Multivariate statistical analysis of chemical and stable isotopic data as indicative of groundwater evolution with reduced exploitation

作者：Fei Liu, Jingkun Zhang, Shiqin Wang, Jiawen Zou, Pinna Zhen · 发表于：Geoscience Frontiers · 年份：2022 · DOI：10.1016/j.gsf.2022.101476 · 被引用次数：39 · 研究领域：Groundwater and Isotope Geochemistry、Geochemistry and Geologic Mapping、Hydrocarbon exploration and reservoir analysis

Groundwater resources in the North China Plain (NCP) are undergoing tremendous changes in response to the operation of groundwater exploitation reduction (GWER) project. To identify groundwater evolution in this complex context, hierarchical cluster analysis (HCA) and principal component analysis (PCA) were combined to interpret an integrated dataset of stable isotopes and chemical data from four sampling campaigns in a pilot area of groundwater control. We proposed a novel HCA approach integrating stable isotopes and chemical signals, which successfully partitioned the groundwater samples into the unconfined and the confined water samples. Stable isotopic evidence showed that the lateral inflow and the surface water may contribute more to groundwater recharge in this region than local modern precipitation. The unconfined water’s main hydrochemical types were Na type with mixed anions, and Na–Cl–SO4 type, while the confined water was mainly Na–Cl and Na–SO4 types. Geochemical processes mainly involved the dissolution/precipitation of halite, gypsum, Glauber's salt, feldspar, calcite and dolomite, as well as the cation exchange. PCA results showed that water–rock interaction (i.e., salinity-based and alkalinity-based processes) predominated the hydrochemical evolution, along with local nitrate contamination resulting from fertilizers and domestic sewage. The GWER project regulated the natural evolution of unconfined water chemistry, and significantly reduced the unconfined wat...