Observations of atmospheric methane and its stable isotope ratio (δ13C) over the Russian Arctic seas from ship cruises in the summer and autumn of 2015

Abstract

The results of experimental measurements of atmospheric methane concentrations and its isotopic composition in the Russian Arctic seas in the summer and autumn of 2015 are discussed. The Keeling plot method and inverse number simulation were used for revealing the factors responsible for elevated methane concentrations over the sea surface. Its maximum concentrations (up to 2050 ppb) were measured over the Kara and Laptev seas, as well as in the port area of Arkhangel’sk. It is shown that tundra and bog ecosystems of Siberia serve as the main sources of methane in the measurement zone (except for the area adjacent to large ports). As a whole, the share of methane from microbiological sources is as high as approximately 43% of the total methane concentrations along the ship route.