The role of methane in internal carbon cycling in Lake Mendota during summer stratification

The rate of methane formation and evasion was estimated during summer stratification from methane profiles and the rate of methane oxidation measured with 14 CH 4 . Organic carbon sedimentation was measured with sedimentation traps. For the deep‐water sediments of Lake Mendota, about 54% of the organic carbon sedimented returns as methane. Methane oxidation at the thermocline is a much more significant process in Lake Mendota than in Lake 227 during summer stratification, apparently because of the higher eddy diffusivity in Lake Mendota, with concomitant transfer of oxygen and nutrients to the zone where methane oxidation occurs.