摘要:
针对缺乏秦岭北麓洪积平原生态协调控制带地下水质量及其生态环境效应研究的问题，以北麓主体-西安段为例，基于2023年12月-2024年1月采集的107件浅层地下水样品，通过Piper三线图、Gibbs图以及主要离子之间的关系，阐释地下水水化学特征及其形成机理；依据《地下水质量标准》（GB/T 14848-2017），查明地下水质量、超标因子及其伴生的生态环境问题。结果表明：地下水整体呈弱碱性，属于淡水，主控阴、阳离子分别为HCO3-和Ca2+，主导水化学类型为HCO3-Ca、HCO3-Ca·Mg、HCO3·SO4-Ca·Mg、HCO3·SO4-Ca和HCO3-Ca·Na型；地下水水化学特征主要受硅酸盐岩和碳酸盐溶解、阳离子交换作用和人类活动的综合影响；水质等级Ⅱ、III、IV和V类分别占比15.89%、52.34%、11.21%和20.56%，造成水质未达标的主要因子是硝酸盐和总硬度；秦岭山前地下水质量较优，而平原区地下水质量相对较差，控制点源污染，减轻面源污染，开展地下水环境治理迫在眉睫。研究结果对加强秦岭地下水资源的开发利用与保护具有重要意义。
Abstract:
In response to the lack of research on the groundwater quality and ecological environmental effects in the ecological coordinated control zone of the alluvial plain at the northern foothills of the Qinling Mountains, taking the main body of the northern foothills - Xi'an section as an example, based on 107 shallow groundwater samples collected from December 2023 to January 2024, this study explains the hydrochemical characteristics and formation mechanism of groundwater through Piper's trilinear diagram, Gibbs diagram, and the relationships between major ions. According to the Quality Standards for Groundwater (GB/T 14848-2017), the quality of groundwater, factors exceeding standards, and associated ecological and environmental issues are identified. The results show that the groundwater is weakly alkaline and belongs to freshwater as a whole. The main controlling anions and cations are HCO3- and Ca2+, respectively; and the dominant hydrochemical types are HCO3-Ca, HCO3-Ca·Mg, HCO3·SO4-Ca·Mg, HCO3·SO4-Ca and HCO3-Ca·Na. The hydrochemical characteristics of groundwater are mainly influenced by the dissolution of silicate rocks and carbonates, cation exchange, and human activities. The water quality grades II, III, IV, and V of groundwater account for 15.89%, 52.34%, 11.21%, and 20.56%, respectively; and the main factors causing substandard water quality are nitrate and total hardness. The groundwater quality in the front of the Qinling Mountains is relatively good, while the groundwater quality in the plain areas is relatively poor, therefore it is urgent to control point source pollution, reduce non-point source pollution, and carry out groundwater environmental governance. The research findings are of great significance for strengthening the development, utilization, and protection of groundwater resources in the Qinling Mountains.
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