Littoral zones as the “hotspots” of nitrous oxide (N 2O) emission in a hyper-eutrophic lake in China

Abstract

N 2O emissions were measured monthly for 1 year using the static chamber method along the littoral and pelagic zones of Meiliang Bay in hyper-eutrophic Taihu Lake. The results indicated that littoral zones were the “hotspots” of N 2O emissions (−278∼2 101 μg N 2O m −2 h −1). While the littoral zone accounted for only 5.4% of the area of Meiliang Bay, the N 2O emissions from the littoral zones were about 43.6% of total emissions from the bay. The importance of spatial variation on N 2O emissions was demonstrated by dividing the lake into four unique zones through cluster analysis. The eulittoral zone was the key area of N 2O emissions with an annual 5% trimmed mean 429.5 μg N 2O m −2 h −1, following by supralittoral (138.8 μg N 2O m −2 h −1), infralittoral (98.9 μg N 2O m −2 h −1), and pelagic zones (15.7 μg N 2O m −2 h −1). Further, N 2O emissions showed a seasonal trend. Excessive N 2O emissions during algal bloom periods suggested that algae played a significant role in the emission of N 2O.