[Methane content in bottom sediments and water mass of the Black Sea]

The methane content in bottom sediments and water column of the Black Sea was determined using various methods of desorption and analysis of gases and various methods of calculating their concentrations. The head-space method with the use of salting out and calculation by internal standard proved to be the most accurate procedure for the analysis of methane concentration in bottom sediments. The methane content in bottom sediments increased with the depth of sediment sampling. In the upper 50-70 cm of shelf sediments, two minimums of methane concentration were revealed; in deep-sea sediments, only one minimum was recorded (in the 20-50 cm horizons). In the water column, methane concentrations slowly grew from the surface to a depth of 150-200 m and abruptly increased to a depth of 700-1200 m, remaining virtually constant in underlying layers. In certain deep-sea regions, peaks of methane content in the 1000-1200 m horizons of the water column were revealed, which were most probably due to local influx of abyssal waters enriched with this gas.