Species dispersion from a closed Namaqualand metalliferous mine into water sources, South Africa
Abstract
South Africa is faced with challenges related to potable water quality, which has periodically deteriorated, coupled with inconsistent supply of tap water to households. On the other hand, South Africa is an important mining region, and nearly every province has remnants of active and closed metalliferous mining sites. Metalliferous mines produce a large quantity of metalliferous solid waste (MSW), which should be effectively managed to minimise the negative effects as it has the potential to produce acid rock drainage (ARD). The mobility of drainage alters the scarce water resources and aquatic species. These challenges are a primary concern to the community in the arid O’Kiep region, which is located in the Namaqualand district, South Africa, whereby the community has few alternatives to groundwater as a source of drinking water. The aim of this study was to assess species dispersion from a closed Namaqualand metalliferous mine into water sources in O’Kiep, Northern Cape province, South Africa. This study aimed to determine the issues related to the deterioration of the surface water quality from the source to the point-of-use (POU) and contributing to the inadequate drinking water supply and shortages in O’Kiep. Quantitative and qualitative assessments of water quality parameters were taken; and the adverse human health outcomes experienced by the residents were surveyed. Furthermore, disease patterns were estimated based on administered questionnaires. Approximately 88% of community members indicated that the water supplied is often turbid, while a high number of people with teeth discolouration (72%) are living in the area and experience diarrhoea-like symptoms, which are likely associated with the ingestion of toxin-contaminated water. This was confirmed by some physicochemical parameters quantified from the drinking water supply system (DWSS), such as sulfate, that were not within the range prescribed for drinking water quality guidelines (SANS241-1, 2015; WHO, 2011). The statistical models did not suggest physicochemical properties as predictors of any of the health symptoms. However, regular monitoring and evaluation of the DWSS are essential for this vulnerable community. From this, it was recommended that a feasible way for water security in O’Kiep might be groundwater resources, as an alternative source to irregular surface water. The hydrogeochemical parameters of groundwater assessed indicated that the continuous consumption of the groundwater without pre-treatment might result in possible human health risks as the groundwater quality index (GWQI) confirmed that the groundwater quality could be classified as being of moderate concern. Furthermore, the hydrogeochemical indices and cationic exchange values indicated that the aquifer is of inland origin, whereas the piper trilinear diagram revealed that the groundwater type in the area is categorised as saline, which was confirmed by sodium adsorption ratio (SAR). Similarly, the seasonal variation of the hydrogeochemical characteristic changes of an open-pit groundwater (OPGW) near a closed metalliferous mine (CMM) were investigated against standards for drinking and irrigation usage. Based on the results, it was evident that the OPGW quality varied seasonally. The PHREEQC model indicated that cation exchanges played a significant role in the groundwater hydrogeochemical characteristic. Furthermore, the seasonal fluctuation in the groundwater quality was attributed to the water-table-level fluctuations, resulting in some instances in a lack of compliance to the drinking water quality guidelines (SANS241-1, 2015; WHO, 2011).
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