| 山前农业区地表河水硝酸盐来源及关键转化机制 |
| 摘要点击 508 全文点击 17 投稿时间：2025-07-04 修订日期：2025-10-08 |
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| 中文关键词 NO3-污染 溶解性有机碳（DOC） 污染来源 转化 PMF模型 MixSIAR模型 |
| 英文关键词 nitrate pollution dissolved organic carbon （DOC） pollution sources transformation PMF model MixSIAR model |
| DOI 10.13227/j.hjkx.202507061 |
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| 中文摘要 |
| 水体NO3-污染已成为全球性环境污染问题，在复杂的水文地质背景下，精确评估地表河水NO3-不同来源及其贡献率是有一定难度的. 基于此，以典型山前集约农业区地表河水为研究对象，利用溶解性有机碳（DOC）对NO3-还原过程进行分析，基于水化学和同位素数据，结合MixSIAR模型和PMF模型2种定量解析模型对河水中NO3-分布特征、来源、贡献率及转化过程进行研究. 结果表明，山前农业区河段NO3-质量浓度[（35.6±12.5） mg·L-1]高于中下游城市区河段[（1.12±1.16） mg·L-1]，地表河水中NO3-主要受硝化作用影响. 在城市区河段中，藻类水生植物的排泄作用造成了DOC积累[（13.5±3.9） mg·L-1]，促进了城市区河段铵的异化还原（DNRA）过程，进而抑制NO3-积累. 尽管MixSIAR模型和PMF模型定量解析结果存在一定差异，但2种模型结果均表明，山前农业区河段高质量浓度NO3-主要是由于粪便和污水排放所导致（MixSIAR：92.0%，PMF：84.1%，贡献率）. 以上成果可为研究区地表河水NO3-污染防控与治理提供靶向性的科学支撑，并为全球其他类似NO3-污染地区提供方法学参考. |
| 英文摘要 |
| Water nitrate （NO3-） pollution is a pressing global environmental issue. Accurately identifying the diverse sources and quantifying the proportional contributions of NO3- in surface river water remains challenging， especially under complex hydrogeological conditions. This study investigated the surface river water in a typical piedmont agricultural area by integrating hydrochemistry， multiple isotopes （δ2H-H2O， δ18O-H2O， δ18O-NO3-， and δ15N-NO3-）， and dissolved organic carbon （DOC）， in combination with two quantitative models （i.e.， Bayesian stable isotope mixing， MixSIAR； positive matrix factorization， PMF）. It aimed to elucidate the distribution patterns， sources， contribution rates， and transformation processes of NO3- in river water. The results indicated that NO3- concentrations in the piedmont agricultural area [（35.6±12.5） mg·L-1] were significantly higher than those in the middle and lower urban reaches [（1.12±1.16） mg·L-1]， with nitrification identified as the primary process regulating NO3- levels. In urban river sections， the excretion by algae and aquatic plants led to the accumulation of DOC [（13.5±3.9） mg·L-1]， which promoted the dissimilatory nitrate reduction to ammonium （DNRA） process， thereby inhibiting NO3- accumulation. Although there were some discrepancies between the quantitative results of the MixSIAR and PMF models， both models consistently indicated that the high NO3- concentrations in the piedmont agricultural river sections were primarily attributed to manure and sewage discharges （MixSIAR： 92.0%， PMF： 84.1%， contribution rate）. These findings provide targeted scientific support for the prevention and control of NO3- pollution in surface water within the study area， while also offering methodological references for other NO3--polluted regions worldwide with similar conditions. |
