Estimation and comparison of the environmental impacts of acid mine drainage‐bearing river water in the Bor and Majdanpek porphyry copper mining areas in Eastern Serbia

Mining activities in the Bor and Majdanpek mining areas in Eastern Serbia started in 1903 and 1961, respectively. Environmental problems in the Bor mining area began after the opening of the Bor mine. Long‐term pollution of river water in the Bor and Majdanpek mining areas has an environmental impact on East Europe because all of the river water from these mining areas flows into the Danube River. However, the sizes of areas with pollution and the differences between the environmental impacts of the Bor and Majdanpek mining areas are not clear. In order to determine the effects of mining activities on river water in the study area, creation of geochemical maps showing the distributions of sulfate, heavy metals, and arsenic; estimation of threshold values to discriminate anomalous values from background values; and comparison of the environmental impacts of the two mining areas were carried out. High concentrations of SO42−, Fe, As, Cu, and Mn were found in the Bor River, Krivelj River, and Bela River located in the Bor mining area. These rivers are characterized by acidic pH ranging from 2.9 to 6.2. High concentrations of these components were also measured in the Small Pek River and the upper reach of the Pek River. These rivers are located in the Majdanpek mining area and are characterized by weakly alkaline pH (7.3–8.4). The acidic river water in the Bor mining area transports large quantities of heavy metals and arsenic downstream (6,900 t/year of Fe, 42 t/year of As, 910 t/year of Cu, and 187 t/year of Mn). On the other hand, the weakly alkaline river water in the Majdanpek mining area transports smaller quantities of heavy metals and arsenic downstream (160 t/year of Fe, 0.1 t/year of As, 6 t/year of Cu, and 272 t/year of Mn). The environmental impact of the Bor mining area is significantly larger than that of the Majdanpek mining area. In addition, on the basis of the distribution of anomalous values in river water, pollution caused by mining activities reaches the Danube River, which is located more than 100 km from the Bor and Majdanpek mining areas. Concentrations of SO42−, Fe, As, Cu, and Mn in the Bela River in the Bor mining area have been greatly decreased after mixing of acidic polluted water of the Bela River with water of the Timok River containing a high bicarbonate concentration. This fact suggests that river water in the Bor and Majdanpek mining areas has sufficient capacity for neutralization. Considering appropriate countermeasures of environmental reclamation, such as artificial neutralization at some important sources of waste water before discharging the waste water from the mining sites, there is a possibility for environmental reclamation in both mining areas because unpolluted river water in the study area has sufficient capacity for neutralization in a natural system.