Ph.D. (Zoology) / The present study deals with the effects of metal-polluted aquatic habitats at five different localities on the Witwatersrand and the Orange Free State on the concentrations of lead, nickel, copper and cadmium in the organs and tissues of the Redknobbed Coot, Fulica cristata, the Sacred Ibis, Threskiornis aethiopicus, and the Reed Cormorant, Phalacrocorax africanus. The physical and chemical conditions of the water and the sediments which prevailed during the period of survey at the various sampling sites suggest that concentrations of parameters such as phosphates, nickel and lead in a number of cases exceeded the limits laid down by Kempster et at. (1980) for acceptable river water quality standards in South Africa. The major sources of pollution responsible for these conditions can primarily be related to sewage, mine and industrial effluents (urban) as well as agricultural practices (rural), respectively. Mining activities were largely responsible for the acidification and miniralization as well as metal pollution of the water and sediments, especially so at the Marievale Bird Sanctuary in the Blesbokspruit catchment area. However, automobiles are suspected to contribute much towards the lead concentrations in the water and sediments at all the sampling sites. Levels of cadmium were generally low and may be the only one of the four metals analysed which truly reflected unpolluted, environmental conditions for this metal in the water and sediments of all the sampling sites. The nutrient loads which suggest mild to moderate eutrophication of the water at all the localities can largely be attributed to sewage effiuents and surface runoff waters from the surrounding townships on the Witwatersrand as well as from inorganic fertilizers from farm lands in the vicinity of the Steynsrus and Senekal farm dams in the Orange Free State. These conditions resulted in the overall increase in primary and secondary production of the affected waters which also coincided with the development of submerged and floating water weeds such as Potamogeton pectinatus and Azolla filiculoides, respectively. The herbivorous Redknobbed Coot and to a lesser extent the piscivorous Reed Cormorant, benefitted directly or indirectly from these conditions. Data obtained during the investigation present a complex situation in terms of the environment and the biological availability of the four metals under discussion. A number of factors in both the abiotic and biotic components may have had an effect on fluctuations in metal concentrations. These may have acted individually and/or synergistically, making the interpretation of the data difficult. Cadmium occurred in the lowest concentrations of all four metals in all four the organs and tissues during all four seasons of investigation. In the case of the rest of the metals as well as the organs and tissues no specific, clear seasonal trend or sequence in the concentrations of the metals was discernible. Copper in the kidney and liver and lead in the bone and blood tissues had the highest mean concentrations over the four seasons of investigation. As far as the winter and summer seasonal tendencies are concerned, statistically significant differences occurred in the concentrations of some metals in specific organs and tissues between the winter and summer seasons, respectively. However, values recorded were not necessarily higher during a particular season. Lead (liver) and cadmium (kidney) concentrations were found to be significantly higher in winter 1991 whilst cadmium and copper (both in the blood) were significantly lower during this same season, compared to winter 1992. Concentrations of nickel did not differ significantly between organs and tissues such as the liver and blood for particular seasons. It was only nickel in the kidney and cadmium in the bone tissue which reflected definite seasonal trends for the four successive seasons of investigation.

The present study was conducted to assess selected heavy metal levels (Cu, Fe, Zn, Ni and Pb) in soil and plants that are irrigated by mixed industrial and domestic wastewater in the Buffalo City region. Three types of samples were studied: soil, water and vegetables (spinach and beetroot). Soil analysis showed that most of the heavy metals were found to be acceptable within the SEPA limits. Most of the heavy metal concentrations found in the wastewater indicate that the water is not suitable for irrigation or for livestock use, according to guidelines from the Department of Water Affairs and Forestry of South Africa. The level of copper in the wastewater effluent exceeded the level specified by SEPA limits. In the wastewater the lead concentration averaged 3.24 and 1.98 ppm in Tshatshu (TS) and Mlakalaka (ML) respectively, which shows that both sites are not suitable for both irrigation and livestock usage. The heavy metal levels (Ni, Pb, and Cu) in both spinach and beetroot samples exceed the criteria specified by the WHO and SEPA standards. The study recommends terminating the usage of effluent for irrigation and further investigation or monitoring in these water sources.

M.Sc. / Please refer to full text to view abstract

M.Sc. / Pollutants present in minute concentrations in aquatic environments and which possess long residence times may be accumulated by aquatic organism such as fish, resulting in adverse affects. Bioaccumulation and biomarker responses are often used to qualify and quantify pollutant exposure and effect, and for this reason form a major part of many environmental assessments. To interpret bioaccumulation and biomarker responses the physico-chemical parameters of the environment should be known. This study aimed to spatially and temporally assess the environmental partitioning of heavy metals in three South African freshwater systems, namely the Pongolapoort Dam, Olifants and Luvuvhu Rivers, and to relate these concentrations to bioaccumulation and biomarker responses in tigerfish, Hydrocynus vittatus. This is because there is relatively little known about the bioaccumulation potential and stress responses of tigerfish to pollutants and they have recently become listed as a protected species. Result from this study showed that there were few differences between seasons in terms of metal bioaccumulation in the Pongolapoort Dam with the exception of Se, Zn and Fe. Selenium and Fe concentrations were linked to concentrations found in the environment, whereas Zn was attributed to a disruption in homeostasis within the fish. Increases in MT were found during the winter months and were attributed to increased metal concentrations at this time, namely Zn and Se, whereas decreases in CEA and PC were observed at this time and were linked to depleted energy reserves, stress and a reduction in the presence of pesticides as a result of decreased runoff during the winter months. It was found in the Olifants and Luvuvhu Rivers that there were no distinct decreases in metal concentrations as the rivers flowed through the KNP, and processes such as rainfall, remobilization of sediments, distance of the study area from the source and geology played a great role in the distribution of metals. Metal concentrations in the Olifants River water, sediment and fish were, for the most part, found to be lower than previous studies, possibly due to improvement in management strategies or increased buffering of this river. Only Al and As were significantly higher in tigerfish from the Olifants River, and this was reflected in high MT concentrations. It was suggested that tigerfish from the Olifants River have developed effective mechanisms for the excretion and detoxification of heavy metals that they are exposed to as a result of extended exposure. Concentrations of AChE were also significantly inhibited in tigerfish from the Olifants River which is indicative of greater concentrations of organophosphates and carbamate pesticides than the other sites. Tigerfish from the Pongolapoort Dam had signifcantly higher levels of MT and significantly inhibited concentrations of AChE in comparison to tigerfish from the Luvuvhu River. The tigerfish from the Luvuvhu River had significantly higher concentrations of Se in muscle tissue. Tigerfish from the Luvuvhu River, also experienced stress as a result of pollution as was apparent from significantly depleted energy reserves in comparison to the other sites under study, and higher concentrations of PC and CYP1A which are typical biomarkers responding to halogenated and aromatic pesticides, such as deltamethrin and endosulfan. It was recommended that further studies be done to assess the presence of pesticides within these systems to determine the contribution of these pollutants to the state of tigerfish

Ph.D. / An investigation was made into the physical, chemical and biological conditions of the Elsburgspruit to establish the extent and quality of pollution over a period of two and a half years from January 1987 June 1989. The results obtained during the investigation can be summarised as follows. Serious faecal pollution as reflected by faecal coliforms, faecal streptococci and coliphage organisms occurs over a large stretch of the river, posing a health risk to the people using the recreational area at' Vosloosrust, downstream from the Elsburgspruit near Kathlehong. The occurrence and large numbers of coliphage organisms occurring at certain sampling localities suggest the possible presence of the pathogenic viruses Salmonella, Pseudomonas and Candida. Effluent and seepage waters from mining areas, discharged into the Elsburgspruit were found to be low in pH and high in concentrations of certain metals such as zinc, manganese and iron. Due to the large volume of this particular effluent, the effects thereof on the water quality and fauna of the streams are felt over a distance of more than seven kilometres. As a result, the recovery of the stream from pollution is severely retarded. A number of species of the numerically dominant aquatic and semi-aquatic macrophytes which occurred within the flood-plain of the Elsburgspruit, were found to be able to absorb and to accumulate substantial concentrations of the various heavy metals, directly from the water, or from adjacent moist soils. It was also found that the Spanish reed, Arundo donax, which covers a large area of the wetland region of the Elsburgspruit in its lower section, absorbed and accumulated substantial quantities of the different heavy metals from the water of the stream. A comparison was made of the extent to which metals are deposited into the sediment under both acidic and alkaline conditions...

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