Methane consumption in decomposing Sphagnum-derived peat

Abstract

Methane production and CH4 consumption by moss-derived peats were measured and related to CH4 emission from the same peats to the atmosphere. Peat samples (0–40 cm depth) maintained under anoxic conditions at 19 C for 40 h produced CH4 at rates ranging from 0.5 to 1.0 μmol 1 peat−1 h−1.The same peat samples exposed to aerobic conditions consumed CH4 without showing a lag between production and consumption, suggesting that an active population of aerobic CH4-consuming microorganisms was present in the mostly anoxic peat. However, anaerobic CH4 oxidation could not be ruled out completely. Rates of methane consumption ranged from 1.6 to 0.2μmol 1 peat−1 h−1. Consumed CH4-C was converted to CO2 rather than biomass, indicating that the consumers used CH4 as an energy source. The difference between integrated rates of CH4 production (6.8 mmol m−2 day−1) and CH4 consumption (5.4 mmol m −2 day−1) represented the available amount of CH4 for atmospheric emission. This estimate agreed with measured emission values from intact peat cores (0.2–0.7 mmol m−2 day−1). The results of these studies emphasize the importance of CH4 consumption in controlling CH4 emissions from peatlands to the atmosphere.