Regulation of Methane Emissions in a Constructed Wetland by Water Table Changes

Riparian wetlands release greenhouse gases and sequestration carbon as well, so their carbon source and carbon sink functions have become some of the key research issues of global climate change. In this present paper, the main controllable factors of the self-designed and constructed riparian wetland, namely hydrological conditions and additional carbon sources, were artificially regulated, and then methane fluxes were measured. The results proved that the methane emissions were significantly positively correlated with the water level heights, and the methane emissions increased exponentially with the rise of water level when the water level was between −20 cm and +20 cm. According to the −20~0 cm water level, a small number of methane emissions was significantly different from the 10 cm and 20 cm water levels, which indicated that higher water level could significantly promote methane emission. When the water level reached above 0 cm, the methane emission gradually increased as the flooding time became longer; it reached the peak value after more than 20 days of flooding after which it decreased, which provided a scientific basis for optimal design and effective management of restored and constructed riparian wetlands, minimizing the methane emissions of riparian wetlands.