Thesis (Ph. D.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Donald L. Sparks, Dept. of Plant & Soil Sciences. Includes bibliographical references.

Thesis (Ph. D.)--University of California, Santa Cruz, 1989. / Typescript. Includes bibliographical references.

Thesis (M.S.)--University of California, Santa Cruz, 1993. / Typescript. Includes bibliographical references (leaves 193-197).

Thesis (Ph. D.)--Washington State University, August 2006. / Includes bibliographical references (p. 82-98).

The Piceance Creek Basin in northwestern Colorado contains extensive oil shale deposits that produce natural gas and which could potentially yield ~1.5 trillion barrels of shale oil. However, much of the oil shale lies at depths too great for traditional mining practices and various innovative approaches for in situ conversion of kerogen to oil have been proposed. A firm understanding of the existing hydrogeochemistry is needed as resulting mineralogical changes or rock-fluid reactions may affect rock porosity and permeability. Using an existing database complied by the USGS, the water chemistry of 267 surface and groundwater samples in the Piceance Creek primary drainage basin have been evaluated by mapping major ion concentrations and mineral saturation indicies with respect to hydrostratigraphic units and geologic structures. Controlling processes have been further assessed using statistical correlation and factor analysis. Results indicate that shallow waters in recharge zones are dominated by mixed cations (Na, Ca, Mg) and bicarbonate anions but with increased depth, groundwater transition to nearly 100% sodium bicarbonate type water. The chemistry of lower aquifer waters are principally controlled by nahcolite dissolution, but evidence of sulfate reduction and cation exchange aid in maintaining a sodium-bicarbonate water type. Ion evolution in surface and upper aquifer waters are influenced by an increase in sulfate concentration which is necessary to evolve water to an intermediate stage with sulfate-dominant anions. The source of sulfate is speculative, but likely due in part to the oxidation of sulfide-enriched groundwater and possible dissolution of sulfate-bearing carbonates. Surface and upper aquifer water chemistry in the northern portion of the basin is the result of discharge of deeper groundwater which is controlled to some degree by preferential pathways created by faults. Lower aquifer water migrates upward and mixes with the less-concentrated near-surface water, resulting in sodium bicarbonate type water in all hydrologic units.

Scaling due to calcium carbonate precipitation is a major problem in cooling water circuits in many of Eskom power stations. Some earlier studies have suggested that the natural organic matter (NOM) present in the cooling water may reduce the amount of scaling by limiting the formation of calcium carbonate precipitation. It is therefore the interest of this study to investigate further the role of the NOM in calcium carbonate precipitation at Hendrina power station. The raw water and cooling water were analysed for the major metal ions, anions, alkalinity, conductivity and total organic matter to determine the precipitation potentials of calcite and aragonite using MINTEQA2 speciation program. The NOM was isolated from the raw and cooling water using ion exchange resins, XAD-8/XAD-4 resins and ultrafiltration membranes with molecular weight cut-offs of 100 kDa, 10 kDa and 1 kDa. The isolated fractions were then characterized by ultraviolet and visible absorbance methods and high performance size exclusion chromatography. The effect of the isolated fractions of the NOM from the cooling water on calcium carbonate precipitation was then investigated. The results indicated the presence calcium carbonate precipitation in the cooling water, but the raw water was undersaturated with calcium carbonate. The NOM isolated from the raw water indicated the predominance of the hydrophobic acid NOM (74.17 %) and to a lower extent the presence of hydrophilic acid NOM (34.49%). The NOM isolated from the cooling water also showed the predominance of the hydrophobic acid NOM (69.25 %) and to a lower extent the presence of the hydrophilic neutral acid NOM (20.13 %) and minimal presence of hydrophilic acid NOM (9.51 %). The results obtained from high pressure size exclusion chromatography analyses indicated that in both the raw water and cooling water the NOM was having a low molecular weight (<13.2030 kDa). The specific ultraviolet absorbance (SUVA) of the raw water was high (>4) which also suggested that it contained predominantly hydrophobic NOM and that of the cooling i water was in the range 2-4 suggesting that it contained a mixture of the hydrophobic and hydrophilic acid NOM. The hydrophobic acid, hydrophilic acid and hydrophilic neutral acid NOM fractions isolated from the cooling water reduced the amount of calcium carbonate precipitate formed in synthetic water sample. This effect was more pronounced with hydrophobic and hydrophilic acid NOM fractions than with the hydrophilic neutral acid NOM fraction. / Dr. M. Shumane

M.Sc. (Zoology) / An investigation was made into the water chemistry, bacteriology and macroinvertebrate fauna of the Elsburg Spruit and its major tributaries within the municipal boundaries of the City of Germiston. From the results obtained it is clear that the main stream and most of its tributaries are seriously affected by a combination of pollutants. Three types of pollution could largely be distinguished namely fecal bacterial contamination of parts of the stream system which may be related to the possible discharge in the stream of domestic sewage. This in turn may be a major source of organic enrichment of the water of the stream at some places. Acid pollution associated with high mineral loads and heavy metal concentrations which in the latter case could be traced to mining regions and industrial areas in the catchment area of the system. Despite the serious disturbance of stream conditions in the upper region of the Elsburg Spruit some recovery does in fact take place in the lower lying regions of the Elsburg Spruit where the stream flows for several kilometers through a natural vlei area. Certain recommendations are made concerning the location and possible elimination of the major sources of pollution.

M.Sc. (Zoology) / Please refer to full text to view abstract

The Hex River Valley is one of the main centres in South Africa for cultivation of table grapes of export quality. The vines require irrigation water, which must be low in dissolved solids. Approximately two thirds of the annual irrigation requirement is obtained from boreholes and the balance from surface water sources. During the early 1960s a deterioration in the quality of the groundwater was noticed, becoming critical in some areas, and borehole yields also declined. The main objectives of this study were therefore to obtain an understanding of the hydrogeological and hydrogeochemical processes operating in the valley to explain the derogation of the groundwater resource and enable optimum utilisation and management of the resource in the future. To achieve these objectives, field work involving exploration drilling, aquifer tests, hydrocensus, long-term monitoring of groundwater levels and surfacewater flows and extensive sampling of the ground and surface waters was carried out. Analysis of these data gave quantitative information on groundwater occurrence, aquifer hydraulic properties, groundwater recharge and storage, chemical characteristics of the ground and surfacewaters and sources of dissolved species. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in