Carbon cycle between lake water and sediment in eutrophic lake, Lake Tega

Abstract

The organic carbon (OC) burial rate was estimated to be 42 gC m^-2 yr^-1 in the eutrophic lake sediment, Lake Tega. This is equivalent to more than 3 times of the global average rate (13 gC m^-2 yr^-1, IPCC 2013) of the inland water sediments. However, comparing with the values for the oligotrophic and mesotrophic lakes that were compiled by Sobek et al. (2009), the OC burial rate of Lake Tega is not significant. The release rate of carbon from the surface of sediment to the water column was estimated to be 10 gC m^-2 day^-1. The burial efficiency of OC that defined as the ratio between net OC burial and gross OC sedimentation, was calculated to be only 1%. That is, no significant OC burial rate of Lake Tega is caused by the rapid mineralization in the sediment and release to the water column. Moreover, the large re-supply of carbon from sediment makes it possible for Lake Tega with high productivity to release of CO₂ to the atmosphere.