Big Soda Lake ( Nevada). 3. Pelagic methanogenesis and anaerobic methane oxidation.

Nearly all the methane oxidation occurred in the anoxic zones of the lake. Rates of anaerobic oxidation exceeded production at all depths studied in both the mixolimnion (2-6 vs. 0.1-1 nmol liter-1 d-1) and monimolimnion (49-85 vs. 1.6-12 nmol liter-1 d-1) of the lake. Thus, a net consumption of methane equivalent to 1.36 mmol m-2 d-1 occurred in the anoxic water column. Anaerobic methane oxidation had a first-order rate constant of 8.1+ or -0.5 X 10-4 d-1, but in situ methane oxidation was of insufficient magnitude to cause a noticeable decrease of ambient dissolved methane levels over an incubation period of 97h. -from Authors