Response of methane emissions to water levels in simulated constructed wetlands

Wetland is an important natural source of methane (CH4) generated under the actions of methanogens in the anaerobic environment. A greenhouse experiment was conducted to quantify the response of methane emissions to water levels by simulating three water levels (10, 20, and 40 cm) in constructed wetlands and the methane was determined by the static chamber-gas chromatograph technique. Pearson correlation analysis showed that the emissions of CH4 were positively correlated with water temperature and air temperature while they were negatively correlated with air humidity. The water levels simulation experiment showed that the emission of CH4 was the highest when the water level was 20 cm and the CH4 concentrations of the water-air interface had different patterns at various water levels in the daytime. In conclusion, water level and temperature should be considered when accounting for greenhouse gas emissions in constructed wetlands as they both have important influences on CH4 emission.