Anaerobic methane oxidation in an East African great lake (Lake Kivu)

摘要: Abstract. This study investigates methane (CH4) oxidation in the water column of Lake Kivu, a deep meromictic tropical lake containing large quantities CH4 anoxic waters. Depth profiles dissolved gases (CH4 and nitrous oxide (N2O)) different potential electron acceptors for anaerobic (AOM) (nitrate, sulfate, iron manganese) were determined during six field campaigns between June 2011 August 2014. Bacterial abundance all along vertical was also by flow cytometry three campaigns, denitrification measurements based on stable isotopes performed twice. Incubation experiments to quantify nitrate consumption rates, with focus AOM, without an inhibitor sulfate-reducing bacteria activity (molybdate). Nitrate rates measured these incubations. Substantial observed oxic waters, upper waters is major donor sustain metabolic processes coupled AOM. The maximum aerobic estimated 27 ± 2 16 ± 8 µmol L−1 d−1, respectively. We decrease AOM when molybdate added half measurements, strongly suggesting occurrence linked sulfate reduction, but increase other half. reduction manganese production tended be higher addition molybdate, 0.6 ± 0.02 11 ± 2 µmol L−1 d−1, respectively, never high enough explain at same depths. put evidence difference relative importance seasons, oxygenated layer thicker (in dry season).