METHANE PRODUCTION AND CONSUMPTION IN TEMPERATE AND SUB-ARCTIC PEAT SOILS - RESPONSE TO TEMPERATURE AND PH

Rates of methane (CH4) production under anaerobic conditions and CH4 consumption under aerobic conditions were studied in slurries of peat samples kept at different temperatures (0-35-degrees-C) and pH values (buffered at pH 3.5-8). Apparent K(m) CH4 for consumption was 1 mum. Optimum temperatures for both processes were about 25-degrees-C but CH4 production showed much more temperature-dependence (activation energies 123-271 kJ mol-1, Q10 values 5.3-16) than did CH4 consumption (activation energies 20-80 kJ mol-1 values 1.4-2.1). In the 0-10-degrees-C range, CH4 production was negligible but CH4 consumption was 13-38% of maximum. Both processes showed optimum pH values which were about 2 pH units higher than the native peat pH in acidic peats and only 0-1 pH unit higher in the more alkaline peats. We conclude that the microflora involved in CH4 metabolism is not well adapted to either low temperatures or low pH values.