Methane in waters and bottom sediments of the North (Severnaya) Dvina mouth area in 2004-2006

Maximum methane concentrations in water and sediments were registered in the delta in segments of channels and branches with low rates of tidal and runoff currents, where domestic and industrial wastewaters are supplied.

In the riverine and marine water mixing zone with its upper boundary, locating far into the delta and moving depending on a phase of the tidal cycle, decrease of methane concentration with salinity increase was observed. The prevailing role in formation of the methane concentration level in water of the mouth area pertains to bottom sediments, which is indicated by close correlation between gas concentrations in these two media.