Water Transport Processes Research Articles

Estudo do efeito do envelhecimento sob radiação UV no transporte de água em filmes de PET reciclados de bebidas carbonatadas

Este trabalho descreve um estudo sobre o efeito do envelhecimento sob radiação UV no transporte de água em filmes planos de PET reciclados de garrafas de bebidas carbonatadas. A partir do formalismo termodinâmico utilizando a relação de Eyring e os resultados de coeficientes de permeabilidade, foram determinadas a entropia e a entalpia de ativação para o transporte da água. Estas funções representadas num gráfico de efeito de compensação termodinâmica permitiram correlacionar a degradação do material, avaliada via espectroscopia na região do infravermelho com transformada de Fourier, com o transporte de água. Foram analisados os possíveis efeitos da presença de estabilizantes, pigmentos e história de processamento.

Numerical simulation of three-dimensional gas/liquid two-phase flow in a proton exchange membrane fuel cell

Investigation into the formation and transport of liquid water in proton exchange membrane fuel cells (PEMFCs) is the key to fuel cell water management. A three-dimensional gas/liquid two-phase flow and heat transfer model is developed based on the multiphase mixture theory. The reactant gas flow, diffusion, and chemical reaction as well as the liquid water transport and phase change process are modeled. Numerical simulations on liquid water distribution and its effects on the performance of a PEMFC are conducted. Results show that liquid water distributes mostly in the cathode, and predicted cell performance decreases quickly at high current density due to the obstruction of liquid water to oxygen diffusion. The simulation results agree well with experimental data.

Removal of CODCr and Nitrogen in Severely Polluted River Water by Bank Filtration

Laboratory column experiments on the colmation layer and a three-year successive field observation at the Xucun and Huangqiao sections of the Kui River—a severely polluted river in the Huai River basin in China—have been carried out. The transport and removal ratios for CODCr, NH4 +-N, and NO3 −-N in river water infiltrated through the riverbed colmation layer, the unsaturated zone, and the saturated aquifer, as well as to the pumping well, were investigated. The results of the column tests show that the colmation layer can effectively clog the infiltration of water and contaminants and the non-conservative contaminants can be effectively adsorbed or degraded by riverbed microbes in the colmation layer and its sludge. The removal ratios were approximately 48–51% for CODCr and NH4 +-N, and 23.5–25.5% for NO3 −-N. Field observations indicate that the colmation layer and the unsaturated zone possess an obvious capacity to adsorb and degrade contaminants. A significant accumulation could be identified at the interface between the unsaturated and saturated zones. In the saturated zone of groundwater, contaminant concentrations declined sharply and were very low at the pumping well. Additionally, one- and two-dimensional numerical models were used to simulate the transport and transformation processes of water and contaminants filtered through the unsaturated zone and the saturated zone, and the model equations were solved numerically with a fully implicit difference method. The good agreement between calculated and measured values suggests the feasibility and reliability of the simulation method.

Identification of ground water flow patterns using particle models

Particle models are often used to simulate transport processes in ground water. The ground water flow pattern is one of the driving parameters of the transport model. In this paper a parameter identification algorithm is developed for particle type models to identify the underlying flow pattern from concentration measurements. The estimation problem is solved with a gradient based algorithm. For each generated particle track, the adjoint track is determined to efficiently compute gradient of the criterion.

Immunohistochemical localisation of aquaporin water channels in the bovine mammary gland

The aquaporins (AQPs) are a family of small integral membrane proteins 28-35kDa in size, sub classified into 2 groups; those selectively permeated by water (the aquaporins; AQP0, AQP1, AQP2, AQP4, AQP5, AQP6 and AQP8) or by water and small organic osmolytes such as glycerol and urea (the aquaglyceroporins; AQP3, AQP7, AQP9 and AQP10). AQPs are expressed in a variety of epithelial tissues where they are responsible for rapid water movement driven by osmotic gradients. The mammary gland produces and secretes milk which consists of water, lipids, electrolytes, vitamins, sugars and specific milk proteins. However, little is known about AQP expression, distribution and function in mammary tissue or about the process of water transport across the mammary epithelium. The only information available relates to the identification of AQP1 and AQP3 in capillary endothelia and epithelial cells of mouse mammary glands respectively (Matsuzaki et al., 2005). Since water delivery to the mammary gland is critical for milk production, which is of major economic importance to the dairy industry, it is necessary to understand the underlying physiology involved. The aim of this study was to determine the expression and distribution of AQPs within the bovine mammary gland.

The effect of mulching and tillage on the water and temperature regimes of a loess soil: Experimental findings and modeling

Crop residues and tillage are being advocated for their potential effectiveness to modify the soil hydrothermal regime. This study was carried out to quantify the effect of straw mulching and rotary hoeing on the soil water and thermal regimes of a loess soil. The field experiment consisted of four treatments: (1) no mulching and no rotary hoeing as control, (2) rotary hoeing, (3) wheat straw mulching, and (4) wheat straw mulching with rotary hoeing. During the study period from 5 August to 20 September 2002, soil water content and pressure head were measured daily at five soil depths (0.05, 0.15, 0.30, 0.45 and 0.60 m). Soil temperatures were measured at hourly resolution at three depths (0.05, 0.15 and 0.30 m). Mulching decreased soil water loss on an average by 0.39 mm d −1 and rotary hoeing increased water loss on an average by 0.12 mm d −1 as compared to control. Volumetric soil water contents at pF 1, 1.8 and 2.5 up to 30 cm depth were highest (0.418, 0.390, and 0.360 m 3 m −3, respectively) with the application of wheat straw mulch and lowest (0.393, 0.363, and 0.333 m 3 m −3, respectively) with the rotary hoeing. Soil thermal conductivity measured at pF 1, 1.8, 2.5, 3, and 3.7 decreased with increasing suctions in all the treatments. However, the tillage and mulching did not affect the soil thermal conductivity. Further, compared with the control, mulching reduced average soil temperatures by 0.74, 0.66, 0.58 °C at 0.05, 0.15, and 0.30 m, respectively, during the study period. The rotary hoeing tillage slightly increased the average soil temperature by 0.21 °C at 0.05 m depth compared to control. The tillage effect did not transmit to deeper depths. The numerical model Hydrus-1D was used to simulate the water and temperature regimes of the treatments. Simulations with hydraulic parameters derived from laboratory measurements did not yield satisfactory results. Only when the hydraulic parameters were optimized by the inverse method, simulations performed well. The largest deviations were observed in the wheat straw mulching treatment. Simulations were further improved by adjusting the potential evaporation rate from the measured data which was achieved by linking the inversion code UCODE to the Hydrus-1D. Soil temperatures at 0.05 and 0.15 m in all the treatments were modeled well, yielding root mean square errors between 0.3 and 1.7 °C. As for soil water, the largest temperature deviations were found for the mulching treatment. All simulations underestimated soil temperatures at 0.30 m. In conclusion, crop residue can be utilized as mulching to improve the soil hydrothermal regime and the Hydrus-1D model can be used as a tool for analyzing water and heat transport processes and for estimating hydraulic transport parameters under field conditions.

Controlling Water Transport in W/O/W Multiple Emulsion

建立了简化的W/O/W（水/油/水）多重乳液乳珠模型--统计平均半径模型,预测出当W/O/W多重乳液内水相水滴之间以及内外水相之间均达到水传递平衡时的内外水相中盐的浓度,从而实现对水传递的控制,以维持W/O/W多重乳液的稳定.按理论预测制备出了不同稳定态的W/O/W多重乳液,利用差分扫描量热仪（DSC）检测了多重乳液中水的传递过程,确定体系在实验状态下的稳定程度,实验结果与理论预测基本吻合.

Numerical modelling of water transport processes in partially-connected tidal basins

In the paper two types of numerical models – a lumped-parameter model and a high-resolution two-dimensional hydrodynamic model – are used to analyse the response of a system of partially-connected tidal basins to inhomogeneous open sea forcing. The equations of the lumped-parameter model, suitable for an arbitrary number of basins with sloping walls, are formulated based on one-dimensional continuity and momentum equations. Numerical solutions to the equations are thoroughly examined, showing the influence of inhomogeneous open sea forcing and of geometrical parameters of the basins on the tidal range and the water transport through the system, with particular emphasis given to inter-basin water exchange and cumulative water transport through basins boundaries. The results of the lumped-parameter model simulations for the tidal basins of the German Wadden Sea are successfully compared with the results of calculations with the two-dimensional hydrodynamic model, which is used to investigate in more detail circulation patterns and the influence of specific local features of inlet bathymetry on the hydrodynamic processes in the study area. The influence of wind on the basins response is discussed as well.

Influence of different vegetation types on saturated hydraulic conductivity in alluvial topsoils

In the Pariž creek catchment (southwestern part of Slovakia), the influence of different vegetation types on selected soil properties in alluvial topsoils was studied. Specifically, the effect on saturated hydraulic conductivity considered as indicator of water transport process and the effect on soil bulk density considered as indicator of soil structure were analysed. Due to the mutual influence of plant roots on soil properties, the root biomass was also estimated and its relationship to the studied soil properties was explored. Reed and tall-sedge wetlands and alluvial wet meadows represented the studied vegetation types. Adjacent arable lands (former grasslands) with corn were included for comparison. In total, 64 samples were used for comparative analysis. A standard methodology for measurement of the saturated hydraulic conductivity, the so-called falling head technique was used on 250 cm3 soil cores. Undisturbed soil samples were taken from the depth of 5 cm. Analysis of variance, mutual comparison of mean values and correlation matrix were used for statistical analyses. Measurements showed significantly higher values of saturated hydraulic conductivity for topsoils in wetlands (6.2 m day−1 on average) compared to mown grasslands (1.47 m day−1) and arable land (0.79 m day−1). The results indicated a specific significance of wetlands in relation to water transport processes in alluvial topsoils.

Source Zone Natural Attenuation at Petroleum Hydrocarbon Spill Sites—II: Application to a Former Oil Field

AbstractPetroleum spills often create persistent “source zones” of hydrocarbon‐impacted soils that are either in direct contact with ground water or in indirect contact through soil moisture infiltration and dissolution. Understanding the natural attenuation of source zones is critical to anticipating their longevity and the future chemical composition of their associated dissolved ground water and vapor plumes. A companion paper to this work presents an approach for site‐specific assessment of source zone natural attenuation (SZNA), based on three levels of data collection and analysis oriented toward answering common questions of interest. Use of this SZNA assessment approach is illustrated here through application to the 3000‐acre former Guadalupe Oil Field in California, where numerous petroleum source zones are present within a dune sand aquifer system. SZNA processes and mass loss rates are assessed through use of data from geochemical profiles of continuous cores, nested ground water wells, and soil‐gas probes. Mass loss rates are estimated by quantifying fluxes of dissolved electron acceptors and degradation products in ground water and in soil gas. Under current conditions, gas transport processes coupled with aerobic and anaerobic biodegradation acting on exposed portions (above the water table) of source zones are the most significant loss mechanisms. Depending on the depth of contamination and other factors, the mass loss rate per unit surface area for those processes varies from approximately 0.1 to 1.0 kg total petroleum hydrocarbons per m2/year. In comparison, mass losses from the submerged part of the source zone and involving ground water transport processes (i.e., dissolution and biodegradation) were estimated to be about approximately 2 orders of magnitude lower. Once aerobically degradable hydrocarbons above the water table are depleted, the slower mass loss processes operating on the submerged parts of the source will control source zone mass loss.

Tracing of water movement through the unsaturated zone of a coarse gravel aquifer by means of dye and deuterated water

To better understand the movement and transport of water and pollution through the coarse gravel unsaturated zone, the presented research was conducted to estimate water flow and transport processes with a tracing experiment in a lysimeter in the Selniska Dobrava. A combined tracing experiment was performed with deuterated water and the fluorescent dye—uranine. The fastest and dominant flow velocities were calculated based on injection time, the first tracer appearance time and the time of highest concentration. Mean flow velocity and vertical dispersion were estimated by an analytical best-fit method using one-dimensional convection–dispersion model. Deuterium was confirmed as an ideal conservative tracer and a more suitable tracer than dye (uranine) for the study of water flow in the unsaturated zone of a coarse gravel aquifer. The retardation factor of the dye as compared with deuterium was 1.13–1.75, which is in agreement with previously published results. Artificial tracers, especially deuterated water, were also identified as a very useful tool to assess other properties and differences in water flow in the unsaturated zone of a coarse gravel aquifer such as velocity and dispersion.

Variation in hydraulic conductivity of mangroves: influence of species, salinity, and nitrogen and phosphorus availability

We investigated how species identity and variation in salinity and nutrient availability influence the hydraulic conductivity of mangroves. Using a fertilization study of two species in Florida, we found that stem hydraulic conductivity expressed on a leaf area basis (Kleaf) was significantly different among species of differing salinity tolerance, but was not significantly altered by enrichment with limiting nutrients. Reviewing data from two additional sites (Panamá and Belize), we found an overall pattern of declining leaf‐specific hydraulic conductivity (Kleaf) with increasing salinity. Over three sites, a general pattern emerges, indicating that native stem hydraulic conductivity (Kh) and Kleaf are less sensitive to nitrogen (N) fertilization when N limits growth, but more sensitive to phosphorus (P) fertilization when P limits growth. Processes leading to growth enhancement with N fertilization are probably associated with changes in allocation to leaf area and photosynthetic processes, whereas water uptake and transport processes could be more limiting when P limits growth. These findings suggest that whereas salinity and species identity place broad bounds on hydraulic conductivity, the effects of nutrient availability modulate hydraulic conductivity and growth in complex ways.

Characterization of sites for geological storage of carbon dioxide

Stefan Bachu is senior advisor for Energy and Carbon Management Geoscience in the Alberta Geological Survey, Alberta Energy and Utilities Board. During his career, he has been involved in various research activities related to the subsurface flow of fluids and heat, with application to the Western Canada sedimentary basin. For more than a decade, Stefan has focused his efforts on the potential for CO2 storage in geological media in Alberta as a mitigation strategy for reducing greenhouse gas emissions into the atmosphere. Because of his expertise in this emerging field, Stefan was appointed lead author and contributed to chapter 5 on CO2 Geological Storage of the IPCC Special Report on CO2 Capture and Storage . In 2004, Stefan served on the CO2 Task Force of the Interstate Oil and Gas Compact Commission and currently is a member of the Natural Sciences and Engineering Research Council (NSERC) Strategic Project Grants Panel for Greenhouse Gas Mitigation and also represents Canada on the Technical Group of the Carbon Sequestration Leadership Forum. Stefan holds advanced degrees in water resources, hydrogeology, and transport processes. Matthias Grobe is a geologist and leader of the Acid Gas and CO2 Storage Section at the Alberta Geological Survey of the Alberta Energy and Utilities Board. He received his M.Sc. degree in geology from the University of Tubingen, Germany, and his Ph.D. in geology from the University of Alberta in Edmonton, Canada, with a focus on the sedimentology and diagenesis of carbonate rocks. He considers geoscience data and knowledge as key components for the assessment of the suitability, capacity, and safety of geological storage options. Matt has been an associate editor for the journal Environmental Geosciences for several years and is currently a member of the Division of Environmental Geosciences Advisory Board. Interpretation of the …

Aspects of ionic diffusion through thick matrices of charged particles

A review of the literature on ionic diffusion through matrices of charged particles shows that many workers have reported higher diffusivity of co-ions than of counterions. If these observations are correct then the requirement of electroneutrality of bulk solutions is violated. In those experiments other, not looked for, ions must have been taking part. It therefore appears that complete chemical analyses of solutions of both up- and downstream sides should be carried out, otherwise misleading inferences may be drawn, with practical consequences. Some researchers have studied transport of water under osmotic pressure differentials across clay membranes. However, a diffusing ion, during its transport from higher concentration to lower concentration, always carries its water of hydration. This second water transport process has not received attention. This suggests that at a critical concentration two transport processes will cancel each other. Attention has been drawn to this second type of water flow and its consequences. In ionic diffusion, each side of the membrane–outside solution interface is subject to the effects of the Nernst layer and Donnan zone. However, these layers and zones are seldom treated quantitatively. This has been carried out in this paper by two different methods. Both methods give identical thicknesses of the Nernst layer and Donnan zone. Finally, the effects of the presence of soluble bivalent salts on the diffusivity of different types of ions have been commented up on. In these cases some of the co-ions diffuse to the upstream side.

Cysteine String Protein Monitors Late Steps in Cystic Fibrosis Transmembrane Conductance Regulator Biogenesis

We examined the role of the cysteine string protein (Csp) in cystic fibrosis transmembrane conductance regulator (CFTR) biogenesis in relation to another J-domain protein, Hdj-2, a recognized CFTR cochaperone. Increased expression of Csp produced a dose-dependent reduction in mature (band C) CFTR and an increase in immature (band B) CFTR. Exogenous expression of Hdj-2 also increased CFTR band B, but unlike Csp, Hdj-2 increased band C as well. The Csp-induced block of CFTR maturation required Hsp70, because a J-domain mutant (H43Q) that interferes with the ability of Csp to stimulate Hsp70 ATPase activity relieved the Csp-induced block of CFTR maturation. Nevertheless, Csp H43Q still increased immature CFTR. Csp-induced band B CFTR was found adjacent to the nucleus, co-localizing with calnexin, and it remained detergent-soluble. These data indicate that Csp did not block CFTR maturation by promoting the aggregation or degradation of immature CFTR. Csp knockdown by RNA interference produced a 5-fold increase in mature CFTR and augmented cAMP-stimulated CFTR currents. Thus, the production of mature CFTR is inversely related to the expression level of Csp. Both Csp and Hdj-2 associated with the CFTR R-domain in vitro, and Hdj-2 binding was displaced by Csp, suggesting common interaction sites. Combined expression of Csp and Hdj-2 mimicked the effect of Csp alone, a block of CFTR maturation. But together, Csp and Hdj-2 produced additive increases in CFTR band B, and this did not depend on their interactions with Hsp70, consistent with direct chaperone actions of these proteins. Like Hdj-2, Csp reduced the aggregation of NBD1 in vitro in the absence of Hsp70. Our data suggest that both Csp and Hdj-2 facilitate the biosynthesis of immature CFTR, acting as direct CFTR chaperones, but in addition, Csp is positioned later in the CFTR biogenesis cascade where it regulates the production of mature CFTR by limiting its exit from the endoplasmic reticulum.

Optimisation of relief classification for different levels of generalisation

Relief plays an important role in the spatial and temporal distribution of soil water and matter transport processes. Each landscape can be segmented into different landform elements based on a digital elevation model. These landforms contain characteristic properties in terms of energy and material balance. Several algorithms are available to classify landscapes at different scales. However, lack of knowledge exists concerning the applicability of relief parameters for landscape stratification for different generalisation levels of underlying data. The objective of this study was to develop a method for agricultural landscapes to classify landform elements across a series of elevation datasets with different spatial resolutions. A non-linear parameter optimisation algorithm was coupled with a relief classification scheme to optimize four classification parameters with regard to environmentally sensitive landforms: shoulder and footslope. Input datasets were based on a LIDAR scan and topographic maps. The magnitude of the optimized relief parameters decreased with decreasing map scale from 1 : 10,000 to 1 : 100,000 or increasing contour line interval. The main conclusion is that if one set of classification rules for a specific landscape was determined for a high-resolution dataset at a small subset, it could be applied for larger areas even if only coarser digital elevation model information were available.

Spatial Association among Soil Hydraulic Properties, Soil Texture, and Geoelectrical Resistivity

Spatial variability of soil hydraulic properties causes considerable variations in water and solute flow and transport processes. It remains a difficult task to determine and describe the spatial pattern of soil physical properties for modeling landscape‐scale vadose zone processes. Strategies that involve measurements of relevant variables and appropriate spatial modeling tools need to be identified for this purpose. The objective of this study was to investigate a nested sampling approach for soil hydraulic properties and associated variables, such as soil texture, in a highly variable soil landscape in northeastern Germany dominated by soils derived from glacial till. Additionally, spatially highly resolved and nondestructive measurements of geoelectrical resistivity were examined for their spatial relation to soil physical and transport properties and their applicability in spatial process models of soil hydraulic property coefficients. Two pedotransfer function (PTF) approaches were applied to gain insight into their capacity to estimate the mean and the spatial variation of soil hydraulic property coefficients, although pedotransfer functions are originally not developed for this purpose. State‐space models estimated the spatial process of hydraulic conductivity at a soil water pressure head of −50 cm and the van Genuchten parameter n with relatively narrow confidence bands, whereas for α confidence was larger. Geoelectrical resistivity supported the estimation of the spatial distribution of soil hydraulic property coefficients. Despite the fact that without calibration, pedotransfer variable estimates did not always represent the mean of the respective variable, there was generally little spatial fluctuation reflected. However, considerable horizontal and vertical variability in soil textural properties existed within the investigated landscape. The findings suggest that state‐space models incorporating intermittent observations and spatial autocovariance behavior provide more flexibility in the estimation of the spatial process of hydraulic functional coefficients than regression type functions only.

SUBSURFACE FLOW MONITORING USING CONSERVATIVE ION IN SANDBARS WITH AND WITHOUT VEGETATION

Riparian sandbar serves as a habitat for some organisms, which is supported by material transport. Sandbars have vegetated area and bare area, each of which support different material cycles based on subsurface water flow. Understanding the importance of water flow, we focused on subsurface water and solute transport processes through sandbars, and monitoring was conducted through measurement of water level of surface and subsurface water and concentration conservative ions. Particularly Cl- gives us time information using its dilution ratio in bare and vegetated sandbar. Additionally by using their ion concentration and flow patterns and retention time for each monitoring well, and the results of 2-D flow analysis of unconfined groundwater, the effects of precipitation and flood are discussed.

WASTEWATER IMPACT ON STREAM TEMPERATURE IN URBAN RIVERS

Thermal environmental in urban river system can be significantly changed due to urbanization. In statistic respect, the long-term change in the stream temperature of an urban river system and its relevant factors are reported by Kinouchi (2005). In this paper, concentrated observation and dynamic simulation about heat transport were approached. Firstly, we clarified the actually state of heat transport in lower reaches of the Ara River by concentrated observation. Next, stream temperature was reproduced using one-dimensional model integrated water and heat transport process. Each parameter was defined by result of field observation. Finally, wastewater impact on stream temperature in lower reaches of the Ara River was quantitatively evaluated using a dynamic simulation model. Consequently, it was found that wastewater increase stream temperature 3°C in the maximum in winter.

A two dimensional partial flooding model for PEMFC

Proton exchange membrane fuel cells (PEMFCs) have attracted much attention in these years. In PEMFCs, liquid/gas two-phase flow is a common phenomenon, which has great influence on fuel cell performance. However, the liquid water transport process has not been satisfactorily modeled yet. In this work, a two dimensional partial flooding model was developed, in which the pore size distribution of the gas diffusion layer (GDL) is taken into consideration in the explanation of fuel cell flooding for the first time. Liquid water produced is considered to flood a fraction of the GDL hydrophobic pores with diameter greater than the capillary condensation threshold diameter, and the unflooded pores will serve as passageway for gas transportation and the corresponding catalyst area is available for electrochemical reaction. Use this model, it is simple to explain membrane dehydration and electrode flooding. Different operation conditions have been studied with the model and the model polarization curves show reasonable accordance with the experimental results.