Contaminant mobilization from an abandoned polymetallic sulfide mine, Mt. Bobija, Serbia

On top of Mt. Bobija, located in Western Serbia and mainly composed of silt- and limestone, outcrops of a massive triassian sulfide ore body with pyrite, sphalerite, galena, tetrahedrite, and barite mineralizations were mined until the late 20th century. Since then, waste-rock dumps located at 1100 m a.s.l. close to the mine were subject to weathering, potentially releasing harmful elements in dissolved or particulate form to downhill freshwater systems (Orovička reka) via erosion channels. In order to screen the distribution of pollutants and their speciation and evaluate the impact of the mine-waste dumps on downhill freshwater systems, sediment samples were taken along erosion channels up to 3800 m from the waste-rock dumps. The samples were air-dried, sieved <2 mm, and analyzed for their bulk chemistry and mineralogy using XRF spectrometry and XRD, respectively. Speciation of potential pollutants was investigated using the BCR sequential extraction method. Bulk chemistry data of waste-rock dumps showed high contents of Cu (247-7360 mg/kg), Pb (873-87360 mg/kg), and Zn (441-37520 mg/kg) as well as elevated concentrations of As (994-2344 mg/kg), Sb (844-2810 mg/kg), and Hg (350-1108 mg/kg). In this talk, we will specify (1) pollutant concentration trends along erosion channels, (2) the speciation of pollutants with increasing distance of the contamination source, and (3) the potential impact of Mt. Bobija mine wastes on downhill freshwater systems.