Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are common
contaminants of sediment, soils and biological tissues. These compounds pose a significant risk to
biological and ecosystem health and functioning due to these compounds being mutagenic,
carcinogenic and are known to disrupt the endocrine system. The bioaccumulation and
biomagnification potential that these compounds possess mean that they are capable of affecting
the entire food chain and are not limited to the organisms that are directly in contact with the
compounds Even though there has been an increase in the attention on identifying the presence
and impacts that these compounds may have in South Africa, the level of attention is lower than
what it is in other countries around the world. Although South Africa has guidelines in place for
other pollutants, such as metals, there are no such guidelines in place to monitor PAHs and PCBs..
Industries are known to release both PAHs and PCBs, mainly from incomplete burning processes
and the release of oils and fuels in the case of PAHs, and from heat transfer fluids in the case of
PCBs. Durban Bay and surrounding areas of eThekwini, KwaZulu-Natal are highly industrialised
with many aquatic systems, in which these contaminants are likely to deposit. The aim of this
research was to determine the concentrations of these compounds by means of chemical analysis
and additionally biological analysis, using the H4IIE-luc bioassay and compare these levels to
international guideline levels. It was found that the concentrations of the 23 analysed PAHs were
6.5–3 235.6 ng.g-1 and the concentration of the PCBs analysed were 0–113.83 ng.g-1. Many sites
were found to be in exceedance of the guideline limits, particularly in the harbour. Toxic
equivalency factors (TEF) were used to gauge the toxic equivalency (TEQ) of the PAHs and PCBs
that were found. The TEQs were generally low, and were below any guideline levels. The assay
revealed the extract containing the PCBs had a bioassay equivalence (BEQ) of 0–93.54 pgTCDDeq.
g-1 and the extract containing the PAHs of 0–776.08 pgTCDD-eq.g-1. With a proportion of the
sites exceeding guideline limits. The BEQ results were two to three orders of magnitude greater
than the TEQs calculated from the concentrations determined by the instrumental analysis,
however, followed a similar trend. Additionally chemical analysis was not performed on a full suite
of compounds that are able to elicit a response from the cells, which could be a reason why the
BEQ and TEQ did not follow a similar trend among some of the samples. It would have been more
beneficial to have performed chemical analysis on the 16 priority PAHs (as determined by the
United States Environmental Protection Agency), the dioxin-like PCBs and polychlorinated
dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDFs) which are all capable of eliciting a response from the cells and have TEF values. The areas that were most affected by
contamination of these compounds was the harbour and surrounding canals, and there was point
source contamination along the Umhlatuzana, Umbilo, and Amanzimnyana Rivers. All dl-PCBs
should be chemically analysed at all the sample areas, as these cause adverse effects to biota. In
addition to this, biota should be sampled to determine concentrations of the compounds to
determine bioavailability and the degree of bioaccumulation in the food chain. Utilising biomarkers
it would be possible to determine stresses of fish. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/12218 |
| Date | January 2014 |
| Creators | Vogt, Natasha Lee |
| Source Sets | North-West University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
Page generated in 0.1921 seconds