Reduced Sulfur Compounds in Bottom Sediments of Lakes at Different Stages of Separation from Kandalaksha Bay of the White Sea (Meromictic Lake Trekhtsvetnoe)

Abstract—The paper presents the results of studying bottom sediments of the Lake Trekhtsvetnoe, which is at the meromictic stage of separation from the White Sea (Kandalaksha Bay). The geochemical parameters of bacterial sulfate reduction are considered: the formation and accumulation of different forms of reduced sulfur with respect to the organic matter and reactive iron contents in sediments. The significant content of reduced sulfur compounds (up to 1.47%) and their distribution in the sediments of Lake Trekhtsvetnoe is due to a fairly active sulfate reduction process. The activity of reduction processes is ensured by the input of labile organic matter into sediments, which is formed due to intensively developing microbial communities in the chemocline zone and in the water core of the lake.