多种同位素和GIS分析揭示了黄土高原地下水中硝酸盐的来源和驱动因素。

IF 7.3 2区 环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES
Environmental Pollution Pub Date : 2025-11-01 Epub Date: 2025-08-21 DOI:10.1016/j.envpol.2025.127022
Shujian Li, Reynold Chow, He Su, Fengpeng Han, Zhi Li
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引用次数: 0

摘要

地下水在氮向水生生态系统的转移中起着关键作用,特别是在干旱区。水资源短缺,加上密集的农业活动,使地下水系统受到非点源污染的巨大压力,强调需要进行有针对性的调查。以中国黄土高原(CLP)为研究对象,采用双同位素分析(δ15N-NO3-、δ18O-NO3-)和水同位素分析(δD-H2O、δ18O-H2O)相结合的方法,采用双框架方法研究了黄土高原的硝酸盐动态。具体而言,我们采用MixSIAR模型量化硝酸盐源贡献,并采用Geographical Detector模型识别空间和季节驱动因素。结果表明:在厚气包带下方,局部活塞流补给占主导地位。硝态氮浓度随井深的增加而降低(0.04 mg/L/m),同时硝态氮同位素特征向土壤有机氮(SN)方向收敛。硝态氮主要来源于SN(43%)和NH4+铵肥料(34%),表明农业相关来源占主导地位。季节模式显示在雨季有轻微的反硝化作用。空间分析表明,土地利用、降水和归一化植被指数(NDVI)是控制硝态氮变异的关键因子。值得注意的是,在植被覆盖较少的地区,降水对硝态氮淋溶有强烈的驱动作用。这些发现表明,尽管硝酸盐在CLP中的运移和转化受其独特的深层渗透带和干旱水文地质条件的支配,但本文开发的综合同位素和空间框架为研究全球其他脆弱深层地下水系统的硝酸盐动态提供了可转移的方法。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Multiple isotopes and GIS analyses reveal sources and drivers of nitrate in the Loess Plateau's groundwater.

Groundwater plays a pivotal role in mediating nitrogen transfer to aquatic ecosystems, particularly in arid regions. Water scarcity, coupled with intensive agricultural activities, has placed the groundwater systems under significant pressure from non-point source pollution, underscoring the need for targeted investigation. Focusing on the Chinese Loess Plateau (CLP), we combined dual-isotope analysis (δ15N-NO3-, δ18O-NO3-) with water isotopes (δD-H2O, δ18O-H2O) and implemented a dual-framework approach to investigate nitrate dynamics. Specifically, we applied the MixSIAR model to quantify nitrate source contributions and employed the Geographical Detector model to identify spatial and seasonal drivers. The results showed that local piston-flow recharge predominates beneath the thick vadose zone. Nitrate concentrations decreased with increasing well depth (0.04 mg/L/m), accompanied by a convergence of nitrate isotopic signatures toward soil organic nitrogen (SN). Nitrate was derived primarily from SN (43 %) and ammonium NH4+ fertilizer (NHF) (34 %), underscoring the dominance of agriculture-related sources. Seasonal patterns revealed minor denitrification during the wet season. Spatial analysis identified land use, precipitation, and the normalized difference vegetation index (NDVI) as key factors controlling nitrate variability. Notably, nitrate leaching was strongly driven by precipitation in regions with sparse vegetation cover. These findings demonstrate that, although nitrate transport and transformation in the CLP are governed by its uniquely deep vadose zone and arid hydrogeological conditions, the integrated isotope and spatial framework developed here provides a transferable approach for investigating nitrate dynamics in other vulnerable deep groundwater systems worldwide.

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来源期刊
Environmental Pollution
Environmental Pollution 环境科学-环境科学
CiteScore
16.00
自引率
6.70%
发文量
2082
审稿时长
2.9 months
期刊介绍: Environmental Pollution is an international peer-reviewed journal that publishes high-quality research papers and review articles covering all aspects of environmental pollution and its impacts on ecosystems and human health. Subject areas include, but are not limited to: • Sources and occurrences of pollutants that are clearly defined and measured in environmental compartments, food and food-related items, and human bodies; • Interlinks between contaminant exposure and biological, ecological, and human health effects, including those of climate change; • Contaminants of emerging concerns (including but not limited to antibiotic resistant microorganisms or genes, microplastics/nanoplastics, electronic wastes, light, and noise) and/or their biological, ecological, or human health effects; • Laboratory and field studies on the remediation/mitigation of environmental pollution via new techniques and with clear links to biological, ecological, or human health effects; • Modeling of pollution processes, patterns, or trends that is of clear environmental and/or human health interest; • New techniques that measure and examine environmental occurrences, transport, behavior, and effects of pollutants within the environment or the laboratory, provided that they can be clearly used to address problems within regional or global environmental compartments.
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