Ecological Risk of Toxic Metal Contamination in Soil around Coal Mine and Thermal Power Plant

Soil samples were collected near the thermal power plant and coal mine (Gacko, Republic of Srpska, Bosnia and Herzegovina) and analyzed to measure the concentration of 16 toxic metals (Pb, Cd, Cr, Ni, Zn, Cu, Hg, As, Mo, Co, Ba, V, Tl, B, S and F). The pollutant with the highest mean concentration was B (3,210.02 mg/kg), followed by the Ba (242 mg/kg), Zn (109.50 mg/kg), V (90 mg/kg), Ni (82.10 mg/kg), Cr (60.22 mg/kg), Cu (46.28 mg/kg), Pb (38.90 mg/kg) and Co (19.25 mg/kg). From the evaluation of the soil pollution indices (contamination factor (CF), pollution load index (PLI), ecological risk assessment (ERI), geoaccumulation index (Igeo) and degree of soil load), it can be seen that the studied soil samples in most cases are contaminated. CF values indicate that all values for Cu, Co, Ba and Va in all samplers, Ni in three samplers and Zn in one sampler indicate a moderate degree of contamination. In all soil samples, the values PLI indicates the presence of soil pollution. This study reveals that Ni for RI index is the toxic metal that poses the highest ecological threat. In according average values for Igeo for all toxic metals are > 5, it can be concluded that the soil belongs to the class "extremely polluted ". The values of degree of soil load for Ba and V load show that V class is a land of very high load (limit values in according of national legislation for Ba is 160 mg/kg and for V is 42 mg/kg). Values for Ni load show that IV class is a land of high loads (limit value 35 mg/kg). In accordance with the obtained results, it is necessary to prioritize the work on sustainable solutions to mitigate the current risks.