We investigated CH
4 oxidation in the water column of Lake Kivu, a deep meromictic tropical lake with CH
4-rich anoxic deep waters. Depth profiles of dissolved gases (CH
4 and N
2O) and a diversity of potential electron acceptors for anaerobic CH
4 oxidation (NO
3?, SO
42?, Fe and Mn oxides) were determined during six field campaigns between June 2011 and August 2014. Denitrification measurements based on stable isotope labelling experiments were performed twice. In addition, we quantified aerobic and anaerobic CH
4 oxidation, NO
3? and SO
42? consumption rates, with and without the presence of an inhibitor of SO
42?-reducing bacteria activity. Aerobic CH
4 production was also measured in parallel incubations with the addition of an inhibitor of aerobic CH
4 oxidation. The maximum aerobic and anaerobic CH
4 oxidation rates were estimated to be 27?±?2 and 16?±?8?μmol/L/d, respectively. We observed a difference in the relative importance of aerobic and anaerobic CH
4 oxidation during the rainy and the dry season, with a greater role for aerobic oxidation during the dry season. Lower anaerobic CH
4 oxidation rates were measured in presence of molybdate in half of the measurements, suggesting the occurrence of linkage between SO
42? reduction and anaerobic CH
4 oxidation. NO
3? consumption and dissolved Mn production rates were never high enough to sustain the measured anaerobic CH
4 oxidation, reinforcing the idea of a coupling between SO
42? reduction and CH
4 oxidation in the anoxic waters of Lake Kivu. Finally, significant rates (up to 0.37?μmol/L/d) of pelagic CH
4 production were also measured in oxygenated waters.
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