Quantify the effects of groundwater level recovery on groundwater nitrate dynamics through a quasi-3D integrated model for the vadose zone-groundwater coupled system

文献类型： 外文期刊

第一作者： Zang, Yongge

作者： Zang, Yongge;Zang, Yongge;Zang, Yongge;Li, Miao;Hou, Xiaoshu;Li, Zhiping;Li, Peng;Sun, Ying;Yu, Bowei

作者机构：

关键词： Groundwater level recovery; Vadose zone-groundwater coupled system; Nitrate leaching flux; Groundwater nitrate; Nitrate accumulation

期刊名称：WATER RESEARCH （ 影响因子：13.4； 五年影响因子：13.847 ）

ISSN： 0043-1354

年卷期： 2022 年 226 卷

页码：

收录情况： SCI

摘要： Groundwater level (GWL) recovery in some semiarid regions, attributed to mitigation countermeasures for groundwater depletion, potentially causes nitrate accumulated in the vadose zone to be introduced into the aquifer. However, the extent to which GWL recovery affects interactions between the vadose zone and saturated aquifers, migration pathways of soil nitrogen and groundwater nitrate dynamics have not been explicitly determined. This study established a quasi-3D feedback model for the vadose zone-groundwater coupled system in a typical GWL recovery area and quantitatively evaluated the effects of GWL recovery on nitrate-N leaching fluxes via the vadose zone and groundwater nitrate-N dynamics. Within the framework of the integrated model, both the water/contaminant leaching fluxes and the depth to groundwater were exchanged at each flow time step. The obtained results reveal that the temporal changes in nitrate-N leaching fluxes depended on the be-haviors of precipitation, farmland irrigation and lithology of the vadose zone, while its spatial patterns were determined by both the GWL undulation and the vertical profiles of nitrate-N content. Furthermore, the GWL recovery caused the magnitude of the nitrate-N leaching fluxes into the aquifer to increase by 44.4%. Along with the GWL recovery, the phreatic aquifer volume increased by 7.47%, and the nitrate-N mass herein increased by 40.06%, which was largely driven by the nitrate-N leaching flux. Consequently, the average groundwater nitrate -N concentration in the GWL recovery region increased by approximately 2.4 mg/L, apart from the artificial recharge route. This finding suggests that the intensified leaching of soil contaminants, given the circumstances of GWL recovery, has a negative effect on groundwater quality. An appropriate groundwater management scheme is therefore urgently required to achieve an optimal balance between GWL recovery and groundwater environment.

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