Source evaluation of atmospheric methane over western Siberia using double stable isotopic signatures

We measured the stable carbon and hydrogen isotope ratios of atmospheric methane (CH4) from western Siberia to obtain information about local CH4 sources. Isotopic mass balance calculations yielded stable hydrogen and carbon isotope values for CH4 released in the Surgut region, ranging from −50‰ to −33‰ and −484‰ to −420‰, respectively. These isotopic source signatures could not be understood in terms of mixing of CH4 from major sources in this region, which include natural wetlands and oil/gas fields. Based on this observation, we suggest the necessity for further investigation of the distribution and isotopic values of CH4 sources in this region.