Methane cycling in the sediments of Lake Washington

Aerobic oxidation is important in the cycling of methane in the sediments of Lake Washington. About half of the methane flux from depth is oxidized to CO2 in the upper 0.7 cm of the sediments and the remainder escapes into the water column. In terms of the total carbon budget of the lake, the upward flux of methane is insignificant with only about 2% of the carbon fixed by primary production being returned as methane. The upward flux of methane, however, does represent about 20% of the organic carbon decomposed within the sediments. In addition, methane oxidation consumcs 7–10% of the total oxygen flux into the sediments. Measured kinetic parameters suggest that methane oxidation is restricted to the top 6–7 mm of sediment where oxygen is present and that the rate of this process is probably controlled by the concentration of methane.