Littoral zones as the “hotspots” of nitrous oxide (N2O) emission in a hyper-eutrophic lake in China

N2O 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 N2O emissions (−278∼2 101 μg N2O m−2 h−1). While the littoral zone accounted for only 5.4% of the area of Meiliang Bay, the N2O emissions from the littoral zones were about 43.6% of total emissions from the bay. The importance of spatial variation on N2O emissions was demonstrated by dividing the lake into four unique zones through cluster analysis. The eulittoral zone was the key area of N2O emissions with an annual 5% trimmed mean 429.5 μg N2O m−2 h−1, following by supralittoral (138.8 μg N2O m−2 h−1), infralittoral (98.9 μg N2O m−2 h−1), and pelagic zones (15.7 μg N2O m−2 h−1). Further, N2O emissions showed a seasonal trend. Excessive N2O emissions during algal bloom periods suggested that algae played a significant role in the emission of N2O.