Methane in the surface waters of Northern Eurasian marginal seas

More than 12 000 measurements of the dissolved methane (CH4) concentrations in the surface waters of Northern Eurasian marginal seas (Barents, Kara, Laptev, Chukchi, and Bering Seas, Sea of Okhotsk, and Sea of Japan) during two marine expeditions (September–October 2011 and 2012) show that all seas are CH4 source to the atmosphere, but the Laptev and East Siberian seas demonstrate the strongest signal.