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>Magister Scientiae - MSc / The present study investigated the application of a multi-method approach to determine groundwater-surface water (GW-SW) interactions to quantify and characterize the quality of water resources in a fractured rock aquifer system in upper catchment of the Berg River (G10A). Demonstrating methods for improved understanding of groundwater and surface water interactions is important for informing development of strategies that ensure effective utilization and management of water resources. Applying a single method to inform innovative strategies for water resources has proved futile. The current study shows how the use of several methods can provide the basis for devising practical strategies for water resource utilization and management. The three methods were applied as follows: First, the base flow separation was used whereby the Chapman and Lynne & Hollick digital filter algorithms were applied to time-series streamflow data from four stream gauging stations in the catchment. The computation from algorithms on three sites (gauging stations) showed that the mean Base Flow Index (BFI) value ranged between 7%-8% for the 2012-2014 periods. This means that discharges from subsurface water storages dominate stream flows throughout the study period. Secondly, the quality of groundwater and surface water was sampled using standard methods. Piper Diagrams generated on Aquachem™ software and radial charts were used to identify the predominant hydrochemical facies. Results showed that Na-Cl was the predominant GW and SW water-type. This means that both GW and SW are mainly influenced by recharging surface water as well as interaction occurring between the rock matrices and infiltrating water. Multivariate statistical analyses were used to evaluate the factors controlling GW and SW chemistry in the upper Berg River catchment and the results showed that GW and SW are influenced by natural processes. Two main factors (a. & b.) were extracted which explained 71.8% of the variation in both GW and SW physicochemical parameters. These factors include water-rock interactions and the recharge of surface water. Cluster Analysis extracted four major clusters that grouped sites with similar physicochemical characteristics together. Finally, differential stream gauging was applied to a 600m reach above the Berg River Dam. Three 200m sub-reaches were used to compute differences in flows between sub-reaches. Stream flow at each sub-reach was estimated using mass balance equations with electrical conductivity measurements during instant salt tracer injection tests. Results indicated that during both the wet season (high flow) dry season (low flow), the river continuously lost water to the subsurface. This was demonstrated by the 0.91m³/s and 2.24m³/s decrease in stream flow along the 600m reach. Dry season flow decreases were less than wet season flow decreases, indicated by markedly lower flow loss in respect to the wet season. This confirms results of the analysis of base flow separation, which indicated that discharges from subsurface storages dominate stream flows during low flow periods. The differential stream gauging approach did not provide distinct points along the selected stream reach where GW-SW interaction occurred; rather it provided a holistic representation of seasonal flow variations along the selected reach. This study showed that upper Berg River catchment is dependent on discharges from subsurface water storages to maintain dry season flows. Furthermore, this study showed that infiltration of surface water and discharge of subsurface water transfers the respective chemical signature of the contributor, meaning that the transfer of water of suitable quality will reduce contamination in the receiving water body (i.e. surface water). Transfer of water between subsurface and surface water contributed an average of 8% of the gauged flows in the catchment between 2012 and 2014, suggesting that the groundwater recharge process dominates this catchment.

This dissertation explores the properties of sulfonated poly(arylene ether sulfone)s for desalination membrane applications. A multi-scale approach is used to understand the relationships between the chemical structure of the polymer, the equilibrium water content, and the bulk properties. The polysulfones investigated here are aromatic polymers with relatively high ion contenremain in the glassy state at room temperature even when fully hydrated. In order to better understand the effects of water on these ionic polysulfones molecular dynamics (MD) simulation is used to investigate ion aggregation and hydration at the atomic scale. MD simulations show that the sulfonate and sodium ions are not simply paired. Instead, they form an ionic network. The molecular nature of melting water within sulfonated polysulfones is also examined by combining differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and MD simulation. Experimental evidence shows that at high ion contents, the spacing between the ionic groups impacts the amount of melting water present in the polymer. We conclude that the amount of melting water in the polymer is more closely related to geometric clustering effects than electrostatic effects. Finally, molecular-scale insight is used to understand the trends in hydrated tensile modulus and hydrated glass transition (Tg) temperatures in sulfonated polysulfones. Polymers with a more rigid backbone show different trends compared to those with a more flexible backbone. The modulus and Tg trends for the more flexible backbone are qualitatively consistent with the increase in intra-chain ionic associations (loops) predicted by the sticky Rouse model. / Doctor of Philosophy / This dissertation investigates new materials that could be used to make better membranes that can remove ions (salt) from water. Existing materials are too soft or too brittle when they are fully immersed in water. Consequently, they must be combined with more durable materials in order to make useful membranes. We would like to design durable ionic polymers (large chain-like molecules with ions attached) that interact with water and other ions in a very specific way in order to make membranes that can remove salt efficiently. The goal of this research is to create tools that can describe how changes to the chemical structure of the polymer impact how the polymer, water, and ions interact with each other so that we can improve membrane properties. We find that the ions on the polymer chain interact with each other to form threads, which can form a network inside of the polymer under the right conditions. When the ions are located far apart on the polymer chain, the ion threads link one polymer chain to another polymer chain. These ionic links strengthen the polymer network. However, when the ions are located closer together on the polymer chain, the chain starts to form loops between neighboring ions. As the number of loops increases, the polymer quickly becomes softer and more gel-like. We also find that water molecules are distributed within the polymer and are not always located next to the ions. When there is more water inside the polymer, the water molecules begin to group together to form clusters. At low temperatures, water molecules that have fewer than four neighboring molecules cannot freeze. However, water in a cluster of five molecules or more can freeze into an ice crystal. The insights gained from this research will help the community to design better polymers for desalination membrane applications.

Approved for public release; distribution is unlimited / Variability of the MABL and its effect on the electromagnetic (EM) refractive structure around the Greenland Sea marginal ice zone were examined. Rawinsonde profiles and surface observations collected from 3 ships during MIZEX-87(20 March-11 April) served as the data set. A program, developed to calculate the refractivity at each vertical level of the rawinsonde profiles, also identified the levels at which trapping, superrefraction and subrefraction occurred. Temporal studies showed that a higher incidence of anomalous refractive layers occurred during periods when the region was under the influence of high pressure. More than 50% of the time, trapping and super-refractive layers were attributed to development of a capping inversion just above the MABL during these periods. Spatial studies showed that the refractive structure varied relative to distance from the ice edge as did the depth of the MABL. An upward slope in refractive layer heights was observed from the ice toward the open water. Significant spatial inhomogeneity was observed over horizontal ranges of less than 100 km. This was attributed to both the large-scale synoptic forcing affecting the region and to variations in the surface fluxes of heat and moisture over the ice and over the water. A range-dependent ray trace model developed at the Naval Ocean Systems Center was used to show how the ray paths of EM waves vary with a changing refractive structures. Keywords: Air water interactions, Greenland Sea, Atmospheric refraction, Electromagnetic wave propagation, Heat flux, Sea ice. Theses. (EDC) / http://archive.org/details/temporalspatialv00grot / Lieutenant, United States Navy

The current thesis presents work on the structure and dynamics of oligosaccharides and polysaccharides as well as the free energetics of carbohydrate-protein interactions. By applying various computational tools such as molecular dynamics simulation, our in-house fast sugar structure prediction software, replica exchange molecular dynamics, homology modeling, umbrella sampling, steered molecular dynamics as well as the thermodynamic integration formalism, we have been able to study the role of water on the surface of homopolysaccharides as well as complex oligosachharides, we have been able to produce a prediction of the bound structure of triantennary oligosaccride on the asialoglycoprotein receptor, we have been able to estimate the free energy of binding of ManΑ1→2Man to the HIV-1 inactivating protein, Cyanovirin-N as well as the relative binding free energies of mutants of Cyanovirin-N to the same ligand.

Combining geochemical data with physical data produces a powerful method for understanding sources and fluxes of waters to river systems. This study highlights this for river systems in regions of complex hydrogeology, shown here through the identification and quantification of base-flow sources to the Verde River and its tributaries within the middle Verde River watershed. Specifically, geochemical tracers (major solutes, stable and radioactive isotopes) characterize the principal aquifers (C, Redwall-Muav, and Verde Formation) and provide a conceptual understanding of the hydrologic connection between them. For the surface-water system, PCA is utilized to identify potential base-flow sources to the Verde River on a several-kilometer scale. Solute mixing diagrams then provide relative inputs of these sources, and when combined with stream discharge, allow for quantification of water sources. The results of this study provide an improved conceptual model that reveals the complexity of groundwater-surface water exchanges in this river basin.

Solid-state NMR spectroscopy was used to site-specifically investigate the protein-water interface of a seven alpha-helical transmembrane protein, Anabaena sensory rhodopsin (ASR). Water-edited experiments, which employ a T2-filter to select for mobile protons, provided a means to detect residues which appear to be in close contact to water molecules, and to gain insights about the water-protein interface of ASR. First, through the application of Lee-Goldburg homonuclear decoupling, it was determined that polarization transfer across this interface is dominated by through-space interaction mechanisms, as opposed to chemical exchange. A series of two-dimensional experiments were also performed to detect polarization transfer along the backbone and to the sidechains of the protein. Residues located in solvent-accessible regions of the protein, such as the B-C loop, were found to obtain polarization quickly, as expected, and in agreement with previous H/D exchange data. Residues known to be in contact with bound crystal water molecules were also detected. In addition to these, we found new residues which appear to be in contact with water, indicating additional HN-H2O interactions, or additional contacts with bound water molecules. Most of these residues were located beside exchangeable regions of ASR. Sidechains of residues located in the cytoplasmic side of helix F were seen to be in close contact with mobile water molecules, supporting evidence of a hydrophilic chain along the cytoplasmic half of the protein, which is suggested to cause a functional outward tilt of the cytoplasmic half of helix F upon light-activation.

Understanding the connection of surface waters to ground-water systems is important when evaluating potential water resources. In the past surface waters and ground-water have been viewed as two different sources of water but more commonly now they are viewed as one connected resource (Winter et al, 1998). The nature of connection between surface and ground-waters varies depending on climatic and geologic settings, as well as anthropogenic influences such as ground-water pumping and manipulation of river flows by dams. This thesis takes advantage of daily stage changes in the Deerfield River to investigate surface water interactions with ground-water in Charlemont, MA. Two dimensional transient numerical models are constructed to simulate ground-water response to river stage changes. These models are coupled to hypothetical mass transport models to investigate mixing mechanisms of conservative solutes under varying hydraulic scenarios. These simulations support the hypothesis that daily stage fluctuations cause a pumping mechanism which drives solutes into ground-water systems adjacent to a river at rates higher then normal flow conditions, or even under certain flood conditions. Riverbed pore-water temperature responses to diurnal temperature fluctuations are measured at two sites along the Deerfield River exposed to the same daily stage changes caused by dams. Temperature and stage data are collected at two sites with differing geologic settings. These data are used to calibrate simple two dimensional models of ground-water flow and heat transport to site specific riverbed hydraulic conductivities. It is suggested that due to the differing depositional environments of the two field sites, hydraulic conductivity of riverbed materials differ, which affects the exchange flux between surface water and ground-water. Understanding the exchange between surface and ground waters under varying hydraulic and geologic conditions is vital to characterizing local water resources and determining ecosystems health.

The McCurtain Creek watershed was proposed for a large reservoir project resulting in the commissioning of this study to assess the site?s geology, hydrogeology, and surface hydrology to find whether or not the site was suitable. Data was collected from 57 geophysical logs from coal exploration boreholes to produce geologic and aquifer cross sections. A program to assess discharge identified surface hydrology characteristics of the stream at five locations. Twenty-seven geotechnical boreholes, 23 standpipe piezometers, and the data from the coal exploration were used to map the water table using ArcGIS 8.3 software. Eighteen piezometers at stream sites, used to measure discharge, assessed groundwater/surface water interactions of the basin. After careful analysis, the results of this study concluded that the geology and hydrology of the basin is sufficient to support the large reservoir although engineering design will be required to mitigate some highly permeable sands for the proposed levee.

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