Geochemical characteristics and estimation of groundwater pollution in catchment areas of Timok and Pek Rivers, Eastern Serbia: Determination of early-stage groundwater pollution in mining areas

Long-term mining activities in the Bor and Majdanpek porphyry copper mining areas located in Eastern Serbia have led to serious environmental problems, the most notable being surface water pollution by heavy metals downstream of the mining sites. However, the geochemical characteristics and environmental impact on groundwater in the mining areas are not clear. This study clarified the geochemistry of groundwater in catchment areas of Timok and Pek Rivers including the Bor and Majdanpek mining areas. In this study, it was also examined whether the combination of geochemical maps and threshold values is appropriate for determination of early-stage groundwater pollution associated with mining activities. Groundwater in the study area was characterized by pH values from 6.4 to 8.8 and a high concentration of HCO3. Groundwater outside the Bor mining area was of good quality and had a low content of trace elements. High concentrations of Ca2+ and SO42- in groundwater were distributed along polluted rivers with mining wastes such as tailings downstream of the Bor mining area, especially in the area along Bela River. The actual concentrations of Ca2+ and SO42- in those groundwater samples exceeded the threshold values that were estimated in this study as the highest natural background concentrations. The anomalous concentrations of Ca2+ and SO42- in groundwater along the polluted rivers are therefore thought to have been caused by mining activities of the Bor mine. Calcium and sulfate anomalies that were estimated by the combination of geochemical maps and threshold values are good indicators for monitoring of early-stage groundwater pollution caused by mining activities in the study area. The procedure of evaluation for early-stage groundwater pollution used in this study is appropriate and widely applicable for the environmental assessment of groundwater having neutral pH in many mining areas.