[Bacterial processes of the methane cycle in the bottom sediments of Baikal lake].

The activity of methanogenic and methanotrophic bacteria was evaluated in bottom sediments of Lake Baikal. Methane concentration in Baikal bottom sediments varied from 0.0053 to 81.7 ml/dm3. Bacterial methane was produced at rates of 0.0004-534.7 microliters CH4/(dm3 day) and oxidized at rates of 0.005-1180 microliters CH4/(dm3 day). Peak methane production and oxidation were observed in Frolikha Bay near a methane vent. Methane was emitted into water at rates of 49.2-4340 microliters CH4/(m2 day). Rates of bacterial methane oxidation in near-bottom water layers ranged from 0.002 to 1.78 microliters/(1 day). Methanogens and methanotrophs were found to play an important role in the carbon cycle through all layers of sediments, particularly in the areas of methane vent and gas-hydrate occurrence.