Current Ecosystem Status of the Anchialine Meromictic Lake Mogilnoe (Kildin Island, Barents Sea)

Lake Mogilnoe is a representative of insufficiently studied meromictic waterbodies located beyond the Arctic Circle and has an underground connection with the Barents Sea. This paper presents some aspects of the lake environmental status based on data on the distribution of sulfur compounds (as a marker of the rate of anaerobic processes in the waterbody), redox-dependent chlorophenolic compounds, and organochlorine compounds from the persistent organic pollutant group in bottom sediments and soils of the lake catchment area. Hydrogen sulfide contamination of lake waters observed throughout the 20th century has been confirmed to be in progress: an increase in hydrogen sulfide concentrations in the monimolimnion (210 mg/L) and increase in its distribution boundary. The contents and specific features of the distribution of reduced sulfur compounds in Lake Mogilnoe sediments are comparable to those in bottom sediments of marine waterbodies with euxinic anoxia. The presence of organochlorine compounds (including persistent organic pollutants) in bottom sediments and soils of the lake catchment area may be related not only to transport by air and water flows, but also to anthropogenic impact on the lake in the 20th century.