Methane formation and consumption processes in the littoral zone of the Rybinsk reservoir

Concentrations of CH4 and the rates of processes of its transformation and oxidation are evaluated in the littoral zone of a large polimictic reservoir in the open-water period. The production of CH4 in bottom sediment was found to vary within 0.07 to 17.32 mmol/(m2 day) and attain its maximum in the late summer. The main factors to control the activity of methanogens were found to be the temperature and the availability of substrates (acetate and H2/CO2. The newly formed methane was oxidized in the top soil layer with a rate of 0.09-17.15 mmol/(m2 day). The rates of processes of biogenic production and consumption of CH4 in silts of screened coast were higher than those in sands of the open coastal zone. Methanotrophs were found to consume >87% of the methane produced. These bacteria accounted for ∼20 and 8% of the total oxygen consumption by bottom sediment in the screened and open littoral zones, respectively. © MAIK "Nauka/Interperiodica" 2002.