Integrating stable isotopes and hydrological models to track nitrogen sources and transport pathways in plateau watersheds: a case study in Southwest China

文献类型： 外文期刊

第一作者： Xu, Qiyu

作者： Xu, Qiyu;Yan, Tiezhu;Zhai, Limei;Lei, Qiuliang;Zhang, Tianpeng;Du, Xinzhong;Liu, Hongbin;Guo, Shufang

作者机构：

关键词： Non-point sources pollution; Nitrate; Hydrological pathway; Stable isotopes; Plateau agricultural watershed

期刊名称：ENVIRONMENTAL POLLUTION （ 影响因子：7.3； 五年影响因子：8.1 ）

ISSN： 0269-7491

年卷期： 2025 年 374 卷

页码：

收录情况： SCI

摘要： Exogenous nitrogen inputs from agriculture and anthropogenic activities have dramatically altered the material cycling processes in the Plateau watershed, leading to a range of water pollution issues. Effective management of nitrogen pollution in water bodies is predicated on clarifying N export loads under different pathways in the watershed, as well as the contributions of different sources. Here, this study proposes an integrated framework that introduces multiple stable isotope techniques (delta D-H2O, delta O-18-H2O, delta N-15-NO3- and delta O-18-NO3-) based on the coupled Eckhardt's digital baseflow filter (ECK) and load estimation model (LOADEST). The integrated approach was applied for the first time in a typical plateau watershed in southwest China. Results showed that baseflow as the Fengyu River watershed (FRW) major hydrologic pathway, provides 69.6 % of the mean annual stream flow and 59.1 % of the mean annual NO3--N load. Furthermore, the FRW average annual TN and NO3--N export is 94.0 t and 55.1 t, respectively. The NO3--N was the primary form of N pollutant, with its average concentration in groundwater being 7 times that in river water. In groundwater, manure and sewage (M&S) and soil nitrogen (SN) contribution rates to NO3--N 53.6 %, and 37.2 %, respectively. While the river water shows low M&S (26.8 %) and high SN (61.5 %) characteristics. It can be seen that the baseflow is a key pathway for coupled waternitrogen export from plateau agricultural watersheds. Blocking the migration of nitrogen-containing pollutants to groundwater is an important measure to control the degradation of the water environment in plateau watersheds from the root cause.

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