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Abstract：
The rapid development of urbanization and agriculture poses serious impacts on groundwater in arid and semi-arid areas, which typically have high groundwater depletion rates. In this study, chemical and isotopic analyses combined with different data interpretation methods (diagrams, bivariate analyses, principal component analysis (PCA), and hierarchical cluster analysis (HCA)) were used to identify the major factors controlling groundwater chemistry in an arid and semi-arid region of North China. Sixty-four groundwater samples (35 from unconfined aquifer, 29 from confined aquifer) were collected in Baotou City, North China, and 17 chemical variables were detected for each sample. The complex hydrochemical types in unconfined groundwater (e.g., HCO3-Ca·Mg, HCO3·Cl-Na·Mg, SO4-Na·Mg, and Cl·SO4-Na types) may be related to anthropogenic activities, while the main hydrochemical types in confined groundwater are HCO3-Ca·Mg, HCO3-Na·Mg, HCO3·Cl-Na·Ca, SO4·HCO3-Na·Mg, and Cl·SO4-Na types. Three component models for unconfined and confined groundwater were revealed using PCA, which explained approximately 79.69% and 80.68% of the data variance, respectively, providing a deeper insight into groundwater composition controlled by geochemistry and anthropogenic activities. Three clusters were yielded from HCA. The factors and identified clusters were verified with hydrochemical investigations. Among the natural factors, the main hydrochemical processes involve the dissolution of various minerals (halite, gypsum, feldspar, fluorite, mirabilite, biotite, dolomite, and calcite), cation exchange, evaporation, and mixing. The anthropogenic factors include domestic sewage intrusion and agricultural activities, which are most likely to lead to further declines in groundwater quality. These findings may be useful for improving groundwater resource management for sustainable development in arid and semi-arid areas.
摘要：
城市化和农业的快速发展对干旱和半干旱地区的地下水造成严重影响,通常地下水耗竭率高。在这项研究中,化学和同位素分析结合不同的数据解释方法(图表，双变量分析，主成分分析(PCA)，和层次聚类分析（HCA））用于确定控制华北干旱和半干旱地区地下水化学的主要因素。64个地下水样本(35个来自无限制含水层，29个来自密闭含水层）在包头市收集，华北,每个样品检测到17个化学变量。无限制地下水中的复杂水化学类型(例如，HCO3-Ca·Mg,HCO3·Cl-Na·Mg，SO4-Na·Mg,和Cl·SO4-Na类型)可能与人为活动有关，而受限地下水中的主要水化学类型是HCO3-Ca·Mg，HCO3-Na·Mg,HCO3·Cl-Na·Ca,SO4·HCO3-Na·Mg,和Cl·SO4-Na类型。使用PCA揭示了无约束和约束地下水的三个分量模型，这解释了大约79.69%和80.68%的数据方差，分别,更深入地了解受地球化学和人为活动控制的地下水组成。从HCA产生三个簇。通过水化学调查验证了因素和已识别的簇。在自然因素中,主要的水化学过程涉及各种矿物的溶解(岩盐，石膏,长石,萤石,芒硝,黑云母,白云石,和方解石)，阳离子交换，蒸发,和混合。人为因素包括生活污水入侵和农业活动，最有可能导致地下水质量进一步下降。这些发现可能有助于改善干旱和半干旱地区的地下水资源管理，以实现可持续发展。
