The spatial distribution of trace element contaminants, associated with gold mining, in lakes, dams, and pans across Benoni, Ekurhuleni

Du Plessis, Devon Murphy
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The City of Benoni, like many other cities in Gauteng, is synonymous with the extensive mining of gold in the Witwatersrand region. The city has several major tailings dams and mine dumps to the centre of the area, which can pose a possible risk of trace metal contamination in the several noticeable dams and pans that can be found within the area. Through extensive fieldwork and x-ray fluorescence (XRF) analysis of various sediment samples taken from several dams and pans across the region, a comprehensive understanding of the spatial distribution of trace metals (As, Cu, Fe, Mn, Ni, Pb, and Zn) associated with gold mining was identified. Further, from this, the distribution of trace metals within each site was also analyzed to identify and consider the varying nature of individual site dynamics. In order to identify the level of pollution at each site, a geoaccumulation index was undertaken, based on natural background levels for the areas. The sites that came across as being the most contaminated across the entire region were Amata Pan, Homestead Dam and Kleinfontein Dam. Amata Pan which is situated further south of the concentration of tailings dams, was the most polluted of all sites, with the main reason being the apparent dumping of oil at the site by a large springs manufacturing company. The most likely source of trace metals at Kleinfontein dam is the large mine dump situated right on the bank of the dam. The possible sources of contamination of Homestead Dam may come from the N12 freeway that is situated south of the site and the inflow of two rivers into the dam. Due to the predominance of wind in the area, there is some contribution of trace metals, across the entire region, from the main tailings’ dams and mine dumps towards the centre of the city area.
A dissertation submitted to the Faculty of Science, in fulfilment of the requirements for the degree of Master of Science, School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, 2019
Du Plessis, Devon Murphy. (2019). The spatial distribution of trace metal contaminants, associated with gold mining, in lakes, dams, and pans across Benoni, Ekurhueni. University of the Witwatersrand,