M.Sc. (Aquatic Health) / Previous studies showed that the upper reaches of the Taaibosspruit catchment in the north eastern region of the Free State, contains elevated concentrations of mercury in the sediment. Additional laboratory-based bioaccumulation studies with sediment-dwelling Chironomidae larvae revealed that the mercury was in a bioavailable form, but it was uncertain to what extent this mercury was in the methylated organic form. Therefore, a study to assess the extent of inorganic- and methylmercury contamination in the water and sediment, as well as the uptake of this pollutant by aquatic and aquatic associated biota was undertaken. This study tested the hypothesis that bioaccumulation of mercury occurs in the different trophic levels of the upper reaches of the Taaibosspruit ecosystem. The objectives of this study were to determine the spatial and temporal physico-chemical characteristics of the water and sediment of the Taaibosspruit system; to determine the extent of mercury distribution within the water and sediment of the Taaibosspruit system; to determine the degree of bioaccumulation and possible biomagnification of mercury by the biota from the different trophic levels of the ecosystem in the Taaibosspruit system; to determine the distribution of cadmium, chromium, copper, lead, manganese and uranium within the water and sediment of this system, as well as the degree of bioaccumulation of these metals by invertebrates and fish; and to determine whether the aquatic macroinvertebrate community structures change along the mercury pollution gradient in the Taaibosspruit system. Sampling was done bi-annually at five sites during late high- and late low flow periods. The reference site is situated on a tributary of the Taaibosspruit, which is not directly influenced by discharges from the industrial complex. In situ water quality parameters were determined at each site and the following samples were collected: water, sediment, aquatic rnacroinvertebrates, vertebrates (fish and amphibian species), as well as noninvasive tissue from birds (feathers). The physico-chemical characteristics of the water were determined by measuring the chlorophyll-a concentrations, nutrient levels and suspended solid content. The sediment was analysed for organic content, water content, as well as sediment particle size distribution. The methylmercury concentrations in the water, sediment and biotic components were determined through cold vapour atomic fluorescence spectrometry, whilst inorganic mercury, cadmium, chromium, copper, lead, manganese and uranium concentrations in these samples were determined through inductively coupled plasma mass spectrometry. All analyses were subjected to appropriate quality analysis and quality control procedures. The relationship between environmental mercury exposure and biological effects was determined using changes in the macroinvertebrate community assemblage structure as the biological endpoint. The invertebrate samples were retained for enumeration and lower taxonomic identification in the laboratory. Data were subjected to the appropriate univariate statistical analysis (oneway ANOVA and regression), as well as multivariate statistical analyses (redundancy and principal component) to study spatial and temporal trends in mercury distribution and associated biological responses. This study showed that elevated concentrations of some nutrients and other dissolved solids were present in the system and that the water quality from the upper catchment of the Taaibosspruit (near the industries) had an impact on the downstream sites. The highest mercury concentrations were found at the sites closer to the industrial complex. These concentrations were higher than the concentrations from the reference site and when compared to international mercury guidelines, it was found to be too high. Comparison of the mercury concentrations in the water and sediment with environmental parameters also revealed that some of these parameters significantly influenced the environmental mercury concentrations. It was found that the biota has bioaccumulated mercury, which has resulted in the biomagnification of methylmercury by the biota from the different trophic levels of the ecosystem from this system. The results of the other six metals showed that the highest concentrations were found at the sites closer to the industries, with very high cadmium and copper concentrations in the water at the site where wastewater from the industries enters the system. These high concentrations in the water, suspended particles and sediment resulted in the accumulation of the metals by the biota present in this system. The sediment-dwelling Chironomidae-larvae bioaccumulated these metals to higher levels than the other biota from this system. The response of aquatic macroinvertebrates to high mercury exposure was dearly visible, as the sites where the environmental mercury concentrations were the highest, had low species richness. The environmental variables also influenced the community structure of the macroinvertebrates by reducing the number of different families at the more impacted sites. The results have shown that some of the fauna in the Taaibosspruit system were reduced in favour of the more tolerant families, namely Chironomidae and Oligochaeta. Thus, it was found that Taaibosspruit system is impacted upon by the surrounding industries, namely by enhancing the bioaccumulation of mercury, and influencing the macroinvertebrate community structure.

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2007 / Urban rivers are the most utilised and yet degraded rivers worldwide. The urban rivers of the Western Cape are no different. The Lourens River flows through the agricultural and urban areas of Somerset West in the Western Cape and as a result is subjected to a variety of pollution sources. In the upper reaches this river flows through two large farms where metal containing pesticides are used. Further downstream it passes through an urban area where a variety of pollution sources could contribute to the contamination of the river. The extent to which the Lourens River, and the ecosystem it supports, is affected by metal pollutants is not known. The aim of this study was to determine the concentrations of metals in the Lourens River as well as the contribution of agricultural and urban activities to metal contamination of the river. Sediment and crab (Potamonautes perlatus) samples were collected over a period of one year from seven sites over the length of the river. Sediment samples were also collected from a sedimentation pond on the bank of the river where orchard run-off water is remediated. Preliminary analysis of samples was done for ten metals (AI, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb and Zn). Results from these analyses determined the selection of six metals (AI, Cr, Cu, Fe, Mn and Zn) for further investigation in this study. The concentrations of metals detected in collected samples varied significantly throughout the sampling period. This can be attributed to various factors such as rainfall patterns, the fact that pesticide application varies throughout the year and other urban activities. AI, Cr, Fe and Zn were found in significantly higher concentrations in the urban areas. These higher levels of contamination, relative to the upper parts of the river, can probably be attributed to various urban activities contributing to the contamination of run-off into the river. The sedimentation pond results revealed high concentrations of AI and Fe, while Cu, Cr, Mn, and Zn were found in lower concentrations. All six metals however followed the same pattern where the first four sampling occasions showed higher concentrations than the last three occasions. It can be concluded that agricultural and urban activities do contribute significantly to the metal contamination of the Lourens River.

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

MENVSC / Department of Ecology and Resource Management / South Africa is highly dependent on coal for production of electricity. The combustion of coal for electricity generation produces waste by-products which include fine ash (fly ash) and coarse ash. Fly ash (FA) is produced in large amounts while its utilization is low due to its classification as a hazardous material. Sasol produces about 7 million tons of FA, while Eskom produces about 28 million tons of coal FA annually. FA is a fine by-product from pulverized coal with detrimental effects on plants, soil or land, animals and human beings, and pollutes the air. The present investigation focuses on the examination of the chemical elements bioaccumulation and phytoremediation potential of Indian mustard (Brassica juncea) and Spinach (Spinacia Oleracea L). X-ray fluorescence (XRF) was used to analyze the elemental composition of FA and soil, Scanning Electron Microscope (SEM) to examine the morphology, while X-ray diffraction (XRD) analysis was used to evaluate the mineralogy of FA. The concentrations of metal and non-metal species that are released from FA on contact with water at different conditions were quantified using ICP-MS. Pot culture experiment was conducted to grow Brassica juncea and Spinacia Oleracea L. using FA and soil as growth medium. Leachates from the pots were collected and analysed using ICP-MS. Plant parts from harvested Brassica juncea and Spinacia Oleracea L. were cut separately and analysed using ICP-MS for the concentrations of different metal and non-metal species in plant parts. Plant parts were also used to estimate biomass and chlorophyll content (leaves). To prepare these plant samples for analysis, the powdered plant sample (0.5 g) was digested through aqua regia (HCL:HNO3 = 3:1 (v/v)) to near dryness using hotplate and filled to 100 mL of MilliQ water. The samples were filtered and directly used to determine the chemical elements concentrations. Blanks and internal standards were used for quality assurance during analysis. Chemical elements that are present in FA and sometimes in higher concentrations are associated with detrimental effects in plants, animals and human beings, hence phytoremediation is vital. Bioconcentration factor (BCF) was used to estimate the metal species accumulation ability of the plants from the FA, FA/soil mixtures, while translocation factor (TF) was used to assess the plant species potential for phytoremediation of coal fly ash dumps. Analysis of Varience (ANOVA) was used to statistically test data using Graphpad software package. Relationship between chemical elements in soil, FA and FA+soil growth media and also different plant parts (root, stem and leaf) of B. juncea and S. Oleracea L were calculated using the t - test, ANOVA-Bartlett test, Mann-Whitney Test and Kruskal-Wallis Statistic (KW) depending on each data set. The physicochemical characterization of coal fly ash showed that FA from Grootvlei power station can be classified as class F with an alkaline pH level of 10.62. It showed that particle morphology of this FA had a lower degree of sphericity with irregular agglomerations of many particles while there were dominant spherical particles and smaller sharp needle like particles. It is also an alumino-silicate material as confirmed by the high SiO2 and Al2O3 content, while soil leachates had an average/neutral pH of 7.22 with very high amounts of Si. In both soil and FA, elements that were expected to be readily available to plants included Ca, Si, K, Ba, Mo, Na, Al, Mg, Sr and non-essential elements (Si, Ba, Na, Al, Sr), which, if uptaken by plants’ roots can have negative impacts in plants. Physicochemical analysis of soil, FA and FA+soil leachates showed that the alkalinity of the FA changed over time and there was also a decrease in the EC due to dissolution iv of soluble major oxides, which was promoted by continuous water irrigation. The soil and FA+soil growth media showed similar results. Chemical elements like B, Mn, Fe and Ba were occurring at higher concentrations in leachates for most weeks in the pot culture experiments. However, it was observed that in the eleventh week of leachate collection all these chemical elements decreased to very low concentrations. This suggest that these chemical elements can be reduced over time as plants are being irrigated which is either due to uptake by plants or washed off with water. Statistically, there was a significant difference for different chemical elements of leachates from different growth media for each plant species (B. juncea and S. Olearcea L.). The overall growth rate shows that S. Oleracea L was better than that of B. juncea especially in the FA media over time, while the biomass of the two plant species showed similar results. After all, even though S. Oleracea L had carotenoid content below detection limits, it had higher chlorophyll b than B. juncea for all growth media in general. But, statistically there was no significant difference between the two plant species in terms of growth rate and biomass; even between the plant parts denoting similar growth performance for the two plant species under study. The bioaccumulation potential of the two plant species showed that chemical elements such as Fe, Mn, Ba, Zn and B were highly accumulated by the different parts of the plants. However, the chemical elements such as of Mo, Ni, Cu, and Cr showed the least concentrations. This trend was similar for all growth media and both plant species but this changes over time for different growth media and plant species as increasing and decreasing trends can be noticed. This led to no significant difference between plant species and also growth media, statistically. High BCF values of Fe, Mn, Ba, Zn and B were observed in the different parts of the plants for both plant species. However, Mo, Ni, Cu, and Cr had BCF values less than 1 for most growth media over time. BCF values in plant parts differed with time, growth media and plant species. Translocation of chemical elements shows that the B. juncea plant proved to be an effective phytoremediation plant species since it is effective in translocation of many chemical elements for different growth media to shoots while S. Oleracea L failed to translocate most chemical elements from stem to leaves although it translocated some from root to shoots. Hence, it can be concluded from the study that both species can be used in phytoremediation of coal fly ash dumps but with B. juncea being the most effective accumulator and translocator of many chemical elements. However, it can be recommended that chelating agents like ethylene diamine tetra acetic acid (EDTA) be introduced to solubilize chemical elements from growth media matrix into growth media solution to facilitate the quick transport of chemical elements into xylem, and increase