Current State of Ecosystem of Anchialine Meromictic Mogilnoye Lake (Kildin Island, Barents Sea)

Mogilnoe Lake is a representative of little-studied meromicic water reservoir beyond the Arctic Circle, which has an underground connection with the Barents Sea. This paper presents some aspects of the ecological state of the lake using data on the distribution of sulfur compounds (as a marker of the intensity of anaerobic processes in water reservoir), redox-dependent chlorophenolic compounds, and organochlorine compounds from the group of persistent organic pollutants in bottom sediments and soils of the lake's catchment area. The progression of hydrogen sulfide contamination of lake waters observed throughout the 20 century has been confirmed: an increase in hydrogen sulfide concentrations in the monimolimnion (210 mg/l) and an increase in the boundary of its distribution are observed. The content of reduced sulfur compounds and the features of their distribution in sediments of Mogilnoe Lake are comparable to those in bottom sediments of marine water bodies with euxinic anoxia. It has been shown that the presence of organochlorine compounds (including persistent organic pollutants) in bottom sediments and soils of catchment area of the lake can be associated not only with transfer by air and water flows, but also as a result of anthropogenic/technogenic impact on the lake in the 20 century.