Contamination of groundwater by potential harmful elements from gold mine tailings and the implications to human health: A case study in Welkom and Virginia, Free State Province, South Africa

Abstract Mining of gold in the Welkom and Virginia areas of the Free State Province in South Africa has produced numerous gold mine tailings, which contain a variety of contaminants. The extent of contamination of groundwater in the area was studied by measuring several water quality indicators at eight sampling sites, and within three zones. The overall contamination of groundwater was quantified by computing a Drinking Water Quality Index (WQI). The results revealed that majority of the groundwater in the Welkom and Virginia areas is unsuitable for drinking, as confirmed by high WQIs. At only three sites was the water samples suitable for drinking. One site revealed water to be of very poor quality, while the remainder 40% of the sites indicated water to be of poor quality. The high indicator microbiological counts also affirmed the poor quality of the groundwater. Faecal coliform bacterial counts were 100% non-compliant to drinking water quality limits when compared to the World Health Organization and South African National Standard on Drinking Water 241, while E. coli counts exceeded both the drinking water quality limits at 50% of the sampling sites. Of the potential harmful elements analysed, Pb and Fe were found to be at toxic levels. For Pb, 40% of the water samples exceeded the drinking water quality limits while 63% of water samples were non-compliant for Fe. This result exposes the poor quality of the groundwater in the Welkom and Virginia areas, which poses a serious threat to the health of the local people, as groundwater is their primary source of drinking water. This research highlights the urgent need for mitigation measures to be introduced by the local authorities to improve the quality of the groundwater in the study area.