The chemical composition, including mercury, of sediments in lakes of the Murmansk Region exposed to pollution by effluents from the mining industry was studied. It was found that the highly toxic and hazardous for the lake ecosystem chalcophile Hg comes from the activities of apatite-nepheline and copper-nickel mines and mills. In the verticaldistribution of Hg in the sediments at the stations situated near the waterbodies receiving effluents from apatite-nepheline mining, there is a near-surface maximum at sediment core depths of 7 to 14 cm amounting to 0.6 to 2.3 μg/g, which is ten times more than the average background content (0.044 µg/g). These values were an order of magnitude higher than the ISQG and PEL standards for Hg developed by the Canadian Council of Ministers of the Environment. The Bolshaya Imandra water area is classified as “markedly polluted” (class III) according to the Norwegian Pollution Control Authority. Hg content in the top 1‑cm sediment layer varies widely from 0.018 to 1.000 µg/g, and the highest mercury concentrations are found in the areas receiving effluents from the apatitenepheline and copper-nickel industry.