Organochlorine compounds in the water of lakes at different stages of isolation from the White Sea

The article presents data on the content and origin of organochlorine compounds (chlorophenolic compounds and volatile chloroform) in stratified water bodies. We carried out a reconnaissance survey of small coastal lakes in the Gulf of Kandalaksha, White Sea (Loukhsky District, Republic of Karelia), not far from the White Sea Biological Station of the Faculty of Biology of the Lomonosov Moscow State University. The study objects were lakes Nizhneye Yershovskoye, Tryokhtsvetnoye, and Bol’shie Khruslomeny, which are currently in different phases of isolation from the sea. A significant content of chlorophenolic compounds in water (up to 49.9 μg/dm3), mainly in the bottom layers of saline meromictic lakes, was determined. Chlorophenolic compounds were represented mainly by mono- and trichlorophenols. Chloroform concentrations ranged from 0.06 to 0.99 μg/ dm3. It has been established that the composition of organochlorine compounds in water of the studied lakes, which are not exposed to direct human impact, was primarily determined by natural sources of these compounds. In the highly reduced conditions of saline lake waters there occurred a decrease in the activity of natural processes of organic matter chlorination with a simultaneous increase in the productivity of reductive dechlorination of chlorophenolic compounds involving anaerobic microorganisms.