Microbial processes at the aerobic-anaerobic interface in the deep-water zone of the black sea

摘要

Chemical and key microbiological processes (assimilation of carbon dioxide, oxidation and formation of methane, and sulfate reduction) occurring at the boundary between the acrobic-anaerobic interface in the deep-water zone of the Black Sea were in vestigated. Measurements were taken at depths from 90 to 300 m at intervals of 5-10 m. The integral rate of the dark assimilation of carbon dioxide varied from 120 to 207 mg C/(m_2 day) with a maximum at the boundary of cyclonic currents. The organic matter (OM) formed from methane comprised less thatn 5% of the OM formed from carbon dioxide. A comparison between the rates of methane oxidation and methane production suggests that methane that is oxidized at depths from 100 to 300 m was formed in deeper water horizons. The maximum rate of sulfate reduction (1230 mg S/(m_2 day)) was observed in the western halistatic region, and the minimum rate (490 mg S/(m_2 day)), in the eastern halistatic region. The average rate of hydrogen sulfide production measured at there deep-sea stations amounted to 755 mg S/(m_2 day), or 276 g S/(m~2 year).