Ecological and geochemical assessment of the state of the Urup River in the area of the Urupsky Mining and Processing Plant

The article is devoted to a comprehensive ecological and geochemical assessment of the Urup River condition in the zone of influence of the spent tailings pond of the Urup Mining and Processing Plant (MPP). The relevance of the study is due to the long-term negative impact of the tailings pond on the aquatic ecosystem, which is manifested in the accumulation of heavy metals in water and bottom sediments, as well as in the deterioration of the quality of water used for water supply and fisheries. Methods. The research methods included field work on collecting samples of water and bottom sediments at six sections of the river, as well as laboratory analyzes using atomic absorption spectrometry to determine the concentrations of heavy metals (Zn, Cu, Pb, Cd, Ni, Co, Fe, Mn). To assess the pollution, the water pollution index (WPI), concentration coefficient (Kc), bottom accumulation coefficient (BAC) and total pollution index (Zc) were used. Results. The results showed significant excess of maximum permissible concentrations (MPC) of heavy metals in water, especially for Pb (up to 119.7 × MPC), Zn (up to 158 × MPC) and Cu (up to 43.5 × MPC). Water quality class varied from VII («extremely dirty») near the tailings storage facility to V («dirty») in remote areas. Bottom sediments were characterized by high levels of Fe, Mn and Zn accumulation, indicating chronic pollution. The findings of the study highlight the need for ongoing monitoring and implementation of measures to reduce anthropogenic load, including rehabilitation of the tailings storage facility.