Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 100-125) Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 1989.

M.Sc. (Aquatic Health) / Located largely in a semi-arid part of the world, South Africa’s water resources, in global terms are extremely scarce and limited. (South Africa is one of the 30 driest countries of the world). South Africa is already categorised as water stressed with annual freshwater availability of less than 1700 mm³ /person (the index for water stress) (Blignaut and Van Heerden, 2009). South Africa is a water scarce country due to low rainfall (less than 500 mm per annum, some parts less than 200 mm: the average of 475 mm is well below the global average of 860 mm p/a.) and due to the uneven distribution of its water resources (more than 60% of the river flow arising from only 20% of the land area) which is a direct result of the climate and topography of the country (Davis and Day, 1998). South Africa is a large piece of land, far larger than for instance Germany (population of 82.7 million- Bergman and Renwick, 2003). When compared, Germany has 2169 cubic meters of water available per person while South Africa has only 1208 (Bergman and Renwick, 2003). Compared with another arid country, Australia has a population of 19.1 million and freshwater resources of 18 722 cubic meters per person (Bergman and Renwick, 2003). South Africa has close to the lowest conversion of rainfall to usable run-off from rivers of all the countries in the world (South Africa 8.6%, Australia 9.8%, and Canada 66%) (Bergman and Renwick, 2003). South Africa will also be negatively impacted by both changes in climate and the prevalence and spread of alien invasive species (Blignaut and Van Heerden, 2009). Prosperity for South Africa depends upon the sound management and utilisation of many resources, with water playing a pivotal role. Any decrease in the quality and therefore the usability of water in South Africa by 1% may result in the loss of 200 000 jobs, a drop of 5.7% of disposable income per capita, and an increase of 5% or R18.1 billion in government spending. This will further result in a 1% decrease in the GDP growth rate (Du Toit, 2010). This is reiterated by a number of other studies.

A research report submitted to the Faculty of Science, in partial fulfilment of the requirements for the degree of Master of Science, University of the Witwatersrand. Johannesburg, 2016. / Mining and associated anthropogenic activities have improved the livelihoods and economy of many countries but negatively impacted the environment and caused detrimental effects on fresh and ground water systems through the generation of acid mine drainage (AMD). The study evaluated three macrophyte species of P. communis, S.corymbosus and T. capensis for uptake of Mg, P, S, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, and Pb in acid mine drainage polluted water. The concentration of elements was also determined in sediments and water so as to calculate the bioconcentration and translocation factors in various parts of the macrophtes. The homogenised plant samples were milled using a Fritsch Pulverisette 6 Mill into pulverized powder and element analysis was done using Spectroscout Geo+ XRF Analyzer Pro. Sediment samples were digested with microwave assisted extraction and analysed by inductively coupled plasma optical emission spectrometry (ICP-OES). Water samples were analysed directly using ICP-OES after filteration with ICP-OES. The concentration levels of these elements in water were compared in all the sites to determine which section of the site (inflow, midflow and outflow) have high amount of the selected elements. The results indicated that elements distribution varied in all the points where the water samples were collected. The concentration level of sediment was compared to the concentration levels of elements in the roots, rhizomes and leaves to determine the translocation and bio concentration factor (TC and BCF). Drinking water quality standards by international organisations were also used as a guideline to compare the concentration levels of elements found in water. Iron (Fe), Nickel (Ni), Manganese (Mn) and Copper (Cu) to determine whether their concentrations in the water were above or below the acceptable levels. the concentrations of Fe, Ni, Mn and Cu were found to be above the international water quality standards for drinking water and their average concentrations was 2230, 282, 5950 and 14080 μg/l respectively. The study found out that in autumn, Mg, S, P, and Mo were highly accumulated by leaves of T. capensis, S. Corymbosus leaves and rhizomes as well as the P. communis leaves and the highest concentrations were 6.61, 72900, 2.00 μg/g respectively. In autumn, Co was the only element highly accumulated by the roots of T. capensis with the highest concentration of 342.80 μg/g. On the other hand, Cr and Fe, was highly accumulated by S. corymbosus roots with the highest concentration of 279.20 and 10.03 μg/g in summer. In summer, Cr, Mn, Ni, Cu, Zn and Pb were highly accumulated by the roots of P. communis and the concentrations were 279.20, 39390, 204.10, 299.50, 813.80 and 47.5 μg/g respectively. The results show that although the plant species accumulated the elements in various concentrations, there was no plant species that accumulated all the selected elements in higher concentrations than the other plant species. They all accumulated a variety of elements in varying amounts and stored them in their different parts. Finally, in all the three plant species analysed, the leaves were the best accumulator of Mg, S, and Mo, whilst the roots were the best accumulators of Cr, Fe, Co, Ni, Cu, Zn and Pb. Since the translocation and bioconcentration factors showed that the macrophyte species accumulated higher concentrations of elements than water and sediments, they can be regarded as hyperaccumulators. Macrophytes species can uptake and accumulate in their different parts various elements and they have the potential to clean the heavy metal polluted sites due to their phytostabilisation and phytoextraction abilities. / LG2017

Shortened periods of inundation due to water management have led to the encroachment and expansion of Carolina willow (Salix caroliniana) in sawgrass (Cladium jamaicense) marsh communities. Morphologic and physiologic differences between sawgrass and willow have potential consequences for microhabitat conditions and ecosystem function such as a reduction in temperatures and light availability and changes in primary productivity. Since it is a woody shrub, willow is often assumed to exhibit higher rates of transpiration than non woody plants, which in turn can affect photosynthesis and carbon exchange and ultimately wetland water management. In this study willow was found to have higher rates of stomatal conductance (gs) and photosynthesis (Anet) than sawgrass. However, sawgrass had greater intrinsic water use efficiency (WUE) than willow. This suggests that willow is capable of greater gas exchange and carbon assimilation than sawgrass but requires more water. Understanding the implications of willow expansion will improve landscape models of wetland water and carbon exchange and inform water management decisions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Wetlands are some of the most diverse and productive ecosystems on earth. Water-level fluctuations determine the ecological function of shallow lakes and wetlands. Currently, anthropogenic modification to water-level fluctuations is the leading source of ecological degradation in lake and wetland ecosystems worldwide. I used wading birds nesting in Lake Okeechobee, as a model system to address the challenges of environmental restoration within an ecosystem greatly impacted by anthropogenic activities. Specifically, I 1) identified environmental factors most important for predicting the number of wading bird nests, 2) tested the assumptions of both the match-mismatch and the threshold hypothesis by modeling the relationship between nesting success and prey density with foraging habitat availability, and 3) measured the stress response of Great (Ardea alba) and Snowy Egrets (Egretta thula) to hydrologically-mediated changes in food availability. Collectively, the results suggest that the number of nests was greatest when area of nesting substrate was high and water-levels were moderate (3.9 - 4.4 m). Nest numbers dropped when either nesting substrate or foraging habitat was limited. My investigation into the predictions of the match-mismatch and threshold hypotheses found that indeed, prey density can reduce or intensify the effects of a mismatch event. The interaction of prey density and foraging habitat availability was significant and positive in both models. Saturation thresholds existed for both fledging success (147 prey (m^2)^-1) and total productivity (189 prey (m^2)^-1), above which high concentrations of prey could sustain nesting when foraging habitat availability was low. Finally, my studies of the stress response support the hypothesis that hydrologic factors associated with prey availability play an important role in regulating nesting patterns, although the level of food limitation the birds experience at the lake was not as severe as expected. Model selection identified foraging habitat availability as most influential to the nestling Great Egret stress response, whereas foraging habitat availability and prey density both influenced nestling Snowy Egret stress response. Moreover, the Snowy Egret stress response was more sensitive to changes in prey availability than was the Great Egret stress response. Temperature and foraging conditions influenced yolk corticosterone concentrations for both egret species. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

This thesis investigates nutrient contribution to six hyper-eutrophic lakes located within close proximity of each other on the Swan Coastal Plain and 20 kilometres south of the Perth Central Business District, Western Australia. The lakes are located within a mixed land use setting and are under the management of a number of state and local government departments and organisations. These are a number of other lakes on the Swan Coastal Plain for which the majority are less than 3 metres in depth and considered as an expression of the groundwater as their base is below the regional groundwater table throughout most of the year. The limited amount of water quality data available for these six lakes and the surface water and groundwater flowing into them has restricted a thorough understanding of the processes influencing the water quality of the lakes. Various private and public companies and organisations have undertaken studies on some of the individual wetlands and there is a wide difference in scientific opinion as to the major source of the nutrients to those wetlands. These previous studies failed to consider regional surface water and groundwater effects on the nutrient fluxes and they predominantly only investigated single wetland systems. This study attempts for the first time to investigate the regional contribution of nutrients to this system of wetlands existing on the Swan Coastal plain. As such, it also includes new research on the nutrient contribution to some of the remaining wetlands. The research findings indicate that the lake sediments represent a considerable store of nutrients (nitrogen and phosphorus). These sediments in turn control the nutrient status of the lake's water column. Surface water is found to contribute on an event-basis load of nutrients to the lakes whilst the groundwater surprisingly appears to contribute a comparatively low input of nutrients but governs the water depth. Analysis of the regional groundwater shows efficient denitrifying abilities as a result of denitrifying bacteria and the transport is localised. Management recommendations for the remediation of the social and environmental value of the lakes include treatment of the lake’s sediments via chemical bonding or atmospheric oxidation; utilising the regional groundwater’s denitrifying abilities to ‘treat’ the surface water via infiltration basins; and investigating the merits of managed or artificial aquifer recharge (MAR).

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 73-81). Also available on the World Wide Web.

Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004. / "August 2004" Includes bibliography. Also available electronically.