Seasonal and Interannual Variations in Physicochemical Parameters and Carbon Isotopic Composition of Lake Beloye (the Selenga Middle Mountains)

The article presents the results of studying the seasonal dynamics of hydrochemical and microbiological parameters of Lake Beloye. The key physicochemical parameters influencing the activity and distribution of degrading bacteria are temperature, organic matter concentration and composition, mineralization, as well as Eh. Research on the influence of seasonal dynamics of physicochemical conditions on microbial communities in Lake Beloye's bottom sediments revealed the active development of a specific alkaliphilic microbial community capable of transforming organic matter. Microbial processes are most intense in the spring and fall, when environmental conditions are most favorable for the development and activity of microbial community. We have detected seasonal peaks in the increase of δ13С organic matter in Lake Beloye’s bottom sediments, which are most likely caused by heterotrophic sulfate-reducing bacteria.