Peculiarities of the Vertical Profiles of CH4 and CO2 Concentrations in the Arctic Seas Sediments

The distribution of CH4 and CO2 concentrations along marine sediment vertical profiles (up to 4 m depth below the sea floor) from different sectors of the Kara, Laptev and East-Siberian Seas (Russian Arctic Seas) is presented. The symbiotic correlation between their concentrations was shown. The correlation coefficient (R) varied from 0.58 to 0.97 for the sediments of the Kara Sea and it did not depend on the CH4 and CO2 distribution along the vertical sediment profile. The concentrations of CH4 and CO2 synchronously increase with depth in the Kara Sea and the highest concentrations of CH4 and CO2 are observed at 170–190 cm. It has been shown that sulfate reduction process, acetogenesis, methanogenesis and methanogenesis involving dimethyl sulfide leads to CH4 and CO2 parallel formation. The δ13C–CO2 value gradually decreases from − 17 to − 27‰ versus VPDB with the sediment depth. The evidence of CO2 deep origin is the δ13C high average value, varying from − 18 to − 10‰.