Methane in the Water and Bottom Sediments of the Mouth Area of the Severnaya Dvina River (White Sea)

摘要

The mouth area of the Severnaya Dvina River is characterized by a high level of methane in the water (from 1.0 to 165.4 μl/l) and in the bottom sediments (from 14 to 65000 μl/kg), being quite comparable to the productive mouth areas of the rivers in the temperate zone. The maximum methane concentrations in the water and sediments were registered in the delta in the segments of channels and branches with low rates of tidal and runoff currents to which domestic and industrial wastewaters are supplied. In the riverine and marine water mixing zone with its upper boundary situated far into the delta and displaced depending on the phase of the tidal cycle, a decrease of the methane amount with the salinity increase was observed. The prevailing role in the formation of the methane content level in the water of the mouth area pertains to the bottom sediments, which is testified to by the close correlation between the gas concentrations in these two media. The existence of periodicity in the variations of the methane content level in the water of the river downstream caused by the tidal effects was found.