Methanogenesis exceeds CH4 consumption in eutrophic lake sediments

Abstract

Lakes and reservoirs collectively contribute significant amounts of methane (CH4) to the global atmosphere. If CH4 production were not at least partially balanced by consumption (oxidation) in most of these systems, they could potentially emit an order of magnitude or more CH4. The impacts of environmental drivers such as trophic status, temperature, and latitude on CH4 production, CH4 oxidation, and the balance of the two processes influence current and future patterns of freshwater CH4 emissions. Using CH4 production and oxidation rates measured with a common methodology (incubations) from over 60 different lakes and reservoirs, we provide novel evidence for lower sediment CH4 oxidation efficiency at high sediment CH4 production rates. We also show a strong positive correlation between sediment CH4 production and lake trophic status. Our results suggest that less efficient CH4 consumption at high CH4 production rates could help explain greater surface emissions often observed in eutrophic lakes globally.