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Assessment of heavy metal pollution in the sediments of Dwars River, South Africa


 The Dwars River in Limpopo Province, South Africa is being affected by anthropogenic activities such as mining, agriculture and human settlement in its catchment. The objectives of the study were to assess trace metal pollution, to determine possible sources of pollutants in the river and the potential impact on the ecosystem, aquatic biota and humans. Water and sediment samples were collected and analyzed for the following selected metals: Cr, Cu, Fe, Mn, Ni, Pb and Zn. The enrichment factor (EF) and geo-accumulation index (Igeo) were used to determine the extent of trace metal pollution in the sediments. The concentrations of Cr, Fe, Mn, Ni, and Zn in the Dwars River sediments were much higher than the average shale values, which indicated that the contamination of these metals might be caused by human activities. The enrichment factor (EF) results showed that Cr and Ni accumulated to severe enriched level, while the Igeo results indicated that Cr, Mn, Ni and Zn were strongly contaminated in the sediments. The main sources of pollutants in the area were mining, wastewater/sewage and agricultural discharges. This may pose a serious threat to the aquatic biota and potential human health risk. It is therefore recommended that proper management strategies should be taken to minimize the impact of these metals on the river.