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Prevalence and significance of organic contaminants and metals in aquatic ecosystems in the Ethekwini area of Kwazulu-Natal
Expanded Title:Persistent organic pollutants (POPs) include a group of contaminants that are receiving ever-increasing attention in water and sediment quality surveys and monitoring programmes in many regions of the world. This attention is related to the fact that these compounds and/or their breakdown products are widely acknowledged as a significant health risk to both ecological and human receptors when present at elevated concentrations. (e.g. direct toxicity, endocrine disruptors, carcinogens). In South Africa there is a very poor understanding of the prevalence of and risks posed by POPs in aquatic ecosystems. The incorporation of POP's management, including monitoring, into policy in South Africa is limited because most of what is known is based on international literature. Fortunately, SA is a signatory to Stockholm Convention and investigations are underway. The overarching aim of this research was to perform a reconnaissance survey in a highly industrialised and urbanised area (Durban) for an extensive suite of persistent organic pollutants in aquatic ecosystems, and to estimate the potential ecological and human health risks of measured concentrations. It was found that the concentrations of POP's selected for the study, mainly exceeded the limits. For example, seventeen organochlorine pesticides and/or metabolites were detected in sediment at concentrations exceeding the method detection limit. Toxaphene was the most frequently detected pesticide, at 13 of the 54 stations sampled. Pesticide and/or their metabolite concentrations at numerous stations exceeded sediment quality guidelines. There is a likelihood that polycyclic aromatic hydrocarbon concentrations in sediment in some rivers and estuaries pose a toxic risk to sediment-dwelling organisms (based on a comparison to USA sediment quality guidelines for the protection of sediment-dwelling organisms of North America. Though all estuaries showed higher than acceptable concentrations of POPs in sediment, the greatest toxicological risk was to the sediment of the Amanzimnyama River. Within each river system studied, the suite of organic chemicals detected in the tissue of fish and mussels generally reflected the suite of chemicals detected in the sediment. The notable exception was for chlordane, which was fairly frequently detected in sediment but was never detected in the tissue of fish and mussels. The fish and mussel species sampled thus appear to provide a reliable indicator of contaminants that are being introduced into the catchments of Durban Bay, as well as Mngeni and Isipingo River estuaries. High concentration pose a serious threat to subsistence fishermen in particular. The actual risks of consuming fish or shell-fish was beyond the scope of this study.
Date Published:01/05/2015
Document Type:Research Report
Document Keywords:Environment, Health, Water Quality
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:1977/1/15
ISBN No:978-1-4312-0662-9
Authors:Newman B; Arabi S; Weerts S; Pieters R; Vogt N
Project No:K5/1977
Organizations:CSIR; North West University
Document Size:1 958 KB
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