Nitrate removal mechanism in riparian groundwater in an intensified agricultural catchment
Nitrate removal mechanism in riparian groundwater in an intensified agricultural catchment
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DOI：
10.1016/j.agwat.2023.108223
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发表时间：
2023-04
影响因子：
6.7
通讯作者：
Zheyu Xie;Yujing Zhang;Zhenyu Zhang;Jinliang Huang
中科院分区：
文献类型：
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作者：
Zheyu Xie;Yujing Zhang;Zhenyu Zhang;Jinliang Huang
地下水和地表水中的硝酸盐污染是农业国家的一个持续问题。河流和河岸含水层之间的过渡区在介导河流硝酸盐输出中起着重要作用，因为它促进了强烈的反硝化作用，从而导致从水生系统中永久去除硝酸盐。然而，控制河岸反硝化作用的基本机制还不清楚。在这项研究中，我们提出了一个为期两年的河流和地下水采样周期沿着中国东南沿海流域的水化学和同位素数据的评估。结果表明，在河岸含水层中的最高的氧消耗和反硝化速率发生在入渗河流的比例与较高的地下水温度。河岸带中的异养微生物反应可能是由河岸含水层中河水中的生物可利用有机碳驱动的。对于从河岸地下水的NO3-去除效率的基本过程，额外的过程大大超过反硝化（12.1%对6.6%的平均值），特别是在最远的距离在冬季的河流。硝态氮污染的平均贡献率以粪污污染最高（54.5%），其次为土壤氮肥（23.7%）、化肥（18.5%）和大气沉降（3.3%）。这项研究为农业水资源管理提供了有价值的指导，其关键发现是河流和地下水之间的高度连通性可能会提高NO3的去除潜力。
Nitrate contamination in ground and surface water is a persistent problem in agricultural countries. The transition zone between rivers and riparian aquifers plays an important role in mediating riverine nitrate export, as it promotes intensive denitrification, resulting in permanent nitrate removal from aquatic systems. However, the underlying mechanisms controlling riparian denitrification are not well understood. In this study, we present an assessment of water chemistry and isotope data from a two-year river and groundwater sampling period along a coastal watershed in Southeast China. The results showed that the highest oxygen depletion and denitrification rates in the riparian aquifer occurred in the infiltrated river proportions with higher groundwater temperatures. Heterotrophic microbial responses in the riparian zone may have been driven by bioavailable organic carbon from the river water in the riparian aquifer. For the underlying processes of NO3-removal efficiency from riparian groundwater, the additional processes substantially surpassed denitrification (mean of 12.1% vs. 6.6%), particularly at the furthest distance from the river in winter. The mean proportional contribution of manure and sewage (54.5%) was the highest for nitrate contamination, followed by soil N fertilizer (23.7%), chemical fertilization (18.5%), and atmospheric deposition (3.3%). This study provides valuable guidance for agricultural water management based on the key finding that high connectivity between rivers and groundwater might improve the NO3-removal potential.