Assessment of soil pollution with heavy metals in the area of tailings dump influence of the Urup mining and processing plant using a wide range of environmental indices

Introduction. Non-ferrous metallurgy enterprises are sources of pollution of adjacent territories. The Urup Mining and Processing Plant (MPP) is the largest mining and processing company for copper, gold and platinum in Southern Russia. The pulp (sludge) of the tailings dump contains a large amount of HM, which are capable of migrating and polluting the soil in the surrounding area. The purpose of the research was to assess the presence and degree of HM soil contamination in the area of influence of the Urupsky MPP tailings dump using a wide range of environmental indices. Materials and methods. The total content of HM (Zn, Cu, As, Cr, Pb, Co, Ni, Sr, V) was determined in powdered soil samples using the X-ray fluorescence method. The presence and degree of soil contamination with HM were assessed using individual and complex calculated indices: the unified pollution index (PI), the pollution index (ZC), the potential environmental risk (PERI), the pollution load index (PLI), the pollution protection index (CSI), the Nemerov pollution index (PINemerov), the pollution probability index (MERMQ), the total background enrichment coefficient (PIN). Results. At a distance of 5 m from the tail, the content of Zn in the soil (0–10 cm) exceeds the concentration in the background soil by 14 times, Cu by 10 times, As by 10 times, Co by 2 times, Ni by 2 times. According to the content of heavy metals in the soil, they form the following series: Zn > Cu > As > Cr > Pb > Co > Ni > Sr > V. Discussion. As the distance from the Urupsky MPP tailings dump increases, the content of HM in the soil decreases. A comparative assessment of the environmental indices showed different degrees of their environmental rigidity (in descending order): PINemerov> PLI > CSI > MERMQ > PIN > PERI = ZC. Conclusion. Judging by most of the environmental indices used, soil pollution is observed only in the immediate vicinity of the tailings dump at a distance of up to 100 m. Resume. The pollution load Index (PLI) and the Nemerov index (PINemerov) are the most “severe” (sensitive), while the total pollution index and potential environmental risk are the “mildest”. It seems advisable to apply the environmental indices of soil pollution of HM in environmental practice, taking into account their environmental rigidity. Suggestions for practical applications and directions for future research. The practical significance of the study lies in the fact that an environmentally safe distance from the tailings dam of the Urupsky MPP has been established. However, it should be borne in mind that the investigated tailings dump has been operating for only 7 years, therefore, soil contamination with HM may increase over time. Accordingly, it is necessary to monitor this process over time.