C43A-0782
Observations of Methane Concentration and d13C-CH4 in the East Siberian Sea Waters

Thursday, 17 December 2015
Poster Hall (Moscone South)
Kseniia Shcherbakova1,2, Julia Steinbach3, Henry Holmstrand3, Denis Kosmach4, Elena Panova5, Orjan Gustafsson3, Igor Peter Semiletov6, Natalia E Shakhova6 and Célia Julia Sapart7, (1)Pacific Oceanological Institute FEB RAS, Vladivostok, Russia, (2)National Research Tomsk Polytechnic University, Tomsk, Russia, (3)Stockholm University, Stockholm, Sweden, (4)Russian Academy of Sciences, Pacific Oceanological Institute FABRAS, Vladivostok, Moscow, Russia, (5)Tomsk Polytechnic University, Tomsk, Russia, (6)University of Alaska Fairbanks, Fairbanks, AK, United States, (7)Université Libre de Bruxelles, Brussel, Belgium
Abstract:
Large amounts of methane (CH4) are stored beneath the East Siberian Arctic Shelf (ESAS) within subsea permafrost, as gas hydrates or free gas underneath. With the ongoing climate warming in that region, there is potential for significant release of CH4 to the water column and eventually to the atmosphere. Over a decade of shipboard expeditions has shown enhanced CH4 levels in large parts of the ESAS waters, but we still lack knowledge on which pools are responsible for the releases, as well release mechanisms and removal processes in the water column.

Here we show dissolved methane concentration and d13C-CH4 data from water column profiles along a transect across the outer East Siberian Sea, ranging from 140°E to 170°E, taken during the SWERUS-C3 expedition in summer 2014.

Elevated CH4 levels were observed throughout the transect; reaching a maximum value of 716nM and a median of 30nM. Due to ice cover in large parts, concentration maxima were mainly located close to the surface or around the picnocline, with the exception of bottom maximum close to a seep area around 160 °N. Initial results for d13C-CH4 range from -60 to -47 per mille vs VPDB.

<< Previous Abstract | Next Abstract >>