Spatial Variations of Methane Distribution in Marine Environment and its Fluxes at the Water-Atmosphere Interface in the Western Sea of Okhotsk

Data of integrated gas-geochemical studies in the 45 cruise of the R/V Akademik M. A. Lavrent'ev in July 2008 were used to study the spatial distribution of methane in the surface seawater layer, the distribution and qualitative composition of hydrocarbon gases in bottom sediments of the northwestern continental shelf, northeastern slope of Sakhalin Island, and Deryugin depression in the Sea of Okhotsk. The specific features of the methane anomalies that form in this case are considered. Tectonic faults and the distribution of oil-and-gas-bearing structures are the main factors governing the formation of hydrocarbon gas fluxes in the study area. The surface water in the entire examined area was found to be oversaturated with methane. A developed model was used to calculated methane fluxes at the water-atmosphere interface and to identify areas with maximal fluxes (up to 324 mol/(km(2) day).