ИСТИНА

Methane is an important greenhouse gas playing a major role in dynamics of climate system. This study focused on methane concentration and genesis in various types of ground ice and permafrost sediments of the West Siberian Arctic. The isotopic composition and volume of methane is indicative of conditions under which ground ice and permafrost was forming and is used in paleoclimatic reconstructions. The data on quantity and genesis of methane was collected from various types of ground ice, such as from Holocene and Pleistocene syngenetic ice wedges, and from the large massive tabular ice bodies more than 25 m thick. Isotopic composition of methane in gas bubbles of syngenetic ice wedges formed in Holocene and the ones formed in Pleistocene confirms atmospheric genesis with concentrations below 0.8 pm. Methane entrapped in tabular ice bodies has bacterial genesis and show considerably higher concentration up to 23pm. Anaerobic environment characteristic of tabular ground ice formation and high organic content of solution provided favorable conditions for methane producing bacteria. Methane production in the sediments below the lake taliks followed by differential freezing of the sediments leads to capping of methane. Warmer climatic conditions and thicker snow cover have resulted in permafrost degradation and decrease of ability of frozen sediments to hold accumulated methane which may result in explosions and formation of deep craters in regions on permafrost. This suggests that events of methane release from permafrost will increase in the future making it an important consideration for economic development of West Siberia region.