Geochemical assessment of soil and water around abandoned gold mine tailings dams: evidence from the Welkom Goldfield, South Africa

Gold mining in Welkom, South Africa, has generated abandoned mine tailings containing potentially toxic elements, some located near residential and agricultural areas. This study evaluated soil and water geochemistry around abandoned tailings, emphasising ecological and human-health risks. Soil and water samples were collected near and away from abandoned mine tailings and analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Soil samples were assessed for total and leachable element concentrations. Water contamination was quantified by computing a drinking water quality index (WQI). Mean soil concentrations (mg/kg) were highest for Fe (18,425), Mn (273) and Cr (200), often highest near tailings. Uranium, detected for the first time in the area, reached 49 mg/kg. Manganese had the highest leachable concentration (15 mg/kg), while As ranged from 3 to 304 mg/kg and exceeded the Dutch (2000) and South Africa’s Department of Environmental Affairs (2008) regulatory limits of 29 and 5.8 mg/kg, respectively. Contamination indices indicated low to high contamination of As, Co, Cr, Ni, Pb and U. Considerable potential ecological risks (E r i ), were noted for As (630) and Pb (85). In water, As, Mn and U exceeded the WHO (2022) drinking water and South Africa’s National Water Act (1998) discharge limits indicating contamination, with acidity driving mobilisation of chemical elements. High WQIs revealed that most of the water is unsuitable for drinking. These findings highlight notable mining related impacts on soil and water and further multidisciplinary research on dust, food crops and human exposure pathways are recommended.