作 者：Chen, N.W., Wu, J.H., Zhou, X.P., Chen, Z.H.,and Lu, T. 影响因子：3.390

刊物名称：AGRICULTURE ECOSYSTEMS & ENVIRONMENT

出版年份：2015

卷：208 页码：37-47

Intensive use of nitrogen (N) fertilizers in agriculture and the release of reduced N in human and animal wastes have substantially enhanced nitrous oxide (N₂O) production from aquatic systems, mainly through nitrification and denitrification. This study investigated the spatial variation of riverine N₂O production and emission from a rivernetwork in a region dominated by agriculture(Jiulong River)in southeast China, as well as river N₂O yield [=△N₂O/(△N₂O +△N₂)×100]. Three measurements, encompassing 29 sampling sites across two main tributaries (North River and West River), were carried out in February, May and October 2011 under various hydrological conditions. The results showed that dissolved N₂O concentrations were always far above saturation (112–4133%), indicating that the river is a major source of N₂O, a potent greenhouse gas. The excess dissolved N₂O (△N₂O) ranged from 4.2 to 363 nmol L^-1, and the water–airfluxes of N₂O varied from 1.1 to 93.8μmol m^-2d^-1. Dissolved inorganic N (DIN) was the key factor controlling the spatial variation of△N₂O. High N₂O production and emission was found in the upper North River where animal and human wastes dominated riverine N sources. River N₂O yield tends to increase during lowflow periods andin dam-modified river stretches, probably due to enhanced in-stream nitrification. Riverine N₂O export to estuary has increased more than 15-fold since the 1980s. Riverine N₂O emission from the Jiulong River falls into the lower range of reported values around the world but is anticipated to increase due to changing hydrology and increasing N loading from agriculture.

Fig.3.Relationships between DIN and N components in the North River (A) and West River (B).