Nitrous oxide emissions from Phragmites australis-dominated zones in a shallow lake

Nitrous oxide (N2O) emissions from Phragmites australis (reed) – dominated zones in Baiyangdian Lake, the largest shallow lake of Northern China, were investigated under different hydrological conditions with mesocosm experiments during the growing season of reeds. The daily and monthly N2O emissions were positively correlated with air temperature and the variation of aboveground biomass of reeds (p < 0.05), respectively. The N2O emissions from reeds were about 45.8–52.8% of that from the sediments. In terms of the effect of hydrological conditions, N2O emissions from the aquatic-terrestrial ecotone were 9.4–26.1% higher than the submerged zone, inferring that the variation of water level would increase N2O emissions. The annual N2O emission from Baiyangdian Lake was estimated to be about 114.2 t. This study suggested that N2O emissions from shallow lakes might be accelerated by the climate change as it has increased air temperature and changed precipitation, causing the variation of water level.

► The daily N2O emissions were significant positively correlated with air temperature.
► The monthly N2O emissions positively correlated with reed aboveground biomass variations.
► The N2O emissions from reeds contributed to 45.8–52.8% of that from the sediment.
► N2O emissions from the aquatic-terrestrial ecotone were 9.4–26.1% higher than the submerged zone.
► N2O emissions from shallow lakes might be accelerated by the climate change.