Soil Methane Production, Anaerobic and Aerobic Oxidation in Porewater of Wetland Soils of the Minjiang River Estuarine, China

Wetlands are important sources of methane emission. Anaerobic oxidation, aerobic oxidation and production of methane as well as dissolved methane are important processes of methane metabolism. We studied methane metabolism and the soil influencing factors. Potential soil methane production, anaerobic oxidation and aerobic oxidation rates, and dissolved methane in soil porewater changed seasonally and the annual average was 21.1 +/- 5.1 mu g g(-1)d(-1), 11.0 +/- 3.9 mu g g(-1)d(-1), 20.9 +/- 5.8 mu g g(-1)d(-1), and 62.9 +/- 20.6 mu mol l(-1), respectively. Potential soil methane production and anaerobic and aerobic oxidation were positively correlated among themselves and with soil pH and negatively correlated with soil redox potential (Eh). Potential soil methane production and aerobic and anaerobic oxidation rates were negatively related to pore soil methane concentration. Thus, the more water-saturated the soil (the lower Eh), the higher its capacity to produce methane. The potential soil capacity for methane oxidation was higher both in the same anaerobic circumstances and when the soil was suddenly subjected to aerobic conditions. The results of this study suggested a buffer effect in the methane balance in wetland areas. The environmental circumstances favoring methane production are also favorable for anaerobic methane oxidation.