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

    2018-06-01

    Graphene is a versatile 2D material and attracts an increasing amount of attention 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 that water flux exhibits an excellent linear behavior with pressure, in agreement with the prediction of the Hagen–Poiseuille equation. Interestingly, the flux for concentrated pore size distribution is around two times larger than that of a 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 clearly be due to the 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.

  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. Understanding Your Water Bill

    Science.gov (United States)

    An easy to way to understand individual water use is to look at your water bill—not just the amount due, but how much water you used. Pull out your water bill and follow our steps to learn more about it.

  6. 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...

  7. High frequency monitoring of pesticides in runoff water to improve understanding of their transport and environmental impacts.

    Science.gov (United States)

    Lefrancq, Marie; Jadas-Hécart, Alain; La Jeunesse, Isabelle; Landry, David; Payraudeau, Sylvain

    2017-06-01

    Rainfall-induced peaks in pesticide concentrations can occur rapidly. Low frequency sampling may therefore largely underestimate maximum pesticide concentrations and fluxes. Detailed storm-based sampling of pesticide concentrations in runoff water to better predict pesticide sources, transport pathways and toxicity within the headwater catchments is lacking. High frequency monitoring (2min) of seven pesticides (Dimetomorph, Fluopicolide, Glyphosate, Iprovalicarb, Tebuconazole, Tetraconazole and Triadimenol) and one degradation product (AMPA) were assessed for 20 runoff events from 2009 to 2012 at the outlet of a vineyard catchment in the Layon catchment in France. The maximum pesticide concentrations were 387μgL -1 . Samples from all of the runoff events exceeded the legal limit of 0.1μgL -1 for at least one pesticide (European directive 2013/39/EC). High resolution sampling used to detect the peak pesticide levels revealed that Toxic Units (TU) for algae, invertebrates and fish often exceeded the European Uniform principles (25%). The point and average (time or discharge-weighted) concentrations indicated up to a 30- or 4-fold underestimation of the TU obtained when measuring the maximum concentrations, respectively. This highlights the important role of sampling methods for assessing peak exposure. High resolution sampling combined with concentration-discharge hysteresis analyses revealed that clockwise responses were predominant (52%), indicating that Hortonian runoff is the prevailing surface runoff trigger mechanism in the study catchment. The hysteresis patterns for suspended solids and pesticides were highly dynamic and storm- and chemical-dependent. Intense rainfall events induced stronger C-Q hysteresis (magnitude). This study provides new insights into the complexity of pesticide dynamics in runoff water and highlights the ability of hysteresis analysis to improve understanding of pesticide supply and transport. Copyright © 2017 Elsevier B.V. All

  8. 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…

  9. Modelling Ballast Water Transport

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  10. Recent Advances in Understanding Flow Dynamics and Transport of Water-Quality Constituents in the Sacramento–San Joaquin River Delta

    Directory of Open Access Journals (Sweden)

    David H. Schoellhamer

    2016-12-01

    Full Text Available doi: https://doi.org/10.15447/sfews.2016v14iss4art1This paper, part of the collection of research comprising the State of Bay–Delta Science 2016, describes advances during the past decade in understanding flow dynamics and how water-quality constituents move within California’s Sacramento–San Joaquin River Delta (Delta. Water-quality constituents include salinity, heat, oxygen, nutrients, contaminants, organic particles, and inorganic particles. These constituents are affected by water diversions and other human manipulations of flow, and they greatly affect the quantity and quality of benthic, pelagic, and intertidal habitat in the Delta. The Pacific Ocean, the Central Valley watershed, human intervention, the atmosphere, and internal biogeochemical processes are all drivers of flow and transport in the Delta. These drivers provide a conceptual framework for presenting recent findings. The tremendous expansion of acoustic and optical instruments deployed in the Delta over the past decade has greatly improved our understanding of how tidal variability affects flow and transport. Sediment is increasingly viewed as a diminishing resource needed to sustain pelagic habitat and tidal marsh, especially as sea level rises. Connections among the watershed, Delta, and San Francisco Bay that have been quantified recently highlight that a landscape view of this system is needed, rather than consideration of each region in isolation. We discuss interactions of multiple drivers and information gaps.

  11. 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.

  12. Fuel cell water transport

    Science.gov (United States)

    Vanderborgh, Nicholas E.; Hedstrom, James C.

    1990-01-01

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

  13. 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...... groundwater movement. Cause and effects of Nr Approach can therefore be spatially disaggregated, i.e. leached Nr applied uphill on agricultural land can for example lead to gaseous N emissions downhill in riparian plains. In the Danish NitroEurope study landscape, lateral translocation of dissolved nitrogen...

  14. Understanding transport barriers through modelling

    International Nuclear Information System (INIS)

    Rozhansky, V

    2004-01-01

    Models of radial electric field formation are discussed and compared with the results of numerical simulations from fluid transport codes and Monte Carlo codes. A comparison of the fluid and Monte Carlo codes is presented. A conclusion is arrived at that all the simulations do not predict any bifurcation of the electric field, i.e. no bifurcation of poloidal rotation from low to high Mach number values is obtained. In most of the simulations, the radial electric field is close to the neoclassical electric field. The deviation from neoclassical electric field at the separatrix due to the existence of a transitional viscous layer is discussed. Scalings for the shear of the poloidal rotation are checked versus simulation results. It is demonstrated that assuming the critical shear to be of the order of 10 5 s -1 , it is possible to obtain a L-H transition power scaling close to that observed in the experiment. The dependence of the threshold on the magnetic field direction, pellet injection, aspect ratio and other factors are discussed on the basis of existing simulations. Transport codes where transport coefficients depend on the turbulence level and scenario simulations of L-H transition are analysed. However, the details of gyrofluid and gyrokinetic modelling should be discussed elsewhere. Simulations of internal transport barrier (ITB) formation are discussed as well as factors responsible for ITB formation

  15. 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

  16. 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.

  17. 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...

  18. Progress in understanding heat transport at JET

    International Nuclear Information System (INIS)

    Mantica, P.; Garbet, X.; Angioni, C.

    2005-01-01

    This paper reports recent progress in understanding heat transport mechanisms either in conventional or advanced tokamak scenarios in JET. A key experimental tool has been the use of perturbative transport techniques, both by ICH power modulation and by edge cold pulses. The availability of such results has allowed careful comparison with theoretical modelling using 1D empirical or physics based transport models, 3D fluid turbulence simulations or gyrokinetic stability analysis. In conventional L- and H-mode plasmas the issue of temperature profile stiffness has been addressed. JET results are consistent with the concept of a critical inverse temperature gradient length above which transport is enhanced by the onset of turbulence. A threshold value R/L Te ∼5 has been found for the onset of stiff electron transport, while the level of electron stiffness appears to vary strongly with plasma parameters, in particular with the ratio of electron and ion heating: electrons become stiffer when ions are strongly heated, resulting in larger R/L Ti values. This behaviour has also been found theoretically, although quantitatively weaker than in experiments. In plasmas characterized by Internal Transport Barriers (ITB), the properties of heat transport inside the ITB layer and the ITB formation mechanisms have been investigated. The plasma current profile is found to play a major role in ITB formation. The effect of negative magnetic shear on electron and ion stabilization is demonstrated both experimentally and theoretically using turbulence codes. The role of rational magnetic surfaces in ITB triggering is well assessed experimentally, but still lacks a convincing theoretical explanation. Attempts to trigger an ITB by externally induced magnetic reconnection using saddle coils have shown that MHD islands in general do not produce a sufficient variation of ExB flow shear to lead to ITB formation. First results of perturbative transport in ITBs show that the ITB is a narrow

  19. Understanding the roles of ligand promoted dissolution, water column saturation and hydrological properties on intense basalt weathering using reactive transport and watershed-scale hydrologic modeling

    Science.gov (United States)

    Perez Fodich, A.; Walter, M. T.; Derry, L. A.

    2016-12-01

    The interaction of rocks with rainwater generates physical and chemical changes, which ultimately culminates in soil development. The addition of catalyzers such as plants, atmospheric gases and hydrological properties will result in more intense and/or faster weathering transformations. The intensity of weathering across the Island of Hawaii is strongly correlated with exposure age and time-integrated precipitation. Intense weathering has resulted from interaction between a thermodynamically unstable lithology, high water/rock ratios, atmospheric gases (O2, CO2) and biota as an organic acid and CO2 producer. To further investigate the role of different weathering agents we have developed 1-D reactive transport models (RTM) to understand mineralogical and fluid chemistry changes in the initially basaltic porous media. The initial meso-scale heterogeneity of porosity makes it difficult for RTMs to capture changes in runoff/groundwater partitioning. Therefore, hydraulic properties (hydraulic conductivity and aquifer depth) are modeled as a watershed parameter appropriate for this system where sub-surface hydraulic data is scarce(1). Initial results agree with field data in a broad sense: different rainfall regimes and timescales show depletion of mobile cations, increasingly low pH, congruent dissolution of olivine and pyroxene, incongruent dissolution of plagioclase and basaltic glass, precipitation of non-crystalline allophane and ferrihydrite, and porosity changes due to dissolution and precipitation of minerals; ultimately Al and Fe are also exported from the system. RTM is used to examine the roles of unsaturation in the soil profile, ligand promoted dissolution of Al- and Fe-bearing phases, and Fe-oxide precipitation at the outcrop scale. Also, we aim to test the use of recession flow analysis to model watershed-scale hydrological properties to extrapolate changes in the runoff/groundwater partitioning. The coupling between weathering processes and hydrologic

  20. Water Transport Mediated by Other Membrane Proteins.

    Science.gov (United States)

    Huang, Boyue; Wang, Hongkai; Yang, Baoxue

    2017-01-01

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

  1. WATER SUPPLY OF TRANSPORT OBJECTS

    OpenAIRE

    Badyuk, N. S.

    2009-01-01

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

  2. 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

  3. Understanding charge transport in molecular electronics.

    Science.gov (United States)

    Kushmerick, J J; Pollack, S K; Yang, J C; Naciri, J; Holt, D B; Ratner, M A; Shashidhar, R

    2003-12-01

    For molecular electronics to become a viable technology the factors that control charge transport across a metal-molecule-metal junction need to be elucidated. We use an experimentally simple crossed-wire tunnel junction to interrogate how factors such as metal-molecule coupling, molecular structure, and the choice of metal electrode influence the current-voltage characteristics of a molecular junction.

  4. Water and solute transport across the peritoneal membrane.

    Science.gov (United States)

    Morelle, Johann; Devuyst, Olivier

    2015-09-01

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

  5. Fast water transport in graphene nanofluidic channels

    Science.gov (United States)

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

    2018-01-01

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

  6. 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

  7. 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...

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

    Indian Academy of Sciences (India)

    †Department of Physics, Government College for Women, Chintamani 563 125, India .... Our attention here is focused on understanding how ion transport takes ...... Almond D P, West A R and Grant R J 1982 Solid State Commun. 44. 1277.

  9. 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 mus...... oriented businesses. The essential reason for understanding business in transport and logistics, especially in this report...

  10. 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

  11. Plant water relations I: uptake and transport

    Science.gov (United States)

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

  12. 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...

  13. 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...

  14. 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)...

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

    Indian Academy of Sciences (India)

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

  16. Water transport in the brain

    DEFF Research Database (Denmark)

    MacAulay, N; Hamann, S; Zeuthen, T

    2004-01-01

    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...

  17. 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

  18. 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...

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

    Science.gov (United States)

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

    1981-01-01

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

  20. 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 ...

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

    Science.gov (United States)

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

    2014-04-01

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

  2. 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

  3. Transport of water through the tropical tropopause

    Science.gov (United States)

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

    1982-01-01

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

  4. 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

  5. Recent Progress on Understanding SEP Acceleration and Transport

    Science.gov (United States)

    Cohen, C.

    2017-12-01

    Joint observations between near-Earth spacecraft and the twin STEREO spacecraft have allowed new examinations of the longitudinal extent of solar energetic particles (SEPs). Although the radial dependence will not be measured in detail until Parker Solar Probe and Solar Orbiter have launched, recent developments in modeling SEP acceleration and transport have revealed interesting dependences on magnetic field configurations and the characteristics of seed particle populations. This talk will review recent SEP in-situ observations along with theoretical studies and their implications for our understanding of SEP acceleration and transport in the inner heliosphere and our expectations for upcoming Solar Orbiter and Parker Solar Probe observations.

  6. 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.

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

    Science.gov (United States)

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

  8. Understanding the dynamics of citrus water use

    CSIR Research Space (South Africa)

    Taylor, NJ

    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-mental...

  9. Water transport in desert alluvial soil

    International Nuclear Information System (INIS)

    Kearl, P.M.

    1982-04-01

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

  10. Application of SPARROW modeling to understanding contaminant fate and transport from uplands to streams

    Science.gov (United States)

    Ator, Scott; Garcia, Ana Maria.

    2016-01-01

    Understanding spatial variability in contaminant fate and transport is critical to efficient regional water-quality restoration. An approach to capitalize on previously calibrated spatially referenced regression (SPARROW) models to improve the understanding of contaminant fate and transport was developed and applied to the case of nitrogen in the 166,000 km2 Chesapeake Bay watershed. A continuous function of four hydrogeologic, soil, and other landscape properties significant (α = 0.10) to nitrogen transport from uplands to streams was evaluated and compared among each of the more than 80,000 individual catchments (mean area, 2.1 km2) in the watershed. Budgets (including inputs, losses or net change in storage in uplands and stream corridors, and delivery to tidal waters) were also estimated for nitrogen applied to these catchments from selected upland sources. Most (81%) of such inputs are removed, retained, or otherwise processed in uplands rather than transported to surface waters. Combining SPARROW results with previous budget estimates suggests 55% of this processing is attributable to denitrification, 23% to crop or timber harvest, and 6% to volatilization. Remaining upland inputs represent a net annual increase in landscape storage in soils or biomass exceeding 10 kg per hectare in some areas. Such insights are important for planning watershed restoration and for improving future watershed models.

  11. 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 ...

  12. Simulation of water movement and NaCl transport

    International Nuclear Information System (INIS)

    Li Xun; Zheng Zhihong; Yang Zeping

    2008-01-01

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

  13. 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

  14. 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...

  15. The water footprint of biofuel-based transport

    NARCIS (Netherlands)

    Gerbens-Leenes, Winnie; Hoekstra, Arjen Ysbert

    2011-01-01

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

  16. 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.

  17. Biologically inspired water purification through selective transport

    International Nuclear Information System (INIS)

    Freeman, E C; Soncini, R M; Weiland, L M

    2013-01-01

    Biologically inspired systems based on cellular mechanics demonstrate the ability to selectively transport ions across a bilayer membrane. These systems may be observed in nature in plant roots, which remove select nutrients from the surrounding soil against significant concentration gradients. Using biomimetic principles in the design of tailored active materials allows for the development of selective membranes for capturing and filtering targeted ions. Combining this biomimetic transport system with a method for reclaiming the captured ions will allow for increased removal potential. To illustrate this concept, a device for removing nutrients from waterways to aid in reducing eutrophication is outlined and discussed. Presented is a feasibility study of various cellular configurations designed for this purpose, focusing on maximizing nutrient uptake. The results enable a better understanding of the benefits and obstacles when developing these cellularly inspired systems. (paper)

  18. Model for tritiated water transport in soil

    International Nuclear Information System (INIS)

    Galeriu, D.; Paunescu, N.

    1999-01-01

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

  19. 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

  20. 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...

  1. 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 ...

  2. 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

  3. Model for radionuclide transport in running waters

    International Nuclear Information System (INIS)

    Jonsson, Karin; Elert, Mark

    2005-11-01

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

  4. 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

    The biogenic monoamine transporters are integral membrane proteins that perform active transport of extracellular dopamine, serotonin and norepinephrine into cells. These transporters are targets for therapeutic agents such as antidepressants, as well as addictive substances such as cocaine...... 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...

  5. 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.

  6. Modeling UTLS water vapor: Transport/Chemistry interactions

    International Nuclear Information System (INIS)

    Gulstad, Line

    2005-01-01

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

  7. 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.

  8. Eddy transport of water vapor in the Martian atmosphere

    Science.gov (United States)

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

    1993-01-01

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

  9. 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

  10. 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

  11. 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.

  12. Molecular mechanisms of water transport in the eye

    DEFF Research Database (Denmark)

    Hamann, Steffen

    2002-01-01

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

  13. 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

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

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  15. Using Transport Diagnostics to Understand Chemistry Climate Model Ozone Simulations

    Science.gov (United States)

    Strahan, S. E.; Douglass, A. R.; Stolarski, R. S.; Akiyoshi, H.; Bekki, S.; Braesicke, P.; Butchart, N.; Chipperfield, M. P.; Cugnet, D.; Dhomse, S.; hide

    2010-01-01

    We demonstrate how observations of N2O and mean age in the tropical and midlatitude lower stratosphere (LS) can be used to identify realistic transport in models. The results are applied to 15 Chemistry Climate Models (CCMs) participating in the 2010 WMO assessment. Comparison of the observed and simulated N2O/mean age relationship identifies models with fast or slow circulations and reveals details of model ascent and tropical isolation. The use of this process-oriented N2O/mean age diagnostic identifies models with compensating transport deficiencies that produce fortuitous agreement with mean age. We compare the diagnosed model transport behavior with a model's ability to produce realistic LS O3 profiles in the tropics and midlatitudes. Models with the greatest tropical transport problems show the poorest agreement with observations. Models with the most realistic LS transport agree more closely with LS observations and each other. We incorporate the results of the chemistry evaluations in the SPARC CCMVal Report (2010) to explain the range of CCM predictions for the return-to-1980 dates for global (60 S-60 N) and Antarctic column ozone. Later (earlier) Antarctic return dates are generally correlated to higher (lower) vortex Cl(sub y) levels in the LS, and vortex Cl(sub y) is generally correlated with the model's circulation although model Cl(sub y) chemistry or Cl(sub y) conservation can have a significant effect. In both regions, models that have good LS transport produce a smaller range of predictions for the return-to-1980 ozone values. This study suggests that the current range of predicted return dates is unnecessarily large due to identifiable model transport deficiencies.

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

    International Nuclear Information System (INIS)

    Meier, Frank; Eigenberger, Gerhart

    2004-01-01

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

  17. 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.

  18. Unsaturated water flow and tracer transport modeling with Alliances

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-15

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

  19. Quantification of free water transport in peritoneal dialysis

    NARCIS (Netherlands)

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

    2004-01-01

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

  20. Increased understanding of neoclassical internal transport barrier on CHS

    International Nuclear Information System (INIS)

    Minami, T.

    2002-01-01

    The recent progress of the study on neoclassical internal transport barrier (N-ITB) of Compact Helical System (CHS) is reported. This barrier is formed due to the positive electric field and the electric field shear that are created by bifurcation of radial electric field with the electron cyclotron (EC) heating on helical devices. Previously N-ITB was observed for ECH plasma, recently N-ITB barrier was also observed for EC (53.2 GHz 2nd harmonic) heated NBI plasma. The N-ITB of EC heated NBI plasma is formed at the outer location (r/a=0.4-0.6) in comparison with that (r/a=0.3) of ECH plasma, so that the improved confinement region is expanded. The improvement in the ion energy transport is also observed and the ion temperature is increased up to 400 eV along with the electron temperature, that is two times higher than that of the plasma without N-ITB. The particle transport is studied by measuring the peak energy of Titanium Kα line intensity with the soft X-ray CCD camera. The energy is shifted from 4.68 kV to 4.73 kV by forming N-ITB. The improvement of the impurity transport has been confirmed inside N-ITB by comparing the experimental result with the MIST code. (author)

  1. 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

  2. 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.

  3. Geochemistry and the understanding of ground-water systems

    Science.gov (United States)

    Glynn, Pierre D.; Plummer, L. Niel

    2005-03-01

    Geochemistry has contributed significantly to the understanding of ground-water systems over the last 50 years. Historic advances include development of the hydrochemical facies concept, application of equilibrium theory, investigation of redox processes, and radiocarbon dating. Other hydrochemical concepts, tools, and techniques have helped elucidate mechanisms of flow and transport in ground-water systems, and have helped unlock an archive of paleoenvironmental information. Hydrochemical and isotopic information can be used to interpret the origin and mode of ground-water recharge, refine estimates of time scales of recharge and ground-water flow, decipher reactive processes, provide paleohydrological information, and calibrate ground-water flow models. Progress needs to be made in obtaining representative samples. Improvements are needed in the interpretation of the information obtained, and in the construction and interpretation of numerical models utilizing hydrochemical data. The best approach will ensure an optimized iterative process between field data collection and analysis, interpretation, and the application of forward, inverse, and statistical modeling tools. Advances are anticipated from microbiological investigations, the characterization of natural organics, isotopic fingerprinting, applications of dissolved gas measurements, and the fields of reaction kinetics and coupled processes. A thermodynamic perspective is offered that could facilitate the comparison and understanding of the multiple physical, chemical, and biological processes affecting ground-water systems. La géochimie a contribué de façon importante à la compréhension des systèmes d'eaux souterraines pendant les 50 dernières années. Les avancées ont portées sur le développement du concept des faciès hydrochimiques, sur l'application de la théorie des équilibres, l'étude des processus d'oxydoréduction, et sur la datation au radiocarbone. D'autres concepts, outils et

  4. 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.

  5. Mineralogy controls on reactive transport of Marcellus Shale waters.

    Science.gov (United States)

    Cai, Zhang; Wen, Hang; Komarneni, Sridhar; Li, Li

    2018-07-15

    Produced or flowback waters from Marcellus Shale gas extraction (MSWs) typically are highly saline and contain chemicals including trace metals, which pose significant concerns on water quality. The natural attenuation of MSW chemicals in groundwater is poorly understood due to the complex interactions between aquifer minerals and MSWs, limiting our capabilities to monitor and predict. Here we combine flow-through experiments and process-based reactive transport modeling to understand mechanisms and quantify the retention of MSW chemicals in a quartz (Qtz) column, a calcite-rich (Cal) column, and a clay-rich (Vrm, vermiculite) column. These columns were used to represent sand, carbonate, and clay-rich aquifers. Results show that the types and extent of water-rock interactions differ significantly across columns. Although it is generally known that clay-rich media retard chemicals and that quartz media minimize water-rock interactions, results here have revealed insights that differ from previous thoughts. We found that the reaction mechanisms are much more complex than merely sorption and mineral precipitation. In clay rich media, trace metals participate in both ion exchange and mineral precipitation. In fact, the majority of metals (~50-90%) is retained in the solid via mineral precipitation, which is surprising because we typically expect the dominance of sorption in clay-rich aquifers. In the Cal column, trace metals are retained not only through precipitation but also solid solution partitioning, leading to a total of 75-99% retention. Even in the Qtz column, trace metals are retained at unexpectedly high percentages (~20-70%) due to precipitation. The reactive transport model developed here quantitatively differentiates the relative importance of individual processes, and bridges a limited number of experiments to a wide range of natural conditions. This is particularly useful where relatively limited knowledge and data prevent the prediction of complex rock

  6. 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

  7. Understanding Ammonium Transport in Bioelectrochemical Systems towards its Recovery

    Science.gov (United States)

    Liu, Ying; Qin, Mohan; Luo, Shuai; He, Zhen; Qiao, Rui

    2016-03-01

    We report an integrated experimental and simulation study of ammonia recovery using microbial electrolysis cells (MECs). The transport of various species during the batch-mode operation of an MEC was examined experimentally and the results were used to validate the mathematical model for such an operation. It was found that, while the generated electrical current through the system tends to acidify (or basify) the anolyte (or catholyte), their effects are buffered by a cascade of chemical groups such as the NH3/NH4+ group, leading to relatively stable pH values in both anolyte and catholyte. The transport of NH4+ ions accounts for ~90% of the total current, thus quantitatively confirming that the NH4+ ions serve as effective proton shuttles during MEC operations. Analysis further indicated that, because of the Donnan equilibrium at cation exchange membrane-anolyte/catholyte interfaces, the Na+ ion in the anolyte actually facilitates the transport of NH4+ ions during the early stage of a batch cycle and they compete with the NH4+ ions weakly at later time. These insights, along with a new and simple method for predicting the strength of ammonia diffusion from the catholyte toward the anolyte, will help effective design and operation of bioeletrochemical system-based ammonia recovery systems.

  8. 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....

  9. 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…

  10. 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/.

  11. Understanding the tariff. Access to the public power transportation network

    International Nuclear Information System (INIS)

    2002-01-01

    Since the European directive of December 19, 1996 about the common rules of the European power market, the eligible companies can chose their power supplier anywhere in Europe. The manager of the French power transportation network (RTE) supplies a network access to these companies according to a tariff fixed by the decree no. 2002-1014 from July 19, 2002. The aim of this document is to explain this tariff: tariffing principles ('mail-stamp' principle, voltage domain, subscribed output power tariffs, input power tariffs), tariffing elements (access to the grid, elements of output tariffs (subscribed power, overload, emergency tariffs, modifications etc..)), invoicing modalities, output tariffs, definitions. (J.S.)

  12. 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.

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

    Science.gov (United States)

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

    2018-01-01

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

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

    Science.gov (United States)

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

    2017-10-27

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

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

    Science.gov (United States)

    Barbara L. Gartner; Frederick C. Meinzer

    2005-01-01

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

  16. 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.

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

    International Nuclear Information System (INIS)

    Zhu, Chongqin; Li, Hui; Meng, Sheng

    2014-01-01

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

  18. 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.

  19. Public responses to water reuse - Understanding the evidence.

    Science.gov (United States)

    Smith, H M; Brouwer, S; Jeffrey, P; Frijns, J

    2018-02-01

    Over the years, much research has attempted to unpack what drives public responses to water reuse, using a variety of approaches. A large amount of this work was captured by an initial review that covered research undertaken up to the early 2000s (Hartley, 2006). This paper showcases post-millennium evidence and thinking around public responses to water reuse, and highlights the novel insights and shifts in emphasis that have occurred in the field. Our analysis is structured around four broad, and highly interrelated, strands of thinking: 1) work focused on identifying the range of factors that influence public reactions to the concept of water reuse, and broadly looking for associations between different factors; 2) more specific approaches rooted in the socio-psychological modelling techniques; 3) work with a particular focus on understanding the influences of trust, risk perceptions and affective (emotional) reactions; and 4) work utilising social constructivist perspectives and socio-technical systems theory to frame responses to water reuse. Some of the most significant advancements in thinking in this field stem from the increasingly sophisticated understanding of the 'yuck factor' and the role of such pre-cognitive affective reactions. These are deeply entrenched within individuals, but are also linked with wider societal processes and social representations. Work in this area suggests that responses to reuse are situated within an overall process of technological 'legitimation'. These emerging insights should help stimulate some novel thinking around approaches to public engagement for water reuse. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Understanding transporter specificity and the discrete appearance of channel-like gating domains in transporters

    Directory of Open Access Journals (Sweden)

    GEORGE eDIALLINAS

    2014-09-01

    Full Text Available Transporters are ubiquitous proteins mediating the translocation of solutes across cell membranes, a biological process involved in nutrition, signaling, neurotransmission, cell communication and drug uptake or efflux. Similarly to enzymes, most transporters have a single substrate binding-site and thus their activity follows Michaelis-Menten kinetics. Substrate binding elicits a series of structural changes, which produce a transporter conformer open towards the side opposite to the one from where the substrate was originally bound. This mechanism, involving alternate outward- and inward-facing transporter conformers, has gained significant support from structural, genetic, biochemical and biophysical approaches. Most transporters are specific for a given substrate or a group of substrates with similar chemical structure, but substrate specificity and/or affinity can vary dramatically, even among members of a transporter family that show high overall amino acid sequence and structural similarity. The current view is that transporter substrate affinity or specificity is determined by a small number of interactions a given solute can make within a specific binding site. However, genetic, biochemical and in silico modeling studies with the purine transporter UapA of the filamentous ascomycete Aspergillus nidulans have challenged this dogma. This review highlights results leading to a novel concept, stating that substrate specificity, but also transport kinetics and transporter turnover, are determined by subtle intramolecular interactions between a major substrate binding site and independent outward- or cytoplasmically-facing gating domains, analogous to those present in channels. This concept is supported by recent structural evidence from several, phylogenetically and functionally distinct transporter families. The significance of this concept is discussed in relationship to the role and potential exploitation of transporters in drug action.

  1. Increased understanding of neoclassical internal transport barrier on CHS

    International Nuclear Information System (INIS)

    Minami, T.; Fujisawa, A.; Iguchi, H.

    2002-10-01

    We report the recent progress of the study on neoclassical internal transport barrier (N-ITB) on Compact Helical System experiment. N-ITB has been observed for EC heated NBI plasma. The improved confinement region for electrons is expanded compared to that of the previous N-ITB plasma heated by only ECH. Moreover, the ion temperature is found to be increased simultaneously by about two to three times (T i (0) ∼ 400-500 eV) with steep gradient region at ρ - 0.6. From the measurement of the averaged peak energy intensity using the soft X-ray CCD camera it is confirmed that the impurity confinement is also improved with N-ITB. The radial electric field is observed to bifurcate into electron root (E r - 15 kV/m) and rather large electric field shear (dE r /dr - 300 kV/m 2 ) is produced in the layer between ion and electron root. (author)

  2. Increased understanding of neoclassical internal transport barrier on CHS

    International Nuclear Information System (INIS)

    Minami, T.; Fujisawa, A.; Iguchi, H.

    2003-01-01

    We report the recent progress of the study on neoclassical internal transport barrier (N-ITB) on Compact Helical System experiment. N-ITB has been observed for EC heated NBI plasma. The improved confinement region for electrons is expanded compared to that of the previous N-ITB plasma heated by only ECH. Moreover, the ion temperature is found to be increased simultaneously by about two to three times (T i (0)∼400-500eV) with steep gradient region at ρ∼0.6. From the measurement of the averaged peak energy intensity using the soft X-ray CCD camera it is confirmed that the impurity confinement is also improved with N-ITB. The radial electric field is observed to bifurcate into electron root (E r ∼15kV/m) and rather large electric field shear (dE r /dr∼300kV/m 2 ) is produced in the layer between ion and electron root. (author)

  3. Increased understanding of neoclassical internal transport barrier on CHS

    International Nuclear Information System (INIS)

    Minami, T.; Fujisawa, A.; Iguchi, H.

    2002-01-01

    We report the recent progress of the study on neoclassical internal transport barrier (N-ITB) on Compact Helical System experiment. N-ITB has been observed for EC heated NBI plasma. The improved confinement region for electrons is expanded compared to that of the previous N-ITB plasma heated by only ECH. Moreover, the ion temperature is found to be increased simultaneously by about two to three times (T i (0)∼400-500eV) with steep gradient region at ρ∼0.6. From the measurement of the averaged peak energy intensity using the soft X-ray CCD camera it is confirmed that the impurity confinement is also improved with N-ITB. The radial electric field is observed to bifurcate into electron root (E r ∼15kV/m) and rather large electric field shear (dE r /dr∼-300kV/m 2 ) is produced in the layer between ion and electron root. (author)

  4. Organic contaminant transport and fate in the subsurface: evolution of knowledge and understanding

    Science.gov (United States)

    Essaid, Hedeff I.; Bekins, Barbara A.; Cozzarelli, Isabelle M.

    2015-01-01

    Toxic organic contaminants may enter the subsurface as slightly soluble and volatile nonaqueous phase liquids (NAPLs) or as dissolved solutes resulting in contaminant plumes emanating from the source zone. A large body of research published in Water Resources Research has been devoted to characterizing and understanding processes controlling the transport and fate of these organic contaminants and the effectiveness of natural attenuation, bioremediation, and other remedial technologies. These contributions include studies of NAPL flow, entrapment, and interphase mass transfer that have advanced from the analysis of simple systems with uniform properties and equilibrium contaminant phase partitioning to complex systems with pore-scale and macroscale heterogeneity and rate-limited interphase mass transfer. Understanding of the fate of dissolved organic plumes has advanced from when biodegradation was thought to require oxygen to recognition of the importance of anaerobic biodegradation, multiple redox zones, microbial enzyme kinetics, and mixing of organic contaminants and electron acceptors at plume fringes. Challenges remain in understanding the impacts of physical, chemical, biological, and hydrogeological heterogeneity, pore-scale interactions, and mixing on the fate of organic contaminants. Further effort is needed to successfully incorporate these processes into field-scale predictions of transport and fate. Regulations have greatly reduced the frequency of new point-source contamination problems; however, remediation at many legacy plumes remains challenging. A number of fields of current relevance are benefiting from research advances from point-source contaminant research. These include geologic carbon sequestration, nonpoint-source contamination, aquifer storage and recovery, the fate of contaminants from oil and gas development, and enhanced bioremediation.

  5. 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.

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

    National Research Council Canada - National Science Library

    Levesque, Victor A; Hammett, K. M

    1997-01-01

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

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

    Science.gov (United States)

    2014-01-01

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

  8. Transport of hydrate slurry at high water cut

    OpenAIRE

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

    2014-01-01

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

  9. Understanding transportation-caused rangeland damage in Mongolia.

    Science.gov (United States)

    Keshkamat, S S; Tsendbazar, N E; Zuidgeest, M H P; Shiirev-Adiya, S; van der Veen, A; van Maarseveen, M F A M

    2013-01-15

    Mongolia, a vast and sparsely populated semi-arid country, has very little formal road infrastructure. Since the 1990s, private ownership and usage of vehicles has been increasing, which has created a web of dirt track corridors due to the communal land tenure and unobstructed terrain, with some of these corridors reaching over 4 km in width. This practice aids wind- and water-aided erosion and desertification, causing enormous negative environmental effects. Little is being done to counter the phenomenon, mainly because the logic of the driving behaviour that causes this dirt road widening is not fully understood. The research in this article postulates that this driving behaviour has rational foundations and is linked to various geographical factors (natural and man-made geographical features). We analysed 11,000 km of arterial routes in the country using spatial statistics and determined that geographically weighted regression (GWR) analysis offers a good explanation for whether, and by how much, the selected geographical factors affect the creation of corridor widths and how their effect varies across the landscape. We determined that corridor widths are correlated to factors such as proximity to river crossings, traffic intensity, and vegetation abundance. Knowing these factors can help local planners and engineers design counter-measures that could help to control and reduce the widths of these corridors, until paved roads can replace the dirt track corridors. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. 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

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

    International Nuclear Information System (INIS)

    Kahook, S.D.

    1992-08-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  13. 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

  14. Understanding Contaminant Transport Pathways at Rocky Flats - A Basis for the Remediation Strategy

    International Nuclear Information System (INIS)

    Paton, Ian

    2008-01-01

    The Rocky Flats Environmental Technology Site (RFETS) is a Department of Energy facility located approximately 16 miles northwest of Denver, Colorado. Processing and fabrication of nuclear weapons components occurred at Rocky Flats from 1952 through 1989. Operations at the Site included the use of several radionuclides, including plutonium-239/240 (Pu), americium-241 (Am), and various uranium (U) isotopes, as well as several types of chlorinated solvents. The historic operations resulted in legacy contamination, including contaminated facilities, process waste lines, buried wastes and surface soil contamination. Decontamination and removal of buildings at the site was completed in late 2005, culminating more than ten years of active environmental remediation work. The Corrective Action Decision/Record of Decision was subsequently approved in 2006, signifying regulatory approval and closure of the site. The use of RFETS as a National Wildlife Refuge is scheduled to be in full operation by 2012. To develop a plan for remediating different types of radionuclide contaminants present in the RFETS environment required understanding the different environmental transport pathways for the various actinides. Developing this understanding was the primary objective of the Actinide Migration Evaluation (AME) project. Findings from the AME studies were used in the development of RFETS remediation strategies. The AME project focused on issues of actinide behavior and mobility in surface water, groundwater, air, soil and biota at RFETS. For the purposes of the AME studies, actinide elements addressed included Pu, Am, and U. The AME program, funded by DOE, brought together personnel with a broad range of relevant expertise in technical investigations. The AME advisory panel identified research investigations and approaches that could be used to solve issues related to actinide migration at the Site. An initial step of the AME was to develop a conceptual model to provide a

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

    African Journals Online (AJOL)

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

  16. 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.…

  17. 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).

  18. Does water transport scale universally with tree size?

    Science.gov (United States)

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

    2005-01-01

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

  19. 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

  20. 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.

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

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  2. Liquid water transport mechanism in the gas diffusion layer

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-01

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

  3. National Waterways Study. Commercial Water Transportation Users.

    Science.gov (United States)

    1981-08-01

    green and stored in covered or pit silos for feed. When corn in used for its grain only, the ears are picked off the plant and the corn is shelled from...among -egions creates a need for the domestic transportation of products and crude to satisfy 206 net demand. The actual behavor of the regions may...distributed as follows: 531 million tons of reserves in the Green River-Hams Fork region (Idaho, Wyoming, Utah, and Colorado); 109 million tons in the Uinta

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

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

    Science.gov (United States)

    Raven, John A; Doblin, Martina A

    2014-12-01

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

  6. 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

  7. 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

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

    NARCIS (Netherlands)

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

    2005-01-01

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

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

    Science.gov (United States)

    Tajkhorshid, Emad; Zhu, Fangqiang; Schulten, Klaus

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

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

    Directory of Open Access Journals (Sweden)

    Istvan Nemeth

    2015-12-01

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

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-14

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

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

    International Nuclear Information System (INIS)

    Sode, Olaseni; Voth, Gregory A.

    2014-01-01

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

  14. 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)

  15. 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)

  16. Water masses as a unifying framework for understanding the Southern Ocean Carbon Cycle

    Directory of Open Access Journals (Sweden)

    D. Iudicone

    2011-05-01

    Full Text Available The scientific motivation for this study is to understand the processes in the ocean interior controlling carbon transfer across 30° S. To address this, we have developed a unified framework for understanding the interplay between physical drivers such as buoyancy fluxes and ocean mixing, and carbon-specific processes such as biology, gas exchange and carbon mixing. Given the importance of density in determining the ocean interior structure and circulation, the framework is one that is organized by density and water masses, and it makes combined use of Eulerian and Lagrangian diagnostics. This is achieved through application to a global ice-ocean circulation model and an ocean biogeochemistry model, with both components being part of the widely-used IPSL coupled ocean/atmosphere/carbon cycle model.

    Our main new result is the dominance of the overturning circulation (identified by water masses in setting the vertical distribution of carbon transport from the Southern Ocean towards the global ocean. A net contrast emerges between the role of Subantarctic Mode Water (SAMW, associated with large northward transport and ingassing, and Antarctic Intermediate Water (AAIW, associated with a much smaller export and outgassing. The differences in their export rate reflects differences in their water mass formation processes. For SAMW, two-thirds of the surface waters are provided as a result of the densification of thermocline water (TW, and upon densification this water carries with it a substantial diapycnal flux of dissolved inorganic carbon (DIC. For AAIW, principal formatin processes include buoyancy forcing and mixing, with these serving to lighten CDW. An additional important formation pathway of AAIW is through the effect of interior processing (mixing, including cabelling that serve to densify SAMW.

    A quantitative evaluation of the contribution of mixing, biology and gas exchange to the DIC evolution per water mass reveals that

  17. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

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

    1982-02-01

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

  18. 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.

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

    Science.gov (United States)

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

    2015-12-01

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

  20. 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.

  1. Concerted orientation induced unidirectional water transport through nanochannels.

    Science.gov (United States)

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

    2009-11-14

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

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Interannual Variability in the Meridional Transport of Water Vapor

    Science.gov (United States)

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

    2000-01-01

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

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

    Science.gov (United States)

    Hodges, R. R., Jr.

    1991-01-01

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

  9. Measuring and modelling water transport on Skaftafellsheioi, Iceland

    NARCIS (Netherlands)

    Dijksma, R.; Avis, Lisette

    2017-01-01

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

  10. 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).

  11. 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…

  12. 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

  13. 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…

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

    Science.gov (United States)

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

    2017-12-15

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

  15. 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 ...

  16. 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...

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

    Science.gov (United States)

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

    2004-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-11-19

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

  19. Understanding the Spatiotemporal Variability of Inherent Water Use Efficiency

    Science.gov (United States)

    Boese, Sven; Jung, Martin; Carvalhais, Nuno; Reichstein, Markus

    2015-04-01

    The global carbon and water cycles are coupled via plant physiology. However, the resulting spatial and temporal covariability of both fluxes on a global scale lacks sufficient understanding. This is required to estimate the impact of atmospheric drought on photosynthesis in water-limited ecosystems. Water use efficiency (WUE) is an essential ecosystem diagnostic defined as the ratio between gross primary productivity (GPP) and transpiration (T). WUE is known to vary with vapour-pressure deficit (VPD) and therefore also in time. The inherent water use efficiency (iWUE) accounts for the VPD effect on WUE and aims at representing a largely time-invariant ecosystem property. However, different ways of describing the functional response of iWUE to VPD are found in the literature. One established iWUE definition was proposed by Beer et al. (2009) and takes the form of iWUE = GPP--VPD- . T (1) A similar definition can be derived from stomatal conductance theories such as Katul et al. (2010) and takes the form of √ -- GPP---VPD- iWUE = T . (2) Here, we use eddy covariance measurements from the FLUXNET database to evaluate both approaches for a globally representative set of biomes including tropical, temperate and semi-arid ecosystems. Testing both definitions in a model-data fusion setup indicated that (2) is more consistent with FLUXNET observations than (1). However, there still remains considerable temporal variability of iWUE which is linked to seasonal changes in VPD. To explore up to which extent the temporal variability of iWUE may be related to the prescribed functional responses to VPD, we treated the exponent of VPD as a global parameter, here termed γ. When γ = 1 the functional response is equivalent to (1), while when γ = 0.5 it corresponds to formulation of model (2)). The global estimate was found to be significantly lower than 0.5, which would have been expected from stomatal conductance theory at leaf level. We assessed whether adding γ as site

  20. 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.

  1. 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...

  2. 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…

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

    NARCIS (Netherlands)

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

    2015-01-01

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

  4. Sociospatial understanding of water politics: Tracing the multi-dimensionality of water reuse

    Directory of Open Access Journals (Sweden)

    Ross Beveridge

    2017-02-01

    Full Text Available Much social science literature on water reuse focuses on problems of acceptance and economic problems, while the spatial and political dimensions remain under-researched. This paper addresses this deficit by reformulating the issue in terms of sociospatial politics of water reuse. It does this by drawing on the work of Mollinga (2008 and the Territory Place Scale Network (TPSN framework (Jessop et al., 2008 to develop an analytical approach to the sociospatial politics of water in general, and water reuse in particular. The paper argues that Mollinga’s understanding of water politics as contested technical/physical, organisational/managerial and regulatory/socioeconomic planes of human interventions can be deepened through further reflection on their implications for the four sociospatial dimensions of the TPSN framework. Such a comprehensive, multidimensional approach re-imagines the politics of water reuse, providing researchers with a heuristic device to trace the interventions through which water reuse plans disrupt existing arrangements, and avoid a concern for individual preferences and simplified notions of barriers and enablers. The potential of the analytical framework is explored using an empirical illustration of water reuse politics in the Berlin-Brandenburg region in Germany.

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

    Science.gov (United States)

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

    2014-09-10

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

  6. 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.

  7. 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

  8. 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

  9. Understanding of flux-limited behaviors of heat transport in nonlinear regime

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yangyu, E-mail: yangyuhguo@gmail.com [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China); Jou, David, E-mail: david.jou@uab.es [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Wang, Moran, E-mail: mrwang@tsinghua.edu [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China)

    2016-01-28

    The classical Fourier's law of heat transport breaks down in highly nonequilibrium situations as in nanoscale heat transport, where nonlinear effects become important. The present work is aimed at exploring the flux-limited behaviors based on a categorization of existing nonlinear heat transport models in terms of their theoretical foundations. Different saturation heat fluxes are obtained, whereas the same qualitative variation trend of heat flux versus exerted temperature gradient is got in diverse nonlinear models. The phonon hydrodynamic model is proposed to act as a standard to evaluate other heat flux limiters because of its more rigorous physical foundation. A deeper knowledge is thus achieved about the phenomenological generalized heat transport models. The present work provides deeper understanding and accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit. - Highlights: • Exploring flux-limited behaviors based on a categorization of existing nonlinear heat transport models. • Proposing phonon hydrodynamic model as a standard to evaluate heat flux limiters. • Providing accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit.

  10. 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.

  11. 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...

  12. Water transport by the bacterial channel alpha-hemolysin

    Science.gov (United States)

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

    1999-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

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

    Science.gov (United States)

    Cheng, Mary Hongying; Coalson, Rob D.

    2012-01-01

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

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

    DEFF Research Database (Denmark)

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

    2003-01-01

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

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

    Science.gov (United States)

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

    2003-01-01

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

  17. Recent Advances in Understanding of Kinetic Interplay Between Phase II Metabolism and Efflux Transport.

    Science.gov (United States)

    Wang, Shuai; Xing, Huijie; Zhao, Mengjing; Lu, Danyi; Li, Zhijie; Dong, Dong; Wu, Baojian

    2016-01-01

    Mechanistic understanding of the metabolism-transport interplay assumes great importance in pharmaceutical fields because the knowledge can help to interpret drug/xenobiotic metabolism and disposition studies as well as the drug-drug interactions in vivo. About 10 years ago, it started to recognize that cellular phase II metabolism is strongly influenced by the excretion (efflux transport) of generated metabolites, a kinetic phenomenon termed "phase II metabolism-transport interplay". This interplay is believed to have significant effects on the pharmacokinetics (bioavailability) of drugs/chemicals undergoing phase II metabolism. In this article, we review the studies investigating the phase II metabolism-transport interplay using cell models, perfused rat intestine, and intact rats. The potential confounding factors in exploring such interplay is also summarized. Moreover, the mechanism underlying the phase II metabolism-transport interplay is discussed. Various studies with engineered cells and rodents have demonstrated that there is an interaction (interplay) between phase II enzymes and efflux transporters. This type of interplay mainly refers to the dependence of phase II (conjugative) metabolism on the activities of efflux transporters. In general, inhibiting efflux transporters or decreasing their expression causes the reductions in metabolite excretion, apparent excretion clearance (CLapp) and total metabolism (fmet), as well as an increase in the intracellular level of metabolite (Ci). The deconjugation mediated by hydrolase (acting as a "bridge") is essential for the interplay to play out based on pharmacokinetic modeling/simulations, cell and animal studies. The hydrolases bridge the two processes (i.e., metabolite formation and excretion) and enable the interplay thereof (a bridging effect). Without the bridge, metabolite formation is independent on its downstream process excretion, thus impact of metabolite excretion on its formation is impossible

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

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

    2014-07-14

    Jul 14, 2014 ... The city has chosen to pipe in water from more than a hundred kilometres away, ... the effects of climate change and urbanization on water availability in such basins in India. ... Villages in Nepal prepare for weather extremes.

  19. 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.

  20. RIVER-RAD, Radionuclide Transport in Surface Waters

    International Nuclear Information System (INIS)

    1996-01-01

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

  1. Mechanisms and modeling development of water transport/phase change in catalyst layers of portion exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yexiang [Dept. of Thermal Engineering, Tsinghua University Beijing (China)], email: Yexiang.Xiao@energy.lth.se; Yuan, Jinliang; Sunden, Bengt [Dept. of Energy Sciences, Faculty of Engineering, Lund University (Sweden)], email: Jinliang.yuan@energy.lth.se, email: bengt.sunden@energy.lth.se

    2011-07-01

    Research on proton exchange membrane fuel cells has shown that incorporation of nanosized catalysts can effectively increase active areas and catalyst activity and make a great contribution to development in performance and catalyst utilization. Multiphase transport processes are as significant and complicated as water generation/transfer processes which occur in nano-structured catalyst layers. A review project has been launched aimed at gaining a comprehensive understanding of the mechanisms of water generation or transport phenomena. It covers catalytic reactions and water-phase change within the catalyst layers. The review proceeds in three main stages: Firstly, it characterizes and reconstructs the nano/micro-structured pores and solid-phases; secondly, it emphasises the importance of sensitive and consistent analysis of various water-phase change and transport schemes; and thirdly, it recommends development of microscopic models for multi-phase transport processes in the pores and the solid phases.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  3. 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

  4. Fish larval transport in the coastal waters through ecological modelling

    Digital Repository Service at National Institute of Oceanography (India)

    George, G.

    are as follows: (i) to find out the influence of environmental parameters on the biology of the given ecosystem (ii) to track larval transport and biological abundance in relation to environmental vari- ables (iii) to compare biological abundance and fish larval... include the following investigations: (i) analysis of satellite chlorophyll data along the southwest coastal waters of India to derive a biological calender for sardine (ii) tracking the larval survival and establish a link between food and sardine inter...

  5. 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).

  6. 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…

  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. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

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

    1982-01-01

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

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  10. 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

  11. 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

  12. Increased understanding of the dynamics and transport in ITB plasmas from multi- machine comparisons

    International Nuclear Information System (INIS)

    Gohil, P.

    2002-01-01

    This paper presents details on: (a) examination and compilation of experimental results on transport from the many machines worldwide to better understand the physics of ITB formation and sustainment; (b) the development of an international database on ITB experimental results to determine the requirements for the formation and sustainment of ITBs, especially for reactor relevant conditions; (c) determining and performing comprehensive tests of theory-based models and simulations using the experimental ITB database. This paper will further present the status of research on critical issues in ITB physics including barrier formation and access conditions, particle and impurity transport, fueling, core-edge integration, profile control and stability as well as issues of accessibility in reactor scale devices such as barriers with T e =T i , barriers with low toroidal rotation and flat density profiles. Results will be presented from many devices providing a clearer understanding of transport and ITB physics in present plasmas and how this understanding can be applied to increase the performance of plasmas in future devices. An ITB database is being developed. (author)

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

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

    Directory of Open Access Journals (Sweden)

    J. van Summeren

    2017-10-01

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

  15. 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

  16. 41 CFR 302-10.5 - May I transport a mobile home over water?

    Science.gov (United States)

    2010-07-01

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

  17. 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)

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Recasting the Understanding of Habits for Behaviour-Oriented Policies in Transportation

    Directory of Open Access Journals (Sweden)

    Kevin Marechal

    2018-03-01

    Full Text Available The role of habits in influencing transportation behaviour is acknowledged in many studies. However, most of these analyses draw on a narrow perspective of habits. In this paper, we adopt a reversed perspective regarding the interplay between habits and rationality. The insightfulness of this perspective is illustrated with the findings of two empirical studies on urban transportation. This paper shows that the underlying structure (i.e., the “genotype” behind the phenotypic manifestation of a habit is essential to grasp for getting a better understanding of the role played by habits in explaining car use. The framework of habitual practices is then put forward in discussing the results. Its rationale is to provide a characterisation of the interconnected elements that make and shape the transportation practices, together with important aspects regarding how they are formed and sustained over time. Adequately picturing both constituent elements as well as dynamic aspects is crucial for explaining the strength of habitual practices and thus car dependence. In doing so, the framework of habitual practices could thus well be of help for policy-makers in reflecting on the design of efficient and innovative interventions for the transition towards more sustainable transportation behaviours.

  3. Long-distance heat transport by hot water

    International Nuclear Information System (INIS)

    Munser, H.; Reetz, B.

    1990-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Wei Gu; Garcia, A.E.; Schoenborn, B.P. [Los Alamos National Laboratory, NM (United States)

    1994-12-31

    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.

  5. 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

  6. 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

  7. Understanding transport pathways in a river system - Monitoring sediments contaminated by an incident

    Science.gov (United States)

    Dietrich, S.; Kleisinger, C.; Hillebrand, G.; Claus, E.; Schwartz, R.; Carls, I.; Winterscheid, A.; Schubert, B.

    2016-12-01

    Experiments to trace transport of sediments and suspended particulate matter on a river scale are an expensive and difficult venture, since it causes a lot of official requirements. In spring 2015, polychlorinated biphenyls (PCB) were released during restoration works at a bridge in the upper part of the Elbe River, near the Czech-German border. In this study, the particle-bound PCB-transport is applied as a tracer for monitoring transport pathways of suspended solids (SS) along a whole river stretch over 700 km length. The incident was monitored by concentration measurements of seven indicator PCB congeners along the inland part of the Elbe River as well as in the Elbe estuary. Data from 15 monitoring stations (settling tanks) as well as from two longitudinal campaigns (grab samples) along the river in July and August 2015 are considered. The total PCB load is calculated for all stations on the basis of monthly contaminant concentrations and daily suspended sediment concentrations. Monte-Carlo simulations assess the uncertainties of the calculated load. 1D water levels and GIS analysis were used to locate temporal storage areas for the SS. It is shown that the ratio of high versus low chlorinated PCB congeners is a suitable tracer to distinguish the PCB load of the incident from the long-term background signal. Furthermore, the reduction of total PCB load within the upper Elbe indicates that roughly 24% of the SS were transported with the water by wash load. Approximately 600 km downstream of the incident site, the PCB-marked wash load was first identified in July 2015. PCB load transported intermittently in suspension was detected roughly 400 km downstream of the incident site by August 2015. In the Elbe Estuary, PCB-marked SS were only found upstream of the steep slope of water depth (approx. 4 to 15 m) within Hamburg harbor that acts as a major sediment sink. Here, SS from the inland Elbe are mixed with lowly contaminated marine material, which may mask the

  8. Understanding Local Ecology: Syllabus for Monitoring Water Quality.

    Science.gov (United States)

    Iowa Univ., Iowa City.

    This syllabus gives detailed information on monitoring water quality for teachers and students. It tells how to select a sample site; how to measure physical characteristics such as temperature, turbidity, and stream velocity; how to measure chemical parameters such as alkalinity, dissolved oxygen levels, phosphate levels, and ammonia nitrogen…

  9. 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

  10. Distribution of Tritium and {sup 137}CS in South Indian Ocean Waters - Implications of Water Transport Processes

    Energy Technology Data Exchange (ETDEWEB)

    Povinec, P. P.; Jeskovsky, M.; Sykora, I. [Comenius University, Faculty of Mathematics, Physics and Informatics, Bratislava (Slovakia); Aoyama, M. [Meteorological Research Institute, Tsukuba (Japan); Gastaud, J.; Levy, I. [International Atomic Energy Agency, Marine Environment Laboratories (Monaco); Hamajima, Y. [Kanazawa University, Low-Level Radioactivity Laboratory, Nomi (Japan); Hirose, K. [Sophia University, Faculty of Science and Technology, Tokyo (Japan); Sanchez-Cabeza, J. A. [Universitat Autonoma de Barcelona, Bellaterra (Spain)

    2013-07-15

    The World Ocean, and specifically the Indian Ocean, plays a significant role in the better understanding of the climate. The distribution of global fallout {sup 3}H, {sup 14}C, {sup 90}Sr, {sup 129}I and {sup 137}Cs in the seawater of the Indian Ocean, after their main injection from atmospheric nuclear weapons tests during the 1960s, have been investigated. Results obtained in the framework of the SHOTS (Southern Hemisphere Ocean Tracer Studies) project are evaluated and compared with previously published data. The enhanced {sup 3}H and {sup 137}Cs levels observed in the south Indian ocean indicate transport of water masses labelled with these radionuclides from the central Pacific Ocean via the Indonesian Seas to the Indian Ocean. The observed surface gradients and presence of several water masses in the south Indian ocean makes this ocean one of the most dynamic parts of the World ocean. (author)

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  12. 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.

  13. Understanding of Neutral Gas Transport in the Alcator C-Mod Tokamak Divertor

    International Nuclear Information System (INIS)

    Stotler, D.P.; Pitcher, C.S.; Boswell, C.J.; LaBombard, B.; Terry, J.L.; Elder, J.D.; Lisgo, S.

    2002-01-01

    A series of experiments on the effect of divertor baffling on the Alcator C-Mod tokamak provides stringent tests on models of neutral gas transport in and around the divertor region. One attractive feature of these experiments is that a trial description of the background plasma can be constructed from experimental measurements using a simple model, allowing the neutral gas transport to be studied with a stand-alone code. The neutral-ion and neutral-neutral elastic scattering processes recently added to the DEGAS 2 Monte Carlo neutral transport code permit the neutral gas flow rates between the divertor and main chamber to be simulated more realistically than before. Nonetheless, the simulated neutral pressures are too low and the deuterium Balmer-alpha emission profiles differ qualitatively from those measured, indicating an incomplete understanding of the physical processes involved in the experiment. Some potential explanations are examined and opportunities for future exploration a re highlighted. Improvements to atomic and surface physics data and models will play a role in the latter

  14. 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.)

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

    KAUST Repository

    Sutton, Christopher; Tummala, Naga Rajesh; Kemper, Travis; Aziz, Saadullah G.; Sears, John; Coropceanu, Veaceslav; Bredas, Jean-Luc

    2017-01-01

    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.

  16. Increased understanding of the dynamics and transport in ITB plasmas from multi-machine comparisons

    International Nuclear Information System (INIS)

    Gohil, P.; Kinsey, J.; Parail, V.

    2003-01-01

    Our understanding of the physics of internal transport barriers (ITBs) is being furthered by analysis and comparisons of experimental data from many different tokamaks worldwide. An international database consisting of scalar and 2-D profile data on ITB plasmas is being developed to determine the requirements for the formation and sustainment of ITBs and to perform tests of theory-based transport models in an effort to improve the predictive capability of the models. Tests of several transport models (JETTO, Weiland model) using the 2-D profile data indicate that there is only limited agreement between the model predictions and the experimental results for the range of plasma conditions examined for the different devices (DIII-D, JET, JT-60U). Gyrokinetic stability analysis of the ITB discharges from these devices indicates that the ITG/TEM growth rates decrease with increased negative magnetic shear and that the ExB shear rate is comparable to the linear growth rates at the location of the ITB. (author)

  17. 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.

  18. Stochastic Modeling Of Field-Scale Water And Solute Transport Through The Unsaturated Zone Of Soils

    DEFF Research Database (Denmark)

    Loll, Per

    were previously thought not to pose a leaching threat. Thus, a reevaluation of our understanding of the mechanisms governing chemical fate in the unsaturated zone of soils has been necessary, in order for us to make better decisions regarding widely different issues such as agricultural management...... of pesticides and nutrients, and risk identification and assessment at polluted (industrial) sites. One of the key factors requiring our attention when we are trying to predict field-scale chemical leaching is spatial variability of the soil and the influence it exerts on both water and chemical transport...

  19. The Association of Cryptosporidium parvum With Suspended Sediments: Implications for Transport in Surface Waters

    Science.gov (United States)

    Searcy, K. E.; Packman, A. I.; Atwill, E. R.; Harter, T.

    2003-12-01

    Understanding the transport and fate of microorganisms in surface waters is of vital concern in protecting the integrity and safety of municipal water supply systems. The human pathogen Cryptosporidium parvum is a particular public health interest, as it is ubiquitous in the surface waters of the United States, it can persist for long periods in the environment, and it is difficult to disinfect in water treatment plants. Due to its small size (5 um), low specific gravity (1.05 g/cm3), and negative surface charge, C. parvum oocysts are generally considered to move through watersheds from their source to drinking water reservoirs with little attenuation. However, the transport of the oocysts in surface waters may be mediated by interactions with suspended sediments. Batch experiments were conducted to determine the extent of C. parvum oocyst attachment to several inorganic and organic sediments under varying water chemical conditions, and settling column experiments were performed to demonstrate how these associations influence the effective settling velocity of C. parvum oocysts. Results from these experiments showed that C. parvum oocysts do associate with inorganic and organic sediments and often settle at the rate of the suspended sediment. The size and surface charge of the host suspended sediment influenced the extent of oocyst attachment as oocysts preferentially associated with particles greater than 3 um, and fewer oocysts associated with particles having a highly negative surface charge. Background water chemical conditions including ionic strength, ion composition, and pH did not have a significant effect on oocyst attachment to suspended sediments.

  20. Liquid Water Transport in the Reactant Channels of Proton Exchange Membrane Fuel Cells

    Science.gov (United States)

    Banerjee, Rupak

    Water management has been identified as a critical issue in the development of PEM fuel cells for automotive applications. Water is present inside the PEM fuel cell in three phases, i.e. liquid phase, vapor phase and mist phase. Liquid water in the reactant channels causes flooding of the cell and blocks the transport of reactants to the reaction sites at the catalyst layer. Understanding the behavior of liquid water in the reactant channels would allow us to devise improved strategies for removing liquid water from the reactant channels. In situ fuel cell tests have been performed to identify and diagnose operating conditions which result in the flooding of the fuel cell. A relationship has been identified between the liquid water present in the reactant channels and the cell performance. A novel diagnostic technique has been established which utilizes the pressure drop multiplier in the reactant channels to predict the flooding of the cell or the drying-out of the membrane. An ex-situ study has been undertaken to quantify the liquid water present in the reactant channels. A new parameter, the Area Coverage Ratio (ACR), has been defined to identify the interfacial area of the reactant channel which is blocked for reactant transport by the presence of liquid water. A parametric study has been conducted to study the effect of changing temperature and the inlet relative humidity on the ACR. The ACR decreases with increase in current density as the gas flow rates increase, removing water more efficiently. With increase in temperature, the ACR decreases rapidly, such that by 60°C, there is no significant ACR to be reported. Inlet relative humidity of the gases does change the saturation of the gases in the channel, but did not show any significant effect on the ACR. Automotive powertrains, which is the target for this work, are continuously faced with transient changes. Water management under transient operating conditions is significantly more challenging and has not

  1. Water activated doping and transport in multilayered germanane crystals

    International Nuclear Information System (INIS)

    Young, Justin R; Johnston-Halperin, Ezekiel; Chitara, Basant; Cultrara, Nicholas D; Arguilla, Maxx Q; Jiang, Shishi; Fan, Fan; Goldberger, Joshua E

    2016-01-01

    The synthesis of germanane (GeH) has opened the door for covalently functionalizable 2D materials in electronics. Herein, we demonstrate that GeH can be electronically doped by incorporating stoichiometric equivalents of phosphorus dopant atoms into the CaGe 2 precursor. The electronic properties of these doped materials show significant atmospheric sensitivity, and we observe a reduction in resistance by up to three orders of magnitude when doped samples are measured in water-containing atmospheres. This variation in resistance is a result of water activation of the phosphorus dopants. Transport measurements in different contact geometries show a significant anisotropy between in-plane and out-of-plane resistances, with a much larger out-of-plane resistance. These measurements along with finite element modeling results predict that the current distribution in top-contacted crystals is restricted to only the topmost, water activated crystal layers. Taken together, these results pave the way for future electronic and optoelectronic applications utilizing group IV graphane analogues. (paper)

  2. The Mars Dust and Water Cycles: Investigating the Influence of Clouds on the Vertical Distribution and Meridional Transport of Dust and Water

    Science.gov (United States)

    Kahre, Melinda A.; Haberle, Robert M.; Hollingsworth, Jeffery L.; Brecht, Amanda S.; Urata, Richard A.

    2015-11-01

    The dust and water cycles are critical to the current Martian climate, and they interact with each other through cloud formation. Dust modulates the thermal structure of the atmosphere and thus greatly influences atmospheric circulation. Clouds provide radiative forcing and control the net hemispheric transport of water through the alteration of the vertical distributions of water and dust. Recent advancements in the quality and sophistication of both climate models and observations enable an increased understanding of how the coupling between the dust and water cycles (through cloud formation) impacts the dust and water cycles. We focus here on the effects of clouds on the vertical distributions of dust and water and how those vertical distributions control the net meridional transport of water. We utilize observations of temperature, dust and water ice from the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO) and the NASA ARC Mars Global Climate Model (MGCM) to show that the magnitude and nature of the hemispheric exchange of water during NH summer is sensitive to the vertical structure of the simulated aphelion cloud belt. Further, we investigate how clouds influence atmospheric temperatures and thus the vertical structure of the cloud belt. Our goal is to isolate and understand the importance of radiative/dynamic feedbacks due to the physical processes involved with cloud formation and evolution on the current climate of Mars.

  3. 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.

  4. 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)

  5. 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)

  6. 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)

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

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  8. 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.

  9. 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

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

    Directory of Open Access Journals (Sweden)

    Yanzhou Qin

    2018-04-01

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

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

    Science.gov (United States)

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

    2000-01-01

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

  13. 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...

  14. Alteration of natural (37)Ar activity concentration in the subsurface by gas transport and water infiltration.

    Science.gov (United States)

    Guillon, Sophie; Sun, Yunwei; Purtschert, Roland; Raghoo, Lauren; Pili, Eric; Carrigan, Charles R

    2016-05-01

    High (37)Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of (37)Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict (37)Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating (37)Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for (37)Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural (37)Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of (37)Ar activity concentrations. The influence of soil water content on (37)Ar production is shown to be negligible to first order, while (37)Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Dynamics of glycerine and water transport across human skin from binary mixtures.

    Science.gov (United States)

    Ventura, S A; Kasting, G B

    2017-04-01

    Skin transport properties of glycerine and water from binary mixtures contacting human skin were determined to better understand the mechanism of skin moisturization by aqueous glycerine formulations. Steady-state permeation for 3 H 2 O and 14 C-glycerine across split-thickness human skin in vitro and desorption dynamics of the same permeants in isolated human stratum corneum (HSC) were experimentally determined under near equilibrium conditions. These data were compared to a priori values developed in the context of a thermodynamic model for binary mixtures of glycerine and water and a previously determined water sorption isotherm for HSC. This allowed the estimation of diffusion and partition coefficients for each permeant in the HSC, as well as HSC thickness, as a function of composition of the contacting solution. These data may be used to estimate water retention and associated HSC swelling related to the absorption and slow release of glycerine from the skin. It took 6+ days for glycerine to completely desorb from HSC immersed in glycerine/water binary solutions. Desorption of both 3 H 2 O and 14 C-glycerine from HSC was slower in pure water than from binary mixtures, a result that is largely explained by the greater swelling of HSC in water. Parametric relationships were developed for water and glycerine intradiffusivities in HSC as functions of HSC water content, and a mutual diffusion coefficient was estimated by analogy with glycerine/water binary solutions. The intradiffusivity of 14 C-glycerine in HSC as inferred from sorption/desorption experiments was shown to be approximately 10-fold less than that inferred from permeation experiments, whereas the corresponding values for 3 H 2 O were comparable. These studies confirm that glycerine enters HSC in substantial quantities and has a long residence time therein. The coupling between bulk water and glycerine transport projected from binary solution data suggests the net effect of glycerine is to slow water

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

    OpenAIRE

    Solomon Ndubuisi Eluozo

    2013-01-01

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

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

    Science.gov (United States)

    2017-10-01

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

  18. Progress Towards Increased Understanding and Control of Internal Transport Barriers on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, E. J. [University of California, Los Angeles; Greenfield, C. M. [General Atomics; Austin, M. E. [University of Texas, Austin; Baylor, Larry R [ORNL; Burrell, K. H. [General Atomics; Casper, T. A. [Lawrence Livermore National Laboratory (LLNL); DeBoo, J. C. [General Atomics; Ernst, D. R. [Princeton Plasma Physics Laboratory (PPPL); Fenzi, C. [University of Wisconsin, Madison; Gohil, P. [General Atomics; Groebner, R. J. [General Atomics; Heidbrink, W. W. [University of California, Irvine; Jackson, G. L. [General Atomics; Jernigan, Thomas C [ORNL; Kinsey, J. E. [Lehigh University, Bethlehem, PA; Lao, L. L. [General Atomics; Makowski, M. A. [Lawrence Livermore National Laboratory (LLNL); Mckee, G. R. [University of Wisconsin, Madison; Murakami, Masanori [ORNL; Peebles, W. A. [University of California, Los Angeles; Prater, R. [General Atomics; Rettig, C. L. [University of California, Los Angeles; Rhodes, T. L. [University of California, Los Angeles; Rost, J. C. [Massachusetts Institute of Technology (MIT); Staebler, G. M. [General Atomics; Stallard, B. W. [Lawrence Livermore National Laboratory (LLNL); Strait, E. J. [General Atomics; Synakowski, E. J. [Princeton Plasma Physics Laboratory (PPPL); Thomas, D. M. [General Atomics; Wade, Mickey R [ORNL; Waltz, R. E. [General Atomics; Zeng, L. [University of California, Los Angeles

    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 τE) with divertor pumping. QDB plasmas are long-pulse high-performance candidates, having maintained a βNH89 product of 7 for 5 energy confinement times (Ti ≤ 16 keV, βN ≤ 2.9, H89 ≤ 2.4, τE ≤ 150 ms, DD neutron rate Sn ≤ 4x1015 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.

  19. 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)

  20. Understanding Non-Equilibrium Charge Transport and Rectification at Chromophore/Metal Interfaces

    Science.gov (United States)

    Darancet, Pierre

    Understanding non-equilibrium charge and energy transport across nanoscale interfaces is central to developing an intuitive picture of fundamental processes in solar energy conversion applications. In this talk, I will discuss our theoretical studies of finite-bias transport at organic/metal interfaces. First, I will show how the finite-bias electronic structure of such systems can be quantitatively described using density functional theory in conjunction with simple models of non-local correlations and bias-induced Stark effects.. Using these methods, I will discuss the conditions of emergence of highly non-linear current-voltage characteristics in bilayers made of prototypical organic materials, and their implications in the context of hole- and electron-blocking layers in organic photovoltaic. In particular, I will show how the use of strongly-hybridized, fullerene-coated metallic surfaces as electrodes is a viable route to maximizing the diodic behavior and electrical functionality of molecular components. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (Argonne). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.

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

    International Nuclear Information System (INIS)

    Andalaft, E.; Labayru, R.

    1992-01-01

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

  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. PMID:26087009

  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. 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.

  5. Simplified estimation technique for organic contaminant transport in ground water

    Energy Technology Data Exchange (ETDEWEB)

    Piver, W T; Lindstrom, F T

    1984-05-01

    The analytical solution for one-dimensional dispersive-advective transport of a single solute in a saturated soil accompanied by adsorption onto soil surfaces and first-order reaction rate kinetics for degradation can be used to evaluate the suitability of potential sites for burial of organic chemicals. The technique can be used to the greatest advantage with organic chemicals that are present in ground waters in small amounts. The steady-state solution provides a rapid method for chemical landfill site evaluation because it contains the important variables that describe interactions between hydrodynamics and chemical transformation. With this solution, solute concentration, at a specified distance from the landfill site, is a function of the initial concentration and two dimensionless groups. In the first group, the relative weights of advective and dispersive variables are compared, and in the second group the relative weights of hydrodynamic and degradation variables are compared. The ratio of hydrodynamic to degradation variables can be rearranged and written as (a/sub L lambda)/(q/epsilon), where a/sub L/ is the dispersivity of the soil, lambda is the reaction rate constant, q is ground water flow velocity, and epsilon is the soil porosity. When this term has a value less than 0.01, the degradation process is occurring at such a slow rate relative to the hydrodynamics that it can be neglected. Under these conditions the site is unsuitable because the chemicals are unreactive, and concentrations in ground waters will change very slowly with distance away from the landfill site.

  6. Understanding Public Engagement in Water Conservation Behaviors and Knowledge of Water Policy: Promising Hints for Extension

    Science.gov (United States)

    Huang, Pei-wen; Lamm, Alexa J.

    2015-01-01

    Sustaining water resources is a primary issue facing Florida Extension. The study reported here identified how experience with water issues and familiarity with water policies affected individuals' engagement in water conservation behaviors. A public opinion survey was conducted online to capture Florida residents' responses. The findings…

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

    OpenAIRE

    Dennis Wichelns

    2014-01-01

    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 maximizi...

  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. 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.

  10. Transport of thermal water from well to thermal baths

    Science.gov (United States)

    Montegrossi, Giordano; Vaselli, Orlando; Tassi, Franco; Nocentini, Matteo; Liccioli, Caterina; Nisi, Barbara

    2013-04-01

    The main problem in building a thermal bath is having a hot spring or a thermal well located in an appropriate position for customer access; since Roman age, thermal baths were distributed in the whole empire and often road and cities were built all around afterwards. Nowadays, the perspectives are changed and occasionally the thermal resource is required to be transported with a pipeline system from the main source to the spa. Nevertheless, the geothermal fluid may show problems of corrosion and scaling during transport. In the Ambra valley, central Italy, a geothermal well has recently been drilled and it discharges a Ca(Mg)-SO4, CO2-rich water at the temperature of 41 °C, that could be used for supplying a new spa in the surrounding areas of the well itself. The main problem is that the producing well is located in a forest tree ca. 4 km far away from the nearest structure suitable to host the thermal bath. In this study, we illustrate the pipeline design from the producing well to the spa, constraining the physical and geochemical parameters to reduce scaling and corrosion phenomena. The starting point is the thermal well that has a flow rate ranging from 22 up to 25 L/sec. The thermal fluid is heavily precipitating calcite (50-100 ton/month) due to the calcite-CO2 equilibrium in the reservoir, where a partial pressure of 11 bar of CO2 is present. One of the most vexing problems in investigating scaling processed during the fluid transport in the pipeline is that there is not a proper software package for multiphase fluid flow in pipes characterized by such a complex chemistry. As a consequence, we used a modified TOUGHREACT with Pitzer database, arranged to use Darcy-Weisbach equation, and applying "fictitious" material properties in order to give the proper y- z- velocity profile in comparison to the analytical solution for laminar fluid flow in pipes. This investigation gave as a result the lowest CO2 partial pressure to be kept in the pipeline (nearly 2

  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. 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 were made by combining the results of hydrological experiments, conducted to assess the effects of afforestation with alien trees on water resources, with an ecological understanding of the spread and establishment of invasive trees. The forecasts were...

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

    International Nuclear Information System (INIS)

    Ostmeyer, R.M.

    1986-01-01

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

  15. Circumpolar Deep Water transport and current structure at the Amundsen Sea shelf break

    Science.gov (United States)

    Assmann, Karen M.; Wåhlin, Anna K.; Heywood, Karen J.; Jenkins, Adrian; Kim, Tae Wan; Lee, Sang Hoon

    2017-04-01

    The West Antarctic Ice Sheet has been losing mass at an increasing rate over the past decades. Ocean heat transport to the ice-ocean interface has been identified as an important contributor to this mass loss and the role it plays in ice sheet stability makes it crucial to understand its drivers in order to make accurate future projections of global sea level. While processes closer to the ice-ocean interface modulate this heat transport, its ultimate source is located in the deep basin off the continental shelf as a core of relatively warm, salty water underlying a colder, fresher shallow surface layer. To reach the marine terminating glaciers and the base of floating ice shelves, this warm, salty water mass must cross the bathymetric obstacle of the shelf break. Glacial troughs that intersect the Amundsen shelf break and deepen southwards towards the ice shelf fronts have been shown to play an important role in transporting warm, salty Circumpolar Deep Water (CDW) towards the ice shelves. North of the shelf break, circulation in the Amundsen Sea occupies an intermediate regime between the eastward Antarctic Circumpolar Current that impinges on the shelf break in the Bellingshausen Sea and the westward southern limb of the Ross Gyre that follows the shelf break in the Ross Sea. Hydrographic and mooring observations and numerical model results at the mouth of the central shelf break trough leading to Pine Island and Thwaites Glaciers show a westward wind-driven shelf break current overlying an eastward undercurrent that turns onto the shelf in the trough. It is thought that the existence of the latter feature facilitates the on-shelf transport of CDW. A less clearly defined shelf break depression further west acts as the main pathway for CDW to Dotson and eastern Getz Ice shelves. Model results indicate that a similar eastward undercurrent exists here driving the on-shelf transport of CDW. Two moorings on the upper slope east of the trough entrance show a

  16. 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.

  17. Coupling Flow & Transport Modeling with Electromagnetic Geophysics to Better Understand Crustal Permeability

    Science.gov (United States)

    Pepin, J.; Folsom, M.; Person, M. A.; Kelley, S.; Gomez-Velez, J. D.; Peacock, J.

    2016-12-01

    Over the last 30 years, considerable effort has focused on understanding the distribution of permeability within the earth's crust and its implications for flow and transport. The scarcity of direct observations makes the description of permeabilities beyond depths of about 3 km particularly challenging. Numerous studies have defined depth-decay relationships for basement permeability, while others note that it is too complex to be characterized by a general relationship. Hydrothermal modeling studies focusing on two geothermal systems within the tectonically active Rio Grande rift of New Mexico suggest that there may be laterally extensive regions of highly permeable (10-14 to 10-12 m2) basement rocks at depths ranging between 4 and 8 km. The NaCl groundwater signature, elevated fracture density, and secondary mineralization of fractured basement outcrops associated with these geothermal systems indicate that there may indeed be significant groundwater flow within the basement rocks of the rift. We hypothesize that there are extensive regions of highly permeable crystalline basement rocks at depths greater than 3 km within the Rio Grande rift. These fractured zones serve as large conduits for geothermal fluids before they ascend to shallow depths through gaps in overlying confining sediments or along faults. To test these hypotheses, we use a combination of geophysical observations and flow and transport modeling. We used electromagnetic geophysics (TEM & MT) to image resistivity in one of the hypothesized deep circulation geothermal systems near Truth or Consequences, NM. The resistivity dataset, in tandem with geochemical and thermal observations, is then used to calibrate a hydrothermal model of the system. This new calibration methodology has the potential to change the way researchers study crustal fluid flow and geothermal systems; thereby providing a tool to explore depths greater than 3 km where minimal data is available. In addition, it has the advantage

  18. Evolution and Transport of Water in the Upper Regolith of Mars

    Science.gov (United States)

    Hudson, T. L.; Aharonson, O.; Schorghofer, N.; Hecht, M. H.; Bridges, N. T.; Green, J. R.

    2003-01-01

    Long standing theoretical predictions [1-3], as well as recent spacecraft observations [4] indicate that large quantities of ice is present in the high latitudes upper decimeters to meters of the Martian regolith. At shallower depths and warmer locations small amounts of H2O, either adsorbed or free, may be present transiently. An understanding of the evolution of water based on theoretical and experimental considerations of the processes operating at the Martian environment is required. In particular, the porosity, diffusivity, and permeability of soils and their effect on water vapor transport under Mars-like conditions have been estimated, but experimental validation of such models is lacking. Goal: Three related mechanisms may affect water transport in the upper Martian regolith. 1) diffusion along a concentration gradient under isobaric conditions, 2) diffusion along a thermal gradient, which may give rise to a concentration gradient as ice sublimes or molecules desorb from the regolith, and 3) hydraulic flow, or mass motion in response to a pressure gradient. Our combined theoretical and experimental investigation seeks to disentangle these mechanisms and determine which process(es) are dominant in the upper regolith over various timescales. A detailed one-dimensional model of the upper regolith is being created which incorporates water adsorption/ desorption, condensation, porosity, diffusivity, and permeability effects. Certain factors such as diffusivity are difficult to determine theoretically due to the wide range of intrinsic grain properties such as particle sizes, shapes, packing densities, and emergent properties such as tortuosity. An experiment is being designed which will allow us to more accurately determine diffusivity, permeability, and water desorption isotherms for regolith simulants.

  19. 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

  20. 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.

  1. 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.

  2. 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....

  3. The metal/water explosion phenomenon - a review of present understanding

    International Nuclear Information System (INIS)

    Vaughan, G.J.

    1980-05-01

    The metal/water explosion phenomenon has led to deaths and damage in several industrial incidents. This paper reviews the current understanding (up to 1978) of the phenomenon in terms of both the experimental evidence and the theoretical models that have been proposed. Complete understanding of the phenomenon has not been achieved and some recommendations are given for future work. (author)

  4. 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

  5. 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...

  6. Linking air and water transport in intact soils to macropore characteristics inferred from X-ray computed tomography

    DEFF Research Database (Denmark)

    Katuwal, S.; Nørgaard, Trine; Møldrup, Per

    2015-01-01

    Soil macropores often control fluid flow and solute transport, and quantification of macropore characteristics including their variability in space and time are essential to predict soil hydraulic and hydrogeochemical functions. In this study, measurements of air and solute transport properties...... and direct macropore visualization by X-ray CT scanning were carried out on 17 large (19-cm diam.; 20-cm length) undisturbed soil columns sampled across a field site (Silstrup, Denmark) with natural gradients in texture and density. Air permeability (ka) at in-situ water content and -20 hPa of matric......-porosity, suggesting that density is the main control of functional soil structure and gas and solute transport at the Silstrup site. Linking gas transport and chemical tracer experiments with X-ray CT based visualization and quantification of macro-porosity was found to be a powerful method to understand field scale...

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  8. What is needed to understand feedback mechanisms from agricultural and climate changes that can alter the hydrological system and the transport of sediments and agricultural chemicals?

    Science.gov (United States)

    Coupe, Richard; Payraudeau, Sylvain; Babcsányi, Izabella; Imfeld, Gwenaël

    2015-04-01

    Modern agriculture activities are constantly changing as producers try to produce a crop, keep their soils fertile, control pests, and prevent contamination of air and water resources. Because most of the world's arable land is already in production we must become more efficient if we are to feed and clothe the world's growing population as well as do this in a sustainable manner; leaving a legacy of fertile soil and clean water resources for our descendants. The objective of this paper is to demonstrate the importance of historical datasets and of developing new strategies to understand the effects of changing agricultural systems on the environment. Scientists who study agriculture and its effects on water must constantly adapt their strategies and evaluate how changing agricultural activities impact the environment. As well as understand from historical datasets on hydrology and agriculture how a changing climate or agricultural activity such as a change in tillage method might impact the processes that determine the movement of agricultural chemicals off of the target site. The 42.7 ha Hohrain (Rouffach, Alsace, France) vineyard experimental catchment offers several examples of how scientists have used historical data from this catchment to understand how the transport of agricultural chemicals may change due to a changing climate as well as how new strategies are developed for understanding the transport of agricultural chemicals. Runoff is a major process of pesticide transport from agricultural land to downstream aquatic ecosystems. The impact of rainfall characteristics on the transport of runoff-related pesticides is crucial to understanding how to prevent or minimize their movement now, but also in understanding how climate change might affect runoff. If we understand how rainfall characteristics affect the transport of pesticides, we can use climate change models to predict how those characteristics might change in the future and be better prepared for

  9. 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

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

    OpenAIRE

    Cheng, Mary Hongying; Coalson, Rob D.

    2012-01-01

    Early crystal structures of prokaryotic CLC proteins identified three Cl– binding sites: internal (Sint), central (Scen), and external (Sext). A conserved external GLU (GLUex) residue acts as a gate competing for Sext. Recently, the first crystal structure of a eukaryotic transporter, CmCLC, revealed that in this transporter GLUex competes instead for Scen. Here, we use molecular dynamics simulations to investigate Cl– transport through CmCLC. The gating and Cl–/H+ transport cycle are inferre...

  11. 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...

  12. 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

  13. Understanding the origin and evolution of water in the Moon through lunar sample studies.

    Science.gov (United States)

    Anand, Mahesh; Tartèse, Romain; Barnes, Jessica J

    2014-09-13

    A paradigm shift has recently occurred in our knowledge and understanding of water in the lunar interior. This has transpired principally through continued analysis of returned lunar samples using modern analytical instrumentation. While these recent studies have undoubtedly measured indigenous water in lunar samples they have also highlighted our current limitations and some future challenges that need to be overcome in order to fully understand the origin, distribution and evolution of water in the lunar interior. Another exciting recent development in the field of lunar science has been the unambiguous detection of water or water ice on the surface of the Moon through instruments flown on a number of orbiting spacecraft missions. Considered together, sample-based studies and those from orbit strongly suggest that the Moon is not an anhydrous planetary body, as previously believed. New observations and measurements support the possibility of a wet lunar interior and the presence of distinct reservoirs of water on the lunar surface. Furthermore, an approach combining measurements of water abundance in lunar samples and its hydrogen isotopic composition has proved to be of vital importance to fingerprint and elucidate processes and source(s) involved in giving rise to the lunar water inventory. A number of sources are likely to have contributed to the water inventory of the Moon ranging from primordial water to meteorite-derived water ice through to the water formed during the reaction of solar wind hydrogen with the lunar soil. Perhaps two of the most striking findings from these recent studies are the revelation that at least some portions of the lunar interior are as water-rich as some Mid-Ocean Ridge Basalt source regions on Earth and that the water in the Earth and the Moon probably share a common origin. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  14. 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.

  15. 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.

  16. Numerical simulation of water flow and Nitrate transport through variably saturated porous media in laboratory condition using HYDRUS 2D

    Science.gov (United States)

    Jahangeer, F.; Gupta, P. K.; Yadav, B. K.

    2017-12-01

    Due to the reducing availability of water resources and the growing competition for water between residential, industrial, and agricultural users, increasing irrigation efficiency, by several methods like drip irrigation, is a demanding concern for agricultural experts. The understanding of the water and contaminants flow through the subsurface is needed for the sustainable irrigation water management, pollution assessment, polluted site remediation and groundwater recharge. In this study, the Windows-based computer software package HYDRUS-2D, which numerically simulates water and solute movement in two-dimensional, variably-saturated porous media, was used to evaluate the distribution of water and Nitrate in the sand tank. The laboratory and simulation experiments were conducted to evaluate the role of drainage, recharge flux, and infiltration on subsurface flow condition and subsequently, on nitrate movement in the subsurface. The water flow in the unsaturated zone model by Richards' equation, which was highly nonlinear and its parameters were largely dependent on the moisture content and pressure head of the partially saturated zone. Following different cases to be considered to evaluate- a) applying drainage and recharge flux to study domains, b) transient infiltration in a vertical soil column and c) subsequently, nitrate transport in 2D sand tank setup. A single porosity model was used for the simulation of water and nitrate flow in the study domain. The results indicate the transient water table position decreases as the time increase significantly by applying drainage flux at the bottom. Similarly, the water table positions in study domains increasing in the domain by applying recharge flux. Likewise, the water flow profile shows the decreasing water table elevation with increasing water content in the vertical domain. Moreover, the nitrate movement was dominated by advective flux and highly affected by the recharge flux in the vertical direction. The

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

    International Nuclear Information System (INIS)

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

    1985-01-01

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

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

    Science.gov (United States)

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

    2018-05-01

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

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

    Science.gov (United States)

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

    1988-01-01

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

  20. 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

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

    Science.gov (United States)

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

    1988-03-01

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

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

    Science.gov (United States)

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

    1988-01-01

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

  3. Transport of water and ions in partially water-saturated porous media. Part 2. Filtration effects

    Science.gov (United States)

    Revil, A.

    2017-05-01

    A new set of constitutive equations describing the transport of the ions and water through charged porous media and considering the effect of ion filtration is applied to the problem of reverse osmosis and diffusion of a salt. Starting with the constitutive equations derived in Paper 1, I first determine specific formula for the osmotic coefficient and effective diffusion coefficient of a binary symmetric 1:1 salt (such as KCl or NaCl) as a function of a dimensionless number Θ corresponding to the ratio between the cation exchange capacity (CEC) and the salinity. The modeling is first carried with the Donnan model used to describe the concentrations of the charge carriers in the pore water phase. Then a new model is developed in the thin double layer approximation to determine these concentrations. These models provide explicit relationships between the concentration of the ionic species in the pore space and those in a neutral reservoir in local equilibrium with the pore space and the CEC. The case of reverse osmosis and diffusion coefficient are analyzed in details for the case of saturated and partially saturated porous materials. Comparisons are done with experimental data from the literature obtained on bentonite. The model predicts correctly the influence of salinity (including membrane behavior at high salinities), porosity, cation type (K+ versus Na+), and water saturation on the osmotic coefficient. It also correctly predicts the dependence of the diffusion coefficient of the salt with the salinity.

  4. U.S. Geological Survey Water science strategy--observing, understanding, predicting, and delivering water science to the nation

    Science.gov (United States)

    Evenson, Eric J.; Orndorff, Randall C.; Blome, Charles D.; Böhlke, John Karl; Hershberger, Paul K.; Langenheim, V.E.; McCabe, Gregory J.; Morlock, Scott E.; Reeves, Howard W.; Verdin, James P.; Weyers, Holly S.; Wood, Tamara M.

    2013-01-01

    This report expands the Water Science Strategy that began with the USGS Science Strategy, “Facing Tomorrow’s Challenges—U.S. Geological Survey Science in the Decade 2007–2017” (U.S. Geological Survey, 2007). This report looks at the relevant issues facing society and develops a strategy built around observing, understanding, predicting, and delivering water science for the next 5 to 10 years by building new capabilities, tools, and delivery systems to meet the Nation’s water-resource needs. This report begins by presenting the vision of water science for the USGS and the societal issues that are influenced by, and in turn influence, the water resources of our Nation. The essence of the Water Science Strategy is built on the concept of “water availability,” defined as spatial and temporal distribution of water quantity and quality, as related to human and ecosystem needs, as affected by human and natural influences. The report also describes the core capabilities of the USGS in water science—the strengths, partnerships, and science integrity that the USGS has built over its 134-year history. Nine priority actions are presented in the report, which combine and elevate the numerous specific strategic actions listed throughout the report. Priority actions were developed as a means of providing the audience of this report with a list for focused attention, even if resources and time limit the ability of managers to address all of the strategic actions in the report.

  5. 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....

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

    Science.gov (United States)

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

    2003-01-01

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

  7. 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...

  8. The Modelling Analysis of the Response of Convective Transport of Energy and Water to Multiscale Surface Heterogeneity over Tibetan Plateau

    Science.gov (United States)

    SUN, G.; Hu, Z.; Ma, Y.; Ma, W.

    2017-12-01

    The land-atmospheric interactions over a heterogeneous surface is a tricky issue for accurately understanding the energy-water exchanges between land surface and atmosphere. We investigate the vertical transport of energy and water over a heterogeneous land surface in Tibetan Plateau during the evolution of the convective boundary layer using large eddy simulation (WRF_LES). The surface heterogeneity is created according to remote sensing images from high spatial resolution LandSat ETM+ images. The PBL characteristics over a heterogeneous surface are analyzed in terms of secondary circulations under different background wind conditions based on the horizontal and vertical distribution and evolution of wind. The characteristics of vertical transport of energy and heat over a heterogeneous surface are analyzed in terms of the horizontal distribution as well as temporal evolution of sensible and latent heat fluxes at different heights under different wind conditions on basis of the simulated results from WRF_LES. The characteristics of the heat and water transported into the free atmosphere from surface are also analyzed and quantified according to the simulated results from WRF_LES. The convective transport of energy and water are analyzed according to horizontal and vertical distributions of potential temperature and vapor under different background wind conditions. With the analysis based on the WRF_LES simulation, the performance of PBL schemes of mesoscale simulation (WRF_meso) is evaluated. The comparison between horizontal distribution of vertical fluxes and domain-averaged vertical fluxes of the energy and water in the free atmosphere is used to evaluate the performance of PBL schemes of WRF_meso in the simulation of vertical exchange of energy and water. This is an important variable because only the energy and water transported into free atmosphere is able to influence the regional and even global climate. This work would will be of great significance not

  9. 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).

  10. 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)

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Iowa Department of Transportation. - Clean Water Act Public Notice

    Science.gov (United States)

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Iowa Department of Transportation, a state agency with its primary office located at 800 Lincoln Way, Ames, IA 50010, for alleged violations at two roadway construction pro

  16. Nebraska Department of Transportation - Clean Water Act Public Notice

    Science.gov (United States)

    The EPA is providing notice of a proposed Administrative Penalty Assessment against the Nebraska Department of Transportation, a state agency located at 1500 Highway 2, Lincoln, NE 68509, for alleged violations of its municipal separate stormwater sewer sy

  17. 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.

  18. A New Scheme for Considering Soil Water-Heat Transport Coupling Based on Community Land Model: Model Description and Preliminary Validation

    Science.gov (United States)

    Wang, Chenghai; Yang, Kai

    2018-04-01

    Land surface models (LSMs) have developed significantly over the past few decades, with the result that most LSMs can generally reproduce the characteristics of the land surface. However, LSMs fail to reproduce some details of soil water and heat transport during seasonal transition periods because they neglect the effects of interactions between water movement and heat transfer in the soil. Such effects are critical for a complete understanding of water-heat transport within a soil thermohydraulic regime. In this study, a fully coupled water-heat transport scheme (FCS) is incorporated into the Community Land Model (version 4.5) to replaces its original isothermal scheme, which is more complete in theory. Observational data from five sites are used to validate the performance of the FCS. The simulation results at both single-point and global scale show that the FCS improved the simulation of soil moisture and temperature. FCS better reproduced the characteristics of drier and colder surface layers in arid regions by considering the diffusion of soil water vapor, which is a nonnegligible process in soil, especially for soil surface layers, while its effects in cold regions are generally inverse. It also accounted for the sensible heat fluxes caused by liquid water flow, which can contribute to heat transfer in both surface and deep layers. The FCS affects the estimation of surface sensible heat (SH) and latent heat (LH) and provides the details of soil heat and water transportation, which benefits to understand the inner physical process of soil water-heat migration.

  19. Understanding the influence of climate change on the embodied energy of water supply.

    Science.gov (United States)

    Mo, Weiwei; Wang, Haiying; Jacobs, Jennifer M

    2016-05-15

    The current study aims to advance understandings on how and to what degree climate change will affect the life cycle chemical and energy uses of drinking water supply. A dynamic life cycle assessment was performed to quantify historical monthly operational embodied energy of a selected water supply system located in northeast US. Comprehensive multivariate and regression analyses were then performed to understand the statistical correlation among monthly life cycle energy consumptions, three water quality indicators (UV254, pH, and water temperature), and five climate indicators (monthly mean temperature, monthly mean maximum/minimum temperatures, total precipitation, and total snow fall). Thirdly, a calculation was performed to understand how volumetric and total life cycle energy consumptions will change under two selected IPCC emission scenarios (A2 and B1). It was found that volumetric life cycle energy consumptions are highest in winter months mainly due to the higher uses of natural gas in the case study system, but total monthly life cycle energy consumptions peak in both July and January because of the increasing water demand in summer months. Most of the variations in chemical and energy uses can be interpreted by water quality and climate variations except for the use of soda ash. It was also found that climate change might lead to an average decrease of 3-6% in the volumetric energy use of the case study system by the end of the century. This result combined with conclusions reached by previous climate versus water supply studies indicates that effects of climate change on drinking water supply might be highly dependent on the geographical location and treatment process of individual water supply systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. 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 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...... 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....

  1. 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

  2. Modeling the Influence of Variable Tributary Inflow on Circulation and Contaminant Transport in a Water Supply Reservoir

    Science.gov (United States)

    Nguyen, L. H.; Wildman, R.

    2012-12-01

    This study characterizes quantitatively the flow and mixing regimes of a water supply reservoir, while also conducting numerical tracer experiments on different operation scenarios. We investigate the effects of weather events on water quality via storm water inflows. Our study site the Kensico Reservoir, New York, the penultimate reservoir of New York City's water supply, is never filtered and thus dependent on stringent watershed protection. This reservoir must meet federal drinking water standards under changing conditions such as increased suburban, commercial, and highway developments that are much higher than the rest of the watershed. Impacts from these sources on water quality are magnified by minor tributary flows subject to contaminants from development projects as other tributaries providing >99% of water to this reservoir are exceedingly clean due to management practices upstream. These threats, coupled with possible changes in the frequency/intensity of weather events due to climate change, increase the potential for contaminants to enter the reservoir and drinking water intakes. This situation provides us with the unique ability to study the effects of weather events on water quality via insignificant storm water inflows, without influence from the major tributaries due to their pristine water quality characteristics. The concentration of contaminants at the drinking water intake depends partially on transport from their point of entry in the reservoir. Thus, it is crucial to understand water circulation in this reservoir and to estimate residence times and water ages at different locations and under different hydrologic scenarios. We described water age, residence time, thermal structure, and flow dynamics of tributary plumes in Kensico Reservoir during a 22-year simulation period using a two-dimensional hydrodynamic and water quality model (CE-QUAL-W2). Our estimates of water age can reach a maximum of ~300 days in deep-reservoir-cells, with

  3. Comparative sodium transport patterns provide clues for understanding salinity and metal responses in aquatic insects.

    Science.gov (United States)

    Scheibener, S A; Richardi, V S; Buchwalter, D B

    2016-02-01

    The importance of insects in freshwater ecosystems has led to their extensive use in ecological monitoring programs. As freshwater systems are increasingly challenged by salinization and metal contamination, it is important to understand fundamental aspects of aquatic insect physiology (e.g., osmoregulatory processes) that contribute to insect responses to these stressors. Here we compared the uptake dynamics of Na as NaCl, NaHCO3 and Na2SO4 in the caddisfly Hydropsyche betteni across a range of Na concentrations (0.06-15.22 mM) encompassing the vast majority of North American freshwater ecosystems. Sulfate as the major anion resulted in decreased Na uptake rates relative to the chloride and bicarbonate salts. A comparison of Na (as NaHCO3) turnover rates in the caddisfly Hydropsyche sparna and the mayfly Maccaffertium sp. revealed different patterns in the 2 species. Both species appeared to tightly regulate their whole body sodium concentrations (at ∼47±1.8 μmol/g wet wt) across a range of Na concentrations (0.06-15.22 mM) over 7 days. However, at the highest Na concentration (15.22 mM), Na uptake rates in H. sparna (419.1 μM Na g(-1) hr(-1) wet wt) appeared close to saturation while Na uptake rates in Maccaffertium sp. were considerably faster (715 g μM Na g(-1) hr(-1) wet wt) and appeared to not be close to saturation. Na efflux studies in H. sparna revealed that loss rates are commensurate with uptake rates and are responsive to changes in water Na concentrations. A comparison of Na uptake rates (at 0.57 mM Na) across 9 species representing 4 major orders (Ephemeroptera, Plecoptera, Trichoptera and Diptera) demonstrated profound physiological differences across species after accounting for the influence of body weight. Faster Na uptake rates were associated with species described as being sensitive to salinization in field studies. The metals silver (Ag) and copper (Cu), known to be antagonistic to Na uptake in other aquatic taxa did not generally

  4. A framework for understanding risk perception, explored from the perspective of the water practitioner.

    Science.gov (United States)

    Dobbie, Meredith Frances; Brown, Rebekah Ruth

    2014-02-01

    Sustainable urban water systems are likely to be hybrids of centralized and decentralized infrastructure, managed as an integrated system in water-sensitive cities. The technology for many of these systems is available. However, social and institutional barriers, which can be understood as deeply embedded risk perceptions, have impeded their implementation. Risk perceptions within the water sector are often unrecognized or unacknowledged, despite their role in risk management generally in informing value judgments and specifically in ranking risks to achieve management objectives. There has been very little examination of the role of these risk perceptions in advancing more sustainable water supply management through the adoption of alternative sources. To address this gap, this article presents a framework that can be used as a tool for understanding risk perceptions. The framework is built on the relational theory of risk and presents the range of human phenomena that might influence the perception of an "object at risk" in relation to a "risk object." It has been synthesized from a critical review of theoretical, conceptual, and empirical studies of perception broadly and risk perception specifically, and interpreted in relation to water practitioners. For a water practitioner, the risk object might be an alternative water system, a component, a process, or a technology, and the object at risk could be public or environmental health, profitability, or professional reputation. This framework has two important functions: to allow practitioners to understand their own and others' risk perceptions, which might differ, and to inform further empirical research. © 2013 Society for Risk Analysis.

  5. 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.

  6. 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.

  7. Sandwich-Cultured Hepatocytes for Mechanistic Understanding of Hepatic Disposition of Parent Drugs and Metabolites by Transporter-Enzyme Interplay.

    Science.gov (United States)

    Matsunaga, Norikazu; Fukuchi, Yukina; Imawaka, Haruo; Tamai, Ikumi

    2018-05-01

    Functional interplay between transporters and drug-metabolizing enzymes is currently one of the hottest topics in the field of drug metabolism and pharmacokinetics. Uptake transporter-enzyme interplay is important to determine intrinsic hepatic clearance based on the extended clearance concept. Enzyme and efflux transporter interplay, which includes both sinusoidal (basolateral) and canalicular efflux transporters, determines the fate of metabolites formed in the liver. As sandwich-cultured hepatocytes (SCHs) maintain metabolic activities and form a canalicular network, the whole interplay between uptake and efflux transporters and drug-metabolizing enzymes can be investigated simultaneously. In this article, we review the utility and applicability of SCHs for mechanistic understanding of hepatic disposition of both parent drugs and metabolites. In addition, the utility of SCHs for mimicking species-specific disposition of parent drugs and metabolites in vivo is described. We also review application of SCHs for clinically relevant prediction of drug-drug interactions caused by drugs and metabolites. The usefulness of mathematical modeling of hepatic disposition of parent drugs and metabolites in SCHs is described to allow a quantitative understanding of an event in vitro and to develop a more advanced model to predict in vivo disposition. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

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

    Directory of Open Access Journals (Sweden)

    Gogina Elena Sergeevna

    2012-12-01

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

  9. 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

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

    International Nuclear Information System (INIS)

    Vierke, Lena; Möller, Axel; Klitzke, Sondra

    2014-01-01

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

  11. 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

    Public special events, like sports games, concerts and festivals are well known to create disruptions in transportation systems, often catching the operators by surprise. Although these are usually planned well in advance, their impact is difficult to predict, even when organisers...... 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...... number of public transportation trips to the special event areas, thereby contributing to a more adaptive transportation system. Furthermore, for multiple concurrent event scenarios, the proposed algorithm is able to disaggregate gross trip counts into their most likely components related to specific...

  12. 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...

  13. 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”....

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. Cost Analysis of Water Transport for Climate Change Impact Assessment

    Science.gov (United States)

    Szaleniec, V.; Buytaert, W.

    2012-04-01

    It is expected that climate change will have a strong impact on water resources worldwide. Many studies exist that couple the output of global climate models with hydrological models to assess the impact of climate change on physical water availability. However, the water resources topology of many regions and especially that of cities can be very complex. Changes in physical water availability do therefore not translate easily into impacts on water resources for cities. This is especially the case for cities with a complex water supply topology, for instance because of geographical barriers, strong gradients in precipitation patterns, or competing water uses. In this study we explore the use of cost maps to enable the inclusion of water supply topologies in climate change impact studies. We use the city of Lima as a case study. Lima is the second largest desert city in the world. Although Peru as a whole has no water shortage, extreme gradients exist. Most of the economic activities including the city of Lima are located in the coastal desert. This region is geographically disconnected from the wet Amazon basin because of the Andes mountain range. Hence, water supply is precarious, provided by a complex combination of high mountain ecosystems including wetlands and glaciers, as well as groundwater aquifers depending on recharge from the mountains. We investigate the feasibility and costs of different water abstraction scenarios and the impact of climate change using cost functions for different resources. The option of building inter basins tunnels across the Andes is compared to the costs of desalinating seawater from the Pacific Ocean under different climate change scenarios and population growth scenarios. This approach yields recommendations for the most cost-effective options for the future.

  19. 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...

  20. 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/.

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

    Science.gov (United States)

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

    2015-11-01

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

  2. 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

  3. 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

  4. 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

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

    Indian Academy of Sciences (India)

    trol salt movement from the soil surface through the root zone to the ground water and stream flows. .... found from the slope of early-time plot of q∞ vs. St. 1/2 and q∞ from the ..... nutrients in the soil water increases, it results in greater total ...

  6. An isotopic view of water and nitrate transport through the vadose zone in Oregon's southern Willamette Valley's Groundwater Management Area

    Science.gov (United States)

    Brooks, J. R.; Pearlstein, S.; Hutchins, S.; Faulkner, B. R.; Rugh, W.; Willard, K.; Coulombe, R.; Compton, J.

    2017-12-01

    Groundwater nitrate contamination affects thousands of households in Oregon's southern Willamette Valley and many more across the USA. The southern Willamette Valley Groundwater Management Area (GWMA) was established in 2004 due to nitrate levels in the groundwater exceeding the human health standard of 10 mg nitrate-N L-1. Much of the nitrogen (N) inputs to the GWMA comes from agricultural fertilizers, and thus efforts to reduce N inputs to groundwater are focused upon improving N management. However, the effectiveness of these improvements on groundwater quality is unclear because of the complexity of nutrient transport through the vadose zone and long groundwater residence times. Our objective was to focus on vadose zone transport and understand the dynamics and timing of N and water movement below the rooting zone in relation to N management and water inputs. Stable isotopes are a powerful tool for tracking water movement, and understanding N transformations. In partnership with local farmers and state agencies, we established lysimeters and groundwater wells in multiple agricultural fields in the GWMA, and have monitored nitrate, nitrate isotopes, and water isotopes weekly for multiple years. Our results indicate that vadose zone transport is highly complex, and the residence time of water collected in lysimeters was much longer than expected. While input precipitation water isotopes were highly variable over time, lysimeter water isotopes were surprisingly consistent, more closely resembling long-term precipitation isotope means rather than recent precipitation isotopic signatures. However, some particularly large precipitation events with unique isotopic signatures revealed high spatial variability in transport, with some lysimeters showing greater proportions of recent precipitation inputs than others. In one installation where we have groundwater wells and lysimeters at multiple depths, nitrate/nitrite concentrations decreased with depth. N concentrations

  7. 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).

  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. UTMTOX, Toxic Chemical Transport in Atmosphere, Ground Water, Sediments

    International Nuclear Information System (INIS)

    1988-01-01

    A - Description of program or function: UTMTOX is a unified transport model for toxic materials. It combines hydrologic, atmospheric, and sediment transport in one computer code and extends the scope to predict the transport of not only trace metals but also many chemical compounds, including organics. UTMTOX is capable of calculating 1) the atmospheric dispersion of up to 20 chemicals from a maximum of 10 point, 10 line, and 10 area sources; 2) deposition of one chemical at a time in both wet and dry form on foliage or the surface of the earth; 3) surface flow and erosion; 4) percolation through the soil to a stream channel; and 5) flow in the stream channel to the outfall of a watershed. B - Method of solution: UTMTOX calculates rates of flux of chemicals from release to the atmosphere, through deposition on a watershed, infiltration, and runoff from the soil to flow in the stream channel and the associated sediment transport. From these values, mass balances can be established, budgets for the chemical can be made, and concentrations in many environmental compartments can be estimated. Since the coupling is established among three major submodels, they can share data

  10. A Bayesian additive model for understanding public transport usage in special events.

    Science.gov (United States)

    Rodrigues, Filipe; Borysov, Stanislav; Ribeiro, Bernardete; Pereira, Francisco

    2016-12-02

    Public special events, like sports games, concerts and festivals are well known to create disruptions in transportation systems, often catching the operators by surprise. Although these are usually planned well in advance, their impact is difficult to predict, even when organisers and transportation operators coordinate. The problem highly increases when several events happen concurrently. To solve these problems, costly processes, heavily reliant on manual search and personal experience, are usual practice in large cities like Singapore, London or Tokyo. This paper presents a Bayesian 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 number of public transportation trips to the special event areas, thereby contributing to a more adaptive transportation system. Furthermore, for multiple concurrent event scenarios, the proposed algorithm is able to disaggregate gross trip counts into their most likely components related to specific events and routine behavior. Using real data from Singapore, we show that the presented model outperforms the best baseline model by up to 26% in R2 and also has explanatory power for its individual components.

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

    Science.gov (United States)

    Sirghi, Lucel

    2012-02-07

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

  12. The Qualities Needed for a Successful Collaboration: A Contribution to the Conceptual Understanding of Collaboration for Efficient Public Transport

    Directory of Open Access Journals (Sweden)

    Robert Hrelja

    2016-06-01

    Full Text Available The creation of an efficient public transport system requires collaborations between formal independent organizations. This paper examines collaborations between public and private organizations and passengers, with the aim of contributing to the conceptual understanding of collaborations on public transport. The study begins by describing previous research on collaboration in the public transport area and in other research fields analytically relevant for public transport. Accordingly, collaboration is defined as an attempt to overcome problems with collective action and to transform a situation in which the various organizations operate independently into a situation where they act in concert to achieve shared objectives. The collaboration process involves the establishment of joint rules and structures that govern the relationship and behavior of the organizations. According to this definition, collaboration is a more sophisticated form of collective action than is indicated by terms such as “co-operation” or “coordination”. Fully-functioning collaboration can be described as a form of “co-action”, as opposed to “individual action”. In co-action, formal independent organizations together reap the benefits of working together and achieve more than if they had acted alone. Co-action can be regarded as a gradual trust-building process that requires qualities such as mutual confidence, an understanding of other organizations’ motivations, and joint problem formulation.

  13. Radionuclide transport along a boreal hill slope - elevated soil water concentrations in riparian forest soils

    Energy Technology Data Exchange (ETDEWEB)

    Lidman, Fredrik; Boily, Aasa; Laudon, Hjalmar [Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeaa (Sweden); Koehler, Stephan J. [Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. 7050, 750 07 Uppsala (Sweden)

    2014-07-01

    The transport of radionuclides from forest ecosystems and out into surface waters is a crucial process for understanding the long-term fate of radionuclides in the boreal landscape. Boreal forests are typically dominated by podzol soils, but the streams draining the forests are often lined by highly organic, often peat-like soils, which the radionuclides must pass through in order to reach the stream. This so-called riparian zone therefore represents a fundamentally different biogeochemical environment than ordinary forest soils, e.g. by exhibiting significantly lower pH and higher concentrations of organic colloids, which significantly can affect the mobility of many radionuclides. Since the riparian zone is the last terrestrial environment that the groundwater is in contact with before it enters the stream, previous research has demonstrated its profound impact on the stream water chemistry. Hence, the riparian soils should also be important for the transport and accumulation of radionuclides. Therefore, soil water was sampled using suction lysimeters installed at different depths along a 22 m long forested hill slope transect in northern Sweden, following the flow pathway of the groundwater from the uphill podzol to the riparian zone near the stream channel. The analyses included a wide range of hydrochemical parameters and many radiologically important elements, e.g. U, Th, Ni, C, Sr, Cs, REEs and Cl. The sampling was repeated ten times throughout a year in order to also capture the temporal variability of the soil water chemistry. The water chemistry of the investigated transect displayed a remarkable change as the groundwater approached the stream channel. Strongly increased concentrations of many elements were observed in the riparian soils. For instance, the concentrations of Th were more than 100 times higher than in the riparian zone than in the uphill forest, suggesting that the riparian zone may be a hotspot for radionuclide accumulation. The reason

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-31

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

  15. Water transport and desalination through double-layer graphyne membranes.

    Science.gov (United States)

    Akhavan, Mojdeh; Schofield, Jeremy; Jalili, Seifollah

    2018-05-16

    Non-equilibrium molecular dynamics simulations of water-salt solutions driven through single and double-layer graphyne membranes by a pressure difference created by rigid pistons are carried out to determine the relative performance of the membranes as filters in a reverse osmosis desalination process. It is found that the flow rate of water through a graphyne-4 membrane is twice that of a graphyne-3 membrane for both single and double-layer membranes. Although the addition of a second layer to a single-layer membrane reduces the membrane permeability, the double-layer graphyne membranes are still two or three orders of magnitude more permeable than commercial reverse osmosis membranes. The minimum reduction in flow rate for double-layer membranes occurs at a layer spacing of 0.35 nm with an AA stacking configuration, while at a spacing of 0.6 nm the flow rate is close to zero due to a high free energy barrier for permeation. This is caused by the difference in the environments on either side of the membrane sheets and the formation of a compact two-dimensional layer of water molecules in the interlayer space which slows down water permeation. The distribution of residence times of water molecules in the interlayer region suggests that at the critical layer spacing of 0.6 nm, a cross-over occurs in the mechanism of water flow from the collective movement of hydrogen-bonded water sheets to the permeation of individual water molecules. All membranes are demonstrated to have a high salt rejection fraction and the double-layered graphyne-4 membranes can further increase the salt rejection by trapping ions that have passed through the first membrane from the feed solution in the interlayer space.

  16. 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)

  17. 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)

  18. Water flow and solute transport through fractured rock

    International Nuclear Information System (INIS)

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

    1991-01-01

    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 depths have been individually measured. These data have been used: - to determine the dimensions of statistically representative volumes of the sheetwork of fractures; - to predict; using discrete flowpath 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 proved the modelling and validated the code to factor of two accuracy, 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. 7 figs., 9 refs

  19. 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

  20. 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.

  1. Understanding parents' concerns about their children with autism taking public school transportation in Los Angeles County.

    Science.gov (United States)

    Angell, Amber M; Solomon, Olga

    2018-05-01

    There are a number of recent US news media reports of children and youth with autism becoming lost, injured, or even dying while taking public school transportation, yet research on this problem is scarce. This ethnographic study examines the experiences of 14 parents whose children with autism take public school transportation in Los Angeles County. We present two case studies of children with autism being "lost" while in transit from school to home on the bus to (1) describe how the situation was experienced, responded to, and managed by the parents; (2) consider three interrelated themes that emerged from interviews with 14 parents, related to children's safety, independence, and participation, across multiple contexts and analytic levels; and (3) discuss the findings in relation to US news media reports of incidents involving children with autism on school buses to identify specific weaknesses in school transportation infrastructure, particularly in the context of privatization, that create conditions in which children with autism can "fall through the cracks" in potentially life-threatening ways. We argue that there is a critical need to address transportation accessibility for individuals on the autism spectrum to ensure their safety and support their independence and community participation.

  2. Hierarchical Theoretical Methods for Understanding and Predicting Anisotropic Thermal Transport Release in Rocket Propellant Formulations

    Science.gov (United States)

    2016-12-08

    University of Illinois at Urbana-Champaign Michael Ortiz, Frank and Ora Lee Marble Professor of Aeronautics and Mechanical Engineering, California...combustion • Formalism and constitutive theory used to describe reactants and their products that reflect the underlying material mechanics and physical...carried out for energetic materials to predict thermo- mechanical and transport properties, phase diagrams, and interfacial structure. Mesoscopic models

  3. Understanding the Contribution of Zinc Transporters in the Function of the Early Secretory Pathway.

    Science.gov (United States)

    Kambe, Taiho; Matsunaga, Mayu; Takeda, Taka-Aki

    2017-10-19

    More than one-third of newly synthesized proteins are targeted to the early secretory pathway, which is comprised of the endoplasmic reticulum (ER), Golgi apparatus, and other intermediate compartments. The early secretory pathway plays a key role in controlling the folding, assembly, maturation, modification, trafficking, and degradation of such proteins. A considerable proportion of the secretome requires zinc as an essential factor for its structural and catalytic functions, and recent findings reveal that zinc plays a pivotal role in the function of the early secretory pathway. Hence, a disruption of zinc homeostasis and metabolism involving the early secretory pathway will lead to pathway dysregulation, resulting in various defects, including an exacerbation of homeostatic ER stress. The accumulated evidence indicates that specific members of the family of Zn transporters (ZNTs) and Zrt- and Irt-like proteins (ZIPs), which operate in the early secretory pathway, play indispensable roles in maintaining zinc homeostasis by regulating the influx and efflux of zinc. In this review, the biological functions of these transporters are discussed, focusing on recent aspects of their roles. In particular, we discuss in depth how specific ZNT transporters are employed in the activation of zinc-requiring ectoenzymes. The means by which early secretory pathway functions are controlled by zinc, mediated by specific ZNT and ZIP transporters, are also subjects of this review.

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

    International Nuclear Information System (INIS)

    Tucci, P.

    2001-01-01

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

  5. 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!

  6. 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.

  7. 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

  8. 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

  9. 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...

  10. 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

  11. 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

  12. 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.

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

    DEFF Research Database (Denmark)

    Walther, Jens Honore; Koumoutsakos, Petros

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

  14. 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

  15. 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

  16. Forms of trace arsenic, cesium, cadmium, and lead transported into river water for the irrigation of Japanese paddy rice fields

    Science.gov (United States)

    Nakaya, Shinji; Chi, Hai; Muroda, Kengo; Masuda, Harue

    2018-06-01

    In this study, we focus on the behavior of geogenic, toxic trace elements, particularly As, Cs, Cd, and Pb, during their transportation in two rivers for irrigation commonly used in monsoon Asia; one river originates from an active volcano, Mt. Asama, and the other originates from a currently inactive volcano, Yatsugatake Mountains in Nagano, Japan. These rivers were investigated to understand the role of river water as a pollutant of rice and other aquatic plants (via irrigation) and aquatic animals. The results indicated that the behavior of toxic trace elements in river water are likely controlled by their interactions with particulate Fe, Al, and Ti compounds. The majority of Pb and Cd is transported as particulate matter with Fe, Al, and Ti, while the majority of As is transported in the dissolved form, predominantly as arsenate, with low abundance of particulate matter. Cs is transported either as the dissolved form or as particulate matter in both rivers. The investigated elements are transported in the rivers as particulate and dissolved forms, and the ratio of these forms is controlled by the pH and presence of particulate Fe, Al, and Ti phases in the river water. With respect to Cs in both rivers, the parameter governing the concentration and transportation of Cs, in the bimodal form (i.e., particulate and dissolved forms), through the river possibly shifts from sorption to pH by particulate Fe-Al-Ti, according to the abrupt increase in the concentration of Cs in the river. The chemical attraction of particulate Fe-Al-Ti for Cs is weaker than that for Pb and Cd, indicating that the lower electronegativity of Cs weakens the chemical attraction on a colloid for the competitive sorption with the other trace elements. The different relationships between As and Fe in the river and in the irrigation water and soil water, as well as those in paddy rice, suggested that As in paddy rice is not directly derived from As in the irrigation water from the river under

  17. 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?

  18. MURI: An Integrated Multi-Scale Approach for Understanding Ion Transport in Complex Heterogeneous Organic Materials

    Science.gov (United States)

    2018-01-12

    small membrane samples. Mechanical properties were tested at 30 and 60°C under dry or water saturated gas conditions. Water in the membrane has a...hydroxide conductivity (Figure 3) of the films was measured under a CO2 free environment, using UHP nitrogen gas . We noticed PCMS-PCOE-PCMS-TTMPP gave a...movement of anions is not confined, thus showing a higher degree of freedom for diffusion. This kind of behaviour can tell us about lack of defined

  19. 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.

  20. 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...... for accelerating the identification of effective solutions in specific cities and in specific planning cultures. For Beijing residents, the bicycle is currently a mode of transport for those with limited education and limited financial resources. The young Beijingers are least likely to cycle. This age difference...... is likely to be partly due to a cohort difference and, thus, indicates a growing problem for cycling in Beijing. On the other hand, clear associations with density and other urban form variables indicate that the proximity environment and urban development policies can also affect cycling. The effect...

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

    OpenAIRE

    Sundling, Catherine

    2015-01-01

    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 ...

  2. 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 ...

  3. 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 ...

  4. 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.

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

    Science.gov (United States)

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

    1972-01-01

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

  6. Water transport monitoring in an unsaturated zone – Case study: lysimeter Selniška dobrava (Slovenia

    Directory of Open Access Journals (Sweden)

    Nina Mali

    2002-12-01

    Full Text Available Pollution transport in an aquifer depends on its structure, upper unsaturated zone and lower saturated zone. In order to understand processes in the unsaturated zone, several hydrogeological field measurements must be done. A field laboratory- lysimeter in Selni{kadobrava was installed for the improvement of field measurements, and explanation of the parameters and processes in the unsaturated zone. The problems, which can be solved by means of investigations in a lysimeter, are defined in this paper. Described are also:concept of investigation planning, construction and equipment of the lysimeter, measurements of unsaturated zone parameters and processes, water sampling for physical, chemical and isotope analysis.

  7. Corrosion products, activity transport and deposition in boiling water reactor recirculation systems

    International Nuclear Information System (INIS)

    Alder, H.P.; Buckley, D.; Grauer, R.; Wiedemann, K.H.

    1989-09-01

    The deposition of activated corrosion products in the recirculation loops of Boiling Water Reactors produces increased radiation levels which lead to a corresponding increase in personnel radiation dose during shut down and maintenance. The major part of this dose rate is due to cobalt-60. The following areas are discussed in detail: - the origins of the corrosion products and of cobalt-59 in the reactor feedwaters, - the consolidation of the cobalt in the fuel pin deposits (activation), - the release and transport of cobalt-60, - the build-up of cobalt-60 in the corrosion products in the recirculation loops. Existing models of the build-up of circuit radioactivity are discussed and the operating experiences from selected reactors are summarised. Corrosion chemistry aspects of the cobalt build-up in the primary circuit have already been studied on a broad basis and are continuing to be researched in a number of centers. The crystal chemistry of chromium-nickel steel corrosion products poses a number of yet unanswered questions. There are major loopholes associated with the understanding of activation processes of cobalt deposited on the fuel pins and in the mass transfer of cobalt-60. For these processes, the most important influence stems from factors associated with colloid chemistry. Accumulation of data from different BWRs contributes little to the understanding of the activity build-up. However, there are examples that the problem of activity build-up can be kept under control. Although many details for a quantitative understanding are still missing, the most important correlations are visible. The activity build-up in the BWR recirculation systems cannot be kept low by a single measure. Rather a whole series of measures is necessary, which influences not only cobalt-60 deposition but also plant and operation costs. (author) 26 figs., 13 tabs., 90 refs

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

    Science.gov (United States)

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

    2015-04-01

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

  9. 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.

  10. 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

  11. 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

  12. 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

  13. Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030

    NARCIS (Netherlands)

    Gerbens-Leenes, Winnie; van Lienden, A.R.; Hoekstra, Arjen Ysbert; van der Meer, Theodorus H.

    2012-01-01

    Concerns over energy security and climate change stimulate developments towards renewable energy. Transport is expected to switch from fossil fuel use to the use of fuel mixtures with a larger fraction of biofuels, e.g. bio-ethanol and biodiesel. Growing biomass for biofuels requires water, a scarce

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

    Science.gov (United States)

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

    2017-09-01

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

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

    Science.gov (United States)

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

    2016-04-29

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

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

    Directory of Open Access Journals (Sweden)

    Mohammad Hajigholizadeh

    2018-03-01

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

  17. 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.

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

    Science.gov (United States)

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

    2018-04-01

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

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

    Directory of Open Access Journals (Sweden)

    M. I. García-Ibáñez

    2018-04-01

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

  20. Carbon dioxide and water transport through plant aquaporins.

    Science.gov (United States)

    Groszmann, Michael; Osborn, Hannah L; Evans, John R

    2017-06-01

    Aquaporins are channel proteins that function to increase the permeability of biological membranes. In plants, aquaporins are encoded by multigene families that have undergone substantial diversification in land plants. The plasma membrane intrinsic proteins (PIPs) subfamily of aquaporins is of particular interest given their potential to improve plant water relations and photosynthesis. Flowering plants have between 7 and 28 PIP genes. Their expression varies with tissue and cell type, through development and in response to a variety of factors, contributing to the dynamic and tissue specific control of permeability. There are a growing number of PIPs shown to act as water channels, but those altering membrane permeability to CO 2 are more limited. The structural basis for selective substrate specificities has not yet been resolved, although a few key amino acid positions have been identified. Several regions important for dimerization, gating and trafficking are also known. PIP aquaporins assemble as tetramers and their properties depend on the monomeric composition. PIPs control water flux into and out of veins and stomatal guard cells and also increase membrane permeability to CO 2 in mesophyll and stomatal guard cells. The latter increases the effectiveness of Rubisco and can potentially influence transpiration efficiency. © 2016 John Wiley & Sons Ltd.

  1. 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

  2. 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

  3. Dynamics of the water circulations in the southern South China Sea and its seasonal transports

    DEFF Research Database (Denmark)

    Daryabor, Farshid; Ooi, See Hai Ooi; Samah, Azizan Abu

    2016-01-01

    -analysis data of the Simple Ocean Data Assimilation. It is found that the seasonal water circulations are mainly driven by the monsoonal wind stress and influenced by the water outflow/inflow and associated currents of the entire South China Sea. The intrusion of the strong current along the East Coast......A three-dimensional Regional Ocean Modeling System is used to study the seasonal water circulations and transports of the Southern South China Sea. The simulated seasonal water circulations and estimated transports show consistency with observations, e.g., satellite altimeter data set and re...... of Peninsular Malaysia and the eddies at different depths in all seasons are due to the conservation of the potential vorticity as the depth increases. Results show that the water circulation patterns in the northern part of the East Coast of Peninsular Malaysia are generally dominated by the geostrophic...

  4. 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.

  5. 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

  6. 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

  7. 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.

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

    Science.gov (United States)

    Sundling, Catherine

    2015-01-01

    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. PMID:26593935

  9. 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.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    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. (paper)

  11. 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.

  12. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Crancon, P.; Pili, E. [CEA Bruyeres-le-Chatel, DIF, 91 (France); Charlet, L. [Univ Grenoble 1, Lab Geophys Interne and Tectonophys LGIT OSUG, CNRS, UJF, UMR5559, F-38041 Grenoble 9 (France)

    2010-07-01

    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 {mu}m 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 {sup 238}U initially present in the soil column and {sup 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)

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

    Science.gov (United States)

    Vanclooster, Marnik

    2010-05-01

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

  15. 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

  16. 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.

  17. Water flow and solute transport using environmental isotopes and modeling

    International Nuclear Information System (INIS)

    Hussein, M.F.

    2001-01-01

    The deep unsaturated zone may be a useful hydrological archive in desert environments characterized by scant or sporadic rainfall and slow percolation of rainwater over decades or even centuries. This moisture archive provides a useful way to distinguish the net downward flow of recharge water, whereas the isotopic composition and concentration of the conservative solutes of the preserved moisture could be used to reconstruct the history of recharge under the prevailing deficient water balance. The major advantage of such coupled approach is to obtain independent estimates of groundwater recharge rates which are normally difficult to evaluate using the hydrological methods applied in the temperate zones. The study was conducted in the Shiekh-Zoweid/Raffa area in the northeastern coastal strip of Sinai Peninsula. Bore-holes were dry-drilled in a line perpendicular to the sea shoreline (using an 8-inch diameter hand-operated rotary rig) for the unsaturated sediment collection from successive 0.5m thick layers down to a depth of 20m. Samples were investigated for the moisture contents and the chemical and isotope composition of this moisture was determined. Physical parameters were also assessed including porosity and volumetric moisture content. Chloride mass-balance was used to calculate recharge rates through the unsaturated zone by predicting the position of the 1963-Tritium peak in the unsaturated column. Analysis of moisture, chloride and deuterium profiles showed three principle peaks (along with minor ones) in Karafin site indicating few major recharge events that have taken place during the last few decades. Adjustment of these episodes has also been attempted using two historical major rainfall events (known from nearby meteorological stations). Application of the methodology in water resources management in arid regions is discussed. (author)

  18. Predicting Soil-Air and Soil-Water Transport Properties During Soil Vapor Extraction

    DEFF Research Database (Denmark)

    Poulsen, Tjalfe

    Increased application of in-situ technology for control and removal of volatile organic compounds (VOC) in the subsurface has made the understanding of soil physical properties and their impact upon contaminant transport even more important. Knowledge of contaminant transport is important when...... properties of undisturbed soil from more easily measurable soil properties are developed. The importance of soil properties with respect to contaminant migration during remediation by soil vapor extraction (SVE) in the unsaturated zone was investigated using numerical simulations....

  19. 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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

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

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Zicai Zhu

    2011-12-01

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

  5. 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.

  6. 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...

  7. MURI: An Integrated Multi-Scale Approach for Understanding Ion Transport in Complex Heterogeneous Organic Materials

    Science.gov (United States)

    2017-09-30

    Thomas A. Witten,f Matthew W. Liberatore,a and Andrew M. Herring,a,* a Department of Chemical and Biological Engineering and bDepartment of Chemistry ...2) To fundamentally understand, with combined experimental and computational approaches, the interplay of chemistry , processing, and morphology on...Society, The International Society of Electrochemistry and The American Institute of Chemical Engineers to give oral and poster presentations. In

  8. Analysis of the Sodium Recirculation Theory of Solute Coupled Water Transport in Small Intestine

    DEFF Research Database (Denmark)

    Larsen, E. H.; Sørensen, Jens Nørkær; Sørensen, J. B.

    2002-01-01

    Our previous mathematical model of solute-coupled water transport through the intestinal epithelium is extended for dealing with electrolytes rather than electroneutral solutes. A 3Na+-2K+ pump in the lateral membranes provides the energy-requiring step for driving transjunctional and translateral......, computations predict that the concentration differences between lis and bathing solutions are small for all three ions. Nevertheless, the diffusion fluxes of the ions out of lis significantly exceed their mass transports. It is concluded that isotonic transport requires recirculation of all three ions....... The computed sodium recirculation flux that is required for isotonic transport corresponds to that estimated in experiments on toad small intestine. This result is shown to be robust and independent of whether the apical entrance mechanism for the sodium ion is a channel, a SGLT1 transporter driving inward...

  9. Vertical transport of water in the Martian boundary layer

    Science.gov (United States)

    Zent, Aaron P.; Haberle, R. M.; Houben, Howard C.

    1993-01-01

    We are continuing our examination of the transport of H2O through the martian boundary layer, and we have written a one-dimensional numerical model of the exchange of H2O between the atmosphere and subsurface of Mars through the planetary boundary layer (PBL). Our goal is to explore the mechanisms of H2O exchange, and to elucidate the role played by the regolith in the local H2O budget. The atmospheric model includes effects of Coriolis, pressure gradient, and frictional forces for momentum, as well as radiation, sensible heat flux, and advection for heat. The model differs from Flasar and Goody by use of appropriate Viking-based physical constants and inclusion of the radiative effects of atmospheric dust. We specify the pressure gradient force or compute it from a simple slope model. The subsurface model accounts for conduction of heat and diffusion of H2O through a porous adsorbing medium in response to diurnal forcing. The model is initialized with depth-independent H2O concentrations (2 kg M(exp -3)) in the regolith, and a dry atmosphere. The model terminates when the atmospheric H2O column abundance stabilizes at 0.1 percent per sol.

  10. The incorporation of boron in fissile transport packages for the transport and interim storage of irradiated light water reactor fuels

    International Nuclear Information System (INIS)

    Hunter, I.J.

    1998-01-01

    Boron is widely used in the nuclear industry for capturing neutrons and it is particularly useful in the criticality control of packages for the transport and interim storage of irradiated light water reactor fuels. Such fuels are typically located in an internal frame of stainless steel or aluminium, referred to as a basket, which locates the fuel assemblies in channels. Transnucleaire has designed and supplied more than 100 baskets of varying types during the past 30 years. Boron has been incorporated in many forms. Early designs of baskets used boron in specific zones to contribute to the control of criticality. Later developments in new materials dispersed boron throughout the basket and gave designers more options for the basic forms which make up the channels. New basket concepts have been developed by Transnucleaire to meet the changing market needs for transport and interim storage and boron continues to play an important role as an efficient thermal neutron absorber. (author)

  11. A constricted quantum Hall system as a beam-splitter: understanding ballistic transport on the edge

    International Nuclear Information System (INIS)

    Lal, Siddhartha

    2007-09-01

    We study transport in a model of a quantum Hall edge system with a gate-voltage controlled constriction. A finite backscattered current at finite edge-bias is explained from a Landauer- Buttiker analysis as arising from the splitting of edge current caused by the difference in the filling fractions of the bulk (ν 1 ) and constriction(ν 2 ) quantum Hall fluid regions. We develop a hydrodynamic theory for bosonic edge modes inspired by this model. The constriction region splits the incident long-wavelength chiral edge density-wave excitations among the transmitting and reflecting edge states encircling it. These findings provide satisfactory explanations for several puzzling recent experimental results. These results are confirmed by computing various correlators and chiral linear conductances of the system. In this way, our results find excellent agreement with some of the recent puzzling experimental results for the cases of ν 1 = 1/3, 1. (author)

  12. National, holistic, watershed-scale approach to understand the sources, transport, and fate of agricultural chemicals

    Science.gov (United States)

    Capel, P.D.; McCarthy, K.A.; Barbash, J.E.

    2008-01-01

    This paper is an introduction to the following series of papers that report on in-depth investigations that have been conducted at five agricultural study areas across the United States in order to gain insights into how environmental processes and agricultural practices interact to determine the transport and fate of agricultural chemicals in the environment. These are the first study areas in an ongoing national study. The study areas were selected, based on the combination of cropping patterns and hydrologic setting, as representative of nationally important agricultural settings to form a basis for extrapolation to unstudied areas. The holistic, watershed-scale study design that involves multiple environmental compartments and that employs both field observations and simulation modeling is presented. This paper introduces the overall study design and presents an overview of the hydrology of the five study areas. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  13. 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.

  14. 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.

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

    Science.gov (United States)

    Whittamore, Jonathan M

    2012-01-01

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

  16. Understanding snow-transport processes shaping the mountain snow-cover

    Directory of Open Access Journals (Sweden)

    R. Mott

    2010-12-01

    Full Text Available Mountain snow-cover is normally heterogeneously distributed due to wind and precipitation interacting with the snow cover on various scales. The aim of this study was to investigate snow deposition and wind-induced snow-transport processes on different scales and to analyze some major drift events caused by north-west storms during two consecutive accumulation periods. In particular, we distinguish between the individual processes that cause specific drifts using a physically based model approach. Very high resolution wind fields (5 m were computed with the atmospheric model Advanced Regional Prediction System (ARPS and used as input for a model of snow-surface processes (Alpine3D to calculate saltation, suspension and preferential deposition of precipitation. Several flow features during north-west storms were identified with input from a high-density network of permanent and mobile weather stations and indirect estimations of wind directions from snow-surface structures, such as snow dunes and sastrugis. We also used Terrestrial and Airborne Laser Scanning measurements to investigate snow-deposition patterns and to validate the model. The model results suggest that the in-slope deposition patterns, particularly two huge cross-slope cornice-like drifts, developed only when the prevailing wind direction was northwesterly and were formed mainly due to snow redistribution processes (saltation-driven. In contrast, more homogeneous deposition patterns on a ridge scale were formed during the same periods mainly due to preferential deposition of precipitation. The numerical analysis showed that snow-transport processes were sensitive to the changing topography due to the smoothing effect of the snow cover.

  17. Variations in Upper-Level Water Vapor Transport Diagnosed from Climatological Satellite Data

    Science.gov (United States)

    Lerner, Jeffrey A; Jedlovee, Gary J.; Atkinson, Robert J.

    1998-01-01

    GOES-7 VAS measurements during the Pathfinder period (1987-88) have been analysed to reveal seasonal and interannual variations in moisture transport. Long term measurements of quality winds and humidity from satellite estimates show superior benefit in diagnosing middle and upper tropospheric large scale climate variations such as ENSO events and direct circulation systems such as the Hadley Cell. A water Vapor Transport Index (WVTI) has been developed to diagnose preferred regions of strong moisture transport and to gauge the seasonal and interannual intensities detected in the GOES viewing area. Second-order variables that may be derived from GOES winds will be also discussed on the poster.

  18. 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.

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

    International Nuclear Information System (INIS)

    Svadlenkova, M.

    1988-01-01

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

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

    Science.gov (United States)

    James, P. B.

    1987-01-01

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

  1. 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.

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

    KAUST Repository

    Hussaini, Irfan S.; Wang, Chao-Yang

    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.

  3. 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

  4. Water transport through tall trees: A vertically-explicit, analytical model of xylem hydraulic conductance in stems.

    Science.gov (United States)

    Couvreur, Valentin; Ledder, Glenn; Manzoni, Stefano; Way, Danielle A; Muller, Erik B; Russo, Sabrina E

    2018-05-08

    Trees grow by vertically extending their stems, so accurate stem hydraulic models are fundamental to understanding the hydraulic challenges faced by tall trees. Using a literature survey, we showed that many tree species exhibit continuous vertical variation in hydraulic traits. To examine the effects of this variation on hydraulic function, we developed a spatially-explicit, analytical water transport model for stems. Our model allows Huber ratio, stem-saturated conductivity, pressure at 50% loss of conductivity, leaf area, and transpiration rate to vary continuously along the hydraulic path. Predictions from our model differ from a matric flux potential model parameterized with uniform traits. Analyses show that cavitation is a whole-stem emergent property resulting from nonlinear pressure-conductivity feedbacks that, with gravity, cause impaired water transport to accumulate along the path. Because of the compounding effects of vertical trait variation on hydraulic function, growing proportionally more sapwood and building tapered xylem with height, as well as reducing xylem vulnerability only at branch tips while maintaining transport capacity at the stem base, can compensate for these effects. We therefore conclude that the adaptive significance of vertical variation in stem hydraulic traits is to allow trees to grow tall and tolerate operating near their hydraulic limits. This article is protected by copyright. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

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

  6. 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

  7. Quantification of the Intracellular Life Time of Water Molecules to Measure Transport Rates of Human Aquaglyceroporins.

    Science.gov (United States)

    Palmgren, Madelene; Hernebring, Malin; Eriksson, Stefanie; Elbing, Karin; Geijer, Cecilia; Lasič, Samo; Dahl, Peter; Hansen, Jesper S; Topgaard, Daniel; Lindkvist-Petersson, Karin

    2017-12-01

    Orthodox aquaporins are transmembrane channel proteins that facilitate rapid diffusion of water, while aquaglyceroporins facilitate the diffusion of small uncharged molecules such as glycerol and arsenic trioxide. Aquaglyceroporins play important roles in human physiology, in particular for glycerol metabolism and arsenic detoxification. We have developed a unique system applying the strain of the yeast Pichia pastoris, where the endogenous aquaporins/aquaglyceroporins have been removed and human aquaglyceroporins AQP3, AQP7, and AQP9 are recombinantly expressed enabling comparative permeability measurements between the expressed proteins. Using a newly established Nuclear Magnetic Resonance approach based on measurement of the intracellular life time of water, we propose that human aquaglyceroporins are poor facilitators of water and that the water transport efficiency is similar to that of passive diffusion across native cell membranes. This is distinctly different from glycerol and arsenic trioxide, where high glycerol transport efficiency was recorded.

  8. Modeling the effects of different irrigation water salinity on soil water movement, uptake and multicomponent solute transport

    Science.gov (United States)

    Lekakis, E. H.; Antonopoulos, V. Z.

    2015-11-01

    Simulation models can be important tools for analyzing and managing irrigation, soil salinization or crop production problems. In this study a mathematical model that describes the water movement and mass transport of individual ions (Ca2+, Mg2+ and Na+) and overall soil salinity by means of the soil solution electrical conductivity, is used. The mass transport equations of Ca2+, Mg2+ and Na+ have been incorporated as part of the integrated model WANISIM and the soil salinity was computed as the sum of individual ions. The model was calibrated and validated against field data, collected during a three year experiment in plots of maize, irrigated with three different irrigation water qualities, at Thessaloniki area in Northern Greece. The model was also used to evaluate salinization and sodification hazards by the use of irrigation water with increasing electrical conductivity of 0.8, 3.2 and 6.4 dS m-1, while maintaining a ratio of Ca2+:Mg2+:Na+ equal to 3:3:2. The qualitative and quantitative procedures for results evaluation showed that there was good agreement between the simulated and measured values of the water content, overall salinity and the concentration of individual soluble cations, at two soil layers (0-35 and 35-75 cm). Nutrient uptake was also taken into account. Locally available irrigation water (ECiw = 0.8 dS m-1) did not cause soil salinization or sodification. On the other hand, irrigation water with ECiw equal to 3.2 and 6.4 dS m-1 caused severe soil salinization, but not sodification. The rainfall water during the winter seasons was not sufficient to leach salts below the soil profile of 110 cm. The modified version of model WANISIM is able to predict the effects of irrigation with saline waters on soil and plant growth and it is suitable for irrigation management in areas with scarce and low quality water resources.

  9. X-ray CT-Derived Soil Characteristics Explain Varying Air, Water, and Solute Transport Properties across a Loamy Field

    DEFF Research Database (Denmark)

    Paradelo Pérez, Marcos; Katuwal, Sheela; Møldrup, Per

    2016-01-01

    -derived parameters by using a best subsets regression analysis. The regression coefficients improved using CTmatrix, limiting macroporosity, and genus density, while the best model for t0.05 used CTmatrix only. The scanning resolution and the time for soil structure development after mechanical activities could......The characterization of soil pore space geometry is important for explaining fluxes of air, water, and solutes through soil and understanding soil hydrogeochemical functions. X-ray computed tomography (CT) can be applied for this characterization, and in this study CT-derived parameters were used...... to explain water, air, and solute transport through soil. Forty-five soil columns (20 by 20 cm) were collected from an agricultural field in Estrup, Denmark, and subsequently scanned using a medical CT scanner. Nonreactive tracer leaching experiments were performed in the laboratory along with measurements...

  10. 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

  11. Design and operational parameters of transportable supercritical water oxidation waste destruction unit

    International Nuclear Information System (INIS)

    McFarland, R.D.; Brewer, G.R.; Rofer, C.K.

    1991-12-01

    Supercritical water oxidation (SCWO) is the destruction of hazardous waste by oxidation in the presence of water at temperatures and pressures above its critical point. A 1 gal/h SCWO waste destruction unit (WDU) has been designed, built, and operated at Los Alamos National Laboratory. This unit is transportable and is intended to demonstrate the SCWO technology on wastes at Department of Energy sites. This report describes the design of the WDU and the preliminary testing phase leading to demonstration

  12. Insights into the subsurface transport of As(V) and Se(VI) in produced water from hydraulic fracturing using soil samples from Qingshankou Formation, Songliao Basin, China.

    Science.gov (United States)

    Chen, Season S; Sun, Yuqing; Tsang, Daniel C W; Graham, Nigel J D; Ok, Yong Sik; Feng, Yujie; Li, Xiang-Dong

    2017-04-01

    Produced water is a type of wastewater generated from hydraulic fracturing, which may pose a risk to the environment and humans due to its high ionic strength and the presence of elevated concentrations of metals/metalloids that exceed maximum contamination levels. The mobilization of As(V) and Se(VI) in produced water and selected soils from Qingshankou Formation in the Songliao Basin in China were investigated using column experiments and synthetic produced water whose quality was representative of waters arising at different times after well creation. Temporal effects of produced water on metal/metalloid transport and sorption/desorption were investigated by using HYDRUS-1D transport modelling. Rapid breakthrough and long tailings of As(V) and Se(VI) transport were observed in Day 1 and Day 14 solutions, but were reduced in Day 90 solution probably due to the elevated ionic strength. The influence of produced water on the hydrogeological conditions (i.e., change between equilibrium and non-equilibrium transport) was evidenced by the change of tracer breakthrough curves before and after the leaching of produced water. This possibly resulted from the sorption of polyacrylamide (PAM (-CH 2 CHCONH 2 -) n ) onto soil surfaces, through its use as a friction reducer in fracturing solutions. The sorption was found to be reversible in this study. Minimal amounts of sorbed As(V) were desorbed whereas the majority of sorbed Se(VI) was readily leached out, to an extent which varied with the composition of the produced water. These results showed that the mobilization of As(V) and Se(VI) in soil largely depended on the solution pH and ionic strength. Understanding the differences in metal/metalloid transport in produced water is important for proper risk management. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. 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)

  14. U- and Th-series nuclides in settling particles: implications to sediment transport through surface waters and interior ocean

    International Nuclear Information System (INIS)

    Sarin, M.M.

    2012-01-01

    The Bay of Bengal is a unique ocean basin receiving large quantities of fresh water and sediment supply from several rivers draining the Indian subcontinent. The annual flux of suspended sediments discharged into the Bay of Bengal is one billion tons, about one-tenth of the global sediment discharge into the ocean. The water and sediment discharge to the Bay, show significant seasonal variation, with maximum transport coinciding with the SW-monsoon (July-September). Earlier studies on the distribution of clay minerals in sediments have led to the suggestion that the sediments of the western Bengal Fan are mainly derived from the Peninsular rivers, whereas rest of the Fan sediments is influenced by the Himalayan rivers. Settling fluxes of particulate matter through the water column of the Bay of Bengal show seasonal trends resulting from monsoon enhanced sediment supply via rivers and biological processes in the water column. It is, thus, important to understand the influence of the seasonally varying particle fluxes on the solute-particle interactions and chemical scavenging processes in the surface and deep waters of the Bay of Bengal. In this context, measurements of U- and Th-series nuclides in the settling particles are most relevant. The radionuclide fluxes ( 230 Th, 228 Th and 210 Pb) in the settling particles provide insight into the role of their removal by vertical particle flux and/or lateral transport (removal at the ocean boundaries). A study carried out in the Northern Bay of Bengal documents that the authigenic flux of 230 Th, as measured in sediment trap samples from deep waters, is balanced by its production in the overhead water column. The sediment mass flux, Al and 228 Th fluxes are similar in the settling particles through shallow and deep waters, suggesting predominant removal by vertical particle flux in the North Bay of Bengal. In the Central Bay, particulate mass, Al and 228 Th fluxes are higher in the trap material from deep waters relative

  15. 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.

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

    International Nuclear Information System (INIS)

    Cao, J.; Djilali, N.

    2000-01-01

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

  17. A Novel Approach of Understanding and Incorporating Error of Chemical Transport Models into a Geostatistical Framework

    Science.gov (United States)

    Reyes, J.; Vizuete, W.; Serre, M. L.; Xu, Y.

    2015-12-01

    The EPA employs a vast monitoring network to measure ambient PM2.5 concentrations across the United States with one of its goals being to quantify exposure within the population. However, there are several areas of the country with sparse monitoring spatially and temporally. One means to fill in these monitoring gaps is to use PM2.5 modeled estimates from Chemical Transport Models (CTMs) specifically the Community Multi-scale Air Quality (CMAQ) model. CMAQ is able to provide complete spatial coverage but is subject to systematic and random error due to model uncertainty. Due to the deterministic nature of CMAQ, often these uncertainties are not quantified. Much effort is employed to quantify the efficacy of these models through different metrics of model performance. Currently evaluation is specific to only locations with observed data. Multiyear studies across the United States are challenging because the error and model performance of CMAQ are not uniform over such large space/time domains. Error changes regionally and temporally. Because of the complex mix of species that constitute PM2.5, CMAQ error is also a function of increasing PM2.5 concentration. To address this issue we introduce a model performance evaluation for PM2.5 CMAQ that is regionalized and non-linear. This model performance evaluation leads to error quantification for each CMAQ grid. Areas and time periods of error being better qualified. The regionalized error correction approach is non-linear and is therefore more flexible at characterizing model performance than approaches that rely on linearity assumptions and assume homoscedasticity of CMAQ predictions errors. Corrected CMAQ data are then incorporated into the modern geostatistical framework of Bayesian Maximum Entropy (BME). Through cross validation it is shown that incorporating error-corrected CMAQ data leads to more accurate estimates than just using observed data by themselves.

  18. 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.

  19. Transport and sorption of volatile organic compounds and water vapor in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tsair-Fuh [Univ. of California, Berkeley, CA (United States)

    1995-07-01

    To gain insight on the controlling mechanisms for VOC transport in porous media, the relations among sorbent properties, sorption equilibrium and intraparticle diffusion processes were studied at the level of individual sorbent particles and laboratory columns for soil and activated carbon systems. Transport and sorption of VOCs and water vapor were first elucidated within individual dry soil mineral grains. Soil properties, sorption capacity, and sorption rates were measured for 3 test soils; results suggest that the soil grains are porous, while the sorption isotherms are nonlinear and adsorption-desorption rates are slow and asymmetric. An intragranular pore diffusion model coupled with the nonlinear Freundlich isotherm was developed to describe the sorption kinetic curves. Transport of benzene and water vapor within peat was studied; partitioning and sorption kinetics were determined with an electrobalance. A dual diffusion model was developed. Transport of benzene in dry and moist soil columns was studied, followed by gaseous transport and sorption in activated carbon. The pore diffusion model provides good fits to sorption kinetics for VOCs to soil and VOC to granular activated carbon and activated carbon fibers. Results of this research indicate that: Intraparticle diffusion along with a nonlinea sorption isotherm are responsible for the slow, asymmetric sorption-desorption. Diffusion models are able to describe results for soil and activated carbon systems; when combined with mass transfer equations, they predict column breakthrough curves for several systems. Although the conditions are simplified, the mechanisms should provide insight on complex systems involving transport and sorption of vapors in porous media.

  20. 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.

  1. Simulation of ground-water flow and solute transport in the Glen Canyon aquifer, East-Central Utah

    Science.gov (United States)

    Freethey, Geoffrey W.; Stolp, Bernard J.

    2010-01-01

    The extraction of methane from coal beds in the Ferron coal trend in central Utah started in the mid-1980s. Beginning in 1994, water from the extraction process was pressure injected into the Glen Canyon aquifer. The lateral extent of the aquifer that could be affected by injection is about 7,600 square miles. To address regional-scale effects of injection over a decadal time frame, a conceptual model of ground-water movement and transport of dissolved solids was formulated. A numerical model that incorporates aquifer concepts was then constructed and used to simulate injection.The Glen Canyon aquifer within the study area is conceptualized in two parts—an active area of ground-water flow and solute transport that exists between recharge areas in the San Rafael Swell and Desert, Waterpocket Fold, and Henry Mountains and discharge locations along the Muddy, Dirty Devil, San Rafael, and Green Rivers. An area of little or negligible ground-water flow exists north of Price, Utah, and beneath the Wasatch Plateau. Pressurized injection of coal-bed methane production water occurs in this area where dissolved-solids concentrations can be more than 100,000 milligrams per liter. Injection has the potential to increase hydrologic interaction with the active flow area, where dissolved-solids concentrations are generally less than 3,000 milligrams per liter.Pressurized injection of coal-bed methane production water in 1994 initiated a net addition of flow and mass of solutes into the Glen Canyon aquifer. To better understand the regional scale hydrologic interaction between the two areas of the Glen Canyon aquifer, pressurized injection was numerically simulated. Data constraints precluded development of a fully calibrated simulation; instead, an uncalibrated model was constructed that is a plausible representation of the conceptual flow and solute-transport processes. The amount of injected water over the 36-year simulation period is about 25,000 acre-feet. As a result

  2. Understanding linkages between global climate indices and terrestrial water storage changes over Africa using GRACE products.

    Science.gov (United States)

    Anyah, R O; Forootan, E; Awange, J L; Khaki, M

    2018-09-01

    Africa, a continent endowed with huge water resources that sustain its agricultural activities is increasingly coming under threat from impacts of climate extremes (droughts and floods), which puts the very precious water resource into jeopardy. Understanding the relationship between climate variability and water storage over the continent, therefore, is paramount in order to inform future water management strategies. This study employs Gravity Recovery And Climate Experiment (GRACE) satellite data and the higher order (fourth order cumulant) statistical independent component analysis (ICA) method to study the relationship between terrestrial water storage (TWS) changes and five global climate-teleconnection indices; El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Madden-Julian Oscillation (MJO), Quasi-Biennial Oscillation (QBO) and the Indian Ocean Dipole (IOD) over Africa for the period 2003-2014. Pearson correlation analysis is applied to extract the connections between these climate indices (CIs) and TWS, from which some known strong CI-rainfall relationships (e.g., over equatorial eastern Africa) are found. Results indicate unique linear-relationships and regions that exhibit strong linkages between CIs and TWS. Moreover, unique regions having strong CI-TWS connections that are completely different from the typical ENSO-rainfall connections over eastern and southern Africa are also identified. Furthermore, the results indicate that the first dominant independent components (IC) of the CIs are linked to NAO, and are characterized by significant reductions of TWS over southern Africa. The second dominant ICs are associated with IOD and are characterized by significant increases in TWS over equatorial eastern Africa, while the combined ENSO and MJO are apparently linked to the third ICs, which are also associated with significant increase in TWS changes over both southern Africa, as well as equatorial eastern Africa. Copyright © 2018

  3. Global change and modern coral reefs: New opportunities to understand shallow-water carbonate depositional processes

    Science.gov (United States)

    Hallock, Pamela

    2005-04-01

    Human activities are impacting coral reefs physically, biologically, and chemically. Nutrification, sedimentation, chemical pollution, and overfishing are significant local threats that are occurring worldwide. Ozone depletion and global warming are triggering mass coral-bleaching events; corals under temperature stress lose the ability to synthesize protective sunscreens and become more sensitive to sunlight. Photo-oxidative stress also reduces fitness, rendering reef-building organisms more susceptible to emerging diseases. Increasing concentration of atmospheric CO 2 has already reduced CaCO 3 saturation in surface waters by more than 10%. Doubling of atmospheric CO 2 concentration over pre-industrial concentration in the 21st century may reduce carbonate production in tropical shallow marine environments by as much as 80%. As shallow-water reefs decline worldwide, opportunities abound for researchers to expand understanding of carbonate depositional systems. Coordinated studies of carbonate geochemistry with photozoan physiology and calcification, particularly in cool subtropical-transition zones between photozoan-reef and heterotrophic carbonate-ramp communities, will contribute to understanding of carbonate sedimentation under environmental change, both in the future and in the geologic record. Cyanobacteria are becoming increasingly prominent on declining reefs, as these microbes can tolerate strong solar radiation, higher temperatures, and abundant nutrients. The responses of reef-dwelling cyanobacteria to environmental parameters associated with global change are prime topics for further research, with both ecological and geological implications.

  4. 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

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

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  6. Anthropogenic contamination of a phreatic drinking water winning: 3-dimensional reactive transport modelling

    NARCIS (Netherlands)

    Griffioen, J.|info:eu-repo/dai/nl/091129265; van der Grift, B.|info:eu-repo/dai/nl/373433484; Maas, D.; van den Brink, C.|info:eu-repo/dai/nl/187443416; Zaadnoordijk, J. W.

    2003-01-01

    Groundwater is contaminated at the regional scale by agricultural activities and atmospheric deposition. A 3-D transport model was set-up for a phreatic drinking water winning, where the groundwater composition was monitored accurately. The winning is situated at an area with unconsolidated

  7. 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...

  8. Transport of Escherichia Coli and solutes during waste water infiltration in an urban alluvial aquifer

    NARCIS (Netherlands)

    Foppen, J.W.A.; van Herwerden, M.; Kebtie, M.; Noman, A.; Schrijven, J.F.; Stuijfzand, P.J.; Uhlenbrook, S.

    2008-01-01

    Recharge of waste water in an unconsolidated poorly sorted alluvial aquifer is a complex process, both physically and hydrochemically. The aim of this paper is to analyse and conceptualise vertical transport mechanisms taking place in an urban area of extensive wastewater infiltration by analysing

  9. 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

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  11. Air and Water Transportation Occupations. Reprinted from the Occupational Outlook Handbook, 1978-79 Edition.

    Science.gov (United States)

    Bureau of Labor Statistics (DOL), Washington, DC.

    Focusing on air and water transportation occupations, this document is one in a series of forty-one reprints from the Occupational Outlook Handbook providing current information and employment projections for individual occupations and industries through 1985. The specific occupations covered in this document include civil aviation workers, air…

  12. Changes in urinary excretion of water and sodium transporters during amiloride and bendroflumethiazide treatment

    DEFF Research Database (Denmark)

    Jensen, Janni M; Mose, Frank H; Kulik, Anna-Ewa O

    2015-01-01

    AIM: To quantify changes in urinary excretion of aquaporin2 water channels (u-AQP2), the sodium-potassium-chloride co-transporter (u-NKCC2) and the epithelial sodium channels (u-ENaC) during treatment with bendroflumethiazide (BFTZ), amiloride and placebo. METHODS: In a randomized, double....... General linear model with repeated measures or related samples Friedman's two-way analysis was used to compare differences. Post hoc Bonferroni correction was used for multiple comparisons of post infusion periods to baseline within each treatment group. RESULTS: At baseline there were no differences in u...... by the constant infusion clearance technique with (51)Cr-EDTA as reference substance. To estimate the changes in water transport via AQP2 and sodium transport via NKCC2 and ENaC, u-NKCC2, the gamma fraction of ENaC (u-ENaCγ), and u-AQP2 were measured at baseline and after infusion with 3% hypertonic saline. U...

  13. Redesigning transport equipment – comparative analysis of energy expenditure (power and water in refrigerators

    Directory of Open Access Journals (Sweden)

    Lisiane Ilha Librelotto

    2015-12-01

    Full Text Available Sustainability is defined as an approach that integrates social, economic and environmental concerns (SEE. This philosophy carries several implications for daily factory work, where culturally, the economic issue is considered most important. This paper provides a case study at a meat and bone-meal (MBM factory, and the preliminary studies of the adaptation of this factory to the SEE philosophy, focusing initially on economic aspect, and its relationship with the two other aspects. It also shows how the design of a conveyor belt - used to transport entrails and feathers from the slaughter site to the byproducts production site - could improve the consumption of power and water resources at the factory studied. Currently, this transport is accomplished manually (for feathers and by pneumatic conveying (for entrails. As a result, it was found that a change in the transport processes to align with the SEE philosophy would allow an 18% reduction of water use.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  15. 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.

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

    Science.gov (United States)

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

    2016-01-01

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

  17. 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.

  18. Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips - Part 1: nonuniform infiltration and soil water redistribution

    OpenAIRE

    Munoz Carpena, R.; Lauvernet, C.; Carluer, N.

    2018-01-01

    Vegetation buffers like vegetative filter strips (VFSs) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in floodplains often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and increase surface pollutant transport during a rainfall-runoff event. Simple and robust components of hydrological models are needed to analyze the impacts of WT in the landscape. To si...

  19. A suggested revision to the specific activity limit for tritiated water transported as LSA-II

    International Nuclear Information System (INIS)

    Nandakumar, A.N.

    2003-01-01

    Tritiated water of specific activity not greater than 0.8 TBq L -1 is classified as LSA-II. This paper demonstrates by some simple calculations that the dose that may result from an accident involving tritiated water of this specific activity is very low and suggests that even if the specific activity limit of tritiated water which may be transported as LSA-II is raised above 0.8 TBq kg -1 , the resulting dose in accident conditions would not be unacceptable. (author)

  20. Understanding the fate and transport of petroleum hydrocarbons from coal tar within gasholders.

    Science.gov (United States)

    Coulon, Frédéric; Orsi, Roberto; Turner, Claire; Walton, Chris; Daly, Paddy; Pollard, Simon J T

    2009-02-01

    Coal tars have been identified as posing a threat to human health due to their toxic, mutagenic and carcinogenic characteristics. Workers involved in former gasholders decommissioning are potentially exposed to relevant concentrations of volatile and semi-volatile hydrocarbons upon opening up derelict tanks and during tar excavation/removal. While information on contaminated sites air-quality and its implications on medium-long term exposure is available, acute exposure issues associated with the execution of critical tasks are less understood. Calculations indicated that the concentration of a given contaminant in the gasholder vapour phase only depends on the coal tar composition, being only barely affected by the presence of water in the gasholder and the tar volume/void space ratio. Fugacity modelling suggested that risk-critical compounds such as benzene, naphthalene and other monocyclic and polycyclic aromatic hydrocarbons may gather in the gasholder air phase at significant concentrations. Gasholder emissions were measured on-site and compared with the workplace exposure limits (WELs) currently in use in UK. While levels for most of the toxic compounds were far lower than WELs, benzene air-concentrations where found to be above the accepted threshold. In addition due to the long exposure periods involved in gasholder decommissioning and the significant contribution given by naphthalene to the total coal tar vapour concentration, the adoption of a WEL for naphthalene may need to be considered to support operators in preventing human health risk at the workplace. The Level I fugacity approach used in this study demonstrated its suitability for applications to sealed environments such as gasholders and its further refining could provide a useful tool for land remediation risk assessors.

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

    Science.gov (United States)

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

    2017-01-01

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

  2. 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

  3. Understanding and predicting climate variations in the Middle East for sustainable water resource management and development

    Science.gov (United States)

    Samuels, Rana

    Water issues are a source of tension between Israelis and Palestinians. In the and region of the Middle East, water supply is not just scarce but also uncertain: It is not uncommon for annual rainfall to be as little as 60% or as much as 125% of the multiannual average. This combination of scarcity and uncertainty exacerbates the already strained economy and the already tensed political situation. The uncertainty could be alleviated if it were possible to better forecast water availability. Such forecasting is key not only for water planning and management, but also for economic policy and for political decision making. Water forecasts at multiple time scales are necessary for crop choice, aquifer operation and investments in desalination infrastructure. The unequivocal warming of the climate system adds another level of uncertainty as global and regional water cycles change. This makes the prediction of water availability an even greater challenge. Understanding the impact of climate change on precipitation can provide the information necessary for appropriate risk assessment and water planning. Unfortunately, current global circulation models (GCMs) are only able to predict long term climatic evolution at large scales but not local rainfall. The statistics of local precipitation are traditionally predicted using historical rainfall data. Obviously these data cannot anticipate changes that result from climate change. It is therefore clear that integration of the global information about climate evolution and local historical data is needed to provide the much needed predictions of regional water availability. Currently, there is no theoretical or computational framework that enables such integration for this region. In this dissertation both a conceptual framework and a computational platform for such integration are introduced. In particular, suite of models that link forecasts of climatic evolution under different CO2 emissions scenarios to observed rainfall

  4. 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)

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

    DEFF Research Database (Denmark)

    Rieckh, Helene; Gerke, Horst; Glæsner, Nadia

    2014-01-01

    In the hummocky ground moraine soil landscape, a spatial continuum of more or less eroded soils developed from till under intensive agricultural cultivation. Water flow and solute transport are affected by the variable soil structural and pedological developments, which are posing a challenge...... for flux estimation. The objective of this study was to investigate transport of water, dissolved organic (DOC), and particulate carbon (PC) through soil profiles of an eroded Haplic Luvisol and a heavily eroded Haplic Regosol. We studied 5 soil horizons in three replicates each: Ap (0-20 cm) and E (20...... boundary. Breakthrough curves for a pre-applied tracer (Br-) on the soil surface and a tracer applied with irrigation water (3H2O) were modeled analytically using CXTFIT. The heterogeneity of the Luvisol horizons was generally higher than that of the Regosol horizons, which relates to the higher...

  6. Rapid Water Transport by Long-Lasting Modon Eddy Pairs in the Southern Midlatitude Oceans

    Science.gov (United States)

    Hughes, Chris W.; Miller, Peter I.

    2017-12-01

    Water in the ocean is generally carried with the mean flow, mixed by eddies, or transported westward by coherent eddies at speeds close to the long baroclinic Rossby wave speed. Modons (dipole eddy pairs) are a theoretically predicted exception to this behavior, which can carry water to the east or west at speeds much larger than the Rossby wave speed, leading to unusual transports of heat, nutrients, and carbon. We provide the first observational evidence of such rapidly moving modons propagating over large distances. These modons are found in the midlatitude oceans around Australia, with one also seen in the South Atlantic west of the Agulhas region. They can travel at more than 10 times the Rossby wave speed of 1-2 cm s-1 and typically persist for about 6 months carrying their unusual water mass properties with them, before splitting into individual vortices, which can persist for many months longer.

  7. 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

  8. 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

  9. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Marttila, H.

    2010-07-01

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

  11. On the need for system alignment in large water infrastructure. Understanding infrastructure dynamics in Nairobi, Kenya

    Directory of Open Access Journals (Sweden)

    Pär Blomkvist

    2017-06-01

    Full Text Available In this article we contribute to the discussion of infrastructural change in Africa, and explore how a new theoretical perspective may offer a different, more comprehensive and historically informed understanding of the trend towards large water infrastructure in Africa. We examine the socio-technical dynamics of large water infrastructures in Nairobi, Kenya, in a longer historical perspective using two concepts that we call intra-systemic alignment and inter-level alignment. Our theoretical perspective is inspired by Large Technical Systems (LTS and Multi-Level Perspective (MLP. While inter-level alignment focuses on the process of aligning the technological system at the three levels of niche, regime and landscape, intra-systemic alignment deals with how components within the regime are harmonised and standardised to fit with each other. We pay special attention to intrasystemic alignment between the supply side and the demand side, or as we put it, upstream and downstream components of a system. In narrating the history of water supply in Nairobi, we look at both the upstream (largescale supply and downstream activities (distribution and payment, and compare the Nairobi case with European history of large infrastructures. We emphasise that regime actors in Nairobi have dealt with the issues of alignment mainly to facilitate and expand upstream activities, while concerning downstream activities they have remained incapable of expanding service and thus integrating the large segment of low-income consumers. We conclude that the present surge of large-scale water investment in Nairobi is the result of sector reforms that enabled the return to a long tradition – a 'Nairobi style' – of upstream investment mainly benefitting the highincome earners. Our proposition is that much more attention needs to be directed at inter-level alignment at the downstream end of the system, to allow the creation of niches aligned to the regime.

  12. 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.

  13. 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.

  14. Moisture harvesting and water transport through specialized micro-structures on the integument of lizards

    Science.gov (United States)

    Comanns, Philipp; Effertz, Christian; Hischen, Florian; Staudt, Konrad; Böhme, Wolfgang

    2011-01-01

    Summary Several lizard species that live in arid areas have developed special abilities to collect water with their bodies' surfaces and to ingest the so collected moisture. This is called rain- or moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even from humid soil. The integument (i.e., the skin plus skin derivatives such as scales) has developed features so that the water spreads and is soaked into a capillary system in between the reptiles' scales. Within this capillary system the water is transported to the mouth where it is ingested. We have investigated three different lizard species which have developed the ability for moisture harvesting independently, viz. the Australian thorny devil (Moloch horridus), the Arabian toadhead agama (Phrynocephalus arabicus) and the Texas horned lizard (Phrynosoma cornutum). All three lizards have a honeycomb like micro ornamentation on the outer surface of the scales and a complex capillary system in between the scales. By investigation of individual scales and by producing and characterising polymer replicas of the reptiles' integuments, we found that the honeycomb like structures render the surface superhydrophilic, most likely by holding a water film physically stable. Furthermore, the condensation of air humidity is improved on this surface by about 100% in comparison to unstructured surfaces. This allows the animals to collect moisture with their entire body surface. The collected water is transported into the capillary system. For Phrynosoma cornutum we found the interesting effect that, in contrast to the other two investigated species, the water flow in the capillary system is not uniform but directed to the mouth. Taken together we found that the micro ornamentation yields a superhydrophilic surface, and the semi-tubular capillaries allow for an efficient passive – and for Phrynosoma directed – transport of water. PMID:21977432

  15. 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.

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

    Science.gov (United States)

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

    2005-05-01

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

  17. 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

  18. Fundamental understanding of liquid water effects on the performance of a PEMFC with serpentine-parallel channels

    International Nuclear Information System (INIS)

    Le, Anh Dinh; Zhou Biao

    2009-01-01

    A three-dimensional and unsteady proton exchange membrane fuel cell (PEMFC) model with serpentine-parallel channels has been incorporated to simulate not only the fluid flow, heat transfer, species transport, electrochemical reaction, and current density distribution but also the behaviors of liquid water in the gas-liquid flow of the channels and porous media. Using this general model, the behaviors of liquid water were investigated by performing the motion, deformation, coalescence and detachment of water droplets inside the channels and the penetration of liquid through the porous media at different time instants. The results showed that: tracking the interface of liquid water in a reacting gas-liquid flow in PEMFC can be fulfilled by using volume-of-fluid (VOF) algorithm combined with solving the conservation equations of continuity, momentum, energy, species transport and electrochemistry; the presence of liquid water in the channels has a significant impact on the flow fields, e.g., the gas flow became unevenly distributed due to the blockage of liquid water where the high pressure would be suddenly built up and the reactant gas transport in the channels and porous media would be hindered by liquid water occupation

  19. 75 FR 8412 - Office of New Reactors: Interim Staff Guidance on Assessing Ground Water Flow and Transport of...

    Science.gov (United States)

    2010-02-24

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

  20. Transport Canada : navigable water protection technical paper on boating safety at dams

    Energy Technology Data Exchange (ETDEWEB)

    Putt, B [Transport Canada, Sarnia, ON (Canada); Di Censo, V M [Transport Canada, Ottawa, ON (Canada)

    2009-07-01

    The Navigable Waters Protection Act (NWPA) was designed to ensure a balance between public rights of navigation and the need to build bridges, dams, and other structures. This paper discussed an owner's guide to navigation safety around water control structures. Developed by Transport Canada, the guide was intended to help owners of water control structures address boating safety matters and assist owners in making applications under the NWPA. The guide was prepared to address amendments made to the NWPA in 2009 as well as to assist owners in identifying potential hazards and interactions by the boating public at water control structures. The guide included information related to signage; navigation aids; barriers and booms; warning alerts and alarms; portage and access around structures; and application requirements. It was concluded that the guide will also provide a summary of legislation that may affect owners of water control structures.

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

    Science.gov (United States)

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

    1996-01-01

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

  2. 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

    -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...

  3. The application of fluid structure interaction techniques within finite element analyses of water-filled transport flasks

    International Nuclear Information System (INIS)

    Smith, C.; Stojko, S.

    2004-01-01

    Historically, Finite Element (FE) analyses of water-filled transport flasks and their payloads have been carried out assuming a dry environment, mainly due to a lack of robust Fluid Structure Interaction (FSI) modelling techniques. Also it has been accepted within the RAM transport industry that the presence of water would improve the impact withstand capability of dropped payloads within containers. In recent years the FE community has seen significant progress and improvement in FSI techniques. These methods have been utilised to investigate the effects of a wet environment on payload behaviour for the regulatory drop test within a recent transport licence renewal application. Fluid flow and pressure vary significantly during a wet impact and the effects on the contents become complex when water is incorporated into the flask analyses. Modelling a fluid environment within the entire flask is considered impractical; hence a good understanding of the FSI techniques and assumptions regarding fluid boundaries is required in order to create a representative FSI model. Therefore, a Verification and Validation (V and V) exercise was undertaken to underpin the FSI techniques eventually utilised. A number of problems of varying complexity have been identified to test the FSI capabilities of the explicit code LS-DYNA, which is used in the extant dry container impact analyses. RADIOSS explicit code has been used for comparison, to provide further confidence in LS-DYNA predictions. Various methods of modelling fluid are tested, and the relative advantages and limitations of each method and FSI coupling approaches are discussed. Results from the V and V problems examined provided sufficient confidence that FSI effects within containers can be accurately modelled

  4. Understanding arsenic mobilization using reactive transport modeling of groundwater hydrochemistry in the Datong basin study plot, China.

    Science.gov (United States)

    Mapoma, Harold Wilson Tumwitike; Xie, Xianjun; Pi, Kunfu; Liu, Yaqing; Zhu, Yapeng

    2016-03-01

    This paper discusses the reactive transport and evolution of arsenic along a selected flow path in a study plot within the central part of Datong basin. The simulation used the TOUGHREACT code. The spatial and temporal trends in hydrochemistry and mineral volume fraction along a flow path were observed. Furthermore, initial simulation of major ions and pH fits closely to the measured data. The study shows that equilibrium conditions may be attained at different stress periods for each parameter simulated. It is noted that the variations in ionic chemistry have a greater impact on arsenic distribution while reducing conditions drive the mobilization of arsenic. The study concluded that the reduction of Fe(iii) and As(v) and probably SO4/HS cycling are significant factors affecting localized mobilization of arsenic. Besides cation exchange and water-rock interaction, incongruent dissolution of silicates is also a significant control mechanism of general chemistry of the Datong basin aquifer.

  5. 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.

  6. Geophysical fluid dynamics understanding (almost) everything with rotating shallow water models

    CERN Document Server

    Zeitlin, Vladimir

    2018-01-01

    The book explains the key notions and fundamental processes in the dynamics of the fluid envelopes of the Earth (transposable to other planets), and methods of their analysis, from the unifying viewpoint of rotating shallow-water model (RSW). The model, in its one- or two-layer versions, plays a distinguished role in geophysical fluid dynamics, having been used for around a century for conceptual understanding of various phenomena, for elaboration of approaches and methods, to be applied later in more complete models, for development and testing of numerical codes and schemes of data assimilations, and many other purposes. Principles of modelling of large-scale atmospheric and oceanic flows, and corresponding approximations, are explained and it is shown how single- and multi-layer versions of RSW arise from the primitive equations by vertical averaging, and how further time-averaging produces celebrated quasi-geostrophic reductions of the model. Key concepts of geophysical fluid dynamics are exposed and inte...

  7. Transportation cost of nuclear off-peak power for hydrogen production based on water electrolysis

    International Nuclear Information System (INIS)

    Shimizu, Saburo; Ueno, Shuichi

    2004-01-01

    The paper describes transportation cost of the nuclear off-peak power for a hydrogen production based on water electrolysis in Japan. The power could be obtainable by substituting hydropower and/or fossil fueled power supplying peak and middle demands with nuclear power. The transportation cost of the off-peak power was evaluated to be 1.42 yen/kWh when an electrolyser receives the off-peak power from a 6kV distribution wire. Marked reduction of the cost was caused by the increase of the capacity factor. (author)

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

    Science.gov (United States)

    Son, Chang H.

    2013-01-01

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

  9. Transport of lincomycin to surface and ground water from manure-amended cropland.

    Science.gov (United States)

    Kuchta, Sandra L; Cessna, Allan J; Elliott, Jane A; Peru, Kerry M; Headley, John V

    2009-01-01

    Livestock manure containing antimicrobials becomes a possible source of these compounds to surface and ground waters when applied to cropland as a nutrient source. The potential for transport of the veterinary antimicrobial lincomycin to surface waters via surface runoff and to leach to ground water was assessed by monitoring manure-amended soil, simulated rainfall runoff, snowmelt runoff, and ground water over a 2-yr period in Saskatchewan, Canada, after fall application of liquid swine manure to cropland. Liquid chromatography tandem mass spectrometry was used to quantify lincomycin in all matrix extracts. Initial concentrations in soil (46.3-117 mug kg(-1)) were not significantly different (p > 0.05) for manure application rates ranging from 60,000 to 95,000 L ha(-1) and had decreased to nondetectable levels by mid-summer the following year. After fall manure application, lincomycin was present in all simulated rainfall runoff (0.07-2.7 mug L(-1)) and all snowmelt runoff (0.038-3.2 mug L(-1)) samples. Concentrations in snowmelt runoff were not significantly different from those in simulated rainfall runoff the previous fall. On average, lincomycin concentrations in ephemeral wetlands dissipated by 50% after 31 d. Concentrations of lincomycin in ground water were generally <0.005 mug L(-1). This study demonstrates that the management practice of using livestock manure from confined animal feeding operations as a plant nutrient source on cropland may result in antimicrobial transport to surface and ground waters.