M.Sc. / The increasing demand for water in South Africa arises from a rapid population growth and supporting industrial development. This demand has to be met from limited water resources that are shared by competing user groups and neighbouring states. Deteriorating water quality further limits the sustainable use of water through point and diffuse source pollution of macro constituents, metals and biocides. Metals in the environment can originate as point sources, including industrial and mining effluent, or diffuse sources from geological origin, agricultural activities, acid mine draining and leachate from dumps. Biocides increase crop yields, protect forests and control vectors of serious human disease, but are in the process also carried to water courses. Bioaccumulation studies have been identified as a method to monitor pollutants in the environment. The analyses of data from bioaccumulation studies share a common problem in having to deal with many independent variables, for example variations in time and space, environmental conditions and biological parameters. The objectives of this study were to; investigate the metal levels in water and metal and biocide bioaccumulation in fish tissues from the Berg, Luvuvhu, Olifants and Sabie Rivers; develop a procedure to predict areas and biocides at risk of causing diffuse source pollution and; evaluate the available data and procedures to propose more efficient and cost effective bioaccumulation programmes. The investigation evaluated current and potential contamination of the selected catchments and identified research needs. Fish tissues and water grab samples were collected in the Berg, Luvuvhu, Olifants and Sabie Rivers. The samples were tested for physical variables and analysed for macro constituents and metal levels according to standard analytical procedures. Fish were caught (gill and seine nets) and larger specimens were selected for tissue analyses. Species were identified and standard length, mass, gender, gonadotrophic development index and age indicators were collected. Standard procedures were used to analyse fish tissues for metal levels with the atomic absorption spectrophotometer (AAS) and biocide levels with gas chromatographic methods. A flow diagram of a statistical methodology was developed to incorporate the effects of all biological parameters in the analyses of bioaccumulation data. The procedures used to calculate human health risks are that of the Risk Assistant package reviewed by the United States Environmental Protection Agency (EPA). A Geographical Information System (GIS) model was developed, incorporating the factors affecting runoff of surface water and biocides, to predict areas and variables that could cause diffuse source pollution. The pH values of the rivers studied ranged from of 7.2 to 8.7 except for the Klipspruit River before its confluence with the Olifants River that had a pH of 4.8. Nutrient levels in the Berg River are within the South African guidelines. Nutrients in the Luvuvhu River mostly exceed the guideline values for ortho-phosphate, ammonia nitrogen, nitrate nitrogen and total phosphorus. In the Olifants River the values for ortho-phosphate, total phosphorus, ammonia nitrogen and nitrate and nitrite nitrogen often exceed the South African guideline values. Nutrients in the Sabie River have low concentrations with only ammonia nitrogen exceeding the guideline values. TDS values in the Olifants River is the highest, which is an indication of the high salt loads in the river. The concentrations of various metals in water from the Berg, Luvuvhu, Sabie and Olifants Rivers exceeded the proposed South African and international guidelines.

Ph.D. / Except for agriculture, the mining industry is considered as not only the oldest but also the most important industry. Mining involves the removal of minerals from the earth's crust for usage by mankind. The disturbance during mining activities such as mining effluent has an effect on the natural aquatic environment. In any freshwater environment, the macroinvertebrates form a vital link between the abiotic envinronment and the organisms in higher trophic levels. It is thus true that specific environmental contaminants, such as mining effluent, may directly affect the survival of macorinvertebrates. The density and diversity of macroinvertebrates is in a direct relation with the water quality. For the purpose of this study, attention was given to the effects of gold and coal mine effluent on the macroinvertebrate fauna, as well as to the determination of metal accumulation from the water through the macroinvertabrates to fish. At Case Study Mine One, with an open water system, acidic conditions of the water caused a reduction in the number and diversity of macroinvertebrates. A closed water system, characteristic of Case Study Mine Two, presented a slightly more abudandant macroinvertebrate population than with the previous mine. The results lead one to conclude that the surface water in this study area is of a better quality. Case Study Mine Three had a complex water circuit and presented a greater number and diversity of macroinvertebrates, with the best water quality of the three mines investigated.

D.Phil. / The entire Olifants . River Catchment is subjected to increasing afforestation, agricultural, domestic, mining, industrial, irrigation and urbanisation activities. These activities have a profound effect on the water quality of the river and its tributaries. This is cause for concern for the water users in the upper catchment, and because the Kruger National Park, one of its downstream water users, is extremely dependent on water of a satisfactory quality to sustain its various ecosystems. It is therefore vitally important to determine to what extent activities in the Upper Catchment of the Olifants River (Mpumalanga), especially in the Witbank and Middelburg areas, influence the water quality of the river. Point sources of pollution in the upper reaches include mining and industrial activities as well as water care works located at various points along the river. These were addressed in a Water Research Commission Project (No. 608/1/97) titled "Lethal and sublethal effects of metals on the physiology of fish: An experimental approach with monitoring support". Although sixteen localities were chosen for the initial project, this study only focussed around the metal ecotoxicology at two localities (Steenkool Spruit and Witbank Dam) in the upper catchment and the effect of metals (copper and zinc) on fish blood physiology. In aquatic ecosystems water quality is an important variable and full assessment of water quality, of Steenkool Spruit (locality 3) and Witbank Dam (locality 7), included evaluation of the chemical, physical and biological characteristics at each of the localities. Water and sediment samples were collected seasonally during the study period, February 1994 to May 1995, and the chemical and physical water quality variables were measured. During the study period three metal bioaccumulation indicator species, Labeo umbratus, Clarias gariepinus and Labeo capensis, were captured from which tissue (gills, liver, muscle and skin) samples were collected. These samples as well as water and sediment samples, were analysed for aluminium, chromium, copper, iron, manganese, nickel, lead and zinc concentrations, using atomic absorption spectrophotometry. In the past routine monitoring of chemical and physical water quality characteristics left scientists and managers with a sizeable pool of data which is often difficult but not impossible to interpret. To standardise and summarise this collection of data an aquatic toxicity index (ATI), WATER2 was developed by Wepener et at (1992). The present study attempted to expand and refine WATER2, which has resulted in the establishment of a new ATI, RAUWater.

M.Sc. / The Kruger National Park is internationally one of the best known conservation areas. The perennial rivers draining eastward towards and through the park are of great importance in maintaining a healthy ecosystem. The Olifants River catchment is the largest of all the rivers flowing through the Kruger National Park. Although this river has ceased flow for three days in 1968, problems experienced in the Olifants River are of a qualitative rather than a quantitative nature. Several factors contribute to the deteriorating water quality of the Olifants River. Urbanization, agricultural, industrial and mining activities in the Phalaborwa area pose a threat to the lower parts of the Olifants River. Pollution has on several occasions lead to mortalities of populations of fish in these parts...

Ph.D. / The Crocodile River catchment, in Mpumalanga, is one the most intensively used catchments in South Africa. The large number of intensively cultivated crops grown in the middle and lower subcatchments; industrial discharges; highly intensive irrigation; and extensive areas of exotic afforestation in the upper and middle sub-catchments has dramatically changed land use patterns within the catchment. The Middle Crocodile River sub-catchment is also impacted by intensive urbanisation; around Nelspruit, KaNyamazane and Matsulu. The Kaap River sub-catchment has been intensively mined for minerals and the impacts of these mining operations are still reflected in the water quality of streams and rivers in this sub-catchment. The downstream uses of the Crocodile River's water quality are the aquatic ecosystem, the Kruger National Park (as the river is the southern boundary of the park) and Mozambique (international obligations). The Crocodile River catchment supports one of the richest fish species diversities in South Africa. It is therefore important to determine the impacts of these land use activities on the fish populations and the potential human health risks if fish are consumed. In the present study data from five gauging stations for each of the main tributaries draining the five sub-catchments (the Upper, Middle and Lower Crocodile River, Kaap and Elands Rivers) were used. The water quality and quantity was determined from Department of Water Affairs and Forestry's (DWAF) National Hydrological Chemical Data Bank. Assessments of water quality (chemical, physical), sediment characteristics, and fish biological characteristics were undertaken at each of the chosen sampling sites. Water and fish samples were collected seasonally on ten sampling trips during the study period, June 1989 to September 1992. Eleven species of fish were collected, by means of gill and seine nets, at eight sites. The biological characteristics of the larger fish captured were measured and tissue (gills, liver, muscle, intestine, ovaries, testes and abdominal fat) samples were collected. These samples were analysed for eleven metals and Pyrethroid, Carbamate, Organochlorine, Organophosphate and Triazine pesticides. Sediment core samples were collected and determinations made of particle size, percentage organics, metals and pesticides. Standard methods were used for the determination of .the metal and pesticide concentrations in the water, sediment and fish tissues. The pesticide use per crop for South Africa was determined from a data-base. This data was used to determine the potential pesticide runoff from the different crops in the sub-catchments and to compare with the sediment and fish tissue levels recorded. The water quality status of the Crocodile River catchment is impacted by a variety of diffuse and point sources of pollution. The water quality indicated that diffuse sources of pollution originated from afforestation in the Upper, Middle and Kaap River sub-catchments; current and abandoned mining activities in the Kaap River sub-catchment; runoff from irrigated lands in the Middle, Lower and Kaap River sub-catchments; and wastes from industrial activities in the Elands and Middle sub-catchments. Point sources of pollution in the Crocodile River include ndustrial and waste water treatment works discharges mainly in the Middle sub-catchment.