Hydrogen Sulfide Contamination of Coastal Lakes at Different Stages of Isolation from the White Sea

The results of studies of four coastal lakes with unique hydrological and hydrochemical structure at different stages of isolation from Kandalaksha Bay of the White Sea are reported for 2012–2019. All waterbodies are characterized by a permanent or seasonal stratified structure; as a result, bacterial sulfate reduction and hydrogen sulfide accumulation, toxic for aerobic life forms, become more active under anaerobic conditions. The highest amount of hydrogen sulfide was recorded in Lake Trekhtsvetnoe, which is at the meromictic stage of isolation.