N_2O emissions from the littoral zone

N2O emissions from macrophyte-covered and bare littoral zones were measured along the gradient from the open water to land in Meiliang Bay, Taihu Lake, by using in-situ closed chamber technique. The results show that N2O emissions from both types of littoral zones were evidently higher than that from adjacent open water (up to 10~100 times). In the macrophyte-covered littoral zone, the highest N2O emissions occurred in the eulittoral zone, where N2O emission was 5~10 times greater than that in the su- pralittoral and infralittoral zones. The N2O emissions ranged from -159.2 μg·m-2·h-1 to 1 565.6 μg·m-2·h-1,with a spatio-temporal variation. The peak value of N2O emission appeared in September and gradually decrease as temperature became low and reed died away. It declined to the minimum in January. From the infralittoral zone to the supralittoral zone, N2O emission increased gradually, the maximum appeared in the eulittoral zone, and then decreased in the supralittoral zone. The results indicate that the littoral zone with a small dimension is potentially important sources of N2O, and the IPCC methodologies for calculating national N2O emission inventories do not explicitly account for N2O production in littoral area,and also suggest that littoral zone plays an important role in nitrogen removing in the eutrophic lakes.