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.
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/1619 |
| Date | January 2006 |
| Creators | Nieuwoudt, Claudine |
| Publisher | North-West University |
| Source Sets | North-West University |
| Detected Language | English |
| Type | Thesis |
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