natural radioactive tracers we have estimated the removal rates of reactive metals from the surface waters and these range over an order of magnitude from most rapid nearshore to least rapid over the upper continental slope. Once removed nearshore, however, these tracers, and the pollutants for which they proxy, do not remain permanently in the sediments but appear to be remobilized (probably by oxidation) during the winter and are reintroduced into the water column. Work on transport and mixing processes of pollutants which are or behave like those in solution has continued along several fronts. Hydrographic data on the structure of the water column continues to give a description of the system that is crucial to understanding geochemical and biological processes which affect pollutants. Hydrographic characterization of water masses from the data sets of cruises has resulted in hypotheses concerning the renewal of shelf water by direct exchange between shelf and upper slope water

  18. Surface-Water to Groundwater Transport of Pharmaceuticals in a Wastewater-Impacted Stream in the U.S.

    Science.gov (United States)

    Bradley, P. M.; Barber, L. B.; Duris, J. W.; Foreman, W. T.; Furlong, E. T.; Hubbard, L. E.; Hutchinson, K. J.; Keefe, S. H.; Kolpin, D. W.

    2014-12-01

    Wastewater pharmaceutical contamination of shallow groundwater is a substantial concern in effluent-dominated streams, due to aqueous mobility and designed bioactivity of pharmaceuticals and due to effluent-driven hydraulic gradients. Improved understanding of the environmental fate and transport of wastewater-derived pharmaceuticals is essential for effective protection of vital aquatic ecosystem services, environmental health, and drinking-water supplies. Substantial longitudinal (downstream) transport of pharmaceutical contaminants has been documented in effluent-impacted streams. The comparative lack of information on vertical and lateral transport (infiltration) of wastewater contaminants from surface-water to hyporheic and shallow groundwater compartments is a critical scientific data gap, given the potential for contamination of groundwater supplies in effluent-impacted systems. Growing dependencies on bank filtration and artificial recharge applications for release of wastewater to the environment and for pretreatment of poor-quality surface-water for drinking water emphasize the critical need to better understand the exchange of wastewater contaminants, like pharmaceuticals, between surface-water and groundwater compartments. The potential transport of effluent-derived pharmaceutical contaminants from surface-water to hyporheic-water and shallow groundwater compartments was examined in a wastewater-treatment-facility (WWTF) impacted stream in Ankeny, Iowa under effluent-dominated (71-99% of downstream flow) conditions. Strong hydraulic gradients and hydrologic connectivity were evident between surface-water and shallow-groundwater compartments in the vicinity of the WWTF outfall. Carbamazepine, sulfamethoxazole, and immunologically-related compounds were detected in groundwater 10-20 meters from the stream bank. Direct aqueous-injection HPLC-MS/MS revealed high percentage detections of pharmaceuticals (110 total analytes) in surface-water and groundwater

  19. Transport Phenomena of Water in Molecular Fluidic Channels

    Science.gov (United States)

    Vo, Truong Quoc; Kim, Bohung

    2016-09-01

    In molecular-level fluidic transport, where the discrete characteristics of a molecular system are not negligible (in contrast to a continuum description), the response of the molecular water system might still be similar to the continuum description if the time and ensemble averages satisfy the ergodic hypothesis and the scale of the average is enough to recover the classical thermodynamic properties. However, even in such cases, the continuum description breaks down on the material interfaces. In short, molecular-level liquid flows exhibit substantially different physics from classical fluid transport theories because of (i) the interface/surface force field, (ii) thermal/velocity slip, (iii) the discreteness of fluid molecules at the interface and (iv) local viscosity. Therefore, in this study, we present the result of our investigations using molecular dynamics (MD) simulations with continuum-based energy equations and check the validity and limitations of the continuum hypothesis. Our study shows that when the continuum description is subjected to the proper treatment of the interface effects via modified boundary conditions, the so-called continuum-based modified-analytical solutions, they can adequately predict nanoscale fluid transport phenomena. The findings in this work have broad effects in overcoming current limitations in modeling/predicting the fluid behaviors of molecular fluidic devices.

  20. Understanding water: Molecular dynamics simulations of solubilized and crystallized myoglobin

    International Nuclear Information System (INIS)

    Wei Gu; Garcia, A.E.; Schoenborn, B.P.

    1994-01-01

    Molecular dynamics simulations were performed on CO myoglobin to evaluate the stability of the bound water molecules as determined in a neutron diffraction analysis. The myoglobin structure derived from the neutron analysis provided the starting coordinate set used in the simulations. The simulations show that only a few water molecules are tightly bound to protein atoms, while most solvent molecules are labile, breaking and reforming hydrogen bonds. Comparison between myoglobin in solution and in a single crystal highlighted some of the packing effects on the solvent structure and shows that water solvent plays an indispensable role in protein dynamics and structural stability. The described observations explain some of the differences in the experimental results of protein hydration as observed in NMR, neutron and X-ray diffraction studies

  1. 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

  2. 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.

  3. Toward a better understanding of the complex geochemical processes governing subsurface contaminant transport

    International Nuclear Information System (INIS)

    Puls, R.W.

    1990-01-01

    Identification and understanding of the geochemical processes, including ion exchange, precipitation, organic partitioning, chemisorption, aqueous complexation, and colloidal stability and transport, controlling subsurface contamination is essential for making accurate predictions of the fate and transport of these constituents. Current approaches to quantify the effect of these processes primarily involve laboratory techniques, including the use of closed static systems (batch experiments) where small amounts of aquifer solids or minerals are contacted with an aqueous phase containing the components of interest for relatively short durations; and dynamic systems (column experiments) where a larger segment of the aquifer is investigated by analyzing the breakthrough profiles of reactive and non-reactive species. Both approaches are constrained by differences in scale, alteration of media during sample collection and use, and spatial variability. More field reactivity studies are needed to complement established laboratory approaches for the determination of retardation factors and scaling factors, corroboration of batch and column results, and validation of sampling techniques. These studies also serve to accentuate areas of geochemical process research where data deficiencies exist, such as the kinetics of adsorption-desorption, metal-organic-mineral interactions, and colloidal mobility. The advantages and disadvantages of the above approaches are discussed in the context of achieving a more completely integrated approach to geochemical transport experiments, with supportive data presented from selected studies. (Author) (16 refs., 4 figs., 2 tabs.)

  4. Understanding the effects of electronic polarization and delocalization on charge-transport levels in oligoacene systems

    KAUST Repository

    Sutton, Christopher

    2017-06-13

    Electronic polarization and charge delocalization are important aspects that affect the charge-transport levels in organic materials. Here, using a quantum mechanical/ embedded-charge (QM/EC) approach based on a combination of the long-range corrected omega B97X-D exchange-correlation functional (QM) and charge model 5 (CM5) point-charge model (EC), we evaluate the vertical detachment energies and polarization energies of various sizes of crystalline and amorphous anionic oligoacene clusters. Our results indicate that QM/EC calculations yield vertical detachment energies and polarization energies that compare well with the experimental values obtained from ultraviolet photoemission spectroscopy measurements. In order to understand the effect of charge delocalization on the transport levels, we considered crystalline naphthalene systems with QM regions including one or five-molecules. The results for these systems show that the delocalization and polarization effects are additive; therefore, allowing for electron delocalization by increasing the size of the QM region leads to the additional stabilization of the transport levels. Published by AIP Publishing.

  5. Understanding the liquid-liquid (water-hexane) interface

    Science.gov (United States)

    Murad, Sohail; Puri, Ishwar K.

    2017-10-01

    Nonequilibrium molecular dynamics simulations are employed to investigate the interfacial thermal resistance of nanoscale hexane-water interfaces subject to an applied heat flux. Our studies show that these liquid-liquid interfaces exhibit behavior significantly dissimilar to that of solid-liquid and solid-vapor interfaces. Notably, the thermal resistance of a hexane-water interface is contingent on the interfacial temperature gradient alone with negligible dependence on the mean interfacial temperature, while the solid-liquid dependent strongly on the interfacial temperature. Application of a heat flux also increases the interface thickness significantly as compared to an equilibrium isothermal interface. Since liquid-liquid interfaces have been proposed for diverse applications, e.g., sensors for wastewater treatment and for extraction of toxic ions from water, they can be designed to be wider by applying a heat flux. This may allow the interface to be used for other applications not possible currently because of the very limited thickness of the interface in isothermal systems.

  6. Potential risk of microplastics transportation into ground water

    Science.gov (United States)

    Huerta, Esperanza; Gertsen, Hennie; Gooren, Harm; Peters, Piet; Salánki, Tamás; van der Ploeg, Martine; Besseling, Ellen; Koelmans, Albert A.; Geissen, Violette

    2016-04-01

    Microplastics, are plastics particles with a size smaller than 5mm. They are formed by the fragmentation of plastic wastes. They are present in the air, soil and water. But only in aquatic systems (ocean and rivers) are studies over their distribution, and the effect of microplastics on organisms. There is a lack of information of what is the distribution of microplastics in the soil, and in the ground water. This study tries to estimate the potential risk of microplastics transportation into the ground water by the activity of earthworms. Earthworms can produce burrows and/or galleries inside the soil, with the presence of earthworms some ecosystem services are enhanced, as infiltration. In this study we observed after 14 days with 5 treatments (0, 7, 28 and 60% w/w microplastics mixed with Populus nigra litter) and the anecic earthworm Lumbricus terrestris, in microcosms (3 replicas per treatment) that macroplastics are indeed deposit inside earthworms burrows, with 7% microplastics on the surface is possible to find 1.8 g.kg-1 microplastics inside the burrows, with a bioaumentation factor of 0.65. Burrows made by earthworms under 60% microplastics, are significant bigger (pmicroplastics in their soil surface. The amount of litter that is deposit inside the burrows is significant higher (pmicroplastics on the surface than without microplastics. The microplastics size distribution is smaller inside the burrows than on the surface, with an abundance of particles under 63 μm.

  7. 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)

  8. 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)

  9. 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.

  10. 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.

  11. 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

  12. Measurements and simulations of water transport in maize plants

    Science.gov (United States)

    Heinlein, Florian; Klein, Christian; Thieme, Christoph; Priesack, Eckart

    2017-04-01

    In Central Europe climate change will become manifest in the increase of extreme weather events like flash floods, heat waves and summer droughts, and in a shift of precipitation towards winter months. Therefore, regional water availability will alter which has an effect on future crop growth, water use efficiency and yields. To better estimate these effects accurate model descriptions of transpiration and other parts of the water balance are important. In this study, we determined transpiration of four maize plants on a field of the research station Scheyern (about 40km North of Munich) by means of sap flow measurement devices (ICQ International Pty Ltd, Australia) using the Heat-Ratio-Method: two temperature probes, 0.5 cm above and below a heater, detect a heat pulse and its speed which facilitates the calculation of sap flow. Additionally, high resolution changes of stem diameters were measured with dendrometers (DD-S, Ecomatik). The field was also situated next to an eddy covariance station which provided latent heat fluxes from the soil-plant system. We also performed terrestrial laser scans of the respective plants to extract the plant architectures. These structures serve as input for our mechanistic transpiration model simulating the water transport within the plant. This model, which has already been successfully applied to single Fagus sylvatica L. trees, was adapted to agricultural plants such as maize. The basic principle of this model is to solve a 1-D Richards equation along the graph of the single plants. A comparison between the simulations and the measurements is presented and discussed.

  13. Studying Drinking Water Quality and its Change During Transportation through Samara Water-Supply Facilities

    Science.gov (United States)

    Kichigin, V. I.; Egorova, Y. A.; Nesterenko, O. I.

    2017-11-01

    The paper investigates changes in water physico-chemical composition and its physical indicators through ζ-potential in residential buildings in eight administrative districts of Samara. The results are processed by the methods of mathematical statistics and presented at the 0.05 level of importance. The sampling points for water in the city districts were chosen with the aid of random numbers tables. It was determined that the quality of drinking water was stable and consistent with the existing standards in Zheleznodorozhniy, Samarskiy, Leninskiy, Octyabrskiy, Kirovsliy, Sovetskiy and Promyshlenniy districts of Samara. The following indicators were taken into account: pH, colour, turbidity, alkalinity, general rigidity, content of ions Ca2 +, Mg2 +. It was also established that drinking water in Kuibyshevskiy district (with all other excellent indicators) had increased mineralization due to the natural hydrological conditions of the water inlet. Some change in the size of zeta-potential of the water was detected during its transportation through the existing water-supplying networks of the city. It was shown that the link between zeta-potential and various kinds of contamination in drinking water is underexplored and requires further detailed study.

  14. 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...

  15. Monitoring water distribution systems: understanding and managing sensor networks

    Directory of Open Access Journals (Sweden)

    D. D. Ediriweera

    2010-09-01

    Full Text Available Sensor networks are currently being trialed by the water distribution industry for monitoring complex distribution infrastructure. The paper presents an investigation in to the architecture and performance of a sensor system deployed for monitoring such a distribution network. The study reveals lapses in systems design and management, resulting in a fifth of the data being either missing or erroneous. Findings identify the importance of undertaking in-depth consideration of all aspects of a large sensor system with access to either expertise on every detail, or to reference manuals capable of transferring the knowledge to non-specialists. First steps towards defining a set of such guidelines are presented here, with supporting evidence.

  16. Using molecular-scale tracers to investigate transport of agricultural pollutants in soil and water

    Science.gov (United States)

    Lloyd, C.; Michaelides, K.; Chadwick, D.; Dungait, J.; Evershed, R. P.

    2012-12-01

    unique to ruminant faeces, were used to trace the transport of sediment-bound pollutants from the slurry which could be transported into water bodies via erosion processes. The results showed that contributions of potential pollutants from the surface and subsurface flow pathways and from the eroded sediment differ according to slope gradient and rainfall intensity. Therefore, as the contribution of each of these pathways changes in response to rainfall and slope gradient, the pollution risk also changes accordingly, as different organic compounds are mobilised at varying rates. Rapid hydrological response to rainfall results in erosion and surface transport of sediment-bound and dissolved pollutants, creating an immediate contamination threat. However, conditions resulting in a slower hydrological response and the predominance of flow percolation over surface runoff results in higher rates of dissolved pollutant transport through the soil layers which risks contamination of subsurface and deeper ground-water systems. These experiments provide insight into the pathways and timing of contaminant transport with potential implications for understanding contamination risk from the transfer of slurry from land to water bodies. Understanding this threat is critical at a time when pressure is on to develop land-management strategies to reduce pollution alongside maintaining food security.

  17. Root for rain : Towards understanding land-use change impacts on the water cycle

    NARCIS (Netherlands)

    Wang-Erlandsson, L.

    2017-01-01

    We live today on a human-dominated planet under unprecedented pressure on both land and water. The water cycle is intrinsically linked to vegetation and land use, and anticipating the consequences of simultaneous changes in land and water systems requires a thorough understanding of their

  18. FEATURES OF TRANSPORT OF CERTAIN ELEMENTS IN WATER NORTH CASPIAN

    Directory of Open Access Journals (Sweden)

    E. V. Chujko

    2013-01-01

    Full Text Available Major influence on the form of migration of trace elements in the North Caspian has Volga runoff. The bulk of the elements in the Volga waters carried in the suspended solids. The exception is zinc, transports mainly in dissolved form.In article presents the results of a study of dissolved and suspended forms of zinc, copper, lead, and manganese in the surface water of the North Caspian Sea from 2002 to 2009. On the basis of the received data the ratio of dissolved and suspended forms of trace elements studied. According to calculations, the bulk of the copper, lead and manganese is carried in the suspended solids. Zinc migrates mainly in dissolved form. The dominant form of migration of the metal increases, depending on the season. For zinc, the migrant in the ionic state, and for copper, lead, manganese, transferring primarily in suspension, in the autumn period the increase in the proportion of dissolved (Zn and suspended forms (Cu, Pb, Mn, respectively. Increase in the proportion of ionic forms of metals in the North Caspian occurred episodically in local areas. Over the entire study period the greatest number of excess dissolved form of weighted metal observed in the central part of the shallow zone predustevogo space p. Volga near the exit of the Kirov and Belinsky channels.

  19. IMS (International Magnetospheric Study) contributions to the understanding of auroral precipitation, transport, and particle sources

    Energy Technology Data Exchange (ETDEWEB)

    Fennell, J.F.

    1985-03-01

    The progress in our understanding of plasma processes throughout the magnetosphere has increased dramatically during the International Magnetospheric Study (IMS) period. In this report the auroral ionosphere as a source of particles for the magnetosphere and the auroral particle acceleration and precipitation are emphasized. Some of the processes involved in the transport of particles from the ionosphere out into the magnetosphere are treated as well as the precipitation of magnetospheric particles into the auroral and subauroral ionosphere. Some of the effects auroral ionospheric ions have on the magnetospheric plasma composition are described. A brief overview of pre-IMS results is also given to set the stage for a description of IMS contributions in these areas.

  20. Progress towards increased understanding and control of internal transport barriers (ITBs) on DIII-D

    International Nuclear Information System (INIS)

    Doyle, E.J.; Greenfield, C.M.; Austin, M.E.

    2001-01-01

    Substantial progress has been made towards both understanding and control of internal transport barriers (ITBs) on DIII-D, resulting in the discovery of a new sustained high performance operating mode termed the Quiescent Double-Barrier (QDB) regime. The QDB regime combines core transport barriers with a quiescent, ELM-free H-mode edge (termed QH-mode), giving rise to separate (double) core and edge transport barriers. The core and edge barriers are mutually compatible and do not merge, resulting in broad core profiles with an edge pedestal. The QH-mode edge is characterized by ELM-free behavior with continuous multiharmonic MHD activity in the pedestal region, and has provided density and impurity control for 3.5 s (>20 τ E ) with divertor pumping. QDB plasmas are long-pulse high-performance candidates, having maintained a β N H 89 product of 7 for 5 energy confinement times (T i ≤16 keV, β N ≤2.9, H 89 ≤2.4, τ E ≤150 ms, DD neutron rate S n ≤4x10 15 s -1 ). The QDB regime has only been obtained in counter-NBI discharges (injection anti-parallel to plasma current) with divertor pumping. Other results include successful expansion of the ITB radius using (separately) both impurity injection and counter-NBI, and the formation of ITBs in the electron thermal channel using both ECH and strong negative central shear (NCS) at high power. These results are interpreted within a theoretical framework in which turbulence suppression is the key to ITB formation and control, and a decrease in core turbulence is observed in all cases of ITB formation. (author)

  1. Geohydrology and possible transport routes of polychlorinated biphenyls in Haiku Valley, Oahu, Hawaii. Water resources investigation

    Energy Technology Data Exchange (ETDEWEB)

    Izuka, S.K.; Hill, B.R.; Shade, P.J.; Tribble, G.W.

    1991-01-01

    The report discusses geohydrologic evidence of ground-water and surface-water movement and sediment transport in an effort to identify routes by which water-borne contaminants may be transported within and beyond Haiku Valley. Specifically, the report describes the geologic framework of the valley and the bearing it has on the movement of ground water, and water budget of the Haiku Valley basin, the exchange between ground water and surface water, and the movement of sediment by surface water. The concentration of PCBs carried in suspended stream sediment is also described.

  2. 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.

  3. 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.

  4. Investigation of interactive effects on water flow and solute transport in sandy loam soil using time domain reflectometry.

    Science.gov (United States)

    Merdun, Hasan

    2012-01-01

    Surface-applied chemicals move through the unsaturated zone with complex flow and transport processes due to soil heterogeneity and reach the saturated zone, resulting in groundwater contamination. Such complex processes need to be studied by advanced measurement and modeling techniques to protect soil and water resources from contamination. In this study, the interactive effects of factors like soil structure, initial soil water content (SWC), and application rate on preferential flow and transport were studied in a sandy loam field soil using measurement (by time domain reflectometry (TDR)) and modeling (by MACRO and VS2DTI) techniques. In addition, statistical analyses were performed to compare the means of the measured and modeled SWC and EC, and solute transport parameters (pore water velocity and dispersion coefficient) in 12 treatments. Research results showed that even though the effects of soil structural conditions on water and solute transport were not so clear, the applied solution moved lower depths in the profiles of wet versus dry initial SWC and high application rate versus low application rates. The effects of soil structure and initial SWC on water and solute movement could be differentiated under the interactive conditions, but the effects of the application rates were difficult to differentiate under different soil structural and initial SWC conditions. Modeling results showed that MACRO had somewhat better performance than VS2DTI in the estimation of SWC and EC with space and time, but overall both models had relatively low performances. The means of SWC, EC, and solute transport parameters of the 12 treatments were divided into some groups based on the statistical analyses, indicating different flow and transport characteristics or a certain degree nonuniform or preferential flow and transport in the soil. Conducting field experiments with more interactive factors and applying the models with different approaches may allow better understanding

  5. Does water content or flow rate control colloid transport in unsaturated porous media?

    Science.gov (United States)

    Knappenberger, Thorsten; Flury, Markus; Mattson, Earl D; Harsh, James B

    2014-04-01

    Mobile colloids can play an important role in contaminant transport in soils: many contaminants exist in colloidal form, and colloids can facilitate transport of otherwise immobile contaminants. In unsaturated soils, colloid transport is, among other factors, affected by water content and flow rate. Our objective was to determine whether water content or flow rate is more important for colloid transport. We passed negatively charged polystyrene colloids (220 nm diameter) through unsaturated sand-filled columns under steady-state flow at different water contents (effective water saturations Se ranging from 0.1 to 1.0, with Se = (θ - θr)/(θs - θr)) and flow rates (pore water velocities v of 5 and 10 cm/min). Water content was the dominant factor in our experiments. Colloid transport decreased with decreasing water content, and below a critical water content (Se colloid transport was inhibited, and colloids were strained in water films. Pendular ring and water film thickness calculations indicated that colloids can move only when pendular rings are interconnected. The flow rate affected retention of colloids in the secondary energy minimum, with less colloids being trapped when the flow rate increased. These results confirm the importance of both water content and flow rate for colloid transport in unsaturated porous media and highlight the dominant role of water content.

  6. Understanding the reaction of nuclear graphite with molecular oxygen: Kinetics, transport, and structural evolution

    Science.gov (United States)

    Kane, Joshua J.; Contescu, Cristian I.; Smith, Rebecca E.; Strydom, Gerhard; Windes, William E.

    2017-09-01

    For the next generation of nuclear reactors, HTGRs specifically, an unlikely air ingress warrants inclusion in the license applications of many international regulators. Much research on oxidation rates of various graphite grades under a number of conditions has been undertaken to address such an event. However, consequences to the reactor result from the microstructural changes to the graphite rather than directly from oxidation. The microstructure is inherent to a graphite's properties and ultimately degradation to the graphite's performance must be determined to establish the safety of reactor design. To understand the oxidation induced microstructural change and its corresponding impact on performance, a thorough understanding of the reaction system is needed. This article provides a thorough review of the graphite-molecular oxygen reaction in terms of kinetics, mass and energy transport, and structural evolution: all three play a significant role in the observed rate of graphite oxidation. These provide the foundations of a microstructurally informed model for the graphite-molecular oxygen reaction system, a model kinetically independent of graphite grade, and capable of describing both the observed and local oxidation rates under a wide range of conditions applicable to air-ingress.

  7. 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.

  8. Radiotracer method to study the transport of mercury(II)chloride from water to sediment and air

    International Nuclear Information System (INIS)

    Karaca, F.; Aras, N.K.

    2004-01-01

    The fate of dissolved Hg(II) in surface waters is an important component of the Hg cycle. A simple experimental methodology was used to understand and measure the transport of Hg(II) from water to air and sediment. The use of radioactive dissolved Hg tracer for the determination of evasion and deposition is found to be a very useful technique. The evasion of mercury was investigated during a 140-hour period. It was observed that about a quarter of mercury chloride remained in the water phase, the other quarter was emitted via the evasion process and half of it deposited in sediment. (author)

  9. Scaling relationship for surface water transport in stream networks and sub-surface flow interaction

    Science.gov (United States)

    Worman, A.

    2005-12-01

    Ground surface topography is known to control the circulation pattern of groundwater and also reflects the surface hydrological pathways through the landscape. This means that similar geometrical distributions typical to the landscape can be related physically-mathematically to the overall circulation of water and solute elements on land. Such understanding is needed in the management of water resources, especially on the watershed scale or larger. This paper outlines a theory by which we represent landscape topography in terms of its Fourier spectrum of a typical wave-function, formally relate this spectrum to the sub-surface flow of water and solute elements. Further, the stream network characteristics is analysed both in terms of the fractal distribution of individual stream lengths and the distribution of total transport distances in the watershed. Empirical relationships between the three types of distributions are established for two example watersheds in the middle and southern Sweden. Because the flow of water and solute elements in the stream network can also be described by convoluting unit solutions over the stream network, this paper describes an approach that relate lanscape topography to hydrological and geochemical circulation. The study shows that surface topography, stream network characteristics and thickness of quaternary deposits controls the circulation pattern of the deep groundwater. The water exchange is controlled by topography on both the continental scale as well as regional scale. The residence of deep groundwater in the stream network - before entering the coastal zone - is, therefore also controlled by the landscape topography.

  10. 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

  11. Water insecurity in a syndemic context: Understanding the psycho-emotional stress of water insecurity in Lesotho, Africa.

    Science.gov (United States)

    Workman, Cassandra L; Ureksoy, Heather

    2017-04-01

    Syndemics occur when populations experience synergistic and multiplicative effects of co-occurring epidemics. Proponents of syndemic theory highlight the importance of understanding the social context in which diseases spread and cogently argue that there are biocultural effects of external stresses such as food insecurity and water insecurity. Thus, a holistic understanding of disease or social vulnerability must incorporate an examination of the emotional and social effects of these phenomena. This paper is a response to the call for a renewed focus on measuring the psycho-emotional and psychosocial effects of food insecurity and water insecurity. Using a mixed-method approach of qualitative interviews and quantitative assessment, including a household demographic, illness, and water insecurity scale, the Household Food Insecurity Access Scale, and the Hopkins Symptoms Checklist-25, this research explored the psycho-emotional effects of water insecurity, food insecurity, and household illness on women and men residing in three low-land districts in Lesotho (n = 75). Conducted between February and November of 2011, this exploratory study first examined the complicated interaction of water insecurity, food insecurity and illness to understand and quantify the relationship between these co-occurring stresses in the context of HIV/AIDS. Second, it sought to separate the role of water insecurity in predicting psycho-emotional stress from other factors, such as food insecurity and household illness. When asked directly about water, qualitative research revealed water availability, access, usage amount, and perceived water cleanliness as important dimensions of water insecurity, creating stress in respondents' daily lives. Qualitative and quantitative data show that water insecurity, food insecurity and changing household demographics, likely resulting from the HIV/AIDS epidemic, are all associated with increased anxiety and depression, and support the conclusion that

  12. Understanding the circulation of geothermal waters in the Tibetan Plateau using oxygen and hydrogen stable isotopes

    International Nuclear Information System (INIS)

    Tan, Hongbing; Zhang, Yanfei; Zhang, Wenjie; Kong, Na; Zhang, Qing; Huang, Jingzhong

    2014-01-01

    Highlights: • Unique geothermal resources in Tibetan Plateau were discussed. • Isotopes were used to trace circulation of geothermal water. • Magmatic water mixing dominates geothermal water evolution. - Abstract: With the uplift of the Tibetan Plateau, many of the world’s rarest and most unique geothermal fields have been developed. This study aims to systematically analyze the characteristics of the hydrogen and oxygen isotopic data of geothermal, river, and lake waters to understand the circulation of groundwater and to uncover the mechanism of geothermal formation in the Tibetan Plateau. Field observations and isotopic data show that geothermal water has higher temperatures and hydraulic pressures, as well as more depleted D and 18 O isotopic compositions than river and lake waters. Thus, neither lakes nor those larger river waters are the recharge source of geothermal water. Snow-melt water in high mountains can vertically infiltrate and deeply circulate along some stretching tensile active tectonic belts or sutures and recharge geothermal water. After deep circulation, cold surface water evolves into high-temperature thermal water and is then discharged as springs at the surface again in a low area, under high water-head difference and cold–hot water density difference. Therefore, the large-scale, high-temperature, high-hydraulic-pressure geothermal systems in the Tibetan Plateau are developed and maintained by rapid groundwater circulation and the heat source of upwelled residual magmatic water. Inevitably, the amount of geothermal water will increase if global warming accelerates the melting of glaciers in high mountains

  13. 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.

  14. 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

  15. Simulating charge transport to understand the spectral response of Swept Charge Devices

    Science.gov (United States)

    Athiray, P. S.; Sreekumar, P.; Narendranath, S.; Gow, J. P. D.

    2015-11-01

    Context. Swept Charge Devices (SCD) are novel X-ray detectors optimized for improved spectral performance without any demand for active cooling. The Chandrayaan-1 X-ray Spectrometer (C1XS) experiment onboard the Chandrayaan-1 spacecraft used an array of SCDs to map the global surface elemental abundances on the Moon using the X-ray fluorescence (XRF) technique. The successful demonstration of SCDs in C1XS spurred an enhanced version of the spectrometer on Chandrayaan-2 using the next-generation SCD sensors. Aims: The objective of this paper is to demonstrate validation of a physical model developed to simulate X-ray photon interaction and charge transportation in a SCD. The model helps to understand and identify the origin of individual components that collectively contribute to the energy-dependent spectral response of the SCD. Furthermore, the model provides completeness to various calibration tasks, such as generating spectral matrices (RMFs - redistribution matrix files), estimating efficiency, optimizing event selection logic, and maximizing event recovery to improve photon-collection efficiency in SCDs. Methods: Charge generation and transportation in the SCD at different layers related to channel stops, field zones, and field-free zones due to photon interaction were computed using standard drift and diffusion equations. Charge collected in the buried channel due to photon interaction in different volumes of the detector was computed by assuming a Gaussian radial profile of the charge cloud. The collected charge was processed further to simulate both diagonal clocking read-out, which is a novel design exclusive for SCDs, and event selection logic to construct the energy spectrum. Results: We compare simulation results of the SCD CCD54 with measurements obtained during the ground calibration of C1XS and clearly demonstrate that our model reproduces all the major spectral features seen in calibration data. We also describe our understanding of interactions at

  16. Review on the development of unidirectional water-transport fibers and fabrics

    Directory of Open Access Journals (Sweden)

    Yaqian XIAO

    2017-08-01

    Full Text Available Unidirectional water-transport fabric is a kind of functional fiber assembles used to realize unidirectional conduction of liquid water, and it could be used for the design and development of clothing with the function of thermal-wet comfort. The development of unidirectional water-transport fabrics from the mechanism of the unidirectional water-transport, selection of fiber and preparation method is summarized. Five key methods to achieve the unidirectional water-transport effect have been reviewed, including the designing of fabric structure, chemical finishing, plasma treatment, electro spinning and photocatalytic treatment. According to the current problems in the research on unidirectional water-transfer fabric, it is proposed that multi-functional unidirectional water-transfer fabrics should be developed by post-treatment finishing technology with adding special functional additives to expand the practical applications.

  17. 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 s...

  18. Water absorption in PEEK and PEI matrices. Contribution to the understanding of water-polar group interactions

    Science.gov (United States)

    Courvoisier, E.; Bicaba, Y.; Colin, X.

    2016-05-01

    The water absorption in two aromatic linear polymers (PEEK and PEI) was studied between 10% and 90% RH at 30, 50 and 70°C. It was found that these polymers display classical Henry and Fick's behaviors. Moreover, they have very close values of equilibrium water concentration C∞ and water diffusivity D presumably because their respective polar groups establish molecular interactions of the same nature with water. This assumption was checked from a literature compilation of values of C∞ and D for a large variety of linear and tridimensional polymers containing a single type of polar group. It was then evidenced that almost all types of carbonyl group (in particular, those belonging to imides, amides and ketones) have the same molar contribution to water absorption, except those belonging to esters which are much less hydrophilic. Furthermore, hydroxyl and sulfone groups are much more hydrophilic than carbonyl groups so that their molar contribution is located on another master curve. On this basis, semi-empirical structure/water transport property relationships were proposed. It was found that C∞ increases exponentially with the concentration of polar groups (presumably because water is doubly bonded), but also with the intensity of their molecular interactions with water. In contrast, D is inversely proportional to C∞, which means that polar group-water interactions slow down the rate of water diffusion.

  19. Environmental (Saprozoic Pathogens of Engineered Water Systems: Understanding Their Ecology for Risk Assessment and Management

    Directory of Open Access Journals (Sweden)

    Nicholas J. Ashbolt

    2015-06-01

    Full Text Available Major waterborne (enteric pathogens are relatively well understood and treatment controls are effective when well managed. However, water-based, saprozoic pathogens that grow within engineered water systems (primarily within biofilms/sediments cannot be controlled by water treatment alone prior to entry into water distribution and other engineered water systems. Growth within biofilms or as in the case of Legionella pneumophila, primarily within free-living protozoa feeding on biofilms, results from competitive advantage. Meaning, to understand how to manage water-based pathogen diseases (a sub-set of saprozoses we need to understand the microbial ecology of biofilms; with key factors including biofilm bacterial diversity that influence amoebae hosts and members antagonistic to water-based pathogens, along with impacts from biofilm substratum, water temperature, flow conditions and disinfectant residual—all control variables. Major saprozoic pathogens covering viruses, bacteria, fungi and free-living protozoa are listed, yet today most of the recognized health burden from drinking waters is driven by legionellae, non-tuberculous mycobacteria (NTM and, to a lesser extent, Pseudomonas aeruginosa. In developing best management practices for engineered water systems based on hazard analysis critical control point (HACCP or water safety plan (WSP approaches, multi-factor control strategies, based on quantitative microbial risk assessments need to be developed, to reduce disease from largely opportunistic, water-based pathogens.

  20. Interventions and Interactions: Understanding Coupled Human-Water Dynamics for Improved Water Resources Management in the Himalayas

    Science.gov (United States)

    Crootof, A.

    2017-12-01

    Understanding coupled human-water dynamics offers valuable insights to address fundamental water resources challenges posed by environmental change. With hydropower reshaping human-water interactions in mountain river basins, there is a need for a socio-hydrology framework—which examines two-way feedback loops between human and water systems—to more effectively manage water resources. This paper explores the cross-scalar interactions and feedback loops between human and water systems in river basins affected by run-of-the-river hydropower and highlights the utility of a socio-hydrology perspectives to enhance water management in the face of environmental change. In the Himalayas, the rapid expansion of run-of-the-river hydropower—which diverts streamflow for energy generation—is reconfiguring the availability, location, and timing of water resources. This technological intervention in the river basin not only alters hydrologic dyanmics but also shapes social outcomes. Using hydropower development in the highlands of Uttarakhand, India as a case study, I first illustrate how run-of-the-river projects transform human-water dynamics by reshaping the social and physical landscape of a river basin. Second, I emphasize how examining cross-scalar feedbacks among structural dynamics, social outcomes, and values and norms in this coupled human-water system can inform water management. Third, I present hydrological and social literature, raised separately, to indicate collaborative research needs and knowledge gaps for coupled human-water systems affected by run-of-the-river hydropower. The results underscore the need to understand coupled human-water dynamics to improve water resources management in the face of environmental change.

  1. Understanding the effectiveness of vegetated streamside management zones for protecting water quality (Chapter 5)

    Science.gov (United States)

    Philip Smethurst; Kevin Petrone; Daniel Neary

    2012-01-01

    We set out to improve understanding of the effectiveness of streamside management zones (SMZs) for protecting water quality in landscapes dominated by agriculture. We conducted a paired-catchment experiment that included water quality monitoring before and after the establishment of a forest plantation as an SMZ on cleared farmland that was used for extensive grazing....

  2. 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

  3. Study of sediment transport in Semarang coastal water using 198 Au radioactive tracer

    International Nuclear Information System (INIS)

    Supriatna, Dadang; Sukarmadijaya, Harun; Barokah

    2000-01-01

    Most nearshore aquatic system adjacent to urban centers are characterized by contaminated fine sediment deposits that were brought in from variety sources. Banjir Kanal Timur, Tambak Lorok and Tenggang are rivers that across of Semarang city and have a mouth at same location, that location are potential pollutant sources for Semarang coastal water, so the knowledge of sediment transport in Semarang coastal is very important for management and sustainable that area. One techniques to understand transport of sediment is radioactive tracer have several major advantages, high detection sensitivity, unique possibility of being measured in situ providu information in the shortest possible time. Specific gravity and particle size distribution analysis indicate that there was on differences between nature sediment compare whit labelled sediment. Contour of movement pattern of radiotracer shows sediment towards North, while disressing moved to left and right direction with mean velocity of 5.65 m/day. Sediment transport rate was calculated of 780.7 kg/m/day with the thickness of the mobile layer sediment 5.2 cm

  4. Organic nature of colloidal actinides transported in surface water environments.

    Science.gov (United States)

    Santschi, Peter H; Roberts, Kimberly A; Guo, Laodong

    2002-09-01

    Elevated levels of (239,240)Pu and 241Am have been present in surficial soils of the Rocky Flats Environmental Technology Site (RFETS), CO, since the 1960s, when soils were locally contaminated in the 1960s by leaking drums stored on the 903 Pad. Further dispersion of contaminated soil particles was by wind and water. From 1998 until 2001, we examined actinide ((239,240)Pu and 241Am) concentrations and phase speciation in the surface environment at RFETS through field studies and laboratory experiments. Measurements of total (239,240)Pu and 241Am concentrations in storm runoff and pond discharge samples, collected during spring and summer times in 1998-2000, demonstrate that most of the (239,240)Pu and 241Am transported from contaminated soils to streams occurred in the particulate (> or = 0.45 microm; 40-90%) and colloidal (approximately 2 nm or 3 kDa to 0.45 microm; 10-60%) phases. Controlled laboratory investigations of soil resuspension, which simulated storm and erosion events, confirmed that most of the Pu in the 0.45 microm filter-passing phase was in the colloidal phase (> or = 80%) and that remobilization of colloid-bound Pu during soil erosion events can be greatly enhanced by humic and fulvic acids present in these soils. Most importantly, isoelectric focusing experiments of radiolabeled colloidal matter extracted from RFETS soils revealed that colloidal Pu is in the four-valent state and is mostly associated with a negatively charged organic macromolecule with a pH(IEP) of 3.1 and a molecular weight of 10-15 kDa, rather than with the more abundant inorganic (iron oxide and clay) colloids. This finding has important ramifications for possible remediation, erosion controls, and land-management strategies.

  5. 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

  6. 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.

  7. Wading through Perceptions: Understanding Human Perceptions of Water Quality in Coastal Waters

    Science.gov (United States)

    Water quality perceptions influence people’s preferences for visiting coastal areas and willingness to participate in activities on or near the water. They also influence people’s social values for a waterbody, sense of place, support for protection of a waterbody, an...

  8. Continuous water-quality and suspended-sediment transport monitoring in the San Francisco Bay, California, water years 2011–13

    Science.gov (United States)

    Buchanan, Paul A.; Downing-Kunz, Maureen; Schoellhamer, David H.; Shellenbarger, Gregory; Weidich, Kurt

    2014-01-01

    The U.S. Geological Survey (USGS) monitors water quality and suspended-sediment transport in the San Francisco Bay. The San Francisco Bay area is home to millions of people, and the bay teems with both resident and migratory wildlife, plants, and fish. Fresh water mixes with salt water in the bay, which is subject both to riverine and marine (tides, waves, influx of salt water) influences. To understand this environment, the USGS, along with its partners, has been monitoring the bay’s waters continuously since 1988. Several water-quality variables are of particular importance to State and Federal resource managers and are monitored at key locations throughout the bay. Salinity, which indicates the relative mixing of fresh and ocean waters in the bay, is derived from specific conductance measurements. Water temperature, along with salinity, affects the density of water, which causes gravity driven circulation patterns and stratification in the water column. Turbidity is measured using light-scattering from suspended solids in water, and is used as a surrogate for suspended-sediment concentration (SSC). Suspended sediment often carries adsorbed contaminants; attenuates sunlight in the water column; deposits on tidal marsh and intertidal mudflats, which can help sustain these habitats as sea level rises; and deposits in ports and shipping channels, which can necessitate dredging. Dissolved oxygen, which is essential to a healthy ecosystem, is a fundamental indicator of water quality, and its concentration is affected by water temperature, salinity, ecosystem metabolism, tidal currents, and wind. Tidal currents in the bay reverse four times a day, and wind direction and intensity typically change on a daily cycle: consequently, salinity, water temperature, suspendedsediment concentration, and dissolvedoxygen concentration vary spatially and temporally throughout the bay, and continuous measurements are needed to observe these changes. The purpose of this fact sheet

  9. Interaction between transcellular and paracellular water transport pathways through Aquaporin 5 and the tight junction complex

    OpenAIRE

    Kawedia, Jitesh D.; Nieman, Michelle L.; Boivin, Gregory P.; Melvin, James E.; Kikuchi, Ken-Ichiro; Hand, Arthur R.; Lorenz, John N.; Menon, Anil G.

    2007-01-01

    To investigate potential physiological interactions between the transcellular and paracellular pathways of water transport, we asked whether targeted deletion of Aquaporin 5 (AQP5), the major transcellular water transporter in salivary acinar cells, affected paracellular transport of 4-kDa FITC-labeled dextran (FITC-D), which is transported through the paracellular but not the transcellular route. After i.v. injection of FITC-D into either AQP5 wild-type or AQP5−/− mice and saliva collection ...

  10. Quantitative imaging of water transport in soil and roots using neutron radiography, D2O and a new numerical model

    Science.gov (United States)

    Zarebanadkouki, M.; Kroener, E.; Ahmed, M. A.; Carminati, A.

    2014-12-01

    Our understanding of soil and plant water relations is currently limited by the lack of experimental methods to measure the water fluxes in soil and plants. Our study aimed to develop a new non-destructive method to measure the local fluxes of water into roots of plants growing in soils. We injected deuterated water (D2O) near the roots of lupines growing in sandy soils, and we used neutron radiography to image the transport of D2O through the root system. The experiments were performed during day, when plants were transpiring, and at night, when transpiration was reduced. The radiographs showed that: 1) the radial transport of D2O from soil and roots depended similarly to diffusion and convection; and 2) the axial transport of D2O along the root xylem was largely dominated by convection. To determine the convective fluxes from the radiographs, we simulated the D2O transport in soils and roots. A dual porosity model was used to describe the apoplastic and symplastic pathways of water across the root tissue. Other features such as the endodermis and the xylem were also included in the model. The D2O transport was modelled solving a convection-diffusion numerical model in soil and plants. The diffusion coefficients of the root tissues were inversely estimated by simulating the experiments at night under the assumption that at night the convective fluxes were negligible. Inverse modelling of the experiment at day gave the profile of water fluxes into the roots. For 24 day-old lupine grown in a sandy soil with uniform water content, our modelling results showed that root water uptake was higher at the proximal parts of the roots near soil surface and it decreased toward the distal parts. The method allows the quantification of the root properties and the regions of root water uptake along root systems growing in soils. Future applications of this method include the characterization of varying root systems, the radial and axial hydraulic conductivity of different root

  11. Analysis of drought characteristics for improved understanding of a water resource system

    Directory of Open Access Journals (Sweden)

    A. T. Lennard

    2014-09-01

    Full Text Available Droughts are a reoccurring feature of the UK climate; recent drought events (2004–2006 and 2010–2012 have highlighted the UK’s continued vulnerability to this hazard. There is a need for further understanding of extreme events, particularly from a water resource perspective. A number of drought indices are available, which can help to improve our understanding of drought characteristics such as frequency, severity and duration. However, at present little of this is applied to water resource management in the water supply sector. Improved understanding of drought characteristics using indices can inform water resource management plans and enhance future drought resilience. This study applies the standardised precipitation index (SPI to a series of rainfall records (1962–2012 across the water supply region of a single utility provider. Key droughts within this period are analysed to develop an understanding of the meteorological characteristics that lead to, exist during and terminate drought events. The results of this analysis highlight how drought severity and duration can vary across a small-scale water supply region, indicating that the spatial coherence of drought events cannot be assumed.

  12. Experimental investigation of gas hydrate formation, plugging and transportability in partially dispersed and water continuous systems

    Science.gov (United States)

    Vijayamohan, Prithvi

    As oil/gas subsea fields mature, the amount of water produced increases significantly due to the production methods employed to enhance the recovery of oil. This is true especially in the case of oil reservoirs. This increase in the water hold up increases the risk of hydrate plug formation in the pipelines, thereby resulting in higher inhibition cost strategies. A major industry concern is to reduce the severe safety risks associated with hydrate plug formation, and significantly extending subsea tieback distances by providing a cost effective flow assurance management/safety tool for mature fields. Developing fundamental understanding of the key mechanistic steps towards hydrate plug formation for different multiphase flow conditions is a key challenge to the flow assurance community. Such understanding can ultimately provide new insight and hydrate management guidelines to diminish the safety risks due to hydrate formation and accumulation in deepwater flowlines and facilities. The transportability of hydrates in pipelines is a function of the operating parameters, such as temperature, pressure, fluid mixture velocity, liquid loading, and fluid system characteristics. Specifically, the hydrate formation rate and plugging onset characteristics can be significantly different for water continuous, oil continuous, and partially dispersed systems. The latter is defined as a system containing oil/gas/water, where the water is present both as a free phase and partially dispersed in the oil phase (i.e., entrained water in the oil). Since hydrate formation from oil dispersed in water systems and partially dispersed water systems is an area which is poorly understood, this thesis aims to address some key questions in these systems. Selected experiments have been performed at the University of Tulsa flowloop to study the hydrate formation and plugging characteristics for the partially dispersed water/oil/gas systems as well as systems where the oil is completely dispersed

  13. 40 CFR Appendix A to Part 112 - Memorandum of Understanding Between the Secretary of Transportation and the Administrator of the...

    Science.gov (United States)

    2010-07-01

    ... water or tank washings from vessels and associated systems used for off-loading vessels. (I) Loading... vehicles or railroad cars. (J) Highway vehicles and railroad cars which are used for the transport of oil... tank washings from vessels, but excluding terminal waste treatment facilities and terminal oil storage...

  14. Transport-limited water splitting at ion-selective interfaces during concentration polarization

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Peder; Bruus, Henrik

    2014-01-01

    We present an analytical model of salt- and water-ion transport across an ion-selective interface based on an assumption of local equilibrium of the water-dissociation reaction. The model yields current-voltage characteristics and curves of water-ion current versus salt-ion current, which are in ...

  15. 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....

  16. 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...

  17. Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer

    Science.gov (United States)

    Griffis, Timothy J.; Wood, Jeffrey D.; Baker, John M.; Lee, Xuhui; Xiao, Ke; Chen, Zichong; Welp, Lisa R.; Schultz, Natalie M.; Gorski, Galen; Chen, Ming; Nieber, John

    2016-04-01

    Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle - an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m) in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL) over a 3-year period (2010 to 2012). These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from -40.2 to -15.9 ‰ and δ2Hv ranged from -278.7 to -113.0 ‰) and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv) of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( > 25 mmol mol-1) indicate that regional evaporation can account

  18. Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer

    Directory of Open Access Journals (Sweden)

    T. J. Griffis

    2016-04-01

    Full Text Available Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle – an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL over a 3-year period (2010 to 2012. These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from −40.2 to −15.9 ‰ and δ2Hv ranged from −278.7 to −113.0 ‰ and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( >  25 mmol mol−1

  19. 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.

  20. Water sorption and transport in dry crispy bread crust

    NARCIS (Netherlands)

    Meinders, M.B.J.; Nieuwenhuijzen, van N.H.; Tromp, R.H.; Hamer, R.J.; Vliet, van T.

    2010-01-01

    Water sorption and dynamical properties of bread crust have been studied using gravimetric sorption experiments. Water uptake and loss were followed while relative humidity (RH) was stepwise in- or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment).

  1. 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

  2. 33 CFR 336.2 - Transportation of dredged material for the purpose of disposal into ocean waters.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Transportation of dredged material for the purpose of disposal into ocean waters. 336.2 Section 336.2 Navigation and Navigable Waters... WATERS OF THE U.S. AND OCEAN WATERS § 336.2 Transportation of dredged material for the purpose of...

  3. Water transport through tomato roots infected with Meloidogyne incognita.

    NARCIS (Netherlands)

    Dorhout, R.; Gommers, F.J.; Kollöffel, C.

    1991-01-01


    The effect of Meloidogyne incognita on water flow in tomato roots was investigated in rooted split-stem cuttings. Total water flow through infected root parts was significantly lower than through comparable uninfected parts. Total water uptake was correlated with total length of the root

  4. Water vapor and gas transport through PEO PBT block copolymers

    NARCIS (Netherlands)

    Metz, S.J.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias

    2002-01-01

    Introduction At the bore well natural gas is saturated with water. Downstream the presence of water may cause: formation of methane hydrates (blocking eventually the pipeline), condensation of water in the pipeline and corrosion effects. A process used for the dehydration of natural gas is glycol

  5. Groundwater quality across scales: impact on nutrient transport to large water bodies

    Science.gov (United States)

    Dürr, Hans; Moosdorf, Nils; Mallast, Ulf

    2017-04-01

    High concentrations of dissolved nutrients such as nitrogen (N) and phosphorus (P) in groundwater are an increasing concern in many areas of the world. Especially regions with high agriculture impact see widespread declining groundwater quality, with considerable uncertainty mainly regarding the impact of phosphorus (P). Implications reach from direct impacts on different water users to discharge of nutrient-rich groundwater to rivers, lakes and coastal areas, where it can contribute to eutrophication, hypoxia or harmful algal blooms. While local-scale studies are abundant and management options exist, quantitative approaches at regional to continental scales are scarce and frequently have to deal with data inconsistencies or are temporally sparse. Here, we present the research framework to combine large databases of local groundwater quality to data sets of climatical, hydrological, geological or landuse parameters. Pooling of such information, together with robust methods such as water balances and groundwater models, can provide constraints such as upper boundaries and likely ranges of nutrient composition in various settings, or for the nutrient transport to large water bodies. Remote Sensing can provide spatial information on the location of groundwater seepage. Results will eventually help to identify focus areas and lead to improved understanding of the role of groundwater in the context of global biogeochemical cycles.

  6. Risk assessment of pesticide transport with water erosion: A conceptual model

    Science.gov (United States)

    Yang, Xiaomei; Van Der Zee, Sjoerd E. A. T. M.; Gai, Lingtong; Wesseling, Jan G.; Ritsema, Coen J.; Geissen, Violette

    2017-04-01

    Pesticides are widely used in agriculture, horticulture, and forestry, and pesticide pollution has become an important issue worldwide. Entraining in runoff and being attached to eroded soil particles, posing a risk to water and soil quality and human health. In order to assess the risk of pesticide during water erosion processes, a simple integrative model of pesticide transport by runoff and erosion was developed. Taking soil hydrological and pesticide behaviour into account, such as water infiltration, erosion, runoff, and pesticide transport and degradation in soil, the conceptual framework was based on the known assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. A sensitivity analysis was conducted and the results indicated that the total amount of pesticide related to soil eroded by water washing increased with slope gradient, rainfall intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became obviously and the time from pesticide sprayed to erosion occurring associated with pesticide degradation negatively influenced the total amount of transported pesticide. The mechanisms involved in pesticide transport, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, thus can be well accounted for pesticide risk assessment especially in the region with intensive pesticide use and soil water erosion events.

  7. Anatomical features associated with water transport in imperforate tracheary elements of vessel-bearing angiosperms

    Science.gov (United States)

    Sano, Yuzou; Morris, Hugh; Shimada, Hiroshi; Ronse De Craene, Louis P.; Jansen, Steven

    2011-01-01

    Background and Aims Imperforate tracheary elements (ITEs) in wood of vessel-bearing angiosperms may or may not transport water. Despite the significance of hydraulic transport for defining ITE types, the combination of cell structure with water transport visualization in planta has received little attention. This study provides a quantitative analysis of structural features associated with the conductive vs. non-conductive nature of ITEs. Methods Visualization of water transport was studied in 15 angiosperm species by dye injection and cryo-scanning electron microscopy. Structural features of ITEs were examined using light and electron microscopy. Key Results ITEs connected to each other by pit pairs with complete pit membranes contributed to water transport, while cells showing pit membranes with perforations up to 2 µm were hydraulically not functional. A close relationship was found between pit diameter and pit density, with both characters significantly higher in conductive than in non-conductive cells. In species with both conductive and non-conductive ITEs, a larger diameter was characteristic of the conductive cells. Water transport showed no apparent relationship with the length of ITEs and vessel grouping. Conclusions The structure and density of pits between ITEs represent the main anatomical characters determining water transport. The pit membrane structure of ITEs provides a reliable, but practically challenging, criterion to determine their conductive status. It is suggested that the term tracheids should strictly be used for conductive ITEs, while fibre-tracheids and libriform fibres are non-conductive. PMID:21385773

  8. Water as a transport medium for waste out of towns

    DEFF Research Database (Denmark)

    Harremoës, P.

    1999-01-01

    The historical background for centralised water management in the cities of the developed world is outlined in order to give the rationale for the technical solutions we have inherited from the last century. The key element is maintaining the hygienic conditions in the cities. The success is illu...... water use, because water is not lost, but polluted, which can be abated. Water can be re-routed and recycled. There are many attractive local solutions for better handling of urban water. (C) 1999 IAWQ Published by Elsevier Science Ltd.-All rights reserved....

  9. A deuterium-based labeling technique for the investigation of rooting depths, water uptake dynamics and unsaturated zone water transport in semiarid environments

    Science.gov (United States)

    Beyer, M.; Koeniger, P.; Gaj, M.; Hamutoko, J. T.; Wanke, H.; Himmelsbach, T.

    2016-02-01

    Non- or minimum-invasive methods for the quantification of rooting depths of plants are rare, in particular in (semi-)arid regions; yet, this information is crucial for the parameterization of SVAT (Soil-Vegetation-Atmosphere Transfer) models and understanding of processes within the hydrological cycle. We present a technique utilizing the stable isotope deuterium (2H) applied as artificial tracer to investigate the vertical extent of the root zone, characterize water uptake dynamics of trees and shrubs at different depths and monitor transport of water through the unsaturated zone of dry environments. One liter of 35% deuterated water (2H2O) was punctually applied at several depths (0.5 m, 1 m, 2 m, 2.5 m and 4 m) at six different plots at a natural forested site in the Cuvelai-Etosha Basin (CEB), Namibia/Angola. Subsequently, uptake of the tracer was monitored by collecting plant samples (xylem and transpired water) up to seven days after tracer injection. Soil profiles at the plots were taken after the campaign and again after six months in order to evaluate the transport and distribution of 2H within the unsaturated zone. Of 162 plant samples taken, 31 samples showed clear signals of artificially introduced 2H, of which all originate from the plots labeled up to 2 m depth. No artificially injected 2H was found in plants when tracer application occurred deeper than 2 m. Results further indicate a sharing of water resources between the investigated shrubs and trees in the upper 1 m whilst tree roots seem to have better access to deeper layers of the unsaturated zone. The soil profiles taken after six months reveal elevated 2H-concentrations from depths as great as 4 m up to 1 m below surface indicating upward transport of water vapor. Purely diffuse transport towards the soil surface yielded an estimated 0.4 mm over the dry season. Results are of particular significance for a more precise parameterization of SVAT models and the formulation of water balances in

  10. 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

  11. Overview of radiotracer experiments for better understanding of wastewater and water treatment plants in Lima (Peru))

    International Nuclear Information System (INIS)

    Calvo, C.S.; Maghella, G.; Mamani, E.; Berne, P.; Brisset, P.; Leclerc, J.-P.

    2004-01-01

    The objectives of this paper are to present an overview of possible applications of the radiotracers for better understanding of water and waste water treatment plants. Numerous experiments have been carried out in different plants located in Lima. Four processes have been investigated: desanders, floculators, clarifiers and digesters. Depending on the studied process, the experimental results have been interpreted at different levels of complexity: from simple troubleshooting to the modelling of the flow behaviour inside the process. (author)

  12. Understanding Municipal Officials' Involvement in Transportation Policies Supportive of Walking and Bicycling.

    Science.gov (United States)

    Zwald, Marissa L; Eyler, Amy A; Goins, Karin Valentine; Brownson, Ross C; Schmid, Thomas L; Lemon, Stephenie C

    Local transportation policies can impact the built environment and physical activity. Municipal officials play a critical role in transportation policy and planning decisions, yet little is known about what influences their involvement. To describe municipal officials' involvement in transportation policies that were supportive of walking and bicycling and to examine individual- and job-related predictors of involvement in transportation policies among municipal officials. A cross-sectional survey was administered online from June to July 2012 to municipal officials in 83 urban areas with a population of 50 000 or more residents across 8 states. A total of 461 municipal officials from public health, planning, transportation, public works, community and economic development, parks and recreation, city management, and municipal legislatures responded to the survey. Participation in the development, adoption, or implementation of a municipal transportation policy supportive of walking or bicycling. Multivariate logistic regression analyses, conducted in September 2013, revealed that perceived importance of economic development and traffic congestion was positively associated with involvement in a municipal transportation policy (odds ratio [OR] = 1.32, 95% confidence interval [CI] = 1.02-1.70; OR = 1.59, 95% CI = 1.26-2.01, respectively). Higher perceived resident support of local government to address economic development was associated with an increased likelihood of participation in a transportation policy (OR = 1.70, 95% CI = 1.24-2.32). Respondents who perceived lack of collaboration as a barrier were less likely to be involved in a transportation policy (OR = 0.78, 95% CI = 0.63-0.97). Municipal officials who lived in the city or town in which they worked were significantly more likely to be involved in a transportation policy (OR = 1.83, 95% CI = 1.05-3.17). Involvement in a local transportation policy by a municipal official was associated with greater

  13. Macroscopic analysis of characteristic water transport phenomena in polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hye-Mi [Graduate School, Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea); Lee, Kwan-Soo; Um, Sukkee [School of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea)

    2008-04-15

    Comprehensive analytical and numerical analyses were performed, focusing on anode water loss, cathode flooding, and water equilibrium for polymer electrolyte fuel cells. General features of water transport as a function of membrane thickness and current density were presented to illustrate the net effect of back-diffusion of water from the cathode to anode over a polymer electrolyte fuel cell domain. First, two-dimensional numerical simulation were performed, showing that the difference in molar concentration of water at the channel outlet is widened as the operating current density increases with a thin membrane (Nafion {sup registered} 111), which was verified by Dong et al. [Distributed performance of polymer electrolyte fuel cells under low-humidity conditions. J Electrochem Soc 2005; 152: A2114-22]. Then, analytical solutions were compared with computational results in predicting those characteristics of water transport phenomena. It was theoretically estimated that the high pressure operation of fuel cells expedites water condensing and results in shorter anode water loss and cathode flooding locations. In this study, it was also found that a thin membrane (Nafion {sup registered} 111) facilitates water transport in the through-membrane direction and therefore water concentration at the anode and cathode channel outlets reaches an equilibrium state particularly at low operating current densities. Moreover, the difference in the anode water concentration between Nafion {sup registered} 111 and Nafion {sup registered} 115 membranes becomes intensified in the in-plane direction under the same water production condition, while the cathode water concentration profiles remains almost same. (author)

  14. Understanding local water conflict and cooperation: The case of Namwala District, Zambia

    Science.gov (United States)

    Funder, Mikkel; Mweemba, Carol; Nyambe, Imasiku; van Koppen, Barbara; Ravnborg, Helle Munk

    Understanding the nature of water conflict and cooperation is a crucial element in water governance within Integrated Water Resources Management (IWRM). Much of the recent attention to the issue has however focused on transboundary aspects, while we know rather less about the nature and dynamics of local water conflict and cooperation. Drawing on the work of the collaborative Competing for Water Research Programme, this article presents selected findings from a quantitative and qualitative mapping and exploration of water conflict and cooperation events in Namwala District of Zambia. It is found that local water competition situations often involve both conflictive and cooperative events in a dynamic succession of each other, but also that the majority of events are conflictive, and that they primarily take place between different types of water uses, and less frequently among the same types of uses. There is a distinct tendency for both conflictive and cooperative events to originate in the dry season, and many events are associated with water infrastructure development, particularly boreholes. The study found that most conflictive and cooperative events took place within individual communities, and only to a lesser extent between two or more communities or between districts. While third parties are involved in some events, these are primarily local village institutions such as Headmen. The article concludes by discussing the implications of these findings for local water governance, including the need to ensure that the very localized nature of such conflict and cooperation events is taken into consideration in the institutional development of IWRM.

  15. Understanding the Spatial and Temporal Variations in Hormone Transport within the Stream Ecosystem

    Science.gov (United States)

    Mallakpour, I.; Ward, A. S.; Basu, N. B.

    2012-12-01

    Agricultural, urban, and industrial activities, including land application of manures and discharge of municipal and industrial wastewater, act as point and nonpoint sources for steroid hormones in soils, water, and sediments. Hormones are endocrine disruptors, and their occurrence in stream ecosystems has been implicated in the decline of certain species and change of sex in fish. Laboratory studies indicate that steroid hormones tend to have moderately large sorption coefficients and relatively short half-lives, from a few hours to a few days, suggesting that their persistence and subsequent leaching from soils will be limited. However, these chemicals continue to be detected in streams, indicating that laboratory studies may not capture the coupled hydrologic and biogeochemical dynamics occurring at the field or stream-reach scale. Understanding the spatial and temporal persistence of these chemicals downstream of a confined animal feeding operation (CAFO) or wastewater treatment plant (WWTP) requires a coupled hydrologic and biogeochemical model that takes into account multiple interacting species, sediment processes, and different aerobic and anaerobic reaction pathways and rates. In this study, we focus on two hormones, estrone (E1) and 17β-estradiol (E2), with redox dynamics controlling the conversion between E1 and E2. A 1D stream-reach model with a main-channel and a hyporheic zone was developed similar to the commonly used OTIS model. Processes such as photolysis, decay, and sorption to sediments were included in the model framework. The inclusion of coupled reactions, with specific reaction rates and pathways driven by different reaction pathway, that in turn can be dynamic during a storm event (for example, increasing discharge might lead to more aerobic conditions), was the novelty of the approach. The modeling framework was then used to quantify the relative importance of the different reaction pathways under varying flow conditions, and evaluate the

  16. Understanding the preconditions for revitalizing bicycle transport in Beijing, with a reference study from Copenhagen

    DEFF Research Database (Denmark)

    Zhao, Chunli

    of transport and planning research by strengthening the knowledge base on the conditions that affect the use of bicycles in the megacities of developing world as well as by exploring the factors governing the populations’ attitudes towards their future mobility. Furthermore, the study contributes...... to revitalize bicycle transport in Beijing. Those policy perspectives include targeting specific socio-demographic groups, increasing public awareness of the benefits of cycling, enhancing the bicycle-friendliness of infrastructure planning and design and prioritizing bicycle transport through comprehensive......With the aim of supporting the development of comprehensive policies for revitalizing bicycle transport in Beijing, this thesis has applied the socio-ecological model to guide the inquiry into the domains: individual, social environment, physical environment and policy. These four domains were...

  17. 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...

  18. 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”....

  19. Residence times and nitrate transport in ground water discharging to streams in the Chesapeake Bay Watershed

    Science.gov (United States)

    Lindsey, Bruce D.; Phillips, Scott; Donnelly, Colleen A.; Speiran, Gary K.; Plummer, Niel; Bohlke, John Karl; Focazio, Michael J.; Burton, William C.; Busenberg, Eurybiades

    2003-01-01

    One of the major water-quality problems in the Chesapeake Bay is an overabundance of nutrients from the streams and rivers that discharge to the Bay. Some of these nutrients are from nonpoint sources such as atmospheric deposition, agricultural manure and fertilizer, and septic systems. The effects of efforts to control nonpoint sources, however, can be difficult to quantify because of the lag time between changes at the land surface and the response in the base-flow (ground water) component of streams. To help resource managers understand the lag time between implementation of management practices and subsequent response in the nutrient concentrations in the base-flow component of streamflow, a study of ground-water discharge, residence time, and nitrate transport in springs throughout the Chesapeake Bay Watershed and in four smaller watersheds in selected hydrogeomorphic regions (HGMRs) was conducted. The four watersheds were in the Coastal Plain Uplands, Piedmont crystalline, Valley and Ridge carbonate, and Valley and Ridge siliciclastic HGMRs.A study of springs to estimate an apparent age of the ground water was based on analyses for concentrations of chlorofluorocarbons in water samples collected from 48 springs in the Chesapeake Bay Watershed. Results of the analysis indicate that median age for all the samples was 10 years, with the 25th percentile having an age of 7 years and the 75th percentile having an age of 13 years. Although the number of samples collected in each HGMR was limited, there did not appear to be distinct differences in the ages between the HGMRs. The ranges were similar between the major HGMRs above the Fall Line (modern to about 50 years), with only two HGMRs of small geographic extent (Piedmont carbonate and Mesozoic Lowland) having ranges of modern to about 10 years. The median values of all the HGMRs ranged from 7 to 11 years. Not enough samples were collected in the Coastal Plain for comparison. Spring samples showed slightly younger

  20. Chapter II.C Transport of Radionuclides through Soil and Ground Water; FINAL

    International Nuclear Information System (INIS)

    Corey, J.C.

    1980-01-01

    The purpose of this report is to provide a clearer perspective of the impact of radionuclides in soil and groundwater, particularly for those not well-versed in soil science, hydrology, and geology. Through nuclear waste disposal or accidents, radionuclides come in contact with soil and groundwater. Man is exposed to radiation as a result of movement (or transport) of the radionuclides into his environment. Water is the principal carrier that induces transport, but chemical characteristics of soil inhibit the transport

  1. Transportation of spent fuel from light water reactors

    International Nuclear Information System (INIS)

    Bernard, H.

    1993-01-01

    The French 'Compagnie Generale des Matieres Nucleaires' - COGEMA - is involved in the whole nuclear fuel cycle about 20 years. Among the different parts of the cycle, the Transport of Radioactive Materials, acting as a link between the differents plants has a great importance. As nuclear material transportation is the only fuel cycle step to be performed on public grounds, the industrial task has to be performed with the utmost stringent safety criteria. COGEMA and associates is now operating a fully mature commercial activity, with some 300 spent fuel shipments per year from its reprocessing customer's reactors to the LA HAGUE plant, either by rail, road or sea. The paper will review the organization of COGEMA transportation business, the level of technology with an update of the casks used for spent fuel, and the operational experience, with a particular view of the maintenance policy. (author)

  2. Water transport through graphene oxide membranes: the roles of driving forces.

    Science.gov (United States)

    Chong, J Y; Wang, B; Li, K

    2018-02-21

    Graphene oxide (GO) membranes have shown excellent selectivities in nanofiltration and pervaporation. However, the water transport mechanisms in the unique membrane laminar structure are still not well understood, especially in pervaporation which involves selective permeation and evaporation. Herein, water transport in GO membranes was tested under two different modes: pressure-driven permeation and pervaporation. The pure water flux was found to be 1-2 orders of magnitude higher in pervaporation due to the large capillary pressure induced by evaporation. The water flux in pervaporation was suggested to be limited by evaporation at room temperature but surface diffusion at high temperature.

  3. 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.

  4. Fate of Uranium During Transport Across the Groundwater-Surface Water Interface

    Energy Technology Data Exchange (ETDEWEB)

    Jaffe, Peter R. [Princeton Univ., NJ (United States); Kaplan, Daniel I. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-30

    Discharge of contaminated groundwater to surface waters is of concern at many DOE facilities. For example, at F-Area and TNX-Area on the Savannah River Site, contaminated groundwater, including uranium, is already discharging into natural wetlands. It is at this interface where contaminants come into contact with the biosphere. These this research addressed a critical knowledge gap focusing on the geochemistry of uranium (or for that matter, any redox-active contaminant) in wetland systems. Understanding the interactions between hydrological, microbial, and chemical processes will make it possible to provide a more accurate conceptual and quantitative understanding of radionuclide fate and transport under these unique conditions. Understanding these processes will permit better long-term management and the necessary technical justification for invoking Monitored Natural Attenuation of contaminated wetland areas. Specifically, this research did provide new insights on how plant-induced alterations to the sediment biogeochemical processes affect the key uranium reducing microorganisms, the uranium reduction, its spatial distribution, the speciation of the immobilized uranium, and its long-term stability. This was achieved by conducting laboratory mesocosm wetland experiments as well as field measurements at the SRNL. Results have shown that uranium can be immobilized in wetland systems. To a degree some of the soluble U(VI) was reduced to insoluble U(IV), but the majority of the immobilized U was incorporated into iron oxyhydroxides that precipitated onto the root surfaces of wetland plants. This U was immobilized mostly as U(VI). Because it was immobilized in its oxidized form, results showed that dry spells, resulting in the lowering of the water table and the exposure of the U to oxic conditions, did not result in U remobilization.

  5. Modeling of water transport through the membrane electrode assembly for direct methanol fuel cells

    Science.gov (United States)

    Xu, C.; Zhao, T. S.; Yang, W. W.

    In this work, a one-dimensional, isothermal two-phase mass transport model is developed to investigate the water transport through the membrane electrode assembly (MEA) for liquid-feed direct methanol fuel cells (DMFCs). The liquid (methanol-water solution) and gas (carbon dioxide gas, methanol vapor and water vapor) two-phase mass transport in the porous anode and cathode is formulated based on classical multiphase flow theory in porous media. In the anode and cathode catalyst layers, the simultaneous three-phase (liquid and vapor in pores as well as dissolved phase in the electrolyte) water transport is considered and the phase exchange of water is modeled with finite-rate interfacial exchanges between different phases. This model enables quantification of the water flux corresponding to each of the three water transport mechanisms through the membrane for DMFCs, such as diffusion, electro-osmotic drag, and convection. Hence, with this model, the effects of MEA design parameters on water crossover and cell performance under various operating conditions can be numerically investigated.

  6. 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 with an in......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...... with an investigation of the distribution and cellular localization of three aquaporins (Aqp1aa, -1ab, and -8ab) in pyloric caeca, middle (M), and posterior (P) intestine of the Atlantic salmon. In vitro iso-osmotic water absorption (J(v)) was higher in SW than FW-trout and was inhibited by (mmol L(-1)): 0.1 KCN (41......%), 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...

  7. Transport of tylosin and tylosin-resistance genes in subsurface drainage water from manured fields

    Science.gov (United States)

    Animal agriculture appears to contribute to the spread of antibiotic resistance genes, but few studies have quantified gene transport in agricultural fields. The transport of tylosin, tylosin-resistance genes (erm B, F, A) and tylosin-resistant Enterococcus were measured in tile drainage water from ...

  8. Development of Telematics and its Application in Water Transport

    Directory of Open Access Journals (Sweden)

    Dražen Kovačević

    2003-01-01

    Full Text Available Significant increase in traffic demand at the end of the 2nd century and the increasing anthropogenic environmental pollutionhave resulted in the need to introduce the telematics-supportedintelligent transport systems in all the traffic branches.The work presents the development and the basic characteristicsof transport systems managed by information and communicationtechnologies. Also, the possible development and advantagesof implementing telematics in the traffic along theriver of Danube through Austria, as well as monitoring sea-goingships and containers in intennodal traffic.

  9. Traffic and transport technology-road, railway, and water-borne transportation

    Science.gov (United States)

    1990-01-01

    This is "Part 2: Case Studies - Chapter 9" of the book, "The Japanese Experience in Technology", and includes the following subsections: Modernization and the railway; The transportation network; Issues in railway policy; Original design and producti...

  10. Understanding the Transport of Patagonian Dust and Its Influence on Marine Biological Activity in the South Atlantic Ocean

    Science.gov (United States)

    Johnson, Matthew; Meskhidze, Nicholas; Kiliyanpilakkil, Praju; Gasso, Santiago

    2010-01-01

    Modeling and remote sensing techniques were applied to examine the horizontal and vertical transport pathways of Patagonian dust and quantify the effect of soluble-iron- laden mineral dust deposition on marine primary productivity in the South Atlantic Ocean (SAO) surface waters. The global chemistry transport model GEOS-Chem, implemented with an iron dissolution scheme, was applied to evaluate the atmospheric transport and deposition of mineral dust and bioavailable iron during two dust outbreaks originating in the source regions of Patagonia. In addition to this "rapidly released" iron, offline calculations were also carried out to estimate the amount of bioavailable iron leached during the residence time of dust in the ocean mixed layer. Model simulations showed that the horizontal and vertical transport pathways of Patagonian dust plumes were largely influenced by the synoptic meteorological patterns of high and low pressure systems. Model-predicted horizontal and vertical transport pathways of Patagonian dust over the SAO were in reasonable agreement with remotely-sensed data. Comparison between remotely-sensed and offline calculated ocean surface chlorophyll-a concentrations indicated that, for the two dust outbreaks examined in this study, the deposition of bioavailable iron in the SAO through atmospheric pathways was insignificant. As the two dust transport episodes examined here represent typical outflows of mineral dust from South American sources, our study suggests that the atmospheric deposition of mineral dust is unlikely to induce large scale marine primary productivity and carbon sequestration in the South Atlantic sector of the Southern Ocean.

  11. Experts’ understandings of drinking water risk management in a climate change scenario

    Directory of Open Access Journals (Sweden)

    Åsa Boholm

    2017-01-01

    Full Text Available The challenges for society presented by climate change are complex and demanding. This paper focuses on one particular resource of utmost necessity and vulnerability to climate change: namely, the provisioning of safe drinking water. From a critical perspective on the role of expertise in risk debates, this paper looks at how Swedish experts understand risk to drinking water in a climate change scenario and how they reason about challenges to risk management and adaptation strategies. The empirical material derives from ten in-depth semi-structured interviews with experts, employed both at government agencies and at universities, and with disciplinary backgrounds in a variety of fields (water engineering, planning, geology and environmental chemistry. The experts understand risk factors affecting both drinking water quality and availability as complex and systemically interrelated. A lack of political saliency of drinking water as a public service is identified as an obstacle to the development of robust adaptation strategies. Another area of concern relates to the geographical, organizational and institutional boundaries (regulatory, political and epistemological between the plethora of public actors with partly overlapping and sometimes unclear responsibilities for the provisioning of safe drinking water. The study concludes that climate change adaptation regarding drinking water provisioning will require a new integration of the knowledge of systemic risk relations, in combination with more efficient agency collaboration based on a clear demarcation of responsibility between actors.

  12. Contribution to Surface Water Contamination Understanding by Pesticides and Pharmaceuticals, at a Watershed Scale

    Directory of Open Access Journals (Sweden)

    Stéphanie Piel

    2012-12-01

    Full Text Available This study aims at understanding the presence of regulated and emerging micropollutants, particularly pesticides and pharmaceuticals, in surface water, regarding spatial and temporal influences at a watershed scale. The study of relations between micropollutants and other water quality and hydroclimatic parameters was carried out from a statistical analysis on historical and experimental data of different sampling sites from the main watershed of Brittany, western France. The outcomes point out the influence of urban and rural areas of the watershed as well as the impact of seasons on contamination variations. This work contributes to health risk assessment related to surface water contamination by micropollutants. This approach is particularly interesting in the case of agricultural watersheds such as the one studied, where more than 80% of surface water is used to produce drinking water.

  13. Evaluating the costs of desalination and water transport

    NARCIS (Netherlands)

    Zhou, Y.; Tol, R.S.J.

    2005-01-01

    Many regions of the world are facing formidable freshwater scarcity. Although there is substantial scope for economizing on the consumption of water without affecting its service level, the main response to water scarcity has been to increase the supply. To a large extent, this is done by

  14. Simulation of Water Transport through a Lipid Membrane

    NARCIS (Netherlands)

    Marrink, Siewert-Jan; Berendsen, Herman J.C.

    1994-01-01

    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

  15. Probing water structure and transport in proton exchange membranes

    NARCIS (Netherlands)

    Ling, X.

    2018-01-01

    Proton exchange membrane fuel cells (PEMFCs) have attracted tremendous attention as alternative energy sources because of their high energy density and practically zero greenhouse gas emission - water is their only direct by-product. Critical to the function of PEMFCs is fast proton and water

  16. Water as a transport medium for waste out of towns

    DEFF Research Database (Denmark)

    Harremoës, P.

    1999-01-01

    is illustrated by the absence of water-borne diseases in the modem developed city. A new paradigm is introduced based on added concern for the use of resources, pollution of the environment and the concern for the welfare of the coming generations. The water resource is not the unsustainable aspect of urban...

  17. 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

    2015-11-23

    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.

  18. Transport modelling in coastal waters using stochastic differential equations

    NARCIS (Netherlands)

    Charles, W.M.

    2007-01-01

    In this thesis, the particle model that takes into account the short term correlation behaviour of pollutants dispersion has been developed. An efficient particle model for sediment transport has been developed. We have modified the existing particle model by adding extra equations for the

  19. Transport of Water, Carbon, and Sediment Through the Yukon River Basin

    Science.gov (United States)

    Brabets, Timothy P.; Schuster, Paul F.

    2008-01-01

    during peak- and low-flow conditions as part of synoptic sampling campaigns. Although the synoptic data do not provide a complete picture of water quality of a particular river through the year, the data do provide a snapshot of water-quality conditions at a particular time of year. Two constituents of interest are suspended sediment and dissolved organic carbon (DOC). Suspended sediment is important because elevated concentrations can adversely affect aquatic life by obstructing fish gills, covering fish spawning sites, and altering habitat of benthic organisms. Metals and organic contaminants also tend to adsorb onto fine-grained sediment. Permafrost thawing has major implications for the carbon cycle. It is critical to understand the processes related to the transport of DOC to surface waters and how long-term climatic changes may alter these processes (Schuster and others, 2004).

  20. Atmospheric Compensation of Variations in Tropical Ocean Heat Transport: Understanding Mechanisms and Implications on Tectonic Timescales

    Science.gov (United States)

    Rencurrel, M. C.; Rose, B. E. J.

    2015-12-01

    The poleward transport of energy is a key aspect of the climate system, with surface ocean currents presently dominating the transport out of deep tropics. A classic study by Stone (1978) proposed that the total heat transport is determined by astronomical parameters and is highly insensitive to the detailed atmosphere-ocean dynamics. On the other hand, previous modeling work has shown that past continental configurations could have produced substantially different tropical ocean heat transport (OHT). How thoroughly does the atmosphere compensate for changes in ocean transport in terms of the top-of-atmosphere (TOA) radiative budget, what are the relevant mechanisms, and what are the consequences for surface temperature and climate on tectonic timescales? We examine these issues in a suite of aquaplanet GCM simulations subject to large prescribed variations in OHT. We find substantial but incomplete compensation, in which adjustment of the atmospheric Hadley circulation plays a key role. We then separate out the dynamical and thermodynamical components of the adjustment mechanism. Increased OHT tends to warm the mid- to high latitudes without cooling the tropics due asymmetries in radiative feedback processes. The warming is accompanied by hydrological cycle changes that are completely different from those driven by greenhouse gases, suggesting that drivers of past global change might be detectable from combinations of hydroclimate and temperature proxies.

  1. The effect of inhomogeneous compression on water transport in the cathode of a PEM fuel cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Berning, Torsten; Kær, Søren Knudsen

    2011-01-01

    layer, micro-porous layer and catalyst layer, excluding the membrane and anode. In the porous media liquid water transport is described by the capillary pressure gradient, momentum loss via the Darcy-Forchheimer equation and mass transfer between phases by a non-equilibrium phase change model....... 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 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....

  2. 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

    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......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...

  3. Robot-Assisted Socio-Hydrologic and Water Quality Understanding in Data Sparse Regions

    Science.gov (United States)

    Peschel, J.; Young, S. N.

    2016-12-01

    This work presents a robot-assisted investigation in the data sparse Arkavathy region near Bangalore, India to understand socio-hydrologic and water quality impacts for agricultural water resources management. In the late 20th century, Arkavathy River flows began declining; consequently, a dependence on the Cauvery River has occurred. Understanding the unknown reasons for this shift is critical for managing local water quantity and quality, specifically for quantifying the socio-hydrologic effects of human intervention through the construction of tanks, or reservoirs that prevent continuous flows. Determining the potential volume of water, and its quality, capable of being stored in these tanks can aid decision-makers to better understand management aspects such as recharge, streamflow, and human health. A case study is presented where small unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs) were demonstrated as low-cost and reliable, high-resolution methodologies for surface data gathering at three locations in the Arkavathy basin during a Summer 2015 field campaign. The most significant finding for this work is that a single farmer in the region could lose one out of every five years worth of annual income if viable surface waters are not available for use.

  4. Understanding transport phenomena in electrochemical energy devices via X-ray nano CT

    Science.gov (United States)

    Tjaden, B.; Lane, J.; Brett, D. J. L.; Shearing, P. R.

    2017-06-01

    Porous support layers in electrochemical devices ensure mechanical stability of membrane assemblies such as solid oxide fuel cells and oxygen transport membranes (OTMs). At the same time, porous layers affect diffusive mass transport of gaseous reactants and contribute to performance losses at high fuel utilisation and conversion ratios. Microstructural characteristics are vital to calculate mass transport phenomena, where tortuosity remains notoriously difficult to determine. Here, the tortuosity of tubular porous support layers of OTMs is evaluated via high resolution X-ray nano computed tomography. The high resolution reveals the complex microstructure of the samples to then execute a selection of image-based tortuosity calculation algorithms. Visible differences between geometric and flux-based algorithms are observed and have thus to be applied with caution.

  5. Science to support the understanding of Ohio's water resources, 2016-17

    Science.gov (United States)

    Shaffer, Kimberly; Kula, Stephanie P.; Shaffer, Kimberly; Kula, Stephanie P.

    2016-12-19

    Ohio’s water resources support a complex web of human activities and nature—clean and abundant water is needed for drinking, recreation, farming, and industry, as well as for fish and wildlife needs. Although rainfall in normal years can support these activities and needs, occasional floods and droughts can disrupt streamflow, groundwater, water availability, water quality, recreation, and aquatic habitats. Ohio is bordered by the Ohio River and Lake Erie; it has over 44,000 miles of streams and more than 60,000 lakes and ponds (State of Ohio, 1994). Nearly all of the rural population obtains drinking water from groundwater sources. The U.S. Geological Survey (USGS) works in cooperation with local, State, and other Federal agencies, as well as universities, to furnish decisionmakers, policy makers, USGS scientists, and the general public with reliable scientific information and tools to assist them in management, stewardship, and use of Ohio’s natural resources. The diversity of scientific expertise among USGS personnel enables them to carry out large- and small-scale multidisciplinary studies. The USGS is unique among government organizations because it has neither regulatory nor developmental authority—its sole product is impartial, credible, relevant, and timely scientific information, equally accessible and available to everyone. The USGS Ohio Water Science Center provides reliable hydrologic and water-related ecological information to aid in the understanding of the use and management of the Nation’s water resources, in general, and Ohio’s water resources, in particular. This fact sheet provides an overview of current (2016) or recently completed USGS studies and data activities pertaining to water resources in Ohio. More information regarding projects of the USGS Ohio Water Science Center is available at http://oh.water.usgs.gov/.

  6. Understanding how to reduce road transport emissions : modelling the impact of eco-driving

    OpenAIRE

    García Castro, Alvaro

    2016-01-01

    Entre los problemas medioambientales más trascendentales para la sociedad, se encuentra el del cambio climático así como el de la calidad del aire en nuestras áreas metropolitanas. El transporte por carretera es uno de los principales causantes, y como tal, las administraciones públicas se enfrentan a estos problemas desde varios ángulos: Cambios a modos de transporte más limpios, nuevas tecnologías y combustibles en los vehículos, gestión de la demanda y el uso de tecnologí...

  7. Earth Day 1990: Lesson Plan and Home Survey--7-12. Energy, Solid Waste/Recycling, Toxics, Transportation, and Water with Fact Sheets and Action Guide.

    Science.gov (United States)

    Holm-Shuett, Amy; Shuett, Greg

    The purpose of this 7-12 curriculum is to provide teachers and other educators with classroom lessons and home surveys that are a starting point for understanding five significant environmental issues - water, toxics, energy, transportation, and solid waste/recycling. While each of these environmental issues is complex and has far-reaching…

  8. Understanding water uptake in bioaerosols using laboratory measurements, field tests, and modeling

    Science.gov (United States)

    Chaudhry, Zahra; Ratnesar-Shumate, Shanna A.; Buckley, Thomas J.; Kalter, Jeffrey M.; Gilberry, Jerome U.; Eshbaugh, Jonathan P.; Corson, Elizabeth C.; Santarpia, Joshua L.; Carter, Christopher C.

    2013-05-01

    Uptake of water by biological aerosols can impact their physical and chemical characteristics. The water content in a bioaerosol can affect the backscatter cross-section as measured by LIDAR systems. Better understanding of the water content in controlled-release clouds of bioaerosols can aid in the development of improved standoff detection systems. This study includes three methods to improve understanding of how bioaerosols take up water. The laboratory method measures hygroscopic growth of biological material after it is aerosolized and dried. Hygroscopicity curves are created as the humidity is increased in small increments to observe the deliquescence point, then the humidity is decreased to observe the efflorescence point. The field component of the study measures particle size distributions of biological material disseminated into a large humidified chamber. Measurements are made with a Twin-Aerodynamic Particle Sizer (APS, TSI, Inc), -Relative Humidity apparatus where two APS units measure the same aerosol cloud side-by-side. The first operated under dry conditions by sampling downstream of desiccant dryers, the second operated under ambient conditions. Relative humidity was measured within the sampling systems to determine the difference in the aerosol water content between the two sampling trains. The water content of the bioaerosols was calculated from the twin APS units following Khlystov et al. 2005 [1]. Biological material is measured dried and wet and compared to laboratory curves of the same material. Lastly, theoretical curves are constructed from literature values for components of the bioaerosol material.

  9. Thermodynamic and transport properties of air/water mixtures

    Science.gov (United States)

    Fessler, T. E.

    1981-01-01

    Subroutine WETAIR calculates properties at nearly 1,500 K and 4,500 atmospheres. Necessary inputs are assigned values of combinations of density, pressure, temperature, and entropy. Interpolation of property tables obtains dry air and water (steam) properties, and simple mixing laws calculate properties of air/water mixture. WETAIR is used to test gas turbine engines and components operating in relatively humid air. Program is written in SFTRAN and FORTRAN.

  10. Water flow and solute transport through fractured rock

    International Nuclear Information System (INIS)

    Bolt, J.E.; Bourke, P.J.; Pascoe, D.M.; Watkins, V.M.B.; Kingdon, R.D.

    1990-09-01

    In densely fractured slate at the Nirex research site in Cornwall, the positions, orientations and hydraulic conductivities of the 380 fractures intersecting a drill hole between 9 and 50 m depth have been individually measured. These data have been used: to determine the dimensions of statistically representative volumes of the network of fractures and to predict, using discrete flow path modelling and the NAPSAC code, the total flows into the fractures when large numbers are simultaneously pressurised along various lengths of the hole. Corresponding measurements, which validated the NAPSAC code to factor of two accuracy for the Cornish site, are reported. Possibilities accounting for this factor are noted for experimental investigation, and continuing, more extensive, inter hole flow and transport measurements are outlined. The application of this experimental and theoretical approach for calculating radionuclide transport in less densely fractured rock suitable for waste disposal is discussed. (Author)

  11. CFD modelling of insulation debris transport phenomena in water flow

    Energy Technology Data Exchange (ETDEWEB)

    Krepper, Eeckhard; Cartland-Glover, Gregory; Grahn, Alexander [Forschungszentrum Rossendorf e.V., Dresden (Germany). Inst. fuer Sicherheitsforschung

    2009-11-15

    The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behaviour of emergency core cooling systems during all types of loss of coolant accidents. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Goerlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Goerlitz, the theoretical modelling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current paper the basic concepts for CFD modelling are described and feasibility studies are presented. (orig.)

  12. The water needs for LDV transportation in the United States

    International Nuclear Information System (INIS)

    King, Carey W.; Webber, Michael E.; Duncan, Ian J.

    2010-01-01

    Concern over increased demand for petroleum, reliable fuel supply, and global climate change has resulted in the US government passing new Corporate Average Fuel Economy standards and a Renewable Fuels Standard. Consequently, the fuel mix for light duty vehicle (LDV) travel in the United States will change over the coming years. This paper explores the embodied water consumption and withdrawal associated with two projections for future fuel use in the US LDV sector. This analysis encompasses conventional and unconventional fossil fuels, corn ethanol, cellulosic ethanol, soy biodiesel, electricity, and hydrogen. The existing mandate in the US to blend ethanol into gasoline had effectively committed 3300 billion liters of irrigation water in 2005 (approximately 2.4% of US 2005 fresh water consumption) for producing fuel for LDVs. With current irrigation practices, fuel processing, and electricity generation, it is estimated that by 2030, approximately 14,000 billion liters of water per year will be consumed and 23,000-27,000 billion liters withdrawn to produce fuels used in LDVs. Irrigation for biofuels dominates projected water usage for LDV travel, but other fuels (coal to liquids, oil shale, and electricity via plug-in hybrid vehicles) will also contribute appreciably to future water consumption and withdrawal, especially on a regional basis. (author)

  13. Understanding and Improving Arterial Roads to Support Public Health and Transportation Goals.

    Science.gov (United States)

    McAndrews, Carolyn; Pollack, Keshia M; Berrigan, David; Dannenberg, Andrew L; Christopher, Ed J

    2017-08-01

    Arterials are types of roads designed to carry high volumes of motorized traffic. They are an integral part of transportation systems worldwide and exposure to them is ubiquitous, especially in urban areas. Arterials provide access to diverse commercial and cultural resources, which can positively influence community health by supporting social cohesion as well as economic and cultural opportunities. They can negatively influence health via safety issues, noise, air pollution, and lack of economic development. The aims of public health and transportation partially overlap; efforts to improve arterials can meet goals of both professions. Two trends in arterial design show promise. First, transportation professionals increasingly define the performance of arterials via metrics accounting for pedestrians, cyclists, transit riders, and nearby residents in addition to motor vehicle users. Second, applying traffic engineering and design can generate safety, air quality, and livability benefits, but we need evidence to support these interventions. We describe the importance of arterials (including exposures, health behaviors, effects on equity, and resulting health outcomes) and make the case for public health collaborations with the transportation sector.

  14. Sedimentary Melanges and Fossil Mass-Transport Complexes: A Key for Better Understanding Submarine Mass Movements?

    NARCIS (Netherlands)

    Pini, Gian Andrea; Ogata, Kei; Camerlenghi, Angelo; Festa, Andrea; Lucente, Claudio Corrado; Codegone, Giulia

    2012-01-01

    Mélanges originated from sedimentary processes (sedimentary mélanges) and olistostromes are frequently present in mountain chains worldwide. They are excellent fossil examples of mass- Transport complexes (MTC), often cropping out in well-preserved and laterally continuous exposures. In this article

  15. A Bayesian Additive Model for Understanding Public Transport Usage in Special Events

    DEFF Research Database (Denmark)

    Rodrigues, Filipe; Borysov, Stanislav S.; Ribeiro, Bernardete

    2017-01-01

    additive model with Gaussian process components that combines smart card records from public transport with context information about events that is continuously mined from the Web. We develop an efficient approximate inference algorithm using expectation propagation, which allows us to predict the total...

  16. 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

  17. 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

  18. Water vapor and gas transport through a poly (butylene terephthalate) poly (ethylene oxide) block copolymer

    NARCIS (Netherlands)

    Metz, S.J.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias

    2002-01-01

    In this paper the transport behavior of water vapor and nitrogen in a poly(butylene terephthalate) poly (ethylene oxide) block copolymer is discussed. This polymer has a high solubility for water (300 cm3 (STP)/cm3 polymer at activity 0.9). A new permeation set up has been built to determine the

  19. 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...

  20. 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

  1. 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

  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. 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

  4. Water-mediated energy transport and structure across a protein-protein interface

    Science.gov (United States)

    Leitner, David

    2010-03-01

    Water molecules embedded within proteins or at the interface between globules play a central role in folding and function. We discuss the influence of interfacial water molecules on energy transport and structure, specifically the role of water at the interface between the two globules of the homodimeric hemoglobin from Scapharca inaequivalvis, which binds oxygen cooperatively. We have studied the water-mediated energy transport in this protein with communication maps and nonequilibrium molecular simulations of energy flow, which reveal the disproportionate amount of energy carried by the water molecules, particularly across the interface, i.e., a larger thermal conductivity of the interfacial waters compared with other parts of the protein, promoting hydrogen bond rearrangements at the interface.

  5. Profiling of sugar transporter genes in grapevine coping with water deficit.

    Science.gov (United States)

    Medici, Anna; Laloi, Maryse; Atanassova, Rossitza

    2014-11-03

    The profiling of grapevine (Vitis vinifera L.) genes under water deficit was specifically targeted to sugar transporters. Leaf water status was characterized by physiological parameters and soluble sugars content. The expression analysis provided evidence that VvHT1 hexose transporter gene was strongly down-regulated by the increased sugar content under mild water-deficit. The genes of monosaccharide transporter VvHT5, sucrose carrier VvSUC11, vacuolar invertase VvGIN2 and grape ASR (ABA, stress, ripening) were up-regulated under severe water stress. Their regulation in a drought-ABA signalling network and possible roles in complex interdependence between sugar subcellular partitioning and cell influx/efflux under Grapevine acclimation to dehydration are discussed. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  6. Modeling and Diagnostics of Fuel Cell Porous Media for Improving Water Transport

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Jeff; M' edici, Ezequiel

    2011-07-01

    When a fuel cell is operating at high current density, water accumulation is a significant cause of performance and component degradation. Investigating the water transport inside the fuel cell is a challenging task due to opacity of the components, the randomness of the porous materials, and the difficulty in gain access to the interior for measurement due to the small dimensions of components. Numerical simulation can provide a good insight of the evolution of the water transport under different working condition. However, the validation of those simulations is remains an issue due the same experimental obstacles associated with in-situ measurements. The discussion herein will focus on pore-network modeling of the water transport on the PTL and the insights gained from simulations as well as in the validation technique. The implications of a recently published criterion to characterize PTL, based on percolation theory, and validate numerical simulation are discussed.

  7. Water Transport and the Evolution of CM Parent Bodies

    Science.gov (United States)

    Coker, Rob; Cohen, Barbara

    2014-01-01

    Meteorites have amino acids and hydrated minerals which constrain the peak temperature ranges they have experienced. CMs in particular have a narrow range (273-325K). Bulk fluid motion during hydration constrained to small scales (less than mm). Some asteroids are known to have hydrated minerals on their surfaces. It is presumed these two facts may be related. Problem: hydration only occurs (significantly) with liquid water; melting water only occurs early on in nebula (1-10 Myrs ANC); in nebula asteroid surface temperature very cold (approximately 150K). Can indigenous alteration produce CMs and/or surface hydration?

  8. Role of air-water interfaces in colloid transport in porous media: A review

    Science.gov (United States)

    Flury, Markus; Aramrak, Surachet

    2017-07-01

    Air-water interfaces play an important role in unsaturated porous media, giving rise to phenomena like capillarity. Less recognized and understood are interactions of colloids with the air-water interface in porous media and the implications of these interactions for fate and transport of colloids. In this review, we discuss how colloids, both suspended in the aqueous phase and attached at pore walls, interact with air-water interfaces in porous media. We discuss the theory of colloid/air-water interface interactions, based on the different forces acting between colloids and the air-water interface (DLVO, hydrophobic, capillary forces) and based on thermodynamic considerations (Gibbs free energy). Subsurface colloids are usually electrostatically repelled from the air-water interface because most subsurface colloids and the air-water are negatively charged. However, hydrophobic interactions can lead to attraction to the air-water interface. When colloids are at the air-water interface, capillary forces are usually dominant over other forces. Moving air-water interfaces are effective in mobilizing and transporting colloids from surfaces. Thermodynamic considerations show that, for a colloid, the air-water interface is the favored state as compared with the suspension phase, except for hydrophilic colloids in the nanometer size range. Experimental evidence indicates that colloid mobilization in soils often occurs through macropores, although matrix transport is also prevalent in absence of macropores. Moving air-water interfaces, e.g., occurring during infiltration, imbibition, or drainage, have been shown to scour colloids from surfaces and translocate colloids. Colloids can also be pinned to surfaces by thin water films and capillary menisci at the air-water-solid interface line, causing colloid retention and immobilization. Air-water interfaces thus can both mobilize or immobilize colloids in porous media, depending on hydrodynamics and colloid and surface

  9. Understanding the Ecological Adoption of Solar Water Heaters Among Customers of Island Economies

    Directory of Open Access Journals (Sweden)

    Pudaruth Sharmila

    2017-04-01

    Full Text Available This paper explores the major factors impacting upon the ecological adoption of solar water heaters in Mauritius. The paper applies data reduction technique by using exploratory factor analysis on a sample of 228 respondents and condenses a set of 32 attributes into a list of 8 comprehensible factors impacting upon the sustained adoption of solar water heater in Mauritius. Multiple regression analysis was also conducted to investigate upon the most predictive factor influencing the adoption of solar water heaters in Mauritius. The empirical estimates of the regression analysis have also depicted that the most determining factor pertaining to the ‘government incentives for solar water heaters’ impacts upon the adoption of solar water heaters. These results can be related to sustainable adoption of green energy whereby targeted incentive mechanisms can be formulated with the aim to accelerate and cascade solar energy adoption in emerging economies. A novel conceptual model was also proposed in this paper, whereby, ecological stakeholders in the sustainable arena could use the model as a reference to pave the way to encourage adoption of solar water heating energy. This research represents a different way of understanding ecological customers by developing an expanding on an original scale development for the survey on the ecological adoption of solar water heaters.

  10. Sense Things in the Big Deep Water Bring the Big Deep Water to Computers so People can understand the Deep Water all the Time without getting wet

    Science.gov (United States)

    Pelz, M.; Heesemann, M.; Scherwath, M.; Owens, D.; Hoeberechts, M.; Moran, K.

    2015-12-01

    Senses help us learn stuff about the world. We put sense things in, over, and under the water to help people understand water, ice, rocks, life and changes over time out there in the big water. Sense things are like our eyes and ears. We can use them to look up and down, right and left all of the time. We can also use them on top of or near the water to see wind and waves. As the water gets deep, we can use our sense things to see many a layer of different water that make up the big water. On the big water we watch ice grow and then go away again. We think our sense things will help us know if this is different from normal, because it could be bad for people soon if it is not normal. Our sense things let us hear big water animals talking low (but sometimes high). We can also see animals that live at the bottom of the big water and we take lots of pictures of them. Lots of the animals we see are soft and small or hard and small, but sometimes the really big ones are seen too. We also use our sense things on the bottom and sometimes feel the ground shaking. Sometimes, we get little pockets of bad smelling air going up, too. In other areas of the bottom, we feel hot hot water coming out of the rock making new rocks and we watch some animals even make houses and food out of the hot hot water that turns to rock as it cools. To take care of the sense things we use and control water cars and smaller water cars that can dive deep in the water away from the bigger water car. We like to put new things in the water and take things out of the water that need to be fixed at least once a year. Sense things are very cool because you can use the sense things with your computer too. We share everything for free on our computers, which your computer talks to and gets pictures and sounds for you. Sharing the facts from the sense things is the best part about having the sense things because we can get many new ideas about understanding the big water from anyone with a computer!

  11. Understanding the geometry of transport: Diffusion maps for Lagrangian trajectory data unravel coherent sets.

    Science.gov (United States)

    Banisch, Ralf; Koltai, Péter

    2017-03-01

    Dynamical systems often exhibit the emergence of long-lived coherent sets, which are regions in state space that keep their geometric integrity to a high extent and thus play an important role in transport. In this article, we provide a method for extracting coherent sets from possibly sparse Lagrangian trajectory data. Our method can be seen as an extension of diffusion maps to trajectory space, and it allows us to construct "dynamical coordinates," which reveal the intrinsic low-dimensional organization of the data with respect to transport. The only a priori knowledge about the dynamics that we require is a locally valid notion of distance, which renders our method highly suitable for automated data analysis. We show convergence of our method to the analytic transfer operator framework of coherence in the infinite data limit and illustrate its potential on several two- and three-dimensional examples as well as real world data.

  12. Applying GPS to enhance understanding of transport-related physical activity.

    Science.gov (United States)

    Duncan, Mitch J; Badland, Hannah M; Mummery, W Kerry

    2009-09-01

    The purpose of the paper is to review the utility of the global positioning system (GPS) in the study of health-related physical activity. The paper draws from existing literature to outline the current work performed using GPS to examine transport-related physical activity, with a focus on the relative utility of the approach when combined with geographic information system (GIS) and other data sources including accelerometers. The paper argues that GPS, especially when used in combination with GIS and accelerometery, offers great promise in objectively measuring and studying the relationship of numerous environmental attributes to human behaviour in terms of physical activity and transport-related activity. Limitations to the use of GPS for the purpose of monitoring health-related physical activity are presented, and recommendations for future avenues of research are discussed.

  13. Understanding the transport properties of YNiBi half- Heusler alloy: An Ab-initio study

    Science.gov (United States)

    Sharma, Sonu; Kumar, Pradeep

    2017-05-01

    In the present work, we have studied the electronic and transport properties of YNiBi half-Heusler alloy by combining the first principles methods with the Boltzmann transport theory. The electronic band structure and total density of states plot suggest the presence of semiconducting ground state in the compound. The value of indirect band gap is found to be ˜0.21 eV. The origin of the band gap is associated primarily with the interaction between the Ni 3d and the Y 4d states. The room temperature value of Seebeck coefficient is ˜230 µVK-1. A moderate power factor of about 12×1014 μ Wcm-1 K-2 s-1 is obtained at 980 k.

  14. Understanding Ionic Transport in Polypyrrole/Nanocellulose Composite Energy Storage Devices

    OpenAIRE

    Srivastav, Shruti; Tammela, Petter; Brandell, Daniel; Sjödin, Martin

    2015-01-01

    Abstract In this work, we aim to resolve different diffusion processes in polypyrrole/cellulose composites using a combination of impedance spectroscopy and finite element simulations. The computational model involves a coupled system of Ohm's law and Fickian diffusion to model electrode kinetics, non-linear boundary interactions at the electrode interfaces and ion transport inside the porous electrodes, thereby generating the impedance response. Composite electrodes are prepared via chemical...

  15. Papers of the CWRA climate change symposium : understanding climate change impacts on Manitoba's water resources

    International Nuclear Information System (INIS)

    2003-01-01

    This symposium provided an opportunity for discussions on climate change issues with particular reference to the impacts on Manitoba's water resources. The presentations addressed issues of importance to governments, scientists, academics, managers, consultants and the general public. Topics of discussion ranged from climate change impacts on water quality, wetlands, hydropower, fisheries and drought, to adaptation to climate change. Recent advances in global and regional climate modelling were highlighted along with paleo-environmental indicators of climate change. The objective was to provide a better understanding of the science of climate change. The conference featured 16 presentations of which 1 was indexed separately for inclusion in this database. refs., tabs., figs

  16. Understanding the Role of Water on Electron-Initiated Processes and Radical Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, Bruce C [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colson, Steven D [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Laufer, Allan H [US Department of Energy Office of Science Office of Basic Energy Sciences; Ray, Douglas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2003-06-10

    On September 26–28, 2002, a workshop entitled “Understanding the Role of Water on Electron-Initiated Processes and Radical Chemistry” was held to assess new research opportunities in electron-driven processes and radical chemistry in aqueous systems. Of particular interest was the unique and complex role that the structure of water plays in influencing these processes. Novel experimental and theoretical approaches to solving long-standing problems in the field were explored. A broad selection of participants from universities and the national laboratories contributed to the workshop, which included scientific and technical presentations and parallel sessions for discussions and report writing.

  17. Aeromonas hydrophila disturbs water and electrolyte transport in ...

    African Journals Online (AJOL)

    Fish diseases create a menace to aquaculture farms. They provoke disastrous economic losses and sanitary risks for the consumer. The present study aims to investigate the effect of the bacteria, Aeromonas hydrophila on water and electrolyte (Na+, K+, Cl-, HCO3 -) flux of Mugil cephalus (L, 1758) intestine. Anterior, middle ...

  18. The hydraulic transportation of thickened sludges | Slatter | Water SA

    African Journals Online (AJOL)

    Industries which pump sludges are under continuous pressure to decrease water content, and increase concentration. Environmentally superior disposal techniques are demanding that such sludges have high mechanical strength properties. This results in a sludge with an increasing viscous character. At high ...

  19. Quantitative analysis of soil chromatography. I. Water and radionuclide transport

    International Nuclear Information System (INIS)

    Reeves, M.; Francis, C.W.; Duguid, J.O.

    1977-12-01

    Soil chromatography has been used successfully to evaluate relative mobilities of pesticides and nuclides in soils. Its major advantage over the commonly used suspension technique is that it more accurately simulates field conditions. Under such conditions the number of potential exchange sites is limited both by the structure of the soil matrix and by the manner in which the carrier fluid moves through this structure. The major limitation of the chromatographic method, however, has been its qualitative nature. This document represents an effort to counter this objection. A theoretical basis is specified for the transport both of the carrier eluting fluid and of the dissolved constituent. A computer program based on this theory is developed which optimizes the fit of theoretical data to experimental data by automatically adjusting the transport parameters, one of which is the distribution coefficient k/sub d/. This analysis procedure thus constitutes an integral part of the soil chromatographic method, by means of which mobilities of nuclides and other dissolved constituents in soils may be quantified

  20. Quantitative analysis of soil chromatography. I. Water and radionuclide transport

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, M.; Francis, C.W.; Duguid, J.O.

    1977-12-01

    Soil chromatography has been used successfully to evaluate relative mobilities of pesticides and nuclides in soils. Its major advantage over the commonly used suspension technique is that it more accurately simulates field conditions. Under such conditions the number of potential exchange sites is limited both by the structure of the soil matrix and by the manner in which the carrier fluid moves through this structure. The major limitation of the chromatographic method, however, has been its qualitative nature. This document represents an effort to counter this objection. A theoretical basis is specified for the transport both of the carrier eluting fluid and of the dissolved constituent. A computer program based on this theory is developed which optimizes the fit of theoretical data to experimental data by automatically adjusting the transport parameters, one of which is the distribution coefficient k/sub d/. This analysis procedure thus constitutes an integral part of the soil chromatographic method, by means of which mobilities of nuclides and other dissolved constituents in soils may be quantified.

  1. Understanding flood-induced water chemistry variability extracting temporal patterns with the LDA method

    Science.gov (United States)

    Aubert, A. H.; Tavenard, R.; Emonet, R.; De Lavenne, A.; Malinowski, S.; Guyet, T.; Quiniou, R.; Odobez, J.; Merot, P.; Gascuel-odoux, C.

    2013-12-01

    Studying floods has been a major issue in hydrological research for years, both in quantitative and qualitative hydrology. Stream chemistry is a mix of solutes, often used as tracers, as they originate from various sources in the catchment and reach the stream by various flow pathways. Previous studies (for instance (1)) hypothesized that stream chemistry reaction to a rainfall event is not unique but varies seasonally, and according to the yearly meteorological conditions. Identifying a typology of flood temporal chemical patterns is a way to better understand catchment processes at the flood and seasonal time scale. We applied a probabilistic model (Latent Dirichlet Allocation or LDA (2)) mining recurrent sequential patterns from a dataset of floods. A set of 472 floods was automatically extracted from a daily 12-year long record of nitrate, dissolved organic carbon, sulfate and chloride concentrations. Rainfall, discharge, water table depth and temperature are also considered. Data comes from a long-term hydrological observatory (AgrHys, western France) located at Kervidy-Naizin. From each flood, a document has been generated that is made of a set of "hydrological words". Each hydrological word corresponds to a measurement: it is a triplet made of the considered variable, the time at which the measurement is made (relative to the beginning of the flood), and its magnitude (that can be low, medium or high). The documents and the number of pattern to be mined are used as input data to the LDA algorithm. LDA relies on spotting co-occurrences (as an alternative to the more traditional study of correlation) between words that appear within the flood documents. It has two nice properties that are its ability to easily deal with missing data and its additive property that allows a document to be seen as a mixture of several flood patterns. The output of LDA is a set of patterns easily represented in graphics. These patterns correspond to typical reactions to rainfall

  2. 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

  3. A Microfluidic Pore Network Approach to Investigate Water Transport in Fuel Cell Porous Transport Layers

    OpenAIRE

    Bazylak, A.; Berejnov, V.; Markicevic, B.; Sinton, D.; Djilali, N.

    2008-01-01

    Pore network modelling has traditionally been used to study displacement processes in idealized porous media related to geological flows, with applications ranging from groundwater hydrology to enhanced oil recovery. Very recently, pore network modelling has been applied to model the gas diffusion layer (GDL) of a polymer electrolyte membrane (PEM) fuel cell. Discrete pore network models have the potential to elucidate transport phenomena in the GDL with high computational efficiency, in cont...

  4. ICON-ART-ISO: Water isotopologues implemented in the chemistry- transport model ICON-ART

    Science.gov (United States)

    Eckstein, Johannes; Ruhnke, Roland; Reinert, Daniel; Pfahl, Stephan

    2017-04-01

    Stable isotopes of water can help to understand processes that have influenced the distribution of water in the atmosphere. Isotope enabled models, capable of simulating the distribution of HDO and H218O, can be a very useful tool for understanding these processes and the distribution of isotope ratios which are observed. We present ICON-ART-ISO, the implementation of water isotopes into the chemistry-transport model ICON-ART. The core of this global model is the ICOsahedral Non-hydrostatic (ICON) modelling framework (Zaengl et al, 2015 (Q. J. R. Meteorol. Soc.)), a joint development of the German Weather Service (DWD) and the Max Planck Institute for Meteorology. The model system ICON-ART (Aerosols and Reactive Trace gases, Rieger et al, 2015 (GMD)) is a two-way coupled extension to ICON, which allows to study the influence of aerosols, trace gases and their chemistry on the atmosphere. We set up ICON-ART-ISO within this framework, profitting from the model infrastructure. We follow the implementation of COSMOiso (Pfahl et al., 2012 (ACP)), the isotope-enabled version of the COSMO model, the predecessor of ICON. In order to include the isotopes in the model, the water cycle is doubled diagnostically for each isotope. By the choice of physical parameters, these modelled isotopes are set to HDO and H218O, but the simulation of a purely diagnostic H2O is also possible. Fractionation, i.e. the change of the isotope ratio changes during phase changes, is considered in evaporation, grid-scale precipitation and convection. For the source of evaporation, a constant isotope ratio is currently used. To consider grid scale precipitation, the processes in the two-moment microphysical scheme by Seifert and Beheng, 2005 (Meteorol. Atmos. Phys.) are diagnostically applied to the isotopes. For convection, the Tiedtke-Bechtold scheme (Bechtold et al., 2013 (JAS)) is used. We present the current status of the model system. All processes have been implemented and we show first

  5. 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.

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

    Science.gov (United States)

    Fuentes, Hector R.

    2018-01-01

    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. PMID:29538335

  7. 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

  8. Understanding and managing the water use of planted forests in a changing environment

    Science.gov (United States)

    Jami Nettles

    2016-01-01

    Forest productivity will only become more important in the future, not just for carbon sequestration and renewable energy but for wood products and economic security for an increasing population. However, the threat of increasing drought and resource scarcity means a need for more explicit characterization of the water use of planted forests and the understanding of...

  9. Understanding the Contribution of Mining and Transportation to the Total Life Cycle Impacts of Coal Exported from the United States

    Directory of Open Access Journals (Sweden)

    Michele Mutchek

    2016-07-01

    Full Text Available The construction of two marine bulk terminals in the Pacific Northwest region of the United States are currently under review and would open up additional thermal coal exports to Asia on the order of almost 100 million additional tonnes per year. The major exporters of coal to Asian markets include Indonesia and Australia. This life cycle analysis (LCA seeks to understand the role of transportation and mining in the cradle-to-busbar environmental impacts of coal exports from the Powder River Basin (PRB to Asian countries, when compared to the competitor countries. This LCA shows that: (1 the most significant greenhouse gas (GHG impacts in the cradle-to-busbar life cycle of coal for power generation come from the combustion of coal in a power plant, even when 90% carbon capture is applied; (2 for non-GHG air impacts, power plant combustion impacts are less dominant and variations in upstream impacts (mining and transportation are more important; and (3 when comparing impacts between countries, upstream impacts vary for both GHG and non-GHG results, but conclusions that rank countries cannot be made. Future research should include expansion to include non-air impacts, potential consequential effects of coal exports, and a better understanding around the characterization of non-GHG ocean transport impacts.

  10. North American water availability under stress and duress: building understanding from simulations, observations and data products

    Science.gov (United States)

    Maxwell, R. M.; Condon, L. E.; Atchley, A. L.; Hector, B.

    2017-12-01

    Quantifying the available freshwater for human use and ecological function depends on fluxes and stores that are hard to observe. Evapotranspiration (ET) is the largest terrestrial flux of water behind precipitation but is observed with low spatial density. Likewise, groundwater is the largest freshwater store, yet is equally uncertain. The ability to upscale observations of these variables is an additional complication; point measurements are made at scales orders of magnitude smaller than remote sensing data products. Integrated hydrologic models that simulate continental extents at fine spatial resolution are now becoming an additional tool to constrain fluxes and address interconnections. For example, recent work has shown connections between water table depth and transpiration partitioning, and demonstrated the ability to reconcile point observations and large-scale inferences. Here we explore the dynamics of large hydrologic systems experiencing change and stress across continental North America using integrated model simulations, observations and data products. Simulations of aquifer depletion due to pervasive groundwater pumping diagnose both stream depletion and changes in ET. Simulations of systematic increases in temperature are used to understand the relationship between snowpack dynamics, surface and groundwater flow, ET and a changing climate. Remotely sensed products including the GRACE estimates of total storage change are downscaled using model simulations to better understand human impacts to the hydrologic cycle. These example applications motivate a path forward to better use simulations to understand water availability.

  11. Characterizing the transplanar and in-plane water transport of textiles with gravimetric and image analysis technique: Spontaneous Uptake Water Transport Tester.

    Science.gov (United States)

    Tang, K P M; Wu, Y S; Chau, K H; Kan, C W; Fan, J T

    2015-04-15

    Water absorption and transport property of textiles is important since it affects wear comfort, efficiency of treatment and functionality of product. This paper introduces an accurate and reliable measurement tester, which is based on gravimetric and image analysis technique, for characterising the transplanar and in-plane wicking property of fabrics. The uniqueness of this instrument is that it is able to directly measure the water absorption amount in real-time, monitor the direction of water transport and estimate the amount of water left on skin when sweating. Throughout the experiment, water supply is continuous which simulates profuse sweating. Testing automation could even minimise variation caused by subjective manipulation, thus enhancing testing accuracy. This instrument is versatile in terms of the fabrics could be tested. A series of shirting fabrics made by different fabric structure and yarn were investigated and the results show that the proposed method has high sensitivity in differentiating fabrics with varying geometrical differences. Fabrics with known hydrophobicity were additionally tested to examine the sensitivity of the instrument. This instrument also demonstrates the flexibility to test on high performance moisture management fabrics and these fabrics were found to have excellent transplanar and in-plane wicking properties.

  12. Characterizing the transplanar and in-plane water transport of textiles with gravimetric and image analysis technique: Spontaneous Uptake Water Transport Tester

    Science.gov (United States)

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

    2015-01-01

    Water absorption and transport property of textiles is important since it affects wear comfort, efficiency of treatment and functionality of product. This paper introduces an accurate and reliable measurement tester, which is based on gravimetric and image analysis technique, for characterising the transplanar and in-plane wicking property of fabrics. The uniqueness of this instrument is that it is able to directly measure the water absorption amount in real-time, monitor the direction of water transport and estimate the amount of water left on skin when sweating. Throughout the experiment, water supply is continuous which simulates profuse sweating. Testing automation could even minimise variation caused by subjective manipulation, thus enhancing testing accuracy. This instrument is versatile in terms of the fabrics could be tested. A series of shirting fabrics made by different fabric structure and yarn were investigated and the results show that the proposed method has high sensitivity in differentiating fabrics with varying geometrical differences. Fabrics with known hydrophobicity were additionally tested to examine the sensitivity of the instrument. This instrument also demonstrates the flexibility to test on high performance moisture management fabrics and these fabrics were found to have excellent transplanar and in-plane wicking properties. PMID:25875329

  13. Biogeochemical Processes Responsible for the Enhanced Transport of Plutonium Under transient Unsaturated Ground Water Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fred J. Molz, III

    2010-05-28

    To better understand longer-term vadose zone transport in southeastern soils, field lysimeter experiments were conducted at the Savannah River Site (SRS) near Aiken, SC, in the 1980s. Each of the three lysimeters analyzed herein contained a filter paper spiked with different Pu solutions, and they were left exposed to natural environmental conditions (including the growth of annual weed grasses) for 11 years. The resulting Pu activity measurements from each lysimeter core showed anomalous activity distributions below the source, with significant migration of Pu above the source. Such results are not explainable by adsorption phenomena alone. A transient variably saturated flow model with root water uptake was developed and coupled to a soil reactive transport model. Somewhat surprisingly, the fully transient analysis showed results nearly identical to those of a much simpler steady flow analysis performed previously. However, all phenomena studied were unable to produce the upward Pu transport observed in the data. This result suggests another transport mechanism such as Pu uptake by roots and upward transport due to transpiration. Thus, the variably saturated flow and reactive transport model was extended to include uptake and transport of Pu within the root xylem, along with computational methodology and results. In the extended model, flow velocity in the soil was driven by precipitation input along with transpiration and drainage. Water uptake by the roots determined the flow velocity in the root xylem, and this along with uptake of Pu in the transpiration stream drove advection and dispersion of the two Pu species in the xylem. During wet periods with high potential evapotranspiration, maximum flow velocities through the xylem would approached 600 cm/hr, orders of magnitude larger that flow velocities in the soil. Values for parameters and the correct conceptual viewpoint for Pu transport in plant xylem was uncertain. This motivated further experiments devoted

  14. Biogeochemical Processes Responsible for the Enhanced Transport of Plutonium Under transient Unsaturated Ground Water Conditions

    International Nuclear Information System (INIS)

    Molz, Fred J. III

    2010-01-01

    To better understand longer-term vadose zone transport in southeastern soils, field lysimeter experiments were conducted at the Savannah River Site (SRS) near Aiken, SC, in the 1980s. Each of the three lysimeters analyzed herein contained a filter paper spiked with different Pu solutions, and they were left exposed to natural environmental conditions (including the growth of annual weed grasses) for 11 years. The resulting Pu activity measurements from each lysimeter core showed anomalous activity distributions below the source, with significant migration of Pu above the source. Such results are not explainable by adsorption phenomena alone. A transient variably saturated flow model with root water uptake was developed and coupled to a soil reactive transport model. Somewhat surprisingly, the fully transient analysis showed results nearly identical to those of a much simpler steady flow analysis performed previously. However, all phenomena studied were unable to produce the upward Pu transport observed in the data. This result suggests another transport mechanism such as Pu uptake by roots and upward transport due to transpiration. Thus, the variably saturated flow and reactive transport model was extended to include uptake and transport of Pu within the root xylem, along with computational methodology and results. In the extended model, flow velocity in the soil was driven by precipitation input along with transpiration and drainage. Water uptake by the roots determined the flow velocity in the root xylem, and this along with uptake of Pu in the transpiration stream drove advection and dispersion of the two Pu species in the xylem. During wet periods with high potential evapotranspiration, maximum flow velocities through the xylem would approached 600 cm/hr, orders of magnitude larger that flow velocities in the soil. Values for parameters and the correct conceptual viewpoint for Pu transport in plant xylem was uncertain. This motivated further experiments devoted

  15. 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.

  16. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

    Directory of Open Access Journals (Sweden)

    Catherine Sundling

    2015-11-01

    Full Text Available Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+ travelers’ motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers’ critical reactions (i.e., cognitive, emotional, and/or behavioral to 77 critical incidents were examined. By applying critical incident technique (CIT, five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers’ access to public transport, key findings were: (a service must be designed so as to strengthen the feeling of being in control throughout the journey; (b extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior.

  17. Understanding the Geographies of Transport and Cultural Heritage: Comparing Two Urban Development Programs in Oslo

    Directory of Open Access Journals (Sweden)

    Anders Tønnesen

    2014-05-01

    Full Text Available This paper elaborates on how policies and strategies for sustainable urban development can be understood and shows how development programs can be strategically important and flexible tools in the creation of the modern city. We examine two typical contemporary cases for urban development, inner city/waterfront and modernistic suburbs, using the two areas of transport and cultural heritage as prisms to explore divergences or convergences between the two programs, and ask: How come two urban development programs within the same city turn out so differently? By comparing these programs, urban development trends relating to entrepreneurialism are highlighted. There are clear differences between the two programs under study, and the paper tries to grasp their internal logic in order to shed light on their strengths and weaknesses. While the city center program has much to do with realizing the commercial potential of the area and strengthening sustainable transport through large-scale changes in infrastructure, such means seem to be outside the scope of the suburban program. Meanwhile, cultural heritage is interwoven with entrepreneurial projection-strategies in the city center, whereas heritage sites and projects are used more as a means for social cohesion in the suburb. The paper concludes that the programs vary in the two policy fields in accordance with the institutionalized and anticipated potential of the urban areas in question.

  18. Recent progress in the understanding of H transport and trapping in W

    Science.gov (United States)

    Schmid, K.; Bauer, J.; Schwarz-Selinger, T.; Markelj, S.; Toussaint, U. v.; Manhard, A.; Jacob, W.

    2017-12-01

    The retention of hydrogen isotopes (HIs) (H, D and T) in the first, plasma exposed wall is one of the key concerns for the operation of future long pulse fusion devices. It affects the particle-, momentum- and energy balance in the scrape off layer as well as the retention of HIs and their permeation into the coolant. The currently accepted picture that is used for interpreting current laboratory and tokamak experiments is that of diffusion hindered by trapping at lattice defects. This paper summarises recent results that show that this current picture of how HIs are transported and retained in W needs to be extended: the modification of the surface (e.g. blistering) can lead to the formation of fast loss channels for near surface HIs. Trapping at single occupancy traps with fixed de-trapping energy fails to explain isotope exchange experiments, instead a trapping model with multi occupancy traps and fill level dependent de-trapping energies is required. The presence of interstitial impurities like N or C may affect the transport of solute HI. The presence of HIs during damage creation by e.g. neutrons stabilises defects and reduces defect annealing at elevated temperatures.

  19. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport.

    Science.gov (United States)

    Sundling, Catherine

    2015-11-18

    Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers' motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers' critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 critical incidents were examined. By applying critical incident technique (CIT), five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers' access to public transport, key findings were: (a) service must be designed so as to strengthen the feeling of being in control throughout the journey; (b) extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c) when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior.

  20. Understanding Air Transportation Market Dynamics Using a Search Algorithm for Calibrating Travel Demand and Price

    Science.gov (United States)

    Kumar, Vivek; Horio, Brant M.; DeCicco, Anthony H.; Hasan, Shahab; Stouffer, Virginia L.; Smith, Jeremy C.; Guerreiro, Nelson M.

    2015-01-01

    This paper presents a search algorithm based framework to calibrate origin-destination (O-D) market specific airline ticket demands and prices for the Air Transportation System (ATS). This framework is used for calibrating an agent based model of the air ticket buy-sell process - Airline Evolutionary Simulation (Airline EVOS) -that has fidelity of detail that accounts for airline and consumer behaviors and the interdependencies they share between themselves and the NAS. More specificially, this algorithm simultaneous calibrates demand and airfares for each O-D market, to within specified threshold of a pre-specified target value. The proposed algorithm is illustrated with market data targets provided by the Transportation System Analysis Model (TSAM) and Airline Origin and Destination Survey (DB1B). Although we specify these models and datasources for this calibration exercise, the methods described in this paper are applicable to calibrating any low-level model of the ATS to some other demand forecast model-based data. We argue that using a calibration algorithm such as the one we present here to synchronize ATS models with specialized forecast demand models, is a powerful tool for establishing credible baseline conditions in experiments analyzing the effects of proposed policy changes to the ATS.

  1. 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

  2. Water-induced charge transport in tablets of microcrystalline cellulose of varying density: dielectric spectroscopy and transient current measurements

    International Nuclear Information System (INIS)

    Nilsson, Martin; Alderborn, Goeran; Stroemme, Maria

    2003-01-01

    Room temperature dielectric frequency response data taken over 13 decades in frequency on microcrystalline cellulose (MCC) tablets of varying density are presented. The frequency response shows on three different processes: the first one is a high-frequency relaxation process whose magnitude increases and reaches a plateau as the tablet density increases. This process is associated with orientational motions of local chain segments via glycosidic bonds. The second relaxation process, related to the presence of water in the MCC matrix, is insensitive to changes in tablet density. At lower frequencies, dc-like imperfect charge transport dominates the dielectric spectrum. The dc conductivity was found to decrease with increasing tablet density and increase exponentially with increasing humidity. Transient current measurements indicated that two different ionic species, protons and OH - ions, lied behind the observed conductivity. At ambient humidity of 22%, only one in a billion of the water molecules present in the tablet matrix participated in long range dc conduction. The diffusion coefficient of the protons and OH - ions were found to be of the order of 10 -9 cm 2 /s, which is the same as for small salt building ions in MCC. This shows that ionic drugs leaving a tablet matrix may diffuse in the same manner as the constituent ions of water and, thus, elucidates the necessity to understand the water transport properties of excipient materials to be able to tailor the drug release process from pharmaceutical tablets

  3. Uranium facilitated transport by water-dispersible colloids in field and soil columns

    International Nuclear Information System (INIS)

    Crancon, P.; Pili, E.; Charlet, L.

    2010-01-01

    The transport of uranium through a sandy podsolic soil has been investigated in the field and in column experiments. Field monitoring, numerous years after surface contamination by depleted uranium deposits, revealed a 20 cm deep uranium migration in soil. Uranium retention in soil is controlled by the ≤ 50 μm mixed humic and clayey coatings in the first 40 cm i.e. in the E horizon. Column experiments of uranium transport under various conditions were run using isotopic spiking. After 100 pore volumes elution, 60% of the total input uranium is retained in the first 2 cm of the column. Retardation factor of uranium on E horizon material ranges from 1300 (column) to 3000 (batch). In parallel to this slow uranium migration, we experimentally observed a fast elution related to humic colloids of about 1-5% of the total-uranium input, transferred at the mean pore-water velocity through the soil column. In order to understand the effect of rain events, ionic strength of the input solution was sharply changed. Humic colloids are retarded when ionic strength increases, while a major mobilization of humic colloids and colloid-borne uranium occurs as ionic strength decreases. Isotopic spiking shows that both 238 U initially present in the soil column and 233 U brought by input solution are desorbed. The mobilization process observed experimentally after a drop of ionic strength may account for a rapid uranium migration in the field after a rainfall event, and for the significant uranium concentrations found in deep soil horizons and in groundwater, 1 km downstream from the pollution source. (authors)

  4. Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Spycher, N.; Xu, T.; Apps, J.; Kharaka, Y.; Birkholzer, J.T.

    2010-11-05

    In this study, reactive transport simulations were used to assess the mobilization and transport of organics with supercritical CO{sub 2} (SCC), and the co-injection and transport of H{sub 2}S with SCC. These processes were evaluated at conditions of typical storage reservoirs, and for cases of hypothetical leakage from a reservoir to an overlying shallower fresh water aquifer. Modeling capabilities were developed to allow the simulation of multiphase flow and transport of H{sub 2}O, CO{sub 2}, H{sub 2}S, as well as specific organic compounds (benzene), coupled with multicomponent geochemical reaction and transport. This included the development of a new simulator, TMVOC-REACT, starting from existing modules of the TOUGH2 family of codes. This work also included an extensive literature review, calculation, and testing of phase-partitioning properties for mixtures of the phases considered. The reactive transport simulations presented in this report are primarily intended to illustrate the capabilities of the new simulator. They are also intended to help evaluate and understand various processes at play, in a more qualitative than quantitative manner, and only for hypothetical scenarios. Therefore, model results are not intended as realistic assessments of groundwater quality changes for specific locations, and they certainly do not provide an exhaustive evaluation of all possible site conditions, especially given the large variability and uncertainty in hydrogeologic and geochemical parameter input into simulations. The first step in evaluating the potential mobilization and transport of organics was the identification of compounds likely to be present in deep storage formations, and likely to negatively impact freshwater aquifers if mobilized by SCC. On the basis of a literature review related to the occurrence of these organic compounds, their solubility in water and SCC, and their toxicity (as reflected by their maximum contaminant levels MCL), benzene was

  5. 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.

  6. 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.

  7. 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.

  8. Continuous water-quality and suspended-sediment transport monitoring in the San Francisco Bay, California, water years 2014–15

    Science.gov (United States)

    Buchanan, Paul A.; Downing-Kunz, Maureen; Schoellhamer, David H.; Livsey, Daniel N.

    2018-03-08

    The U.S. Geological Survey (USGS) monitors water quality and suspended-sediment transport in the San Francisco Bay (bay) as part of a multi-agency effort to address management, water supply, and ecological concerns. The San Francisco Bay area is home to millions of people, and the bay teems both with resident and with migratory wildlife, plants, and fish. Freshwater mixes with salt water in the bay, which is subject both to riverine influences (floods, droughts, managed reservoir releases and freshwater diversions) and to marine influences (tides, waves, effects of salt water). To understand this environment, the USGS, along with its partners (see “Acknowledgements”), has been monitoring the bay’s waters continuously since 1988. Several water-quality variables are of particular importance to State and Federal resource managers and are monitored at key locations throughout the bay (fig. 1). Salinity, which indicates the relative mixing of fresh and ocean waters in the bay, is derived from specific conductance measurements. Water temperature, along with salinity, affects the density of water, which controls gravity-driven circulation patterns and stratification in the water column. Turbidity, a measure of light scattered from suspended particles in the water, is used to estimate suspended-sediment concentration (SSC). Suspended sediment affects the bay in multiple ways: attenuation of sunlight in the water column, affecting phytoplankton growth; deposition on tidal marsh and intertidal mudflats, which can help sustain these habitats as sea level rises; deposition in ports and shipping channels, which can necessitate dredging; and often, adsorption of contaminants, affecting their distribution and concentrations in the environment. Dissolved oxygen concentration, essential to a healthy ecosystem and a fundamental indicator of water quality, is affected by water temperature, salinity, ecosystem metabolism, tidal currents, and wind. Tidal currents in the bay

  9. Towards a better understanding and behavior recognition of inhabitants in smart cities. A public transport case

    OpenAIRE

    Klimek, Radoslaw; Kotulski, Leszek

    2015-01-01

    The idea of modern urban systems and smart cities requires monitoring and careful analysis of different signals. Such signals can originate from different sources and one of the most promising is the BTS, i.e. base transceiver station, an element of mobile carrier networks. This paper presents the fundamental problems of elicitation, classification and understanding of such signals so as to develop context-aware and pro-active systems in urban areas. These systems are characterized by the omn...

  10. Analysis of the sodium recirculation theory of solute-coupled water transport in small intestine.

    Science.gov (United States)

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

    2002-07-01

    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 flows of water across the epithelium with recirculation of the diffusible ions maintained by a 1Na+-1K+-2Cl- cotransporter in the plasma membrane facing the serosal compartment. With intracellular non-diffusible anions and compliant plasma membranes, the model describes the dependence on membrane permeabilities and pump constants of fluxes of water and electrolytes, volumes and ion concentrations of cell and lateral intercellular space (lis), and membrane potentials and conductances. Simulating physiological bioelectrical features together with cellular and paracellular fluxes of the sodium ion, 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 uphill water flux, or an electroneutral Na+-K+-2Cl- cotransporter.

  11. Ecosystem function in waste stabilisation ponds: Improving water quality through a better understanding of biophysical coupling

    Science.gov (United States)

    Ghadouani, Anas; Reichwaldt, Elke S.; Coggins, Liah X.; Ivey, Gregory N.; Ghisalberti, Marco; Zhou, Wenxu; Laurion, Isabelle; Chua, Andrew

    2014-05-01

    Wastewater stabilisation ponds (WSPs) are highly productive systems designed to treat wastewater using only natural biological and chemical processes. Phytoplankton, microbial communities and hydraulics play important roles for ecosystem functionality of these pond systems. Although WSPs have been used for many decades, they are still considered as 'black box' systems as very little is known about the fundamental ecological processes which occur within them. However, a better understanding of how these highly productive ecosystems function is particularly important for hydrological processes, as treated wastewater is commonly discharged into streams, rivers, and oceans, and subject to strict water quality guidelines. WSPs are known to operate at different levels of efficiency, and treatment efficiency of WSPs is dependent on physical (flow characteristics and sludge accumulation and distribution) and biological (microbial and phytoplankton communities) characteristics. Thus, it is important to gain a better understanding of the role and influence of pond hydraulics and vital microbial communities on pond performance and WSP functional stability. The main aim of this study is to investigate the processes leading to differences in treatment performance of WSPs. This study uses a novel and innovative approach to understand these factors by combining flow cytometry and metabolomics to investigate various biochemical characteristics, including the metabolite composition and microbial community within WSPs. The results of these analyses will then be combined with results from the characterisation of pond hydrodynamics and hydraulic performance, which will be performed using advanced hydrodynamic modelling and advanced sludge profiling technology. By understanding how hydrodynamic and biological processes influence each other and ecosystem function and stability in WSPs, we will be able to propose ways to improve the quality of the treatment using natural processes, with

  12. Water transport through cement-based barriers-A preliminary study using neutron radiography and tomography

    Energy Technology Data Exchange (ETDEWEB)

    Brew, D.R.M. [ANSTO (Australian Nuclear Science and Technology Organisation), Menai, NSW 2234 (Australia)], E-mail: dbr@ansto.gov.au; Beer, F.C. de; Radebe, M.J.; Nshimirimana, R. [Necsa (South African Nuclear Energy Corporation), Pretoria (South Africa); McGlinn, P.J.; Aldridge, L.P.; Payne, T.E. [ANSTO (Australian Nuclear Science and Technology Organisation), Menai, NSW 2234 (Australia)

    2009-06-21

    In this preliminary study we use neutron radiography and tomography to examine differences in water transport through cement pastes and mortars. Bulk residual water contents and sorptivity curves determined using neutron radiography are compared with data obtained gravimetrically. In addition, macro-pore volume distributions of each sample were measured. Furthermore, it was possible to use neutron radiography to monitor the change in the mass of water when samples were dried or when water moved into the samples. The trends and absolute values of weight loss and gain obtained using both approaches are very consistent for mortars, especially when a neutron-scattering correction is applied.

  13. 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....

  14. Understanding youth motivation for water onion (Crinum thaianum J. Schulze conservation in Thailand

    Directory of Open Access Journals (Sweden)

    Nuttasun Athihirunwong

    2018-01-01

    Full Text Available Water Onion is an aquatic plant endemic to the coastal plains of southern Thailand. The species is listed as endangered on the IUCN Red List. Despite rapidly declining stocks, the species is not protected under any Thai legislation nor under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES. At the local level, Water Onion is protected and conserved by young people and adults for various socio-economic reasons. The study explored the participation and underlying conservation motivations of 312 youths in Kapoe district, Ranong province. Using principal component analysis, the youth's motivation for Water Onion conservation was classified into four categories: pro-social, pro-nature, social image, and extrinsic. The results from a logit regression indicated that pro-nature is one of the key motivational factors enhancing actual youth participation in the protection and conservation of Water Onion. It is important for policy makers to understand the effects of various types of motivation on different policy mechanisms in order to craft more effective policies that can further enhance youth participation in conservation initiatives. Keywords: biodiversity conservation, endemic species, pro-nature motivation, water onion, youth

  15. Transients of Water Distribution and Transport in PEM Fuel Cells

    KAUST Repository

    Hussaini, Irfan S.

    2009-01-01

    The response of polymer electrolyte membrane (PEM) fuel cells to a step change in load is investigated experimentally in this work. Voltage undershoot, a characteristic feature of transient response following a step increase in current, is due to transients of water distribution in the membrane and ionomers occurring at subsecond time scales. The use of humidified reactants as a means to control the magnitude of voltage undershoot is demonstrated. Further, the response under a step decrease in current density is explored to determine the existence of hysteresis. Under sufficiently humidified conditions, the responses under forward and reverse step changes are symmetric, but under low relative humidity conditions, voltage undershoot is twice as large as the overshoot. © 2009 The Electrochemical Society.

  16. Transients of Water Distribution and Transport in PEFCs

    KAUST Repository

    Hussaini, Irfan

    2008-01-01

    Response of PEM fuel cells to a step-change in load is investigated experimentally in this work. Voltage undershoot, a characteristic feature of such transient response, is shown to be due to transients of water distribution in membrane phase occurring at sub-second time scales. Use of humidified reactants as a means to control magnitude of voltage undershoot has been demonstrated. Constant stoichiometry operation under certain current-step conditions is found to result in reactant starvation, potentially leading to cell shut down. Further, response under step decrease in current density has been explored to determine existence of hysteresis. Under sufficiently humidified conditions, response under forward and reverse step changes are found to be symmetric, but under low RH conditions, voltage undershoot is found to be twice as large as the overshoot. © The Electrochemical Society.

  17. 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

  18. Transport properties of water molecules confined between hydroxyapaptite surfaces: A Molecular dynamics simulation approach

    Science.gov (United States)

    Prakash, Muthuramalingam; Lemaire, Thibault; Di Tommaso, Devis; de Leeuw, Nora; Lewerenz, Marius; Caruel, Matthieu; Naili, Salah

    2017-10-01

    Water diffusion in the vicinity of hydroxyapatite (HAP) crystals is a key issue to describe biomineralization process. In this study, a configuration of parallel HAP platelets mimicking bone nanopores is proposed to characterize the nanoscopic transport properties of water molecules at HAP-water surface and interfaces using various potential models such as combination of the Core-Shell (CS) model, Lennard-Jones (LJ) potentials with SPC or SPC/E water models. When comparing all these potentials models, it appears that the core-shell potential for HAP together with the SPC/E water model more accurately predicts the diffusion properties of water near HAP surface. Moreover, we have been able to put into relief the possibility of observing hydroxyl (OH-) ion dissociation that modifies the water structure near the HAP surface.

  19. Understanding Indian Institutional Networks and Participation in Water Management Adaptation to Climate Change

    Science.gov (United States)

    Azhoni, A.; Holman, I.; Jude, S.

    2014-12-01

    Adaptation to climate change for water management involves complex interactions between different actors and sectors. The need to understand the relationships between key stakeholder institutions (KSIs) is increasingly recognized. The complexity of water management in India has meant that enhancing adaptive capacity through improved inter-institutional networks remains a challenge for both government and non-governmental institutions. To analyse such complex inter-actions this study has used Social Network and Stakeholder Analysis tools to quantify the participation of, and interactions between, each KSI in the climate change adaptation and water discourse based on keyword analysis of their online presence. Using NodeXL, a Social Network Analysis tool, network diagrams have been used to evaluate the inter-relationships between these KSIs. Semi-structured interviews were conducted with twenty-five KSIs to identify the main barriers to adaptation and to triangulate the findings of the e-documents analysis. The analysis found that there is an inverse relationship between institutions' reference to water and climate change in their web-documents. Most institutions emphasize mitigation rather than adaptation. Bureaucratic delays, poor coordination between the KSIs, unclear policies and systemic deficiencies are identified as key barriers to improving adaptive capacity within water management to climate change. However, the increasing attention being given to the perceived climate change impacts on the water sector and improving the inter-institutional networks are some of the opportunities for Indian water institutions. Although websites of Union Government Institutions seldom directly hyperlink to one another, they are linked through "bridging" websites which have the potential to act as brokers for enhancing adaptive capacity. The research has wider implications for analysis of complex inter-disciplinary and inter-institutional issues involving multi stakeholders.

  20. 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...... concentration of fluid emerging from lis is then significantly larger than the concentration in lis. Thus, in absence of external driving forces the model generates isotonic transport provided a component of the solute flux emerging downstream lis is taken up by cells through the serosal membrane and pumped...

  1. Performance of a Cross-Flow Humidifier with a High Flux Water Vapor Transport Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-30

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  2. Mg/Ca and Sr/Ca as novel geochemical proxies for understanding sediment transport processes within coral reefs

    Science.gov (United States)

    Gacutan, J.; Vila-Concejo, A.; Nothdurft, L. D.; Fellowes, T. E.; Cathey, H. E.; Opdyke, B. N.; Harris, D. L.; Hamylton, S.; Carvalho, R. C.; Byrne, M.; Webster, J. M.

    2017-10-01

    Sediment transport is a key driver of reef zonation and biodiversity, where an understanding of sediment dynamics gives insights into past reef processes and allows the prediction of geomorphic responses to changing environmental conditions. However, modal conditions within the back-reef seldom promote sediment transport, hence direct observation is inherently difficult. Large benthic foraminifera (LBF) have previously been employed as 'tracers' to infer sediment transport pathways on coral reefs, as their habitat is largely restricted to the algal flat and post-mortem, their calcium carbonate test is susceptible to sediment transport forces into the back-reef. Foraminiferal test abundance and post-depositional test alteration have been used as proxies for sediment transport, although the resolution of these measures becomes limited by low test abundance and the lack of variation within test alteration. Here we propose the novel use of elemental ratios as a proxy for sediment transport. Two species, Baculogypsina sphaerulata and Calcarina capricornia, were analysed using a taphonomic index within One Tree and Lady Musgrave reefs, Great Barrier Reef (Australia). Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to determine Mg/Ca and Sr/Ca and these ratios were compared with taphonomic data. Decreases in test Mg/Ca accompany increases in Sr/Ca in specimens from algal-flat to lagoonal samples in both species, mirroring trends indicated by taphonomic values, therefore indicating a relationship with test alteration. To delineate mechanisms driving changes in elemental ratios, back-scattered electron (BSE) images, elemental mapping and in situ quantitative spot analyses by electron microprobe microanalysis (EPMA) using wavelength dispersive X-ray spectrometers (WDS) were performed on un-altered algal flat and heavily abraded tests for both species. EPMA analyses reveal heterogeneity in Mg/Ca between spines and the test wall, implying the loss of

  3. Towards understanding thermodynamics and energy transport in strings of trapped ions

    Science.gov (United States)

    Ramm, Michael; Pruttivarasin, Thaned; Talukdar, Ishan; Haeffner, Hartmut

    2012-06-01

    We report experiments on laser induced heating of ions confined in a linear Paul trap. Specifically, we investigate the mechanism of melting of a crystallized ion chain due to heating by light detuned blue from an atomic resonance. In these experiments, we observe the decay of ion fluorescence as we shine laser light on either the entire ion string or a small subset. From these measurements we hope to extract information on the thermodynamic properties of such Coulomb crystals. Understanding these properties, together with the ability to address individual ions will facilitate the study of excitation transfer dynamics along the chain.

  4. Hydrology of prairie wetlands: Understanding the integrated surface-water and groundwater processes

    Science.gov (United States)

    Hayashi, Masaki; van der Kamp, Garth; Rosenberry, Donald O.

    2016-01-01

    Wetland managers and policy makers need to make decisions based on a sound scientific understanding of hydrological and ecological functions of wetlands. This article presents an overview of the hydrology of prairie wetlands intended for managers, policy makers, and researchers new to this field (e.g., graduate students), and a quantitative conceptual framework for understanding the hydrological functions of prairie wetlands and their responses to changes in climate and land use. The existence of prairie wetlands in the semi-arid environment of the Prairie-Pothole Region (PPR) depends on the lateral inputs of runoff water from their catchments because mean annual potential evaporation exceeds precipitation in the PPR. Therefore, it is critically important to consider wetlands and catchments as highly integrated hydrological units. The water balance of individual wetlands is strongly influenced by runoff from the catchment and the exchange of groundwater between the central pond and its moist margin. Land-use practices in the catchment have a sensitive effect on runoff and hence the water balance. Surface and subsurface storage and connectivity among individual wetlands controls the diversity of pond permanence within a wetland complex, resulting in a variety of eco-hydrological functionalities necessary for maintaining the integrity of prairie-wetland ecosystems.

  5. Understanding and quantifying focused, indirect groundwater recharge from ephemeral streams using water table fluctuations

    Science.gov (United States)

    Cuthbert, M. O.; Acworth, R. I.; Andersen, M. S.; Larsen, J. R.; McCallum, A. M.; Rau, G. C.; Tellam, J. H.

    2016-02-01

    Understanding and managing groundwater resources in drylands is a challenging task, but one that is globally important. The dominant process for dryland groundwater recharge is thought to be as focused, indirect recharge from ephemeral stream losses. However, there is a global paucity of data for understanding and quantifying this process and transferable techniques for quantifying groundwater recharge in such contexts are lacking. Here we develop a generalized conceptual model for understanding water table and groundwater head fluctuations due to recharge from episodic events within ephemeral streams. By accounting for the recession characteristics of a groundwater hydrograph, we present a simple but powerful new water table fluctuation approach to quantify focused, indirect recharge over both long term and event time scales. The technique is demonstrated using a new, and globally unparalleled, set of groundwater observations from an ephemeral stream catchment located in NSW, Australia. We find that, following episodic streamflow events down a predominantly dry channel system, groundwater head fluctuations are controlled by pressure redistribution operating at three time scales from vertical flow (days to weeks), transverse flow perpendicular to the stream (weeks to months), and longitudinal flow parallel to the stream (years to decades). In relative terms, indirect recharge decreases almost linearly away from the mountain front, both in discrete monitored events as well as in the long-term average. In absolute terms, the estimated indirect recharge varies from 80 to 30 mm/a with the main uncertainty in these values stemming from uncertainty in the catchment-scale hydraulic properties.

  6. A new analytical approach to understanding nanoscale lead-iron interactions in drinking water distribution systems.

    Science.gov (United States)

    Trueman, Benjamin F; Gagnon, Graham A

    2016-07-05

    High levels of iron in distributed drinking water often accompany elevated lead release from lead service lines and other plumbing. Lead-iron interactions in drinking water distribution systems are hypothesized to be the result of adsorption and transport of lead by iron oxide particles. This mechanism was explored using point-of-use drinking water samples characterized by size exclusion chromatography with UV and multi-element (ICP-MS) detection. In separations on two different stationary phases, high apparent molecular weight (>669 kDa) elution profiles for (56)Fe and (208)Pb were strongly correlated (average R(2)=0.96, N=73 samples representing 23 single-unit residences). Moreover, (56)Fe and (208)Pb peak areas exhibited an apparent linear dependence (R(2)=0.82), consistent with mobilization of lead via adsorption to colloidal particles rich in iron. A UV254 absorbance peak, coincident with high molecular weight (56)Fe and (208)Pb, implied that natural organic matter was interacting with the hypothesized colloidal species. High molecular weight UV254 peak areas were correlated with both (56)Fe and (208)Pb peak areas (R(2)=0.87 and 0.58, respectively). On average, 45% (std. dev. 10%) of total lead occurred in the size range 0.05-0.45 μm. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Climate change intensification of horizontal water vapor transport in CMIP5

    Science.gov (United States)

    Lavers, David A.; Ralph, F. Martin; Waliser, Duane E.; Gershunov, Alexander; Dettinger, Michael D.

    2015-07-01

    Global warming of the Earth's atmosphere is hypothesized to lead to an intensification of the global water cycle. To determine associated hydrological changes, most previous research has used precipitation. This study, however, investigates projected changes to global atmospheric water vapor transport (integrated vapor transport (IVT)), the key link between water source and sink regions. Using 22 global circulation models from the Climate Model Intercomparison Project Phase 5, we evaluate, globally, the mean, standard deviation, and the 95th percentiles of IVT from the historical simulations (1979-2005) and two emissions scenarios (2073-2099). Considering the more extreme emissions, multimodel mean IVT increases by 30-40% in the North Pacific and North Atlantic storm tracks and in the equatorial Pacific Ocean trade winds. An acceleration of the high-latitude IVT is also shown. Analysis of low-altitude moisture and winds suggests that these changes are mainly due to higher atmospheric water vapor content.

  8. The understanding of the R7T7 glass blocks long term behavior: chemical and transport coupling in fractured media

    International Nuclear Information System (INIS)

    Chomat, L.

    2008-04-01

    The long term behavior of nuclear waste glass blocks depends highly on chemical reactions which occur at the surface in contact with water. Studies carried out on inactive fractured glass blocks show that fracture networks play a significant part in reactive surface area. Nevertheless, the complexity of results interpretation, due to a weak knowledge of fracture networks and local lixiviation conditions, does not allow us to comprehend the physical and chemical mechanisms involved. Model cracks are a key step to study chemical and transport coupling in fractured media. Crack lixiviation in aggressive conditions (pH≥11) show that the crack's position (horizontal or vertical) determines the dominant transport mechanism (respectively diffusion or convection induced by gravity). This gravity driven flow seems to be negligible in lower pH conditions. The convective velocity is estimated by a 1D model of reactive transport. Two other parameters are studied: the influence of thermal gradient and the influence of interconnected cracks on alteration. A strong retroactive effect of convection, due to thermal gradient, on the alteration kinetic is observed inside the crack. These works lead to a complete alteration experiment of a 163 crack network subject to a thermal gradient. The use of the geochemical software, HYTEC, within the framework of this study shows the potential of the software which is however limited by the kinetics law used. (author)

  9. 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.

  10. Water transport and clustering behavior in homopolymer and graft copolymer polylactide

    Energy Technology Data Exchange (ETDEWEB)

    Du, An; Koo, Donghun; Theryo, Grayce; Hillmyer, Marc A.; Cairncross, Richard A. (Drexel); (UMM)

    2015-02-19

    Polylactide is a bio-based and biodegradable polymer well-known for its renewable origins. Water sorption and clustering behavior in both a homopolymer polylactide and a graft copolymer of polylactide was studied using the quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) technique. The graft copolymer, poly(1,5-cyclooctadiene-co-5-norbornene-2-methanol-graft-D,L-lactide), contained polylactide chains (95 wt.%) grafted onto a hydrophobic rubbery backbone (5 wt.%). Clustering is an important phenomenon in the study of water transport properties in polymers since the presence of water clusters can affect the water diffusivity. The HCC method using the thermal power signals and Van't Hoff's law were both employed to estimate the water sorption enthalpy. Sorption enthalpy of water in both polymers was determined to be approximately -40 kJ/mol for all water activity levels. Zimm-Lundberg analysis showed that water clusters start to form at a water activity of 0.4. The engaged species induced clustering (ENSIC) model was used to curve fit sorption isotherms and showed that the affinity among water molecules is higher than that between water molecules and polymer chains. All the methods used indicate that clustering of water molecules exists in both polymers.

  11. Continuous directional water transport on the peristome surface of Nepenthes alata

    Science.gov (United States)

    Chen, Huawei; Zhang, Pengfei; Zhang, Liwen; Liu, Hongliang; Jiang, Ying; Zhang, Deyuan; Han, Zhiwu; Jiang, Lei

    2016-04-01

    Numerous natural systems contain surfaces or threads that enable directional water transport. This behaviour is usually ascribed to hierarchical structural features at the microscale and nanoscale, with gradients in surface energy and gradients in Laplace pressure thought to be the main driving forces. Here we study the prey-trapping pitcher organs of the carnivorous plant Nepenthes alata. We find that continuous, directional water transport occurs on the surface of the ‘peristome’—the rim of the pitcher—because of its multiscale structure, which optimizes and enhances capillary rise in the transport direction, and prevents backflow by pinning in place any water front that is moving in the reverse direction. This results not only in unidirectional flow despite the absence of any surface-energy gradient, but also in a transport speed that is much higher than previously thought. We anticipate that the basic ‘design’ principles underlying this behaviour could be used to develop artificial fluid-transport systems with practical applications.

  12. On the water transport of animals with special reference to Denmark.

    Science.gov (United States)

    Katić, Ivan; Bajt, Vesna Vucevac

    2009-01-01

    Transport of animals by water is a very old way of transport because it is relatively cheap and safe, with a minimum loss of animals. Waterways have been used for the transport of living animals and various goods from ancient times, for example in Ancient Egypt and the Roman Empire. Later, Vikings were so successful in their conquests because they always had trained horses aboard. It is believed that the colonization of America was possible because Spaniards were also bringing many horses with them. Danish possessions in the Caribbean owe much of their economic success in the period between 1820 and 1920 to permanent supply of cheap mules and other equides from South America. Mules were used for agricultural purposes and for work in sugar-cane mills. In the 20th century, a significant number of animals was transported to German and British colonies in South Africa. During the First and the Second World War, animals were also transported by water; measures were taken to meet the fundamental physiological requirements, and a veterinarian accompanied animals on long voyages. These precautions resulted in minimum transport losses.

  13. 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.

  14. The effects of gas diffusion layers structure on water transportation using X-ray computed tomography based Lattice Boltzmann method

    Science.gov (United States)

    Jinuntuya, Fontip; Whiteley, Michael; Chen, Rui; Fly, Ashley

    2018-02-01

    The Gas Diffusion Layer (GDL) of a Polymer Electrolyte Membrane Fuel Cell (PEMFC) plays a crucial role in overall cell performance. It is responsible for the dissemination of reactant gasses from the gas supply channels to the reactant sites at the Catalyst Layer (CL), and the adequate removal of product water from reactant sites back to the gas channels. Existing research into water transport in GDLs has been simplified to 2D estimations of GDL structures or use virtual stochastic models. This work uses X-ray computed tomography (XCT) to reconstruct three types of GDL in a model. These models are then analysed via Lattice Boltzmann methods to understand the water transport behaviours under differing contact angles and pressure differences. In this study, the three GDL samples were tested over the contact angles of 60°, 80°, 90°, 100°, 120° and 140° under applied pressure differences of 5 kPa, 10 kPa and 15 kPa. By varying the contact angle and pressure difference, it was found that the transition between stable displacement and capillary fingering is not a gradual process. Hydrophilic contact angles in the region of 60°<θ < 90° showed stable displacement properties, whereas contact angles in the region of 100°<θ < 140° displayed capillary fingering characteristics.

  15. Effect of passive transport of water through plasma membrane in production of extracellular enzyme.

    Science.gov (United States)

    Mahmoodi, M; Najafpour, G D; Mohammadi, M

    2017-02-01

    In this article, availability and control of water in solid-state fermentation (SSF) were investigated. Based on passive transport of water through plasma membranes, a new model was proposed for calculation and control of water activities in the mixture of solids. The validity of theoretical model and accuracy of the proposed model were proved by experimental data. This model was used for production of pectinases via mixed-SSF with the aid of a rotary drum bioreactor. It was found that in case of extracellular enzyme production, the new model is in good agreement with experimental data for the control of water activities in the mixed-SSF. Exact control of water activity in SFF, the production of endo- and exo-pectinases was relatively enhanced. Based on theoretical view point, the prominence of this new model in control of water activity was also proved.

  16. Open data used in water sciences - Review of access, licenses and understandability

    Science.gov (United States)

    Falkenroth, Esa; Lagerbäck Adolphi, Emma; Arheimer, Berit

    2016-04-01

    The amount of open data available for hydrology research is continually growing. In the EU-funded project SWITCH-ON (Sharing Water-related Information to Tackle Changes in the Hydrosphere - for Operational Needs: www.water-switch-on.eu), we are addressing water concerns by exploring and exploiting the untapped potential of these new open data. This work is enabled by many ongoing efforts to facilitate the use of open data. For instance, a number of portals provide the means to search for open data sets and open spatial data services (such as the GEOSS Portal, INSPIRE community geoportal or various Climate Services and public portals). However, in general, many research groups in water sciences still hesitate in using this open data. We therefore examined some limiting factors. Factors that limit usability of a dataset include: (1) accessibility, (2) understandability and (3) licences. In the SWITCH-ON project we have developed a search tool for finding and accessing data with relevance to water science in Europe, as the existing ones are not addressing data needs in water sciences specifically. The tool is filled with some 9000 sets of metadata and each one is linked to water related key-words. The keywords are based on the ones developed within the CUAHSI community in USA, but extended with non-hydrosphere topics, additional subclasses and only showing keywords actually having data. Access to data sets: 78% of the data is directly accessible, while the rest is either available after registration and request, or through a web client for visualisation but without direct download. However, several data sets were found to be inaccessible due to server downtime, incorrect links or problems with the host database management system. One possible explanation for this could be that many datasets have been assembled by research project that no longer are funded. Hence, their server infrastructure would be less maintained compared to large-scale operational services

  17. Soil heterogeneity effects on water and solute transport. Methodological comparison in different climates

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Hiroshi

    1996-11-01

    Spatial heterogeneity of soils is important to consider for soil water and solute transport. The results of the present work indicated that spatial heterogeneity affects all investigated soils and for widely varying climates. Both soil water content and temperature patterns for a bare and vegetated transect in a typical sand dune area in China indicated preferential transport of soil water after rainfall. Infiltrating soil water appeared to follow paths that had high water content before the rainfall. The effect of rainfall was therefore not a larger uniformity of soil water, but rather increasing variability. Preferential flow was observed by tracer and dye in Tunisia. The experimental data indicated a high degree of bypass or preferential flow within small plots and non-sigmoid breakthrough curves suggesting tailing phenomena and immobile fractions of soil water. The groundwater tracer concentration increased up to twice the concentration of the water in the unsaturated zone withdrawn from different depths. This consequently shows that bypass directly to the groundwater occurred also for unsaturated conditions. Soil layering appeared to be a significant cause for preferential flow for both sand and clay soils. The results also showed great variability for hydraulic properties in terms of van Genuchten parameters for a small plot in a temperate climate. The present work supports the dual-porosity hypothesis. But findings also indicate that the observation scale is important to consider when averaging the process in time and space. 95 refs, 7 figs, 1 tab

  18. Transport Membrane Condenser for Water and Energy Recovery from Power Plant Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Dexin Wang

    2012-03-31

    The new waste heat and water recovery technology based on a nanoporous ceramic membrane vapor separation mechanism has been developed for power plant flue gas application. The recovered water vapor and its latent heat from the flue gas can increase the power plant boiler efficiency and reduce water consumption. This report describes the development of the Transport Membrane Condenser (TMC) technology in details for power plant flue gas application. The two-stage TMC design can achieve maximum heat and water recovery based on practical power plant flue gas and cooling water stream conditions. And the report includes: Two-stage TMC water and heat recovery system design based on potential host power plant coal fired flue gas conditions; Membrane performance optimization process based on the flue gas conditions, heat sink conditions, and water and heat transport rate requirement; Pilot-Scale Unit design, fabrication and performance validation test results. Laboratory test results showed the TMC system can exact significant amount of vapor and heat from the flue gases. The recovered water has been tested and proved of good quality, and the impact of SO{sub 2} in the flue gas on the membrane has been evaluated. The TMC pilot-scale system has been field tested with a slip stream of flue gas in a power plant to prove its long term real world operation performance. A TMC scale-up design approach has been investigated and an economic analysis of applying the technology has been performed.

  19. Modeling Nitrogen Fate and Transport at the Sediment-Water Interface

    Science.gov (United States)

    Diffusive mass transfer at media interfaces exerts control on the fate and transport of pollutants originating from agricultural and urban landscapes and affects the con-ditions of water bodies. Diffusion is essentially a physical process affecting the distribution and fate of va...

  20. Logistics of water and salt transport through the plant: structure and functioning of the xylem

    NARCIS (Netherlands)

    Boer, de A.H.; Volkov, V.

    2003-01-01

    The xylem is a long-distance transport system that is unique to higher plants. It evolved into a very sophisticated plumbing system ensuring controlled loading/unloading of ions and water and their effective translocation to the required sinks. The focus of this overview will be the intrinsic

  1. Logistics of water and salt transport through the plant design and fuctioning of the xylem

    NARCIS (Netherlands)

    de Boer, A.H.; Volkov, V.

    2003-01-01

    The xylem is a long-distance transport system that is unique to higher plants. It evolved into a very sophisticated plumbing system ensuring controlled loading/unloading of ions and water and their effective translocation to the required sinks. The focus of this overview will be the intrinsic

  2. Using SRμCT to define water transport capacity in Picea abies

    Science.gov (United States)

    Lautner, Silke; Lenz, Claudia; Hammel, Jörg; Moosmann, Julian; Kühn, Michael; Caselle, Michele; Vogelgesang, Matthias; Kopmann, Andreas; Beckmann, Felix

    2017-10-01

    Water transport from roots to shoots is a vital necessity in trees in order to sustain their photosynthetic activity and, hence, their physiological activity. The vascular tissue in charge is the woody body of root, stem and branches. In gymnosperm trees, like spruce trees (Picea abies (L.) Karst.), vascular tissue consists of tracheids: elongated, protoplast- free cells with a rigid cell wall that allow for axial water transport via their lumina. In order to analyze the over-all water transport capacity within one growth ring, time-consuming light microscopy analysis of the woody sample still is the conventional approach for calculating tracheid lumen area. In our investigations at the Imaging Beamline (IBL) operated by the Helmholtz-Zentrum Geesthacht (HZG) at PETRA III storage ring of the Deutsches Elektronen-Synchrotron DESY, Hamburg, we applied SRμCT on small wood samples of spruce trees in order to visualize and analyze size and formation of xylem elements and their respective lumina. The selected high-resolution phase-contrast technique makes full use of the novel 20 MPixel CMOS area detector developed within the cooperation of HZG and the Karlsruhe data by light microscopy analysis and, hence, prove, that μCT is a most appropriate method to gain valid information on xylem cell structure and tree water transport capacity.

  3. Carbon dioxide transport in alligator blood and its erythrocyte permeability to anions and water

    DEFF Research Database (Denmark)

    Jensen, F B; Wang, T; Jones, D R

    1998-01-01

    + binding. Erythrocyte volume, plasma pH, and plasma HCO3- concentration also varied little with the degree of oxygenation. Diffusional water permeability was higher in oxygenated than deoxygenated RBCs. The RBCs have rapid band 3-mediated Cl- and HCO3- transport, which was not affected by degree...

  4. Transport of water vapor and inert gas mixtures through highly selective and highly permeable polymer membranes

    NARCIS (Netherlands)

    Metz, S.J.; van de Ven, W.J.C.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias

    2005-01-01

    This paper studies in detail the measurement of the permeation properties of highly permeable and highly selective polymers for water vapor/nitrogen gas mixtures. The analysis of the mass transport of a highly permeable polymer is complicated by the presence of stagnant boundary layers at feed and

  5. Water flow induced transport of Pseudomonas fluorescens cells through soil columns as affected by inoculant treatment

    NARCIS (Netherlands)

    Hekman, W.E.; Heijnen, C.E.; Trevors, J.T.; Elsas, van J.D.

    1994-01-01

    Water flow induced transport of Pseudomonas fluorescens cells through soil columns was measured as affected by the inoculant treatment. Bacterial cells were introduced into the topsoil of columns, either encapsulated in alginate beads of different types or mixed with bentonite clay in concentrations

  6. The cellular contribution to effluent potassium and its relation to free water transport during peritoneal dialysis

    NARCIS (Netherlands)

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

    2007-01-01

    BACKGROUND: Aquaporin-1 (AQP-1) dysfunction is one of the valid theories for decreased free water transport (FWT) in long-term peritoneal dialysis (PD) ultrafiltration failure (UFF). We questioned whether apoptosis of peritoneal cells could be reflected in an increased release of cellular (CR) K(+)

  7. Analysis of the sodium recirculation theory of solute-coupled water transport in small intestine

    DEFF Research Database (Denmark)

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

    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...... permeabilities and pump constants of fluxes of water and electrolytes, volumes and ion concentrations of cell and lateral intercellular space (lis), and membrane potentials and conductances. Simulating physiological bioelectrical features together with cellular and paracellular fluxes of the sodium ion......, 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...

  8. 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

  9. 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.

  10. Interaction between transcellular and paracellular water transport pathways through Aquaporin 5 and the tight junction complex.

    Science.gov (United States)

    Kawedia, Jitesh D; Nieman, Michelle L; Boivin, Gregory P; Melvin, James E; Kikuchi, Ken-Ichiro; Hand, Arthur R; Lorenz, John N; Menon, Anil G

    2007-02-27

    To investigate potential physiological interactions between the transcellular and paracellular pathways of water transport, we asked whether targeted deletion of Aquaporin 5 (AQP5), the major transcellular water transporter in salivary acinar cells, affected paracellular transport of 4-kDa FITC-labeled dextran (FITC-D), which is transported through the paracellular but not the transcellular route. After i.v. injection of FITC-D into either AQP5 wild-type or AQP5-/- mice and saliva collection for fixed time intervals, we show that the relative amount of FITC-D transported in the saliva of AQP5-/- mice is half that in matched AQP5+/+ mice, indicating a 2-fold decrease in permeability of the paracellular barrier in mice lacking AQP5. We also found a significant difference in the proportion of transcellular vs. paracellular transport between male and female mice. Freeze-fracture electron microscopy revealed an increase in the number of tight junction strands of both AQP5+/+ and AQP5-/- male mice after pilocarpine stimulation but no change in strand number in female mice. Average acinar cell volume was increased by approximately 1.4-fold in glands from AQP5-/- mice, suggesting an alteration in the volume-sensing machinery of the cell. Western blots revealed that expression of Claudin-7, Claudin-3, and Occludin, critical proteins that regulate the permeability of the tight junction barrier, were significantly decreased in AQP5-/- compared with AQP5+/+ salivary glands. These findings reveal the existence of a gender-influenced molecular mechanism involving AQP5 that allows transcellular and paracellular routes of water transport to act in conjunction.

  11. Comparison of Contaminant Transport in Agricultural Drainage Water and Urban Stormwater Runoff.

    Directory of Open Access Journals (Sweden)

    Ehsan Ghane

    Full Text Available Transport of nitrogen and phosphorus from agricultural and urban landscapes to surface water bodies can cause adverse environmental impacts. The main objective of this long-term study was to quantify and compare contaminant transport in agricultural drainage water and urban stormwater runoff. We measured flow rate and contaminant concentration in stormwater runoff from Willmar, Minnesota, USA, and in drainage water from subsurface-drained fields with surface inlets, namely, Unfertilized and Fertilized Fields. Commercial fertilizer and turkey litter manure were applied to the Fertilized Field based on agronomic requirements. Results showed that the City Stormwater transported significantly higher loads per unit area of ammonium, total suspended solids (TSS, and total phosphorus (TP than the Fertilized Field, but nitrate load was significantly lower. Nitrate load transport in drainage water from the Unfertilized Field was 58% of that from the Fertilized Field. Linear regression analysis indicated that a 1% increase in flow depth resulted in a 1.05% increase of TSS load from the City Stormwater, a 1.07% increase in nitrate load from the Fertilized Field, and a 1.11% increase in TP load from the Fertilized Field. This indicates an increase in concentration with a rise in flow depth, revealing that concentration variation was a significant factor influencing the dynamics of load transport. Further regression analysis showed the importance of targeting high flows to reduce contaminant transport. In conclusion, for watersheds similar to this one, management practices should be directed to load reduction of ammonium and TSS from urban areas, and nitrate from cropland while TP should be a target for both.

  12. Comparison of Contaminant Transport in Agricultural Drainage Water and Urban Stormwater Runoff.

    Science.gov (United States)

    Ghane, Ehsan; Ranaivoson, Andry Z; Feyereisen, Gary W; Rosen, Carl J; Moncrief, John F

    2016-01-01

    Transport of nitrogen and phosphorus from agricultural and urban landscapes to surface water bodies can cause adverse environmental impacts. The main objective of this long-term study was to quantify and compare contaminant transport in agricultural drainage water and urban stormwater runoff. We measured flow rate and contaminant concentration in stormwater runoff from Willmar, Minnesota, USA, and in drainage water from subsurface-drained fields with surface inlets, namely, Unfertilized and Fertilized Fields. Commercial fertilizer and turkey litter manure were applied to the Fertilized Field based on agronomic requirements. Results showed that the City Stormwater transported significantly higher loads per unit area of ammonium, total suspended solids (TSS), and total phosphorus (TP) than the Fertilized Field, but nitrate load was significantly lower. Nitrate load transport in drainage water from the Unfertilized Field was 58% of that from the Fertilized Field. Linear regression analysis indicated that a 1% increase in flow depth resulted in a 1.05% increase of TSS load from the City Stormwater, a 1.07% increase in nitrate load from the Fertilized Field, and a 1.11% increase in TP load from the Fertilized Field. This indicates an increase in concentration with a rise in flow depth, revealing that concentration variation was a significant factor influencing the dynamics of load transport. Further regression analysis showed the importance of targeting high flows to reduce contaminant transport. In conclusion, for watersheds similar to this one, management practices should be directed to load reduction of ammonium and TSS from urban areas, and nitrate from cropland while TP should be a target for both.

  13. Increasing water vapor transport to the Greenland Ice Sheet revealed using self-organizing maps

    Science.gov (United States)

    Mattingly, Kyle S.; Ramseyer, Craig A.; Rosen, Joshua J.; Mote, Thomas L.; Muthyala, Rohi

    2016-09-01

    The Greenland Ice Sheet (GrIS) has been losing mass in recent decades, with an acceleration in mass loss since 2000. In this study, we apply a self-organizing map classification to integrated vapor transport data from the ERA-Interim reanalysis to determine if these GrIS mass loss trends are linked to increases in moisture transport to Greenland. We find that "moist" days (i.e., days featuring anomalously intense water vapor transport to Greenland) were significantly more common during 2000-2015 compared to 1979-1994. Furthermore, the two most intense GrIS melt seasons during the last 36 years were either preceded by a record percentage of moist winter days (2010) or occurred during a summer with a record frequency of moist days (2012). We hypothesize that moisture transport events alter the GrIS energy budget by increasing downwelling longwave radiation and turbulent fluxes of sensible and latent energy.

  14. Dual-permeability model for water flow and solute transport in shrinking soils

    Science.gov (United States)

    Coppola, Antonio; Gerke, Horst; Comegna, Alessandro; Basile, Angelo

    2014-05-01

    A dual-permeability approach was extended to describe preferential water flow and solute transport in shrinking soils. In the approach, the soil is treated as a dual-permeability bulk porous medium consisting of dynamic interacting matrix and fractures pore domains. Water flow and solute transport in both the domains are described by the Richards' equation and advection-dispersion equation, respectively. In the model the contributions of the two regions to water flow and solute transport is changed dynamically according to the shrinkage characteristic exhibited under soil drying. Aggregate deformation during wetting/drying cycles is assumed to change only the relative proportions of voids in the fractures and in the aggregates, while the total volume of pores (and thus the layer thickness) remains unchanged. Thus, the partial contributions of the fracture and aggregate domains, are now a function of the water content (or the pressure head h), while their sum, the bulk porosity, is assumed to be constant. Any change in the aggregate contribution to total porosity is directly converted into a proportional change in the fracture porosity. This means that bulk volume change during shrinkage is mainly determined by change in crack volume rather than by change in layer thickness. This simplified approach allows dealing with an expansive soil as with a macroscopically rigid soil. The model was already tested by investigating whether and how well hydraulic characteristics obtained under the assumption of "dynamic" dual-permeability hydraulic parameterizations, or, alternatively, assuming the rigidity of the porous medium, reproduced measured soil water contents in a shrinking soil. Here we will discuss theoretical implications of the model in terms of relative importance of the parameters involved. The relative importance will be evaluated for different flow and transport processes and for different initial and top boundary conditions. Key words: Preferential flow and

  15. 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

  16. Fundamental Understanding of Crack Growth in Structural Components of Generation IV Supercritical Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Iouri I. Balachov; Takao Kobayashi; Francis Tanzella; Indira Jayaweera; Palitha Jayaweera; Petri Kinnunen; Martin Bojinov; Timo Saario

    2004-11-17

    This work contributes to the design of safe and economical Generation-IV Super-Critical Water Reactors (SCWRs) by providing a basis for selecting structural materials to ensure the functionality of in-vessel components during the entire service life. During the second year of the project, we completed electrochemical characterization of the oxide film properties and investigation of crack initiation and propagation for candidate structural materials steels under supercritical conditions. We ranked candidate alloys against their susceptibility to environmentally assisted degradation based on the in situ data measure with an SRI-designed controlled distance electrochemistry (CDE) arrangement. A correlation between measurable oxide film properties and susceptibility of austenitic steels to environmentally assisted degradation was observed experimentally. One of the major practical results of the present work is the experimentally proven ability of the economical CDE technique to supply in situ data for ranking candidate structural materials for Generation-IV SCRs. A potential use of the CDE arrangement developed ar SRI for building in situ sensors monitoring water chemistry in the heat transport circuit of Generation-IV SCWRs was evaluated and proved to be feasible.

  17. 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)

  18. Relative turbulent transport efficiency and flux-variance relationships of temperature and water vapor

    Science.gov (United States)

    Hsieh, C. I.

    2016-12-01

    This study investigated the relative transport efficiency and flux-variance relationships of temperature and water vapor, and examined the performance of using this method for predicting sensible heat (H) and water vapor (LE) fluxes with eddy-covariance measured flux data at three different ecosystems: grassland, paddy rice field, and forest.The H and LE estimations were found to be in good agreement with the measurements over the three fields. The prediction accuracy of LE could be improved by around 15% if the predictions were obtained by the flux-variance method in conjunction with measured sensible heat fluxes. Moreover, the paddy rice field was found to be a special case where water vapor follows flux-variance relation better than heat does. The flux budget equations of heat and water vapor were applied to explain this phenomenon. Our results also showed that heat and water vapor were transported with the same efficiency above the grassland and rice paddy. For the forest, heat was transported 20% more efficiently than evapotranspiration.

  19. 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

  20. 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

  1. Effects of Cholesterol on the Thermodynamics and Kinetics of Passive Transport of Water through Lipid Membranes.

    Science.gov (United States)

    Issack, Bilkiss B; Peslherbe, Gilles H

    2015-07-23

    While it has long been known that cholesterol reduces the permeability of biological membranes to water, the exact mechanism by which cholesterol influences transmembrane permeation is still unclear. The thermodynamic and kinetic contributions to the transport of water across mixed DPPC/cholesterol bilayers of different composition are thus examined by molecular dynamics simulations. Our analyses show that cholesterol decreases transmembrane permeability to water mainly by altering the thermodynamics of water transport. In particular, the free-energy barrier to permeation is magnified in the dense bilayer interior and the partitioning of water is significantly lowered. The changes are observed to correlate quantitatively well with the cholesterol-dependent density and thickness of the bilayers. In contrast, diffusion coefficients are relatively insensitive to cholesterol concentration, except in the sparsely populated center of the bilayer. Diffusion of water in cholesterol-containing bilayers appears to be related to changes in the free area in the middle of the bilayer and to the solute cross-sectional area in the denser hydrophobic regions. Overall, cholesterol is found to have an inhibitory effect on the permeation of water at all concentrations investigated, although bilayers containing cholesterol concentrations up to 20 mol % display a more dramatic dependence on cholesterol content than at higher concentrations. Our results show that it is possible to quantitatively reproduce the relative effects of cholesterol on lipid bilayer permeability from molecular dynamics simulations.

  2. Water level determination for transportation projects : mean high water manual, final report, November 2009.

    Science.gov (United States)

    2009-11-01

    To ensure proficient network management and safe usage of navigable waterways especially in waters that are : subject to tides, it is essential that the height of the water at various tidal phases be known. This knowledge is also : essential for prop...

  3. 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.

  4. 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.

  5. Dynamics of the Water Circulations in the Southern South China Sea and Its Seasonal Transports

    Science.gov (United States)

    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. PMID:27410682

  6. 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.

  7. Dynamics of the Water Circulations in the Southern South China Sea and Its Seasonal Transports.

    Directory of Open Access Journals (Sweden)

    Farshid Daryabor

    Full Text Available 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.

  8. 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

    While the zebrafish is commonly used for studies of developmental biology and toxicology, very little is known about their osmoregulatory physiology. The present investigation of Na(+) and Cl(-) transport revealed that the zebrafish is able to tolerate extremely low ambient ion concentrations and...

  9. Water stress inhibits hydraulic conductance and leaf growth in rice seedlings but not the transport of water via mercury-sensitive water channels in the root

    Science.gov (United States)

    Lu; Neumann

    1999-05-01

    The mechanisms by which moderate water stress (adding polyethylene glycol 6000 to the root medium) induces a sustained inhibition of growth in emerging first leaves of intact rice (Oryza sativa) seedlings was investigated under growth-chamber conditions. Early (24 h) inhibition of leaf growth was not related to changes in root size or in osmotic potential gradients and cell wall-yielding characteristics in the leaf-expansion zone of stressed seedlings. However, reductions in root-to-leaf hydraulic conductance (L) were measured in two rice cultivars after 4 or 24 h at various levels of water stress, and these reductions correlated well with the inhibition of leaf growth. We assayed L by a psychrometric method and, in intact seedlings, by a novel osmotic-jump method. The addition of 0.5 mM HgCl2 to the root medium to inhibit water transport through Hg-sensitive water channels in the roots did not inhibit leaf growth in unstressed seedlings. However, both leaf growth and L were additionally reduced (by 49% and 43%, respectively) within minutes of adding HgCl2 to roots of water-stressed seedlings. Water stress therefore appeared to increase the transport of water via Hg-sensitive water channels. Other mechanisms were apparently involved in inhibiting overall L and leaf growth.

  10. 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

  11. Co-current air-water flow in downward sloping pipes : Transport of capacity reducing gas pockets in wastewater mains

    NARCIS (Netherlands)

    Pothof, I.W.M.

    2011-01-01

    Air-water flow is an undesired condition in many systems for the transportation of water or wastewater. Air in storm water tunnels may get trapped and negatively affect the system. Air pockets in hydropower tunnels or sewers may cause blow-back events and inadmissible pressure spikes. Water pipes

  12. Numerical and experimental investigations for insulation particle transport phenomena in water flow

    Energy Technology Data Exchange (ETDEWEB)

    Krepper, Eckhard [Forschungszentrum Dresden Rossendorf e.V., (FZD), Institute of Safety Research, P.O. Box 510119, D-01314 Dresden (Germany)], E-mail: E.Krepper@fzd.de; Glover, Gregory Cartland; Grahn, Alexander; Weiss, Frank-Peter [Forschungszentrum Dresden Rossendorf e.V., (FZD), Institute of Safety Research, P.O. Box 510119, D-01314 Dresden (Germany); Alt, Soeren; Hampel, Rainer; Kaestner, Wolfgang; Kratzsch, Alexander; Seeliger, Andre [University of Applied Science Zittau/Goerlitz, Theodor Koerner Allee 16, D-02763 Zittau (Germany)

    2008-08-15

    The investigation of insulation debris generation, transport and sedimentation becomes more important with regard to reactor safety research for pressurized and boiling water reactors, when considering the long-term behaviour of emergency core coolant systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of a disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb or impinge on the emergency core cooling systems. Open questions of generic interest are for example the particle load on strainers and corresponding pressure-drop, the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow. A joint research project on such questions is being performed in cooperation with the University of Applied Science Zittau/Goerlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation and the development of computational fluid dynamic (CFD) models for the description of particle transport phenomena in coolant flow. While the experiments are performed at the University Zittau/Goerlitz, the theoretical work is concentrated at Forschungszentrum Dresden-Rossendorf. In the present paper, the basic concepts for computational fluid dynamic (CFD) modelling are described and experimental results are presented. Further experiments are designed and feasibility studies were performed.

  13. Understanding the impact of polymer self-organization on the microstructure and charge transport in poly(3-hexylthiophene)

    Science.gov (United States)

    Aiyar, Avishek R.

    current revealed in the above study provided substantial impetus to understand the role of single chain effects on macroscopic charge transport in P3HT. We report that differences in regioregularity of side chain attachment in poly(3-hexylthiophene) (P3HT) as small as ca. 4% are sufficient to induce dramatic changes in the electronic and morphological properties of the material. Casting the electronic absorption spectra in the framework of Spano's model reveals that the conjugation length of the polymer chain is surprisingly sensitive to regioregularity. This observation correlates well with the field effect mobilities that are attenuated by one to two orders of magnitude in the lower regioregularity polymer film. We suggest that the increased intrachain order coupled with a reduced fraction of grain boundaries in the higher RR film is responsible for the reported differences. These studies serve as important pieces in the microstructure-charge transport puzzle. A greater insight into the correlation is obtained by devising a technique to tune the crystallinity of the P3HT films and correlating that with the field effect mobility. We shown the formation of ordered supramolecular precursors in P3HT solutions through the application of low intensity ultrasound. These precursors survive the casting process, resulting in a dramatic increase in the degree of crystallinity of the thin films obtained by spin coating. The crystallinity of the films is tunable, with a continuous evolution of meso-scale structures observed as a function of ultrasonic irradiation time. A multiphase solid state morphology is obtained that in turn results in a percolation type charge transport mechanism. This investigation is then extended to understand the role of process conditions, the solvent used and molecular parameters such as regioregularity.

  14. A multi-diagnostic approach to understanding high-latitude plasma transport during the Halloween 2003 storm

    Directory of Open Access Journals (Sweden)

    P. Yin

    2008-09-01

    Full Text Available During the Halloween 2003 storm event, significant electron density enhancements at elevated F-layer altitudes were recorded by the EISCAT and ESR radars in northern Europe between 20:00 and 24:00 UT on 30 October. At the same time, a sequence of optical images from Qaanaaq in northern Greenland captured a series of eastward-propagating polar cap patches. In this paper, an advanced 4-D tomographic method based on the assimilation of global GPS data, coupled to a predictive Kalman filtering technique, has been used to reveal the linkage between these ionospheric structures. The combination of the various data sources has clearly established the time history of this extreme event, in which high-density plasma was uplifted in the dayside ionosphere and convected anti-sunward across the polar cap to European high latitudes at an elevated F-layer. Using this multi instrument approach, we can differentiate between those density structures observed at the ESR which occurred as a result of cross-polar transport and those more likely to have been produced by in-situ soft particle precipitation, a distinction which is supported by the ESR and EISCAT data. The multi-diagnostic approach reported here has the potential significantly to extend our current understanding of high latitude plasma transport and the origin of electron density enhancements.

  15. "Sticky"-Ends-Guided Creation of Functional Hollow Nanopores for Guest Encapsulation and Water Transport.

    Science.gov (United States)

    Huo, Yanping; Zeng, Huaqiang

    2016-05-17

    Commercial uses of water-transporting aquaporins for seawater desalination and wastewater reclamation/reuse are being investigated in both academia and the industry. Presently, structural complexity, stability, scalability, and activity reconstitution of these costly channel proteins still present substantial challenges to scientists and engineers. An attractive strategy is to develop robust synthetic water channels able to mimic the water-transporting function of aquaporins for utility in the making of next generation of water channel-based biomimetic porous membranes for various water purification applications. In sharp contrast to burgeoning development in constructing synthetic ion channels over the past four decades, very limited progress has been made in the area of synthetic water channels. A handful of such examples include the first report by Percec in 2007 (Percec et al. J. Am. Chem. Soc. 2007, 129, 11698-11699), which was followed by Barboiu in 2011 (Barboiu et al. Angew. Chem., Int. Ed. 2011, 50, 11366-11372), Gong and Hou in 2012 (Gong et al. Nat. Commun. 2012, 3, 949; Hou et al. J. Am. Chem. Soc. 2012, 134, 8384-8387), and Zeng in 2014 (Zeng et al. J. Am. Chem. Soc. 2014, 136, 14270-14276). Radically deviating from the fact that the discovery of novel synthetic channel systems with desired transport selectivity is most often empirical and very often serendipitous, we have instead adopted a more rational designer approach whereby molecular building blocks have been carefully designed from scratch to perform their intended built-in functions. Our designer journey started in 2008, two years after I started leading a group at the National University of Singapore. Since then, we have been actively investigating the use of designed water-binding "aquafoldamers" to construct synthetic water channels for the rapid and selective transport of water molecules ideally with the exclusion of all other nonproton molecular species. Toward this goal, we designed and

  16. Measurement of Membrane Characteristics Using the Phenomenological Equation and the Overall Mass Transport Equation in Ion-Exchange Membrane Electrodialysis of Saline Water

    Directory of Open Access Journals (Sweden)

    Yoshinobu Tanaka

    2012-01-01

    Full Text Available The overall membrane pair characteristics included in the overall mass transport equation are understandable using the phenomenological equations expressed in the irreversible thermodynamics. In this investigation, the overall membrane pair characteristics (overall transport number , overall solute permeability , overall electro-osmotic permeability and overall hydraulic permeability were measured by seawater electrodialysis changing current density, temperature and salt concentration, and it was found that occasionally takes minus value. For understanding the above phenomenon, new concept of the overall concentration reflection coefficient ∗ is introduced from the phenomenological equation. This is the aim of this investigation. ∗ is defined for describing the permselectivity between solutes and water molecules in the electrodialysis system just after an electric current interruption. ∗ is expressed by the function of and . ∗ is generally larger than 1 and is positive, but occasionally ∗ becomes less than 1 and becomes negative. Negative means that ions are transferred with water molecules (solvent from desalting cells toward concentrating cells just after an electric current interruption, indicating up-hill transport or coupled transport between water molecules and solutes.

  17. Crossing Scales and Disciplines to Understand Challenges for Climate Change Adaptation and Water Resources Management in Chile and Californi

    Science.gov (United States)

    Vicuna, S.; Melo, O.; Meza, F. J.; Medellin-Azuara, J.; Herman, J. D.; Sandoval Solis, S.

    2017-12-01

    California and Chile share similarities in terms of climate, ecosystems, topography and water use. In both regions, the hydro-climatologic system is characterized by a typical Mediterranean climate, rainy winters and dry summers, highly variable annual precipitation, and snowmelt-dependent water supply systems. Water use in both regions has also key similarities, with the highest share devoted to high-value irrigated crops, followed by urban water use and a significant hydropower-driven power supply system. Snowmelt-driven basins in semiarid regions are highly sensitive to climate change for two reasons, temperature effects on snowmelt timing and water resources scarcity in these regions subject to ever-increasing demands. Research in both regions also coincide in terms of the potential climate change impacts. Expected impacts on California and Chile water resources have been well-documented in terms of changes in water supply and water demand, though significant uncertainties remain. Both regions have recently experienced prolonged droughts, providing an opportunity to understand the future challenges and potential adaptive responses under climate change. This study connects researchers from Chile and California with the goal of understanding the problem of how to adapt to climate change impacts on water resources and agriculture at the various spatial and temporal scales. The project takes advantage of the complementary contexts between Chile and California in terms of similar climate and hydrologic conditions, water management institutions, patterns of water consumption and, importantly, a similar challenge facing recent drought scenarios to understand the challenges faced by a changing climate.

  18. Water and Salt Transport Properties of Triptycene-Containing Sulfonated Polysulfone Materials for Desalination Membrane Applications.

    Science.gov (United States)

    Luo, Hongxi; Aboki, Joseph; Ji, Yuanyuan; Guo, Ruilan; Geise, Geoffrey M

    2018-01-31

    A series of triptycene-containing sulfonated polysulfone (TRP-BP) materials was prepared via condensation polymerization, and the desalination membrane-relevant fundamental water and salt transport properties (i.e., sorption, diffusion, and permeability coefficients) of the polymers were characterized. Incorporating triptycene into sulfonated polysulfone increased the water content of the material compared to sulfonated polysulfone materials that do not contain triptycene. No significant difference in salt sorption was observed between TRP-BP membranes and other sulfonated polysulfone membranes, suggesting that the presence of triptycene in the polymer did not dramatically affect thermodynamic interactions between salt and the polymer. Both water and salt diffusion coefficients in the TRP-BP membranes were suppressed relative to other sulfonated polysulfone materials with comparable water content, and these phenomena may result from the influence of triptycene on polymer chain packing and/or free-volume distribution, which could increase the tortuosity of the transport pathways in the polymers. Enhanced water/salt diffusivity selectivity was observed for some of the TRP-BP membranes relative to those materials that did not contain triptycene, and correspondingly, incorporation of triptycene into sulfonated polysulfone resulted in an increase, particularly for acid counterion form TRP-BP materials, in water/salt permeability selectivity, which is favorable for desalination membrane applications.

  19. Swelling kinetics and electrical charge transport in PEDOT:PSS thin films exposed to water vapor.

    Science.gov (United States)

    Sarkar, Biporjoy; Jaiswal, Manu; Satapathy, Dillip K Kumar

    2018-04-16

    We report the swelling kinetics and evolution of the electrical charge transport in poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films subjected to water vapor. Polymer films swell by the diffusion of water vapor and are found to undergo structural relaxations. Upon exposure to water vapor, primarily the hygroscopic PSS shell, which surrounds the conducting PEDOT-rich cores, takes up water vapor and subsequently swells. We found that the degree of swelling largely depends on the PEDOT to PSS ratio. Swelling driven microscopic rearrangement of the conducting PEDOT-rich cores in the PSS matrix strongly influences the electrical charge transport of the polymer film. Swelling induced increase as well as decrease of electrical resistance are observed in polymer films having different PEDOT to PSS ratio. This anomalous charge transport behavior in PEDOT:PSS films is reconciled by taking into account the contrasting swelling behavior of the PSS and the conducting PEDOT-rich cores leading to spatial segregation of PSS in films with PSS as a minority phase and by a net increase in mean separation between conducting PEDOT-rich cores for films having abundance of PSS. © 2018 IOP Publishing Ltd.

  20. 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 < 0.05) influence of the applied ultrasonic power on the identified kinetic parameters: effective moisture diffusivity and 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.

  1. Water and chloride transport in a fine-textured soil in a feedlot pen

    Science.gov (United States)

    Veizaga, E. A.; Rodríguez, L.; Ocampo, C. J.

    2015-11-01

    Cattle feeding in feedlot pens produces large amounts of manure and animal urine. Manure solutions resulting from surface runoff are composed of numerous chemical constituents whose leaching causes salinization of the soil profile. There is a relatively large number of studies on preferential flow characterization and modeling in clayed soils. However, research on water flow and solute transport derived from cattle feeding operations in fine-textured soils under naturally occurring precipitation events is less frequent. A field monitoring and modeling investigation was conducted at two plots on a fine-textured soil near a feedlot pen in Argentina to assess the potential of solute leaching into the soil profile. Soil pressure head and chloride concentration of the soil solution were used in combination with HYDRUS-1D numerical model to simulate water flow and chloride transport resorting to the concept of mobile/immobile-MIM water for solute transport. Pressure head sensors located at different depths registered a rapid response to precipitation suggesting the occurrence of preferential flow-paths for infiltrating water. Cracks and small fissures were documented at the field site where the % silt and % clay combined is around 94%. Chloride content increased with depth for various soil pressure head conditions, although a dilution process was observed as precipitation increased. The MIM approach improved numerical results at one of the tested sites where the development of cracks and macropores is likely, obtaining a more dynamic response in comparison with the advection-dispersion equation.

  2. 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

  3. Regional water implications of reducing oil imports with liquid transportation fuel alternatives in the United States.

    Science.gov (United States)

    Jordaan, Sarah M; Diaz Anadon, Laura; Mielke, Erik; Schrag, Daniel P

    2013-01-01

    The Renewable Fuel Standard (RFS) is among the cornerstone policies created to increase U.S. energy independence by using biofuels. Although greenhouse gas emissions have played a role in shaping the RFS, water implications are less understood. We demonstrate a spatial, life cycle approach to estimate water consumption of transportation fuel scenarios, including a comparison to current water withdrawals and drought incidence by state. The water consumption and land footprint of six scenarios are compared to the RFS, including shale oil, coal-to-liquids, shale gas-to-liquids, corn ethanol, and cellulosic ethanol from switchgrass. The corn scenario is the most water and land intense option and is weighted toward drought-prone states. Fossil options and cellulosic ethanol require significantly less water and are weighted toward less drought-prone states. Coal-to-liquids is an exception, where water consumption is partially weighted toward drought-prone states. Results suggest that there may be considerable water and land impacts associated with meeting energy security goals through using only biofuels. Ultimately, water and land requirements may constrain energy security goals without careful planning, indicating that there is a need to better balance trade-offs. Our approach provides policymakers with a method to integrate federal policies with regional planning over various temporal and spatial scales.

  4. Effects of water content on reactive transport of Sr in Chernobyl sand columns

    Energy Technology Data Exchange (ETDEWEB)

    Szenknect, S. [CEA, Tracers Applications Laboratory, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Dewiere, L.; Ardois, C. [IRSN, Environment and Emergency Operations Division, Geosphere-related Risk Analysis Department, BP 17, 92262 Fontenay-aux-Roses (France); Gaudet, J.P. [UMR 5564 (CNRS/IRD/INPG/UJF), LTHE, BP 53, 38041 Grenoble Cedex 9 (France)

    2005-07-01

    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. Transportation

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    Here is the decree of the thirtieth of July 1998 relative to road transportation, to trade and brokerage of wastes. It requires to firms which carry out a road transportation as well as to traders and to brokers of wastes to declare their operations to the prefect. The declaration has to be renewed every five years. (O.M.)

  6. A 3-D functional-structural grapevine model that couples the dynamics of water transport with leaf gas exchange.

    Science.gov (United States)

    Zhu, Junqi; Dai, Zhanwu; Vivin, Philippe; Gambetta, Gregory A; Henke, Michael; Peccoux, Anthony; Ollat, Nathalie; Delrot, Serge

    2017-12-23

    Predicting both plant water status and leaf gas exchange under various environmental conditions is essential for anticipating the effects of climate change on plant growth and productivity. This study developed a functional-structural grapevine model which combines a mechanistic understanding of stomatal function and photosynthesis at the leaf level (i.e. extended Farqhuhar-von Caemmerer-Berry model) and the dynamics of water transport from soil to individual leaves (i.e. Tardieu-Davies model). The model included novel features that account for the effects of xylem embolism (fPLC) on leaf hydraulic conductance and residual stomatal conductance (g0), variable root and leaf hydraulic conductance, and the microclimate of individual organs. The model was calibrated with detailed datasets of leaf photosynthesis, leaf water potential, xylem sap abscisic acid (ABA) concentration and hourly whole-plant transpiration observed within a soil drying period, and validated with independent datasets of whole-plant transpiration under both well-watered and water-stressed conditions. The model well captured the effects of radiation, temperature, CO2 and vapour pressure deficit on leaf photosynthesis, transpiration, stomatal conductance and leaf water potential, and correctly reproduced the diurnal pattern and decline of water flux within the soil drying period. In silico analyses revealed that decreases in g0 with increasing fPLC were essential to avoid unrealistic drops in leaf water potential under severe water stress. Additionally, by varying the hydraulic conductance along the pathway (e.g. root and leaves) and changing the sensitivity of stomatal conductance to ABA and leaf water potential, the model can produce different water use behaviours (i.e. iso- and anisohydric). The robust performance of this model allows for modelling climate effects from individual plants to fields, and for modelling plants with complex, non-homogenous canopies. In addition, the model provides a

  7. Transport behavior of surrogate biological warfare agents in a simulated landfill: Effect of leachate recirculation and water infiltration

    KAUST Repository

    Saikaly, Pascal

    2010-11-15

    An understanding of the transport behavior of biological warfare (BW) agents in landfills is required to evaluate the suitability of landfills for the disposal of building decontamination residue (BDR) following a bioterrorist attack on a building. Surrogate BW agents, Bacillus atrophaeus spores and Serratia marcescens, were spiked into simulated landfill reactors that were filled with synthetic building debris (SBD) and operated for 4 months with leachate recirculation or water infiltration. Quantitative polymerase chain reaction (Q-PCR) was used to monitor surrogate transport. In the leachate recirculation reactors, <10% of spiked surrogates were eluted in leachate over 4 months. In contrast, 45% and 31% of spiked S. marcescens and B. atrophaeus spores were eluted in leachate in the water infiltration reactors. At the termination of the experiment, the number of retained cells and spores in SBD was measured over the depth of the reactor. Less than 3% of the total spiked S. marcescens cells and no B. atrophaeus spores were detected in SBD. These results suggest that significant fractions of the spiked surrogates were strongly attached to SBD. © 2010 American Chemical Society.

  8. Numerical simulation of micro-scale flow and colloid transport near air-water interface in unsaturated porous media

    Science.gov (United States)

    Shi, Grace; Lazouskaya, Volha; Jin, Yan; Wang, Lian-Ping

    2008-11-01

    This work is motivated by the need to understand colloid-facilitated transport of contaminants in unsaturated soil porous media. Unsaturated soil is characterized by the presence of moving air-water interface within micro-scale flow passage of soil porous media. Previous experimental observations using confocal microscopy reveal the importance of air-water interface and contact line on the retention of colloids. Here we develop a computational approach to model the transport and retention of colloids near the interfacial region. First, we simulate the microscale flow field near the interfacial region by simultaneously employing a mesoscopic lattice Boltzmann equation approach and a macroscopic volume-of-fluid approach. We will examine how the flow field changes with capillary number, Reynolds number, density ratio, and viscosity ratio. Numerical issues such as stability and spurious currents for interfacial flow simulation will be discussed. We then track the motion of colloids by solving colloids equation of motion including hydrodynamic forces and physicochemical forces, to study the trajectories of colloids and the likely retention sites. Numerical results will be compared with parallel visualization experiments.

  9. A modified QWASI model for fate and transport modeling of mercury between the water-ice-sediment in Lake Ulansuhai.

    Science.gov (United States)

    Liu, Yu; Li, Changyou; Anderson, Bruce; Zhang, Sheng; Shi, Xiaohong; Zhao, Shengnan

    2017-06-01

    Mercury contamination from industrial and agricultural drainage into lakes and rivers is a growing concern in Northern China. Lake Ulansuhai, located in Hetao irrigation district in Inner Mongolia, is the only sink for the all industrial and agricultural drainage and sole outlet for this district to the Yellow River, which is one of the main source of drinking water for the numerous cities and towns downstream. Because Ulansuahi is ice-covered during winter, the QWASI model was modified by adding an ice equation to get a more accurate understanding of the fate and transport of mercury within the lake. Both laboratory and field tests were carried out during the ice growth period. The aquivalence and mass balance approaches were used to develop the modified QWASI + ice model. The margins of error between the modelled and the measured average concentrations of Hg in ice, water, and sediment were 30%, 26.2%, and 19.8% respectively. These results suggest that the new QWASI + ice model could be used to more accurately represent the fate and transport of mercury in the seasonally ice-covered lakes, during the ice growth period. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Coarse-grained model of nanoscale segregation, water diffusion, and proton transport in Nafion membranes

    Science.gov (United States)

    Vishnyakov, Aleksey; Mao, Runfang; Lee, Ming-Tsung; Neimark, Alexander V.

    2018-01-01

    We present a coarse-grained model of the acid form of Nafion membrane that explicitly includes proton transport. This model is based on a soft-core bead representation of the polymer implemented into the dissipative particle dynamics (DPD) simulation framework. The proton is introduced as a separate charged bead that forms dissociable Morse bonds with water beads. Morse bond formation and breakup artificially mimics the Grotthuss hopping mechanism of proton transport. The proposed DPD model is parameterized to account for the specifics of the conformations and flexibility of the Nafion backbone and sidechains; it treats electrostatic interactions in the smeared charge approximation. The simulation results qualitatively, and in many respects quantitatively, predict the specifics of nanoscale segregation in the hydrated Nafion membrane into hydrophobic and hydrophilic subphases, water diffusion, and proton mobility. As the hydration level increases, the hydrophilic subphase exhibits a percolation transition from a collection of isolated water clusters to a 3D network of pores filled with water embedded in the hydrophobic matrix. The segregated morphology is characterized in terms of the pore size distribution with the average size growing with hydration from ˜1 to ˜4 nm. Comparison of the predicted water diffusivity with the experimental data taken from different sources shows good agreement at high and moderate hydration and substantial deviation at low hydration, around and below the percolation threshold. This discrepancy is attributed to the dynamic percolation effects of formation and rupture of merging bridges between the water clusters, which become progressively important at low hydration, when the coarse-grained model is unable to mimic the fine structure of water network that includes singe molecule bridges. Selected simulations of water diffusion are performed for the alkali metal substituted membrane which demonstrate the effects of the counter-ions on

  11. The influence of water on the structural and transport properties of model ionic liquids.

    Science.gov (United States)

    Spohr, Heidrun V; Patey, G N

    2010-06-21

    Molecular dynamics simulations are used to investigate the influence of water on model ionic liquids. Several models, where the ions vary in size, and in the location of the charge with respect to the center of mass, are considered. Particular attention is focused on the variation in transport properties (diffusion coefficients, shear viscosity, and electrical conductivity) with water concentration. An effort is made to identify the underlying physical reasons for water's influence. The results for our model ionic liquids fall loosely into two categories, depending on the molecular characteristics of the constituent ions. If the ion size disparity is not too large (cation:anion diameter ratio water concentration. This agrees with what is commonly observed experimentally for room temperature ionic liquids (RTILs). For these systems, we do not find changes in the equilibrium structure that can account for the strong influence of water on the transport properties. Rather, by varying the molecular mass of water in our simulations, we demonstrate that the dominant effect of water can be dynamical in origin. In RTIL-water mixtures, the molecular mass of water is generally much less than that of the ions it replaces. These lighter water molecules tend to displace much heavier counterions from the ion coordination shells. This reduces caging and increases the diffusivity, which leads to higher conductivities and lower viscosities. For models with a larger ion size disparity (3:1), or in charge-off-center systems, where strong directional ion pairs are important in the pure ionic liquid, the behavior can be quite different. In these systems, the diffusion coefficients and electrical conductivity can still display conventional behavior and increase when water is added even though the reasons for this can be more complex than in the simpler cases noted above. However, in these systems the viscosity can increase, sometimes quite steeply, with increasing water concentration. We

  12. Carbon-water Cycling in the Critical Zone: Understanding Ecosystem Process Variability Across Complex Terrain

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, Holly [Univ. of Colorado, Boulder, CO (United States); Brooks, Paul [Univ. of Utah, Salt Lake City, UT (United States); Univ. of Arizona, Tucson, AZ (United States)

    2016-06-16

    One of the largest knowledge gaps in environmental science is the ability to understand and predict how ecosystems will respond to future climate variability. The links between vegetation, hydrology, and climate that control carbon sequestration in plant biomass and soils remain poorly understood. Soil respiration is the second largest carbon flux of terrestrial ecosystems, yet there is no consensus on how respiration will change as water availability and temperature co-vary. To address this knowledge gap, we use the variation in soil development and topography across an elevation and climate gradient on the Front Range of Colorado to conduct a natural experiment that enables us to examine the co-evolution of soil carbon, vegetation, hydrology, and climate in an accessible field laboratory. The goal of this project is to further our ability to combine plant water availability, carbon flux and storage, and topographically driven hydrometrics into a watershed scale predictive model of carbon balance. We hypothesize: (i) landscape structure and hydrology are important controls on soil respiration as a result of spatial variability in both physical and biological drivers: (ii) variation in rates of soil respiration during the growing season is due to corresponding shifts in belowground carbon inputs from vegetation; and (iii) aboveground carbon storage (biomass) and species composition are directly correlated with soil moisture and therefore, can be directly related to subsurface drainage patterns.

  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. Understanding the Warm Water Volume Precursor of ENSO Events and its Interdecadal Variation

    Science.gov (United States)

    Neske, S.; McGregor, S.

    2018-02-01

    A wind forced ocean model is used to decompose the equatorial Pacific warm water volume (WWV) between 1980 and 2016 into two components: the (i) adjusted wind response, which is found by letting the model evolve unforced for three months, and (ii) instantaneous wind response, which are the instantaneous WWV changes due to Ekman transports. Our results suggest that roughly half of WWV variability is only as predictable as the winds that drive the instantaneous change. Separate examinations of pre-2000 and post-2000 periods reveal (i) nearly equal importance of instantaneous and adjusted responses for the pre-2000 period and (ii) dominance of the instantaneous response during the post-2000 period, which is most apparent during the recharged phase. This increasing instantaneous contribution prominence explains the post-2000 reduction in WWV/El Niño-Southern Oscillation sea surface temperature lead times (from six to nine months pre-2000 down to three months post-2000) and is consistent with the reduction in post-2000 El Niño-Southern Oscillation prediction skill.

  15. 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.

  16. Water flow and multicomponent solute transport in drip-irrigated lysimeters

    Science.gov (United States)

    Raij, Iael; Šimůnek, Jiří; Ben-Gal, Alon; Lazarovitch, Naftali

    2016-08-01

    Controlled experiments and modeling are crucial components in the evaluation of the fate of water and solutes in environmental and agricultural research. Lysimeters are commonly used to determine water and solute balances and assist in making sustainable decisions with respect to soil reclamation, fertilization, or irrigation with low-quality water. While models are cost-effective tools for estimating and preventing environmental damage by agricultural activities, their value is highly dependent on the accuracy of their parameterization, often determined by calibration. The main objective of this study was to use measured major ion concentrations collected from drip-irrigated lysimeters to calibrate the variably saturated water flow model HYDRUS (2D/3D) coupled with the reactive transport model UNSATCHEM. Irrigation alternated between desalinated and brackish waters. Lysimeter drainage and soil solution samples were collected for chemical analysis and used to calibrate the model. A second objective was to demonstrate the potential use of the calibrated model to evaluate lower boundary design options of lysimeters with respect to leaching fractions determined using drainage water fluxes, chloride concentrations, and overall salinity of drainage water, and exchangeable sodium percentage (ESP) in the profile. The model showed that, in the long term, leaching fractions calculated with electrical conductivity values would be affected by the lower boundary condition pressure head, while those calculated with chloride concentrations and water fluxes would not be affected. In addition, clear dissimilarities in ESP profiles were found between lysimeters with different lower boundary conditions, suggesting a potential influence on hydraulic conductivities and flow patterns.

  17. Surface deformation induced by water pumping for construction of Mass Rapid Transportation in Taipei basin

    Science.gov (United States)

    Hu, J. C.; Wu, P. C.; Tung, H.; Tsai, M. C.

    2017-12-01

    In 1968, there were 2,200 wells in the Taipei Basin used for water supply to meet the requirement of high population density. The overuse of ground water lead to the land subsidence rate up to 5 cm/yr. Although the government had already begun to limit groundwater pumping since 1968, the groundwater in the Taipei Basin demonstrated temporary fluctuation induced by pumping water for large deep excavation site or engineering usage. The previous study based on precise leveling suggested that the surface deformation was highly associated with the recovery of water level. In 1989, widespread uplift dominated in Taipei basin due to the recovery of ground water Table. In this study, we use 37 high-resolution X-band COSMO-SkyMed radar images from May 2011 to April 2015 to characterize deformation pattern in the period of construction of Mass Rapid Transportation (MRT). We also use 30 wells and 380 benchmarks of precise leveling in Taipei basin to study the correlation of surface deformation and change of ground water table. The storability is roughly constant across most of the aquifer with values between 0.8 x 10-4 and 1.3 x 10-3. Moreover, the high water pumping in two major aquifers, Jignme and Wuku Foramtions, before the underground construction for MRT led to inflict surface deformation and no time delay observed for surface deformation during the water pumping. It implies that the poro-elastic effect dominates in major aquifers in Taipei basin.

  18. 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

  19. 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)

  20. 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.

  1. CFD-modeling of insulation debris transport phenomena in water flow

    Energy Technology Data Exchange (ETDEWEB)

    Krepper, Eckhard, E-mail: E.Krepper@fzd.d [Forschungszentrum Dresden-Rossendorf, Institute of Safety Research, Bautzner Landstrasse 128, 01328 Dresden (Germany); Cartland-Glover, Gregory; Grahn, Alexander; Weiss, Frank-Peter [Forschungszentrum Dresden-Rossendorf, Institute of Safety Research, Bautzner Landstrasse 128, 01328 Dresden (Germany); Alt, Soeren; Hampel, Rainer; Kaestner, Wolfgang; Seeliger, Andre [University of Applied Sciences Zittau/Goerlitz (FH), Theodor-Koerner-Allee 16, 02763 Zittau (Germany)

    2010-09-15

    The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behavior of emergency core cooling systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb/impinge on the emergency core cooling systems. Open questions of generic interest are the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow and the particle load on strainers and corresponding pressure drop. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Goerlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Goerlitz, the theoretical modeling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current paper the basic concepts for CFD-modeling are described and feasibility studies including the conceptual design of the experiments are presented.

  2. FEATURES OF ADMINISTRATIVEJURISDICTIONAL ACTIVITY OF EMPLOYEES OF POLICE IN ENSURING PUBLIC SAFETY ON WATER TRANSPORT

    OpenAIRE

    L. B. Panfilova; E. A. Sychev

    2016-01-01

    The article attempts to reveal the concept of administrative and jurisdictional activity of the police to ensure public safety on water transport, the features of the stages of proceedings on administrative offenses. Under the administrative process is commonly understood outside the law enforcement activities of the executive authorities, local government agencies and other entities authorized by the state to resolve the limits of their competence in specific legal cases arising on the basis...

  3. 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.

  4. Transport and Retention of Concentrated Oil-in-Water Emulsions in Sandy Porous Media

    Science.gov (United States)

    Muller, K.; Esahani, S. G.; Steven, C. C.; Ramsburg, A.

    2015-12-01

    Oil-in-water emulsions are widely employed to promote biotic reduction of contaminants; however, emulsions can also be used to encapsulate and deliver active ingredients required for long-term subsurface treatment. Our research focuses on encapsulating alkalinity-releasing particles in oil-in-water emulsions for sustained control of subsurface pH. Typical characteristics of these emulsions include kinetically stable for >20 hr; 20% soybean oil; 1 g/mL density; 8-10 cP viscosity; and 1.5 μm droplet d50, with emulsions developed for favorable subsurface delivery. The viscosity of the oil-in-water emulsions was found to be a function of oil content. Ultimately we aim to model both emulsion delivery and alkalinity release (from retained emulsion droplets) to provide a description of pH treatment. Emulsion transport and retention was investigated via a series of 1-d column experiments using varying particle size fractions of Ottawa sand. Emulsions were introduced for approximately two pore volumes followed by a flush of background solution (approx. ρ=1 g/mL; μ=1cP). Emulsion breakthrough curves exhibit an early fall on the backside of the breakthrough curve along with tailing. Deposition profiles are found to be hyper-exponential and unaffected by extended periods of background flow. Particle transport models established for dilute suspensions are unable to describe the transport of the concentrated emulsions considered here. Thus, we explore the relative importance of additional processes driving concentrated droplet transport and retention. Focus is placed on evaluating the role of attachment-detachment-straining processes, as well as the influence of mixing from both viscous instabilities and variable water saturation due to deposited mass.

  5. Modeling of Ultrathin Catalyst Layers in Polymer Electrolyte Fuel Cells: Proton Transport and Water Management

    OpenAIRE

    Chan, Karen Ka Wing

    2013-01-01

    Ultrathin catalyst layers (UTCLs) are emerging as a promising alternative to conventional catalyst layers in polymer electrolyte fuel cells. In comparison, UTCLs have dramatically reduced Pt loading and thicknesses and are ionomer–free. We explore two open questions in the theory of UTCLs (1) the proton transport mechanism within the ionomer–free layer and (2) water management in membrane electrode assemblies (MEAs) with UTCLs. To investigate (1), we present a UTCL model, which assumes the pr...

  6. Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single Family Homes (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, J.; Withers, C.; Martin, E.; Moyer, N.

    2012-10-01

    This document focuses on managing the driving forces which move air and moisture across the building envelope. While other previously published Measure Guidelines focus on elimination of air pathways, the ultimate goal of this Measure Guideline is to manage drivers which cause air flow and water vapor transport across the building envelope (and also within the home), control air infiltration, keep relative humidity (RH) within acceptable limits, avoid combustion safety problems, improve occupant comfort, and reduce house energy use.

  7. Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single-Family Homes

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, James [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States); Withers, Charles [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States); Martin, Eric [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States); Moyer, Neil [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States)

    2012-10-01

    This report is a revision of an earlier report titled: Measure Guideline: Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single-Family Homes. Revisions include: Information in the text box on page 1 was revised to reflect the most accurate information regarding classifications as referenced in the 2012 International Residential Code. “Measure Guideline” was dropped from the title of the report. An addition was made to the reference list.

  8. Influences of Dam Operations in Groundwater-Surface Water Mixing Zones: Towards Multiscale Understanding

    Science.gov (United States)

    Stegen, J.; Scheibe, T. D.; Chen, X.; Huang, M.; Arntzen, E.; Garayburu-Caruso, V. A.; Graham, E.; Johnson, T. C.; Strickland, C. E.

    2017-12-01

    The installation and operation of dams have myriad influences on ecosystems, from direct effects on hydrographs to indirect effects on marine biogeochemistry and terrestrial food webs. With > 50000 existing and > 3700 planned large dams world-wide there is a pressing need for holistic understanding of dam impacts. Such understanding is likely to reveal unrecognized opportunities to modify dam operations towards beneficial outcomes. One of the most dramatic influences of daily dam operations is the creation of `artificial intertidal zones' that emerge from short-term increases and decreases in discharge due to hydroelectric power demands; known as hydropeaking. There is a long history of studying the influences of hydropeaking on macrofauna such as fish and invertebrates, but only recently has significant attention been paid to the hydrobiogeochemical effects of hydropeaking. Our aim here is to develop an integrated conceptual model of the hydrobiogeochemical influences of hydropeaking. To do so we reviewed available literature focusing on hydrologic and/or biogeochemical influences of hydropeaking. Results from these studies were collated into a single conceptual model that integrates key physical (e.g., sediment transport, hydromorphology) and biological (e.g., timescale of microbiome response) processes. This conceptual model highlights non-intuitive impacts of hydropeaking, the presence of critical thresholds, and strong interactions among processes. When examined individually these features suggest context dependency, but when viewed through an integrated conceptual model, common themes emerge. We will further discuss a critical next step, which is the local to regional to global evaluation of this conceptual model, to enable multiscale understanding. We specifically propose a global `hydropeaking network' of researchers using common methods, data standards, and analysis techniques to quantify the hydrobiogeochemical effects of hydropeaking across biomes. We

  9. Transportation

    National Research Council Canada - National Science Library

    Allshouse, Michael; Armstrong, Frederick Henry; Burns, Stephen; Courts, Michael; Denn, Douglas; Fortunato, Paul; Gettings, Daniel; Hansen, David; Hoffman, Douglas; Jones, Robert

    2007-01-01

    .... The ability of the global transportation industry to rapidly move passengers and products from one corner of the globe to another continues to amaze even those wise to the dynamics of such operations...

  10. Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates

    Science.gov (United States)

    Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.

    2017-04-01

    The role of glaciers in landscape evolution is central to the interactions between climate and tectonic forces at high latitudes and in mountainous regions. Sediment yields from glacierized basins are used to quantify contemporary erosion rates on seasonal to decadal timescales, often under the assumption that subglacial water flow is the main contributor to these yields. Two recent studies have furthermore used such sediment fluxes to calibrate a glacial erosion rule, where erosion rate scales with ice sliding speed raised to a power greater than one. Subglacial sediment transport by water flow has however seldom been studied, thus the controls on sediment yield from glacierized basins remain enigmatic. To bridge this gap, we develop a 1-D model of morphodynamics in semi-circular bedrock-floored subglacial channels. We adapt a sediment conservation law from the fluvial literature, developed for both mixed bedrock / alluvial and alluvial conditions, to subglacial channels. Channel evolution is a function of the traditional melt-opening due to viscous heat dissipation from the water flow, and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. Using a simple ice geometry representing a land-terminating glacier, we find that the shear stresses produced by the water flow on the bed decrease significantly near the terminus. As the ice thins, creep closure decreases and large hydraulic potential gradients cannot be sustained. The resulting gradients in sediment transport lead to a bottleneck, and sediment accumulates if the sediment supply is adequate. A similar bottleneck occurs if a channel is well established and water discharge drops. Whether such constriction happens in space of time, in the presence of a sufficiently large sediment supply sediment accumulates temporarily near the terminus, followed shortly thereafter by enhanced sediment transport. Reduction in the cross-sectional area

  11. 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

    diffusion layer, microporous layer, and catalyst layer, excluding the membrane and anode. In the porous media liquid water transport is described by the capillary pressure gradient, momentum loss via the Darcy-Forchheimer equation, and mass transfer between phases by a nonequilibrium phase change model...... 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.......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...

  12. Hydrogeochemical processes governing the origin, transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters

    Science.gov (United States)

    Nordstrom, D. Kirk

    2011-01-01

    The formation of acid mine drainage from metals extraction or natural acid rock drainage and its mixing with surface waters is a complex process that depends on petrology and mineralogy, structural geology, geomorphology, surface-water hydrology, hydrogeology, climatology, microbiology, chemistry, and mining and mineral processing history. The concentrations of metals, metalloids, acidity, alkalinity, Cl-, F- and SO42- found in receiving streams, rivers, and lakes are affected by all of these factors and their interactions. Remediation of mine sites is an engineering concern but to design a remediation plan without understanding the hydrogeochemical processes of contaminant mobilization can lead to ineffective and excessively costly remediation. Furthermore, remediation needs a goal commensurate with natural background conditions rather than water-quality standards that might bear little relation to conditions of a highly mineralized terrain. This paper reviews hydrogeochemical generalizations, primarily from US Geological Survey research, that enhance our understanding of the origin, transport, and fate of contaminants released from mined and mineralized areas.

  13. 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)

  14. Numerical Modeling of Water Flow and Salt Transport in Bare Saline Soil Subjected to Transient Evaporation

    Science.gov (United States)

    Geng, X.; Boufadel, M.; Saleh, F. S.

    2014-12-01

    It has been found that evaporation over bare soil plays an important role in subsurface solute transport processes. A numerical study, based on a density-dependent variably saturated groundwater flow model MARUN, was conducted to investigate subsurface flow and salt transport in bare saline aquifers subjected to transient evaporation. The bulk aerodynamic formulation was adopted to simulate transient evaporation rate at ground surface. Subsurface flow pattern, moisture distribution, and salt migration were quantified. Key factors likely affecting this process, including saturated hydraulic conductivity, capillary drive, air humidity, and surrounding water supply, were examined. The results showed that evaporation induced an upward flow pattern, which led to a high saline plume formed beneath the evaporation zone. In absence of surrounding water supply, as the humidity between the ground surface and air tended to equilibrium, evaporation-induced density gradient generated pore water circulations around the plume edge and caused the salt to migrate downwards with "finger" shapes. It was found that capillary properties and atmospheric condition had significant impacts on subsurface moisture distribution and salt migration in response to the evaporation. Larger capillary fringe and/or lower air humidity would allow evaporation to extract more water from the ground. It would induce a larger and denser saline plume formed beneath the evaporation zone. The results also suggested that the presence of the surrounding water supply (represented as a constant water table herein) could provide a steady evaporation rate at the ground surface; meanwhile, in response to the evaporation, a hydraulic gradient was formed from the water supply boundary, which induced an inclined upper saline plume with greater density far from the supply boundary.

  15. 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...

  16. Invasive alien plants and water resources in South Africa: current understanding, predictive ability and research challenges

    CSIR Research Space (South Africa)

    Gorgens, AHM

    2004-01-01

    Full Text Available from which a detailed understanding of biophysical processes can be developed; applied or predictive research from which an understanding of processes can be scaled up to predict generic outcomes; integrative research where a predictive understanding...

  17. The Effect of Cirrus Clouds on Water Vapor Transport in the Upper Troposphere and Lower Stratosphere

    Science.gov (United States)

    Lei, L.; McCormick, M. P.; Anderson, J.

    2017-12-01

    Water vapor plays an important role in the Earth's radiation budget and stratospheric chemistry. It is widely accepted that a large percentage of water vapor entering the stratosphere travels through the tropical tropopause and is dehydrated by the cold tropopause temperature. The vertical transport of water vapor is also affected by the radiative effects of cirrus clouds in the tropical tropopause layer. This latter effect of cirrus clouds was investigated in this research. The work focuses on the tropical and mid-latitude region (50N-50S). Water vapor data from the Microwave Limb Sounder (MLS) and cirrus cloud data from the Cloud-Aerosol Lidar and Infrared pathfinder Satellite Observation (CALIPSO) instruments were used to investigate the relationship between the water vapor and the occurrence of cirrus cloud. A 10-degree in longitude by 10-degree in latitude resolution was chosen to bin the MLS and CALIPSO data. The result shows that the maximum water vapor in the upper troposphere (below 146 hPa) is matched very well with the highest frequency of cirrus cloud occurrences. Maximum water vapor in the lower stratosphere (100 hPa) is partly matched with the maximum cirrus cloud occurrence in the summer time. The National Oceanic and Atmospheric Administration Interpolated Outgoing Longwave Radiation data and NCEP-DOE Reanalysis 2 wind data were used also to investigate the relationship between the water vapor entering the stratosphere, deep convection, and wind. Results show that maximum water vapor at 100 hPa coincides with the northern hemisphere summer-time anticyclone. The effects from both single-layer cirrus clouds and cirrus clouds above the anvil top on the water vapor entering the stratosphere were also studied and will be presented.

  18. U.S. power generation, water stress, and climate change: using science to understand "water-smart" electricity-sector decision making

    Science.gov (United States)

    Rogers, J. H.; Frumhoff, P. C.; Averyt, K.; Newmark, R. L.

    2012-12-01

    In 2011, nearly 90 percent of U.S. electricity came from thermoelectric (steam-producing) power plants that use water for cooling. These water demands can tax rivers and aquifers, threaten fish and wildlife, and spark conflicts between power plants and other water users. Climate change, driven by in large part by emissions from fossil fuel-based electricity generation, is adding to the strain. Higher temperatures raise electricity demand and lower cooling-system efficiency, while drought and changes in precipitation patterns may make freshwater supplies less reliable. Here we report new findings on the impacts, present and projected, of power-plant water use on local water stress across the United States, and its implications for understanding what constitutes "water-smart" energy decision making. This work was carried out under the auspices of the Energy and Water in a Warming World initiative (EW3), a research and outreach collaboration designed to inform and motivate U.S. public awareness and science-based public policy at the energy-water nexus. The research has involved cataloguing the water use characteristics of virtually every U.S. power generator in the nation to develop a robust assessment of the water resource implications of cooling the nation's power plants. By analyzing local water supply and demand conditions across the nation, we identified water basins where current power plant water use appears to contribute strongly to local water supply stress, and where water-intensive electricity choices could substantially exacerbate water stress. We also identified other potential approaches to considering stress, particularly related to water temperature. The research has also involved analyzing the water implications of different electricity pathways in the United States over the next 40 years. We used a high-resolution electricity model to generate a range of electricity mixes, particularly in the context of a carbon budget, and assessed the water

  19. The application of electrical resistance measurements to water transport in lime-masonry systems

    Science.gov (United States)

    Ball, R. J.; Allen, G. C.; Carter, M. A.; Wilson, M. A.; Ince, C.; El-Turki, A.

    2012-03-01

    The paper describes an experimental determination of impedance spectroscopy derived resistance measurements to record water transport in lime-masonry systems. It strongly supports the use of Sharp Front theory and Boltzmann's distribution law of statistical thermodynamics to corroborate the data obtained. A novel approach is presented for the application of impedance measurements to the water transport between freshly mixed mortars and clay brick substrates. Once placed, fresh mortar is dewatered by brick and during this time the volume fraction water content of the mortar is reduced. An equation is derived relating this change in water content to the bulk resistance of the mortar. Experimental measurements on hydraulic lime mortars placed in contact with brick prisms confirm the theoretical predictions. Further, the results indicate the time at which dewatering of a mortar bed of given depth is completed. The technique has then potential to be applied for in situ monitoring of dewatering as a means of giving insight into the associated changes in mechanical and chemical properties.

  20. 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.

  1. Understanding interannual variability in the distribution of, and transport processes affecting, the early life stages of Todarodes pacificus using behavioral-hydrodynamic modeling approaches

    Science.gov (United States)

    Kim, Jung Jin; Stockhausen, William; Kim, Suam; Cho, Yang-Ki; Seo, Gwang-Ho; Lee, Joon-Soo

    2015-11-01

    To understand interannual variability in the distribution of the early life stages of Todarodes pacificus summer spawning population, and to identify the key transport processes influencing this variability, we used a coupled bio-physical model that combines an individual-based model (IBM) incorporating ontogenetic vertical migration for paralarval behavior and temperature-dependent survival process with a ROMS oceanographic model. Using the distribution of paralarvae observed in the northern East China Sea (ECS) during several field cruises as an end point, the spawning ground for the summer-spawning population was estimated to extend from southeast Jeju Island to the central ECS near 29°N by running the model backwards in time. Running the model forward, interannual variability in the distribution of paralarvae predicted by the model was consistent with that observed in several field surveys; surviving individuals in the northern ECS were substantially more abundant in late July 2006 than in 2007, in agreement with observed paralarval distributions. The total number of surviving individuals at 60 days after release based on the simulation throughout summer spawning period (June-August) was 20,329 for 2006, compared with 13,816 for 2007. The surviving individuals were mainly distributed in the East/Japan Sea (EJS), corresponding to a pathway following the nearshore branch of the Tsushima Warm Current flowing along the Japanese coast during both years. In contrast, the abundance of surviving individuals was extremely low in 2007 compared to 2006 on the Pacific side of Japan. Interannual variability in transport and survival processes made a substantial impact on not only the abundance of surviving paralarvae, but also on the flux of paralarvae to adjacent waters. Our simulation results for between-year variation in paralarval abundance coincide with recruitment (year n + 1) variability of T. pacificus in the field. The agreement between the simulation and field

  2. Circulation and water mass transports on the East Antarctic shelf in the Mertz Glacier region

    Science.gov (United States)

    Martin, Antoine; Houssais, Marie-Noëlle; Le Goff, Hervé; Marec, Claudie; Dausse, Denis

    2017-08-01

    The East Antarctic shelf off Adélie-George V Land is known to be an important region for Dense Shelf Water (DSW) formation as a result of intense sea ice production in the Mertz Glacier Polynya during the winter season. It is also a region where the warm modified Circumpolar Deep Water (mCDW) penetrates onto the shelf during the summer. Using hydrographic observations from a summer survey in 2008 we implement a box inverse model to propose a comprehensive view of the steady state circulation on this shelf in summer. Additional information from mooring observations collected on the depression slope is used to provide context to the retrieved circulation scheme. Over the depression slope, the summer baroclinic structure of the currents is found to contrast with the almost barotropic structure in winter. The summer circulation is strongly constrained by the DSW distribution and forms a clockwise circulation primarily transporting the fresh surface waters and the warm mCDW around the dome of DSW. Over the upper flank of the Mertz Bank, the inflow branch transports the mCDW towards the Mertz Glacier, while, over the lower part of the slope, the outflow branch returns to the sill a diluted mode of the same water mass. A total of 0.19 Sv of mCDW inflows at the sill and two-third reach the Mertz Glacier and recirculate in front of it, allowing the mCDW to penetrate into the deeper part of the depression. Possible scenarios of interaction between the mCDW and the DSW with the glacier are examined. It is shown that, despite the water mass pathways and transports suggest possible ice-ocean interaction, both lateral and basal melting were likely small in summer 2008. Finally, our results suggest that, in addition to bathymetric features, the distribution of the residual DSW which is left from the preceding winter sets up regional pressure gradients which provide a seasonal control on the shelf circulation. In particular, the spring collapse of the convective patch would

  3. Integrating Norm Activation Model and Theory of Planned Behavior to Understand Sustainable Transport Behavior: Evidence from China

    Directory of Open Access Journals (Sweden)

    Yuwei Liu

    2017-12-01

    Full Text Available With increasing urbanization in China, many cities are facing serious environmental problems due to continuous and substantial increase in automobile transportation. It is becoming imperative to examine effective ways to reduce individual automobile use to facilitate sustainable transportation behavior. Empirical, theory-based research on sustainable transportation in China is limited. In this research, we propose an integrated model based on the norm activation model and the theory of planned behavior by combining normative and rational factors to predict individuals’ intention to reduce car use. Data from a survey of 600 car drivers in China’s three metropolitan areas was used to test the proposed model and hypotheses. Results showed that three variables, perceived norm of car-transport reduction, attitude towards reduction, and perceived behavior control over car-transport reduction, significantly affected the intention to reduce car-transport. Personal norms mediated the relationship between awareness of consequences of car-transport, ascription of responsibility of car-transport, perceived subjective norm for car-transport reduction, and intention to reduce car-transport. The results of this research not only contribute to theory development in the area of sustainable transportation behavior, but also provide a theoretical frame of reference for relevant policy-makers in urban transport management.

  4. Integrating Norm Activation Model and Theory of Planned Behavior to Understand Sustainable Transport Behavior: Evidence from China.

    Science.gov (United States)

    Liu, Yuwei; Sheng, Hong; Mundorf, Norbert; Redding, Colleen; Ye, Yinjiao

    2017-12-18

    With increasing urbanization in China, many cities are facing serious environmental problems due to continuous and substantial increase in automobile transportation. It is becoming imperative to examine effective ways to reduce individual automobile use to facilitate sustainable transportation behavior. Empirical, theory-based research on sustainable transportation in China is limited. In this research, we propose an integrated model based on the norm activation model and the theory of planned behavior by combining normative and rational factors to predict individuals' intention to reduce car use. Data from a survey of 600 car drivers in China's three metropolitan areas was used to test the proposed model and hypotheses. Results showed that three variables, perceived norm of car-transport reduction, attitude towards reduction, and perceived behavior control over car-transport reduction, significantly affected the intention to reduce car-transport. Personal norms mediated the relationship between awareness of consequences of car-transport, ascription of responsibility of car-transport, perceived subjective norm for car-transport reduction, and intention to reduce car-transport. The results of this research not only contribute to theory development in the area of sustainable transportation behavior, but also provide a theoretical frame of reference for relevant policy-makers in urban transport management.

  5. 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

  6. 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

  7. Understanding the SOL flow in L-mode plasma on divertor tokamaks, and its influence on the plasma transport

    International Nuclear Information System (INIS)

    Asakura, Nobuyuki

    2007-01-01

    Significant progress has been made in understanding the driving mechanisms in SOL mass transport along the magnetic field lines (SOL flow). SOL flow measurements by Mach probes and impurity plume have been performed in L-mode plasma at various poloidal locations in divertor tokamaks. All results showed common SOL flow patterns: subsonic flow with parallel Mach number (M parallel ) of 0.2-1 was generated from the Low-Field-Side (LFS) SOL to the High-Field-Side (HFS) divertor for the ion ∇B drift towards the divertor. The SOL flow pattern was formed mainly by LFS-enhanced asymmetry in diffusion and by classical drifts. In addition, divertor detachment and/or intense puffing-and-pump enhanced the HFS SOL flow. Most codes have incorporated drift effects, and asymmetric diffusion was modelled to simulate the fast SOL flow. Influences of the fast SOL flow on the impurity flow in the SOL, shielding from core plasma, and deposition profile, were directly observed in experiments

  8. Interactive ion-mediated sap flow regulation in olive and laurel stems: physicochemical characteristics of water transport via the pit structure.

    Directory of Open Access Journals (Sweden)

    Jeongeun Ryu

    Full Text Available Sap water is distributed and utilized through xylem conduits, which are vascular networks of inert pipes important for plant survival. Interestingly, plants can actively regulate water transport using ion-mediated responses and adapt to environmental changes. However, ionic effects on active water transport in vascular plants remain unclear. In this report, the interactive ionic effects on sap transport were systematically investigated for the first time by visualizing the uptake process of ionic solutions of different ion compositions (K+/Ca2+ using synchrotron X-ray and neutron imaging techniques. Ionic solutions with lower K+/Ca2+ ratios induced an increased sap flow rate in stems of Olea europaea L. and Laurus nobilis L. The different ascent rates of ionic solutions depending on K+/Ca2+ ratios at a fixed total concentration increases our understanding of ion-responsiveness in plants from a physicochemical standpoint. Based on these results, effective structural changes in the pit membrane were observed using varying ionic ratios of K+/Ca2+. The formation of electrostatically induced hydrodynamic layers and the ion-responsiveness of hydrogel structures based on Hofmeister series increase our understanding of the mechanism of ion-mediated sap flow control in plants.

  9. Interactive ion-mediated sap flow regulation in olive and laurel stems: physicochemical characteristics of water transport via the pit structure.

    Science.gov (United States)

    Ryu, Jeongeun; Ahn, Sungsook; Kim, Seung-Gon; Kim, TaeJoo; Lee, Sang Joon

    2014-01-01

    Sap water is distributed and utilized through xylem conduits, which are vascular networks of inert pipes important for plant survival. Interestingly, plants can actively regulate water transport using ion-mediated responses and adapt to environmental changes. However, ionic effects on active water transport in vascular plants remain unclear. In this report, the interactive ionic effects on sap transport were systematically investigated for the first time by visualizing the uptake process of ionic solutions of different ion compositions (K+/Ca2+) using synchrotron X-ray and neutron imaging techniques. Ionic solutions with lower K+/Ca2+ ratios induced an increased sap flow rate in stems of Olea europaea L. and Laurus nobilis L. The different ascent rates of ionic solutions depending on K+/Ca2+ ratios at a fixed total concentration increases our understanding of ion-responsiveness in plants from a physicochemical standpoint. Based on these results, effective structural changes in the pit membrane were observed using varying ionic ratios of K+/Ca2+. The formation of electrostatically induced hydrodynamic layers and the ion-responsiveness of hydrogel structures based on Hofmeister series increase our understanding of the mechanism of ion-mediated sap flow control in plants.

  10. Greenland englacial drainage: conditions favoring water transport through a fractured aquifer

    Science.gov (United States)

    Creyts, T. T.; Fountain, A. G.

    2015-12-01

    Recently, the subglacial hydrology of glaciers and ice sheets has garnered intense interest because of its effects on ice sliding and potential ice sheet responses leading to sea level rise. Less attention has focused on the englacial water system that connects surface meltwater sources to the basal drainage system. Observations of englacial drainage have revealed diametrically opposed behaviors, so that understanding the role of the englacial system is critical to developing knowledge of ice sheet responses. The englacial connections either enhance or limit subglacial processes, including sliding. Some observations show cases where water drainage is mainly through an englacial system of fractures so that water flow at the bed is stunted. Other observations show static englacial water systems that play little role in drainage with primary drainage routes being along the bed. Here, we use a thermomechanical model of englacial water flow to understand the interaction between ice and water along these connections. We assume that water flow is through a series of connected fractures analogous to crevassed Greenland outlet glaciers. The fractures are modified by ice flow, and freezing and melting of the water system. Simple mathematical analyses show trade offs between closure rates and melting rates that determine the englacial flowpaths. From numerical experiments, we show that the dominance of englacial flow follows the locations of both bed overdeepenings and areas where the basal water system is compressed dynamically. The preponderance of overdeependenings in Greenland suggests that englacial systems may be favored in critical areas of ice sheet flow. We conclude by relating the insights from the analytic and numerical results to the broad scale patterns of change of the Greenland Ice Sheet.

  11. 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

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

    International Nuclear Information System (INIS)

    K. Rehfeldt

    2004-01-01

    This report is an updated analysis of water-level data performed to provide the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]) (referred to as the saturated zone (SZ) site-scale flow model or site-scale SZ flow model in this report) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for calibration of groundwater flow models. This report also contains an expanded discussion of uncertainty in the potentiometric-surface map. The analysis of the potentiometric data presented in Revision 00 of this report (USGS 2001 [DIRS 154625]) provides the configuration of the potentiometric surface, target heads, and hydraulic gradients for the calibration of the SZ site-scale flow model (BSC 2004 [DIRS 170037]). Revision 01 of this report (USGS 2004 [DIRS 168473]) used updated water-level data for selected wells through the year 2000 as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain based on an alternative interpretation of perched water conditions. That revision developed computer files containing: Water-level data within the model area (DTN: GS010908312332.002); A table of known vertical head differences (DTN: GS010908312332.003); and A potentiometric-surface map (DTN: GS010608312332.001) using an alternative concept from that presented by USGS (2001 [DIRS 154625]) for the area north of Yucca Mountain. The updated water-level data presented in USGS (2004 [DIRS 168473]) include data obtained from the Nye County Early Warning Drilling Program (EWDP) Phases I and II and data from Borehole USW WT-24. This document is based on Revision 01 (USGS 2004 [DIRS 168473]) and expands the discussion of uncertainty in the potentiometric-surface map. This uncertainty assessment includes an analysis of the impact of more recent water-level data and the impact of adding data from the EWDP Phases III and IV wells. In addition to being utilized

  13. Polyacrylate–water partitioning of biocidal compounds: Enhancing the understanding of biocide partitioning between render and water

    DEFF Research Database (Denmark)

    Bollmann, Ulla E.; Ou, Yi; Mayer, Philipp

    2014-01-01

    In recent years, the application of polymer-based renders and paints for façade coatings of buildings has risen enormously due to the increased mounting of thermal insulation systems. These materials are commonly equipped with biocides - algaecides, fungicides, and bactericides - to protect the m...... between the polymer - in this case polyacrylate - and water were studied using glass fibre filters coated with polyacrylate. The polyacrylate-water partition constants (logKAcW) of ten biocides used in construction material varied between 1.66 (isoproturon) and 3.57 (dichloro......-N-octylisothiazolinone). The correlation of the polyacrylate-water partition constants with the octanol-water partition constants is significant, but the polyacrylate-water partition constants were predominantly below octanol-water partition constants (Kow). The comparison with render-water distribution constants showed that estimating...

  14. Transport of Ocean Waters between the Pacific Ocean and the Gulf of California

    Science.gov (United States)

    Collins, Curtis; Castro-Valdez, Ruben; Mascarenhas, Affonso; Margolina, Tetyana

    2014-05-01

    Ocean transports between the Pacific Ocean and the Gulf of California contribute to the seasonal heating and cooling of the Gulf and add high salinity waters to the surface and upper thermocline waters of the Pacific. These transports have been measured by 1) moored arrays of temperature, salinity and pressure instruments on either side of the entrance to the Gulf in water 130 m deep and 2) shipboard hydrographic measurements across the Gulf along a section between Sinaloa and Baja California. The moored measurements extended from November 2003 to May 2006 and the hydrographic section was occupied eighteen times between 1992 and 2013. Results of these measurements are described in this presentation. The moored measurements resolved baroclinic transport at 40 and 80 dbar referenced to 120 dbar. Geostrophic flow was into (out) the Gulf from May to October (November to April). Mean transport into (out) of the Gulf at 40 dbar was 5.6 x 103 m3/s (4.2 x 103 m3/s) and at 80 dbar was 1.3 x 103 m3/s (1.8 x 103 m3/s). Maximum and minimum geostrophic velocities were observed about July 1 and December 1, respectively, and were about three times as large as the mean values. Steric heights at the mooring locations were compared to satellite sea level height anomalies. Agreement was good and provided a more robust measure of the annual cycle of the mean surface geostrophic flow and transport because 9 years of continuous observations were available. The hydrographic measurements indicated predominately cyclonic flow patterns with inflow along Sinaloa and outflow along Baja California. During periods of strong exchange, narrow deep jets were observed to develop over the continental slopes of Sinaloa and Baja California. Overturning circulation within the Gulf is clearly indicated by the patterns of salinity along the hydrographic sections in which inflows of fresher Pacific waters (S34.8 for densities between 25 and 26 kg/m3) along Baja California. Geostrophic velocities for these

  15. 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)

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

    International Nuclear Information System (INIS)

    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 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)

  17. 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......-blinded, placebo-controlled, 3-way crossover study we examined 23 healthy subjects on a standardized diet and fluid intake. The subjects were treated with amiloride 5 mg, BFTZ 1.25 mg or placebo twice a day for 4.5 d before each examination day. On the examination day, glomerular filtration rate was measured...... 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...

  18. 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.

  19. 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

  20. Understanding urban water performance at the city-region scale using an urban water metabolism evaluation framework.

    Science.gov (United States)

    Renouf, Marguerite A; Kenway, Steven J; Lam, Ka Leung; Weber, Tony; Roux, Estelle; Serrao-Neumann, Silvia; Choy, Darryl Low; Morgan, Edward A

    2018-06-15

    Water sensitive interventions are being promoted to reduce the adverse impacts of urban development on natural water cycles. However it is currently difficult to know the best strategy for their implementation because current and desired urban water performance is not well quantified. This is particularly at the city-region scale, which is important for strategic urban planning. This work aimed to fill this gap by quantifying the water performance of urban systems within city-regions using 'urban water metabolism' evaluation, to inform decisions about water sensitive interventions. To do this we adapted an existing evaluation framework with new methods. In particular, we used land use data for defining system boundaries, and for estimating natural hydrological flows. The criteria for gauging the water performance were water efficiency (in terms of water extracted externally) and hydrological performance (how much natural hydrological flows have changed relative to a nominated pre-urbanised state). We compared these performance criteria for urban systems within three Australian city-regions (South East Queensland, Melbourne and Perth metropolitan areas), under current conditions, and after implementation of example water sensitive interventions (demand management, rainwater/stormwater harvesting, wastewater recycling and increasing perviousness). The respective water efficiencies were found to be 79, 90 and 133 kL/capita/yr. In relation to hydrological performance, stormwater runoff relative to pre-urbanised flows was of most note, estimated to be 2-, 6- and 3- fold, respectively. The estimated performance benefits from water sensitive interventions suggested different priorities for each region, and that combined implementation of a range of interventions may be necessary to make substantive gains in performance. We concluded that the framework is suited to initial screening of the type and scale of water sensitive interventions needed to achieve desired water

  1. Field Observations of Hydrodynamics, Sediment Transport, and Water and Sediment Quality in the Hudson-Raritan Estuary

    Science.gov (United States)

    Bruno, M. S.; Glenn, S.; Chant, R.; Rankin, K.; Korfiatis, G.; Dimou, N.; Creed, E.; Fullerton, B.; Pence, A.; Burke, P.; Haldeman, C.; Hires, R.; Hunter, E.

    2002-12-01

    , during 21 tributary flow "events", each having an approximate duration of 1 week. The measurement program included 3 fixed mooring stations and 5 shipboard locations. Each mooring consisted of an acoustic Doppler current profiler; a high-resolution pressure sensor; an OBS; a CTD; and a laser-based scatterometer. The ship-board measurements included vertical current profiles using a towed acoustic Doppler current profiler; CTD measurements; OBS measurements; suspended sediment concentration and particle size spectrum using a laser-based scatterometer; and chemical characterization of water and suspended sediment samples. The water and sediment quality measurements were obtained using a specially designed Trace Organics Platform Sampler. This sampler allowed for the measurement of low-level concentrations of PCBs (108 congeners), dioxins/furans, Pesticides, PAHs and metals (Hg, Cd, Pb). Preliminary analysis of the data has improved our understanding of the circulation and sediment transport patterns in this region of the estuary, including the influence of extreme tributary flow events, local winds, and anthropogenic effects such as port structures, vessels, and the navigation channels, and has identified the most highly contaminated reaches of the tributaries.

  2. Water use impacts of future transport fuels: role of California's climate policy & National biofuel policies (Invited)

    Science.gov (United States)

    Teter, J.; Yeh, S.; Mishra, G. S.; Tiedeman, K.; Yang, C.

    2013-12-01

    In the coming decades, growing demand for energy and water and the need to address climate change will create huge challenges for energy policy and natural resource management. Synergistic strategies must be developed to conserve and use both resources more efficiently. California (CA) is a prime example of a region where policymakers have began to incorporate water planning in energy infrastructure development. But more must be done as CA transforms its energy system to meet its climate target. We analyze lifecycle water use of current and future transport fuel consumption to evaluate impacts & formulate mitigation strategies for the state at the watershed scale. Four 'bounding cases' for CA's future transportation demand to year 2030 are projected for analysis: two scenarios that only meet the 2020 climate target (business-as-usual, BAU) with high / low water use intensity, and two that meet long-term climate target with high / low water use intensity (Fig 1). Our study focuses on the following energy supply chains: (a) liquid fuels from conventional/unconventional oil & gas, (b) thermoelectric and renewable generation technologies, and (c) biofuels (Fig 2-3). We develop plausible siting scenarios that bound the range of possible water sources, impacts, and dispositions to provide insights into how to best allocate water and limit water impacts of energy development. We further identify constraints & opportunities to improve water use efficiency and highlight salient policy relevant lessons. For biofuels we extend our scope to the entire US as most of the biofuels consumed in California are and will be produced from outside of the state. We analyze policy impacts that capture both direct & indirect land use effects across scenarios, thus addressing the major shortcomings of existing studies, which ignore spatial heterogeneity as well as economic effects of crop displacement and the effects of crop intensification and extensification. We use the agronomic

  3. Understanding the structural drivers governing glass-water interactions in borosilicate based model bioactive glasses.

    Science.gov (United States)

    Stone-Weiss, Nicholas; Pierce, Eric M; Youngman, Randall E; Gulbiten, Ozgur; Smith, Nicholas J; Du, Jincheng; Goel, Ashutosh

    2018-01-01

    borosilicate based model melt-quenched bioactive glass system has been studied to depict the impact of thermal history on its molecular structure and dissolution behavior in water. It has been shown that the methodology of quenching of the glass melt impacts the dissolution rate of the studied glasses by 1.5×-3× depending on the changes induced in their molecular structure due to variation in thermal history. Further, a recommendation has been made to study dissolution behavior of bioactive glasses using surface area of the sample - to - volume of solution (SA/V) approach instead of the currently followed mass of sample - to - volume of solution approach. The structural and chemical dissolution data obtained from bioactive glasses following the approach presented in this paper can be used to develop the structural descriptors and potential energy functions over a broad range of bioactive glass compositions. Realizing the goal of designing third generation bioactive glasses requires a thorough understanding of the complex sequence of reactions that control their rate of degradation (in physiological fluids) and the structural drivers that control them. In this article, we have highlighted some major experimental challenges and choices that need to be carefully navigated in order to unearth the mechanisms governing the chemical dissolution behavior of borosilicate based bioactive glasses. The proposed experimental approach allows us to gain a new level of conceptual understanding about the composition-structure-property relationships in these glass systems, which can be applied to attain a significant leap in designing borosilicate based bioactive glasses with controlled dissolution rates tailored for specific patient and disease states. Copyright © 2017 Acta Materialia Inc. All rights reserved.

  4. A proposed strategy for the validation of ground-water flow and solute transport models

    International Nuclear Information System (INIS)

    Davis, P.A.; Goodrich, M.T.

    1991-01-01

    Ground-water flow and transport models can be thought of as a combination of conceptual and mathematical models and the data that characterize a given system. The judgment of the validity or invalidity of a model depends both on the adequacy of the data and the model structure (i.e., the conceptual and mathematical model). This report proposes a validation strategy for testing both components independently. The strategy is based on the philosophy that a model cannot be proven valid, only invalid or not invalid. In addition, the authors believe that a model should not be judged in absence of its intended purpose. Hence, a flow and transport model may be invalid for one purpose but not invalid for another. 9 refs

  5. Multiple environmental tracers for a better understanding of water flux in a wetland area (La Bassée, France)

    International Nuclear Information System (INIS)

    Gourcy, L.; Brenot, A.

    2011-01-01

    Understanding water exchange between groundwater and streams, or groundwater/surface-water relationships, is of primary importance for solving conflicts related to water use and for restoring water ecosystems. To this end, a combination of classic geochemical tools and isotopic tools were tested on the Bassée study site, located in the alluvial plain of the River Seine, to see whether they are relevant for tracing multiple and complex groundwater/surface-water relationships. The Ca/Sr ratio associated with Sr isotopes shows contrasted values and suggests that infiltration of surface water to groundwater increases when approaching the Seine. Furthermore, stable isotopes of the water molecule indicate that water from gravel-pit lakes may infiltrate into groundwater. Tritium and CFC tools confirmed surface-water influence on the Alluvial and Chalk aquifers. This geochemical approach, tested on the Bassée site, clearly demonstrates the need of using various geochemical tools for describing groundwater/surface-water relationships, and can be conclusively addressed to other case studies for helping decision makers in their management of natural water resources.

  6. Experimental characterization of the water transport properties of PEM fuel cells diffusion media

    Science.gov (United States)

    Ramos-Alvarado, Bladimir; Sole, Joshua D.; Hernandez-Guerrer