Li Baoling, Han Dongmei, Yang Lihu, Song Xianfang, Qin Mingzhou, Diamantopoulos Efstathios
College of Geographical Sciences, Faculty of Geographical Science and Engineering, Henan University, Zhengzhou, 450046, China; Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; University of Copenhagen, Department of Plant and Environmental Sciences, Copenhagen, 1871, Denmark.
Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Res. 2025 Apr 15;271:121065. doi: 10.1016/j.envres.2025.121065. Epub 2025 Feb 7.
Nitrate pollution in water environment is a serious problem worldwide. Identifying nitrate sources and transformations in the riparian aquifer is critical for effectively controlling and mitigating nitrate contamination, especially in sluice-controlled rivers. This study employs an integrated approach combining hydrochemical analysis, isotopes (δO-HO, δH-HO, δN-NO and δO-NO), quantification of nitrogen (N) functional genes and a Bayesian mixing model (MixSIAR) to comprehensively investigates nitrate sources and transformation processes in the riparian groundwater of a sluice-controlled Shaying River, China. Results revealed severe nitrate contamination in both the river (mean: 2.33-5.25 mg/L) and the riparian groundwater (mean: 0.42-24.46 mg/L). Manure and sewage were the primary sources (66.20-91.20 %) of nitrate contamination in both river and riparian groundwater. Key processes influencing nitrate dynamics in riparian groundwater included mixing with river water, external N supply, and transformation processes such as nitrification, vegetation uptake and anammox. We found that when sluices are closed, the nitrate concentration in riparian groundwater decreases. In contrast, during the flood season with sluices open, the nitrate concentration in the river water increases. This study also developed the first conceptual model illustrating the impact of sluice regulation on riparian nitrate dynamics, highlighting the complex interplay between sluice operations, hydrological conditions, and biogeochemical processes that govern nitrate behavior. These findings provide valuable insights into nitrate dynamics in riparian aquifers of sluice-controlled rivers, offering a robust scientific foundation for targeted nutrient management strategies in the Shaying River Basin and similar regulated environments globally.
水环境中的硝酸盐污染是一个全球性的严重问题。识别河岸带含水层中的硝酸盐来源和转化对于有效控制和减轻硝酸盐污染至关重要，尤其是在有闸控的河流中。本研究采用了一种综合方法，结合水化学分析、同位素（δO-H₂O、δH-H₂O、δ¹⁵N-NO₃和δ¹⁸O-NO₃）、氮（N）功能基因定量以及贝叶斯混合模型（MixSIAR），全面研究了中国沙颍河闸控河段河岸带地下水的硝酸盐来源和转化过程。结果显示，河流（均值：2.33 - 5.25mg/L）和河岸带地下水（均值：0.42 - 24.46mg/L）均受到严重的硝酸盐污染。粪便和污水是河流和河岸带地下水中硝酸盐污染的主要来源（66.20% - 91.20%）。影响河岸带地下水硝酸盐动态的关键过程包括与河水混合、外部氮供应以及硝化、植被吸收和厌氧氨氧化等转化过程。我们发现，当闸门关闭时，河岸带地下水中的硝酸盐浓度会降低。相反，在汛期闸门打开时，河水中的硝酸盐浓度会增加。本研究还建立了第一个概念模型，阐明了闸控对河岸带硝酸盐动态的影响，突出了闸门运行、水文条件和控制硝酸盐行为的生物地球化学过程之间的复杂相互作用。这些发现为闸控河流河岸带含水层中的硝酸盐动态提供了有价值的见解，为沙颍河流域及全球类似调控环境下的针对性养分管理策略提供了坚实的科学基础。
