Identifying nitrate sources and transformations in an agricultural watershed in Northeast China: Insights from multiple isotopes

第一作者：	Wu, Yao
英文第一作者：	Wu, Yao
联系作者：	Zhang, Guangxin; Qi, Peng
英文联系作者：	Zhang, Guangxin; Qi, Peng
发表年度：	2023
卷：	340
摘要：	Accurate identification of riverine nitrate sources is required for preventing and controlling nitrogen contami-nation in agricultural watersheds. The water chemistry and multiple stable isotopes (delta 15N-NO3, delta 18O-NO3, delta 2H-H2O, and delta 18O-H2O) of the river water and groundwater in an agricultural watershed in China's northeast black soil region were analyzed to better understand the sources and transformations of riverine nitrogen. Results showed that nitrate is an important pollutant that affects water quality in this watershed. Affected by factors such as seasonal rainfall changes and spatial differences in land use, the nitrate concentrations in the river water showed obvious temporal and spatial variations. The riverine nitrate concentration was higher in the wet season than in the dry season, and higher downstream than upstream. The water chemistry and dual nitrate isotopes revealed that riverine nitrate came primarily from manure and sewage (M&S). Results from the SIAR model showed that it accounted for more than 40% of riverine nitrate in the dry season. The proportional contribution of M&S decreased during the wet season due to the increased contribution of chemical fertilizers and soil ni-trogen induced by large amounts of rainfall. The delta 2H-H2O and delta 18O-H2O signatures implied that interactions occurred between the river water and groundwater. Considering the large accumulation of nitrates in the groundwater, restoring groundwater nitrate levels is essential for controlling riverine nitrate pollution. As a systematic study on the sources, migration, and transformations of nitrate/nitrogen in agricultural watersheds in black soil regions, this research can provide a scientific support for nitrate pollution management in the Xinli-cheng Reservoir watershed and provide a reference for other watersheds in black soil regions in the world with similar conditions.
刊物名称：	JOURNAL OF ENVIRONMENTAL MANAGEMENT
参与作者：	Wu, Y (Wu, Yao) [1] ; Ju, HY (Ju, Hanyu) [1] ; Jiang, H (Jiang, Hao) [2] ; Zhang, GX (Zhang, Guangxin) [1] ; Qi, P (Qi, Peng) [1] ; Li, Z (Li, Zan) [1]