Peculiarities of CH4 and CO2 Distribution in Sediments of the Arctic Seas

Abstract

The distribution of the concentrations of CH4 and CO2 and other gases in the sediments of the Kara, Laptev and East Siberian seas was studied. A correlation was found between CH4 and CO2 in most sediment cores. The correlation coefficient R for the sediments of the Kara Sea ranges from 0.58 to 0.97 and does not depend on the gas distribution with depth. Methanogenesis in marine sediments is presumably associated with sulfate reduction, and hydrogenotrophic methanogenesis leads to an increase in CH4 concentration against the background of high CO2 concentration. The high concentration of dimethyl sulfide in the sediments indicates the simultaneous formation of CH4 and CO2 through methylotrophic methanogenesis with the participation of CH3SCH3. In the upper layers of the sediment, opposite trends in the CH4 and CO2 distribution can be observed. The fact that the correlation coefficients between CH4 and CO2 gases in the sediments of the Laptev Sea acquire both negative and positive values is probably related to the fact that gas formation processes in the upper layers of the sediment captured by short columns differ from those of deep layers.