Past and present monitoring results of acid mine drainage around copper mines and smelter in Bor, Serbia

The first recorded environmental protests in Bor, Serbia, began in 1906, only 3 years after the mining and smelting of copper ores started. In 1931, one of the first results of chemical analysis of river water were issued, stating that the content of free acid (as H₂SO₄) in Bor River just after the mine was 0.0168 %. Another report from 1935 stated that the pH value of Bor River was 4.5, the concentration of Fe was 81 mg/L, and the concentration of Cu was 22 mg/L. At that time, sampling and analysis of river water were initiated by the rebellious local community who wanted compensation for the damage made to their agricultural fields. Throughout the years, the pollution of Bor River became a norm, and researchers from Serbia and the world investigated the pollution from the physical, chemical, mineralogical, and microbiological aspects. From 2015 to 2021, the pH value of Bor River ranged from 2.1 to 6.3, the concentration of Fe ranged from 66 to 355 mg/L, and the concentration of Cu ranged from 4 to 116 mg/L, depending on the intensity of mining and smelting activities. These more recent results are not so different from those about a century before. However, since the mining and smelting combine Bor changed its ownership in 2018, the monitoring of the pollution became more advanced, and there are more reclamation activities. Several automatic monitoring stations with inductively coupled plasma optical emission spectrometers or mass spectrometers (ICP-OES or ICP-MS) were installed in the field by the polluted rivers for the purpose of monitoring. Water from the largest acid mine drainage accumulation, the Robule Lake, was treated, drained, and in 2023. the Robule Lake does not exist anymore. Additional monitoring and reclamation activities are expected which could reduce the pollution of Bor River in the future.