Water resources in South Africa are scarce, and should therefore be protected against pollutants, also from persistent organic pollutants (POPs). POPs are a global concern due to their ubiquitous presence, persistence and toxicity. This is emphasised by the Stockholm Convention on POPs, which aims at reducing and ultimately eliminating them. South Africa signed and ratified the treaty, and it became international law on 17 May 2004, but there is still a lack of information regarding POPs in South Africa. This study focussed on establishing the levels of POPs and other organic pollutants, which included various organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), dioxin-like compounds (DLCs), non-dioxin-like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ether (PBDE). Sampling regions included the industrial cities – Cape Town, Richards Bay, Durban and Bloemfontein, and low-income, high density residential areas surrounding a wetland in Soweto/Lenasia and Botshabelo. Additionally, rivers flowing into neighbouring countries, rivers in the vicinity of paper and pulp producers and high altitude rivers were included. Sediment samples were firstly screened for the presence of DLCs by the H4IIE-luc bio-assay, whereafter sites eliciting quantifiable responses were selected for further chemical analysis by high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS). Of the 96 sites, only 23 had quantifiable levels of DLCs. These sites were mainly of industrial, semi-industrial or low-income residential nature. PAHs were the predominant class of compounds at most of the sites, while OCPs and PCBs were present in moderate concentrations and PBDEs in minor concentrations. The concentration of pollutants measured in South African soils and sediments were intermediate when compared to the levels measured in some European, Asian and Scandinavian countries, with the exception of a few sites where exceptionally high levels of compounds were measured. The carbon content normalized concentrations of certain compounds at some of the sites exceeded the Canadian sediment quality guidelines. The estimated cancer risk associated with dermal absorption of OCPs measured in this study was negligible when compared to the background cancer risk expected for South Africans due to life style factors. However, it was estimated that dermal exposure to PCBs, DLCs and PAHs may lead to severe increases in cancer cases, and may seriously impact on human health. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Persistent organic pollutants (POPs) are a threat to the environment and human health because they are ubiquitous, resistant to degradation, can bio-accumulate in organisms and bio-magnify in food chains. They have a detrimental effect on the reproductive, nervous and immunity systems of vertebrates. An international treaty, the Stockholm Convention on POPs, came into force in 2004 and aims to limit and eventually prohibit any use and unintentional production of POPs. South Africa ratified the Convention in 2002. Those compounds currently listed by the Stockholm Convention as POPs include chlorinated pesticides such as dichlorodiphenyltrichlorethane (DDT), chlordane and dieldrin, and industry-related compounds such as polychlorinated biphenyls (PCBs) and hexachlorobenzene. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are also regarded as POPs but - together with some PCBs - they are the unintentional result of anthropogenic activity. This study focussed on the PCDDs, PCDFs and dioxin-like PCBs in the aquatic environment of South Africa particularly because the water resources in this country are under pressure. Despite the fact that South Africa has the sources of these compounds, little is known about the levels of these three groups of compounds. The concentration of twelve dioxin-like PCBs, seven PCDDs and ten PCDFs were determined for 22 sites selected on the grounds of their proximity to possible pollution sources. Analytical determinations included gas chromatography/mass spectrometry and a cell-based bio-assay, the H4IIE-/17C reporter gene assay. Possible sources of the observed pollution were inferred using the following statistical investigative methods: principal component and hierarchical cluster analysis. Seven of the sites had levels higher than the threshold effect concentration of Canada's sediment quality guidelines of 0.85 ngTEQ kg'1 (Toxic Equivalency Quotient). The other sites had lower levels. The highest concentration, 17.8 ng TEQ kg"1, was measured at a site in the southern Gauteng Province. Most of the PCDD/F pollution seemed to have come from combustion sources related to human activity, rather than industrial combustion. Most of the dioxin-like PCB pollution seemed to have been from commercial PCB preparations. Future research would require better characterisation of the sources in order to reduce the formation of these compounds, but also to better understand the exposure and risk scenarios, if humans are to be in close contact with these sources. / Thesis (Ph.D. (Zoology))--North-West University, Potchefstroom Campus, 2008.

Philosophiae Doctor - PhD / Natural products have been a source of many pharmaceutical drugs and a number of drugs that are currently used in the treatment of cancer are derivatives of compounds originally isolated from natural products. There is evidence that extracts of Tulbaghia violacea can be used to treat cancer. The activation of apoptosis in cancer cells is a target for the development of novel anti-cancer drugs since one of the characteristics of cancer cells is resistance to apoptosis due to the deregulation of biochemical pathways leading to apoptosis. In fact, many current anti-cancer drugs exert their effects through the activation of apoptosis. Previous studies showed that extracts of T.violacea induce apoptosis in cancer cells and one study reported on the isolation of a compound (methyl-ԃ-D-glucopyranoside), which is responsible for the pro-apoptotic activity of the T.violacea extract. Therefore the aim of this study was to investigate the anti-cancer activity of methyl-ԃ-Dglucopyranoside and extracts prepared from T.violacea. In this study the pro-apoptotic activity of methyl-ԃ-D-glucopyranoside and extracts prepared from T.violacea were investigated on a panel of human cancer cell lines, which included HepG2, MCF7, H157, HT29 and the non-cancerous cell line, KMST6. The induction of apoptosis was evaluated by flow cytometry using several bioassays which measures biochemical events (caspase activation, phosphatidylserine externalisation and reactive oxygen species (ROS) production that is associated with the induction of apoptosis. The results demonstrated that the effects of methyl--D-glucopyranoside on cultured cells are transient and that the cells recover from the effects of methyl--D-glucopyranoside. This suggested thatmethyl-ԃ-D-glucopyranoside is not the compound responsible for the pro-apoptotic bioactivity in the T.violacea extract. This study also showed that cytotoxic and pro-apoptotic bioactivity of the leaf-extract was significantly higher in comparison to the tuber-extract. The bioactivity of the organic solvent extracts (dichloromethane, hexane, methanol and 50% methanol/water) of T.violacea leaves was also significantly higher than water extracts of T.violacea leaves. A comparison of the different organic extracts prepared from the T.violacea leaves showed that the highest activity was observed for the dichloromethane and hexane extracts. In an effort to identify the bioactive compound(s) the dichloromethane extract was subjected to Versaflash® column chromatography. However, due to problems experienced with the solubility of the dichloromethane sub-fractions, these compounds could not be tested for their bioactivity. Palmitone (16-hentriacontanone) was identified as one of the major compounds present in the dichloromethane sub-fractions. This compound was previously shown to have anticonvulsant bioactivity but there is no evidence in the literature that it has anti-cancer or pro-apoptotic activities. Fingerprinting of the methanol extract showed the presence of long chain fatty acid derivatives, flavonoids and allicin derivatives in the methanol extract. Although, this study failed to isolate the pro-apoptotic bioactive compound(s) present in the extracts of T.violacea, it confirmed that extracts of this plant induce apoptosis in cultured human cancer cell lines.

Concern on a global scale gave rise to the founding of the Stockholm Convention on persistent organic pollutants (POPs) with a view to restrict the use and production of these toxic chemicals. As a signatory, South Africa is legally bound to abide to the Convention’s objectives, including participating in relevant research and monitoring. However, developing countries such as South Africa have limited information concerning POPs, partially because these countries do not have sufficient analytical capabilities, and thus method development and refinement are necessary. One group of POPs consisting of polychlorinated dibenzo-pdioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs), collectively referred to as dioxins, are of particular concern due to their high toxicity and persistence. Additionally, the analysis of dioxins is recognised as one of the most analytically challenging of its kind. This study investigated the effect of different preparatory protocols on the semi-quantification of dioxins using the H4IIE-luc-reporter gene assay. The protocols evaluated were either Soxhlet or pressurised liquid extraction (PLE) combined with a manual acid digestion, gel permeation chromatography (GPC) and Florisil fractionation clean-up procedure as well as the automated Total Rapid Prep™(TRP) system which makes use of a PLE combined with a multi-layer silica, alumina and carbon column clean-up procedure. To evaluate the protocols, an eight point matrix matched calibration curve, two soil samples and a certified reference material (CRM) were used. The extracts were semi-quantified by the H4IIE-luc bio-assay. During the course of the assay, the appropriateness of different standards was investigated, and a mixed standard containing all 17 toxic PCDD/Fs was chosen for quantification. During the data review process, higher bioassay equivalent (BEQ) values were obtained from PLE compared to Soxhlet extraction, while no statistically significant difference (Kruskal-Wallis ANOVA: p > 0.05) was found between the assay quantifications for the different preparatory techniques. However, the results of the H4IIE bio-assay were larger than the expected values. The identity of the chemicals that were in all likelihood responsible for the higher response was investigated through instrumental analysis using comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GCxGC-TOFMS). Instrumental results indicated a high level of PAHs in the extracts, which could lead to super induction of the aryl hydrocarbon receptor (AhR) and therefore, to a positive bias in the results. Instrumental screening proved that all selected preparatory protocols were inadequate at removing interfering compounds and not sufficiently selective for PCDD/Fs, although the TRP was more successful in removing interferences. The high matrix interference hindered peak identification. Additionally, as indicated by instrumental analysis, the weak recovery of PCDD/Fs could be ascribed to high evaporation temperatures. The effect of different reference standards in the H4IIE bio-assay used during semi-quantification needs further investigation; similarly, the optimisation of extraction, evaporation and clean-up protocols and the use of different GCxGC-TOFMS column combinations aimed at more efficient separation needs to be investigated. The assistance of the National Metrology Institute (funded through the Department of Trade and Industry) towards this research is hereby acknowledged. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.

Concern on a global scale gave rise to the founding of the Stockholm Convention on persistent organic pollutants (POPs) with a view to restrict the use and production of these toxic chemicals. As a signatory, South Africa is legally bound to abide to the Convention’s objectives, including participating in relevant research and monitoring. However, developing countries such as South Africa have limited information concerning POPs, partially because these countries do not have sufficient analytical capabilities, and thus method development and refinement are necessary. One group of POPs consisting of polychlorinated dibenzo-pdioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs), collectively referred to as dioxins, are of particular concern due to their high toxicity and persistence. Additionally, the analysis of dioxins is recognised as one of the most analytically challenging of its kind. This study investigated the effect of different preparatory protocols on the semi-quantification of dioxins using the H4IIE-luc-reporter gene assay. The protocols evaluated were either Soxhlet or pressurised liquid extraction (PLE) combined with a manual acid digestion, gel permeation chromatography (GPC) and Florisil fractionation clean-up procedure as well as the automated Total Rapid Prep™(TRP) system which makes use of a PLE combined with a multi-layer silica, alumina and carbon column clean-up procedure. To evaluate the protocols, an eight point matrix matched calibration curve, two soil samples and a certified reference material (CRM) were used. The extracts were semi-quantified by the H4IIE-luc bio-assay. During the course of the assay, the appropriateness of different standards was investigated, and a mixed standard containing all 17 toxic PCDD/Fs was chosen for quantification. During the data review process, higher bioassay equivalent (BEQ) values were obtained from PLE compared to Soxhlet extraction, while no statistically significant difference (Kruskal-Wallis ANOVA: p > 0.05) was found between the assay quantifications for the different preparatory techniques. However, the results of the H4IIE bio-assay were larger than the expected values. The identity of the chemicals that were in all likelihood responsible for the higher response was investigated through instrumental analysis using comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GCxGC-TOFMS). Instrumental results indicated a high level of PAHs in the extracts, which could lead to super induction of the aryl hydrocarbon receptor (AhR) and therefore, to a positive bias in the results. Instrumental screening proved that all selected preparatory protocols were inadequate at removing interfering compounds and not sufficiently selective for PCDD/Fs, although the TRP was more successful in removing interferences. The high matrix interference hindered peak identification. Additionally, as indicated by instrumental analysis, the weak recovery of PCDD/Fs could be ascribed to high evaporation temperatures. The effect of different reference standards in the H4IIE bio-assay used during semi-quantification needs further investigation; similarly, the optimisation of extraction, evaporation and clean-up protocols and the use of different GCxGC-TOFMS column combinations aimed at more efficient separation needs to be investigated. The assistance of the National Metrology Institute (funded through the Department of Trade and Industry) towards this research is hereby acknowledged. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.

South Africa ratified the Stockholm Convention (SC), which became legally binding on 17 May 2004. This Convention targets 12 particularly toxic persistent organic pollutants (POPs) for virtual elimination. The Convention also requires parties to reduce the release of organochlorine pesticides and the intentionally- and unintentionally-produced POPs such as dioxins, furans and polychlorinated biphenyls (PCBs) (referred to as dioxin-like chemicals). Dioxins are a heterogeneous mixture of chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) congeners. These substances were never intentionally produced but are produced as by-products of industrial processes (such as metallurgical processes and bleaching of paper pulp). They can also be formed during natural processes such as volcanic eruptions and forest fires. The largest contributor to releases of PCDD/Fs in the environment is incomplete combustion from waste incinerators leading to the unintentional production of these compounds. Polychlorinated biphenyls (PCBs) are used in transformers and capacitors, but can also be formed unintentionally during industrial and thermal processes. Dioxin-like chemicals (PCDD/Fs and/or PCBs) are classified as persistent because of the following characteristics: lipophilicity and hydrophobicity; resistance to photolytic, chemical and biological degradation and they are able to travel long distances. As South Africa is a semiarid region, POPs will be less prone to travel here because these substances favour colder regions with high soil organic matter. Fish, predatory birds, mammals (including humans) absorb high concentrations of POPs through the process of bio-concentration, leading to bio-accumulation of these substances in the fatty tissue. PCDD/Fs occur as unwanted trace contaminants in air, water, land, in residues and products (such as consumer goods e.g. paper and textiles). The distribution of these chemicals into various matrices is problematic since they cause damage to the environment and human health. These chemicals pose a threat to human health when found in high concentrations that may lead to acute hepatoxicity and dermal toxicity (chloracne). Long-term exposure to low concentrations of these substances might lead to chronic effects such as reproductive problems and carcinogenicity. Since ferrous and non-ferrous metal production is a source of dioxin-like chemicals, a platinum mine in the Limpopo Province, South Africa, was selected for this investigation. The aim of the study was to determine if there are dioxin-like chemicals associated with platinum mining and processing, and if the H4IIE reporter gene bio-assay could be used to semi-quantify and assess the potencies of the complex environmental and process samples by determining their Toxic Equivalency Quotients (TEQ). The implications of the sources to the formation of dioxin-like chemicals regarding the SC were investigated and recommendations were made to improve this study. Samples were collected from tailings dams, woodchips, a dumpsite and slag from the smelter at Union Section. Samples were extracted with the Soxhlet apparatus using hexane as solvent. The percentage total organic carbon (%TOC) was determined for each sample to normalise the data. The method used was the Walkley-Black method. In determining the TEQ of each sample, the H4IIE luc cell line was used. The cells of the H4IIE luc line are genetically modified rat hepatoma cells stably transfected with a luciferase firefly gene. The luciferase gene is activated by the presence of dioxin-like compounds and the concentration of the enzyme is measured as relative light units (RLUs). The amount of RLUs is directly proportional to the dioxin load in the extract. This method is rapid, cost and time-effective in determining the TEQ when compared to chemical analysis. The TEQ2o-valuesin the various samples, as determined with the H4IIE luc cell line, ranged from 0.007 ngTEQ/kg to 54.06 ngTEQ/kg. Thermal processes at the smelter, sorption of hydrophobic organic compounds (HOCs) to soil and tailings, and external sources such as anthropogenic activities contributed to high TEQ2o-values. Climatic conditions, wind, precipitation, and solubility of HOCs into surfactants lead to low TEQ20. The smelter at Union Section had a very high TEQ20of 44.62 ngTEQ/kg compared to Impala Platinum mine (5.15 ngTEQ/kg). This implies that workers at Union Section are possibly exposed to low and high concentrations of dioxin-like chemicals. Long-term exposure to these compounds could lead to bio-accumulation in the fatty tissue of the mine workers, leading to chronic effects such as reproductive problems and cancer. The air emission of the furnace at the smelter was 0.03 gTEQ/annum and the release of the PCDD/Fs into the slag was 0.60 gTEQ/annum. By effectively managing the smelter it is possible to reduce the TEQ. The TEQ of each sample increased due to normalising the data. The normalised TEQ20 ranged from 0.94 ng TEQ/kg to 42497.48 ngTEQ/kg. Dioxin-like chemicals are present on a platinum mine, but at varying quantities and the effects of these compounds might be detrimental to the environment and the workers at the platinum mine. Further analyses of the health impacts associated with the platinum mine are needed. The H4IIE reporter gene bio-assay could be used to effectively determine the TEQ of each sample. Although this investigation has identified the formation and presence of dioxin-like chemicals at certain stages of mining and processing, not all of the processes were investigated. Some of these processes have the potential to add, and even destroy, these chemicals, affecting potential human exposure and amounts released to the environment. This, however, requires further investigation. The financial assistance of the National Research Foundation (NRF) towards this research is hereby acknowledged. Opinions expressed and conclusions arrived at, are those of the author and are not necessarily to be attributed to the NRF. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.

South Africa ratified the Stockholm Convention (SC), which became legally binding on 17 May 2004. This Convention targets 12 particularly toxic persistent organic pollutants (POPs) for virtual elimination. The Convention also requires parties to reduce the release of organochlorine pesticides and the intentionally- and unintentionally-produced POPs such as dioxins, furans and polychlorinated biphenyls (PCBs) (referred to as dioxin-like chemicals). Dioxins are a heterogeneous mixture of chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) congeners. These substances were never intentionally produced but are produced as by-products of industrial processes (such as metallurgical processes and bleaching of paper pulp). They can also be formed during natural processes such as volcanic eruptions and forest fires. The largest contributor to releases of PCDD/Fs in the environment is incomplete combustion from waste incinerators leading to the unintentional production of these compounds. Polychlorinated biphenyls (PCBs) are used in transformers and capacitors, but can also be formed unintentionally during industrial and thermal processes. Dioxin-like chemicals (PCDD/Fs and/or PCBs) are classified as persistent because of the following characteristics: lipophilicity and hydrophobicity; resistance to photolytic, chemical and biological degradation and they are able to travel long distances. As South Africa is a semiarid region, POPs will be less prone to travel here because these substances favour colder regions with high soil organic matter. Fish, predatory birds, mammals (including humans) absorb high concentrations of POPs through the process of bio-concentration, leading to bio-accumulation of these substances in the fatty tissue. PCDD/Fs occur as unwanted trace contaminants in air, water, land, in residues and products (such as consumer goods e.g. paper and textiles). The distribution of these chemicals into various matrices is problematic since they cause damage to the environment and human health. These chemicals pose a threat to human health when found in high concentrations that may lead to acute hepatoxicity and dermal toxicity (chloracne). Long-term exposure to low concentrations of these substances might lead to chronic effects such as reproductive problems and carcinogenicity. Since ferrous and non-ferrous metal production is a source of dioxin-like chemicals, a platinum mine in the Limpopo Province, South Africa, was selected for this investigation. The aim of the study was to determine if there are dioxin-like chemicals associated with platinum mining and processing, and if the H4IIE reporter gene bio-assay could be used to semi-quantify and assess the potencies of the complex environmental and process samples by determining their Toxic Equivalency Quotients (TEQ). The implications of the sources to the formation of dioxin-like chemicals regarding the SC were investigated and recommendations were made to improve this study. Samples were collected from tailings dams, woodchips, a dumpsite and slag from the smelter at Union Section. Samples were extracted with the Soxhlet apparatus using hexane as solvent. The percentage total organic carbon (%TOC) was determined for each sample to normalise the data. The method used was the Walkley-Black method. In determining the TEQ of each sample, the H4IIE luc cell line was used. The cells of the H4IIE luc line are genetically modified rat hepatoma cells stably transfected with a luciferase firefly gene. The luciferase gene is activated by the presence of dioxin-like compounds and the concentration of the enzyme is measured as relative light units (RLUs). The amount of RLUs is directly proportional to the dioxin load in the extract. This method is rapid, cost and time-effective in determining the TEQ when compared to chemical analysis. The TEQ2o-valuesin the various samples, as determined with the H4IIE luc cell line, ranged from 0.007 ngTEQ/kg to 54.06 ngTEQ/kg. Thermal processes at the smelter, sorption of hydrophobic organic compounds (HOCs) to soil and tailings, and external sources such as anthropogenic activities contributed to high TEQ2o-values. Climatic conditions, wind, precipitation, and solubility of HOCs into surfactants lead to low TEQ20. The smelter at Union Section had a very high TEQ20of 44.62 ngTEQ/kg compared to Impala Platinum mine (5.15 ngTEQ/kg). This implies that workers at Union Section are possibly exposed to low and high concentrations of dioxin-like chemicals. Long-term exposure to these compounds could lead to bio-accumulation in the fatty tissue of the mine workers, leading to chronic effects such as reproductive problems and cancer. The air emission of the furnace at the smelter was 0.03 gTEQ/annum and the release of the PCDD/Fs into the slag was 0.60 gTEQ/annum. By effectively managing the smelter it is possible to reduce the TEQ. The TEQ of each sample increased due to normalising the data. The normalised TEQ20 ranged from 0.94 ng TEQ/kg to 42497.48 ngTEQ/kg. Dioxin-like chemicals are present on a platinum mine, but at varying quantities and the effects of these compounds might be detrimental to the environment and the workers at the platinum mine. Further analyses of the health impacts associated with the platinum mine are needed. The H4IIE reporter gene bio-assay could be used to effectively determine the TEQ of each sample. Although this investigation has identified the formation and presence of dioxin-like chemicals at certain stages of mining and processing, not all of the processes were investigated. Some of these processes have the potential to add, and even destroy, these chemicals, affecting potential human exposure and amounts released to the environment. This, however, requires further investigation. The financial assistance of the National Research Foundation (NRF) towards this research is hereby acknowledged. Opinions expressed and conclusions arrived at, are those of the author and are not necessarily to be attributed to the NRF. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.

Water resources in South Africa are scarce, and should therefore be protected against pollutants, also from persistent organic pollutants (POPs). This is emphasised by the Stockholm Convention on POPs, which aims at reducing and ultimately eliminating POPs. South Africa signed and ratified the treaty, and it became international law on 17 May 2004. POPS are highly stable, toxic, hydrophobic and lipophilic compounds, with the ability to accumulate in biological tissues. Previous research had shown that dioxin-like POPS are present in the aquatic environments of South Africa, with the highest concentrations of these substances measured in industrialised areas of South Africa. The present study aimed at investigating the extent of polychlorinated dibenzo-para-dioxin (PCDD), polychlorinated dibenzo-furan (PCDF) and polychlorinated biphenyl (PCB) pollution in the Vaal Triangle, by targeting aquatic sediments and biota. Sediment samples were collected from the Blesbok Spruit, Taaibos Spruit, Leeu Spruit and Suikerbosrand River, and fish tissue samples were collected from Blesbok Spruit and Suikerbosrand River, to determine bio-accumulation. The samples were extracted with organic solvents, cleaned-up and fractionated. Raw extracts and fractions were analysed with the H4IIE-luc reporter gene bio-assay. This bio-assay is a rapid, sensitive and relatively cost-effective method, which measures the effects of dioxin-like compounds on rat hepatoma cells, transfected with firefly luciferase gene. Selected samples were analysed with gas chromatographylmass spectrometry (GCIMS) to confirm results. Only one site had quantifiable amounts of dioxin-like substances in the sediment, measured to be 52.35 ng/kg [Effective Concentration 50 (EC 50)]. This value exceeds many of the European and USA quality guidelines, proposed for sediments. No dioxin-like substances were found in fish tissues. The absence of PCDD/Fs and PCBs in aquatic sediments and fish tissues from the Vaal Triangle area might be due to the climatic conditions of the area, dilution effects in streams, and degradation of these compounds by UV-radiation and microbial organisms. / Thesis (M. Environmental Science (Water Science))--North-West University, Potchefstroom Campus, 2007.

Water resources in South Africa are scarce, and should therefore be protected against pollutants, also from persistent organic pollutants (POPs). This is emphasised by the Stockholm Convention on POPs, which aims at reducing and ultimately eliminating POPs. South Africa signed and ratified the treaty, and it became international law on 17 May 2004. POPS are highly stable, toxic, hydrophobic and lipophilic compounds, with the ability to accumulate in biological tissues. Previous research had shown that dioxin-like POPS are present in the aquatic environments of South Africa, with the highest concentrations of these substances measured in industrialised areas of South Africa. The present study aimed at investigating the extent of polychlorinated dibenzo-para-dioxin (PCDD), polychlorinated dibenzo-furan (PCDF) and polychlorinated biphenyl (PCB) pollution in the Vaal Triangle, by targeting aquatic sediments and biota. Sediment samples were collected from the Blesbok Spruit, Taaibos Spruit, Leeu Spruit and Suikerbosrand River, and fish tissue samples were collected from Blesbok Spruit and Suikerbosrand River, to determine bio-accumulation. The samples were extracted with organic solvents, cleaned-up and fractionated. Raw extracts and fractions were analysed with the H4IIE-luc reporter gene bio-assay. This bio-assay is a rapid, sensitive and relatively cost-effective method, which measures the effects of dioxin-like compounds on rat hepatoma cells, transfected with firefly luciferase gene. Selected samples were analysed with gas chromatographylmass spectrometry (GCIMS) to confirm results. Only one site had quantifiable amounts of dioxin-like substances in the sediment, measured to be 52.35 ng/kg [Effective Concentration 50 (EC 50)]. This value exceeds many of the European and USA quality guidelines, proposed for sediments. No dioxin-like substances were found in fish tissues. The absence of PCDD/Fs and PCBs in aquatic sediments and fish tissues from the Vaal Triangle area might be due to the climatic conditions of the area, dilution effects in streams, and degradation of these compounds by UV-radiation and microbial organisms. / Thesis (M. Environmental Science (Water Science))--North-West University, Potchefstroom Campus, 2007.