Nitrous oxide (N2O) fluxes and their relationships with water‐sediment characteristics in a hyper‐eutrophic shallow lake, China

Abstract

Nitrous oxide (N2O) fluxes were measured in hyper‐eutrophic Meiliang Bay of Lake Taihu by the static chamber method for two years. The lake was an important source of atmospheric N2O. Large temporal variations were recorded for N2O fluxes, ranging from −278 to 2101 μg N2O m−2 h−1 in the littoral zone and from −177 to 164 μg N2O m−2 h−1 in the pelagic zone, with the highest N2O emissions observed during the algal bloom. Wide spatial variation in N2O fluxes occurred in the littoral zone responding to water‐sediment variables, while such variation was not found in the pelagic zone. In the infralittoral zone, the redox condition, temperature and nitrogen (N) sources controlled the N2O fluxes, whereas the influences of these parameters on N2O fluxes were weak in the pelagic zone. This difference indicated that N cycling was more intensive in the littoral zone than in the pelagic zone. A multiple linear regression model against principal components indicated that water‐column denitrification and the carbon (C) and N contents of the sediment affected the N2O exchange in the infralittoral zone. Water‐column inorganic N content affected the consumption of atmospheric N2O significantly in both zones.