STATE OF WATER BODIES IN THE AREA OF INFLUENCE OF MINING AND PROCESSING ENTERPRISES (CASE STUDY OF LOVOZERSKY MINING AND PROCESSING PLANT)

Abstract

Introduction. This extended study is the first to analyze the chemical composition of the surface waters and bottom sediments of the lakes affected to various extents by Lovozersky Mining and Processing Plant (Revda urban settlement, Murmansk Region) performing mining and processing of rare metal ores. Methods. During the study, we used data obtained in the course of research in 1995–2005 and 2019–2020. Water and bottom sediment samples were analyzed using various methods. The total contents of elements in the bottom sediments were compared with the background values or, in their absence, with the clarke contents of elements in the Earth’s crust. To assess the level of pollution in the Sergevan River receiving wastewater from the plant, the maximum pollution index was calculated. Results. Over the past 35 years, the chemical composition of the surface waters of nearby water bodies underwent minor changes. No significant excess of maximum permissible concentrations for fishery water bodies was found. The comparison of the contents of heavy metals in the bottom sediments collected from Lakes Ilma and Krivoye with the background values revealed contamination of the Lake Ilma with strontium, zinc and manganese. Besides, a multiple excess of the content of rare earth elements (La, Ce, Pr, Nd), Nb and Ta was established in the bottom sediments of Lake Ilma in comparison with that in Lake Krivoye. The analysis of the river water samples taken at different distances upstream and downstream the site of wastewater discharge confirmed the assumption about the pollution of the Sergevan River by wastewater from the plant. Conclusion. The pollution of the water bodies is mainly caused by wastewater discharged from the plant, however, the increased content of rare earth elements in the bottom sediments of Lake Ilma may be due to air transport of particles of loparite ore concentration tailings, drainage from tailing dams, or degradation of underlying rocks.