近十年来黄河中下游河水硝酸盐含量和来源变化及影响因素分析
- Changes of nitrate content and sources and influencing factors along the middle and lower reaches of the Yellow River in recent ten years
- 基金项目：国家自然科学基金重点项目(52039001)；黄河流域生态保护和高质量发展联合研究项目(2022-YRUC-01-0202)
- 摘要：黄河流域生态保护和高质量发展是国家重大发展战略,但黄河水质低于全国平均水平,入海总氮浓度高于其它大型河流。硝酸盐作为河流中主要的含氮化合物,探究河流硝酸盐含量和来源的时空变化,评价流域环境管理措施对河流硝酸盐的影响,对缓解河流氮污染具有重要作用。然而,黄河中下游河水硝酸盐含量和来源及其在环境管理措施实施后的时空变化尚不清楚。因此,本研究分析了2011、2023和2024年黄河中下游流域河水硝酸盐的浓度和同位素组成(Δ17O、δ15N和δ18O-NO3-),结合δ15N/Δ17O-NO3-稳定同位素SIAR模型,探讨了河水硝酸盐含量和来源的时空变化特征,分析了流域环境管理措施的影响。结果表明,近十年来,黄河中下游河水硝酸盐浓度呈下降趋势,平均浓度由4.4 mg N /L降至2.6 mg N /L。黄河水系硝酸盐含量的变化与流域生态环境管理措施的实施密切相关,对化肥施用量的严格控制、水土流失的治理以及污水处理效率的提高减少了入河氮负荷。而且,面源和点源污染对黄河中下游河水硝酸盐的相对贡献发生了变化,来自土壤氮和化肥所代表面源污染的贡献由约70%降低至约50%,污水粪肥所代表点源的贡献由约30%增加至约50%,说明未来应在继续治理水土流失等面源污染的基础上,加强对点源污染的治理和控制。研究结果为进一步调整和制定削减河流氮污染的政策提供了科学依据,对于提升黄河水质、改善渤海富营养化污染现状等具有重要意义。
- Abstract：The ecological protection and high-quality development in the Yellow River Basin is an important national development strategy. The water quality of the Yellow River remains below the national average, with its total nitrogen concentration discharging into the sea surpassing that of other major rivers. Nitrate, as the predominant nitrogen-containing compound in rivers, plays a vital role in mitigating nitrogen pollution. Understanding its spatiotemporal variations, sources, and the influence of environmental management measures is crucial. Despite this importance, the spatiotemporal changes in nitrate content and sources in the middle and lower reaches of the Yellow River (MLYR) and their response to environmental management interventions remain poorly understood. To address this gap, this study analyzed the concentration and isotopic compositions (Δ17O, δ15N, and δ18O-NO3-) of nitrate, combined with the Stable Isotope Analysis in R model based on δ15N/Δ17O-NO3-, explored the spatiotemporal variations in nitrate content and sources, and assessed the impact of watershed environmental management measures along the MLYR in 2011, 2023, and 2024. Results showed a remarkable decline in nitrate concentrations in the MLYR over the past decade, with average levels decreasing from 4.4 mg N/L to 2.6 mg N/L. This reduction is closely linked to ecological and environmental management measures, including stricter fertilizer application controls, enhanced soil erosion management, and improved wastewater treatment efficiency. Additionally, the relative contributions of non-point and point source pollution to nitrate have shifted: non-point sources, such as soil nitrogen and fertilizers, declined from approximately 70% to 50%, while point sources, including sewage and manure, increased from approximately 30% to 50%. These findings highlight the need for intensified management of point source pollution alongside continued efforts to mitigate non-point sources like soil erosion. This study provides valuable insights for adjusting and formulating policies to control nitrate pollution, contributing to improved water quality in the Yellow River and mitigating eutrophication in the Bohai Sea.
