The dynamics and origin of groundwater salinity in the northeast Hufu Plain

The aim of this research is to identify the dynamic characteristics and origins of groundwater salinity in the Hufu Plain. Samples of groundwater were taken from wells throughout the Hufu Plain. Geochemical analyses using integrated ionic ratios with a variety of graphical approaches, saturation indices, and the GIS method were performed to distinguish the sources of groundwater salinity. The results indicated that the groundwater can be classified into five main types. The cation and anion trends were Ca2+ > Na+ > Mg2+ > K+ and HCO3− > SO42− > Cl− > NO3−, respectively. Groundwater quality in the Hufu Plain is influenced by the chemical weathering of rock-forming minerals. The variation in saturation indices for different minerals indicated that groundwater salinization was controlled to some degree by human activities in the Hufu Plain. Groundwater salinity is not only governed by mineral weathering and dissolution (such as calcite, aragonite, dolomite, and gypsum) but also significantly influenced by anthropogenic inputs (such as fertilizer, pesticide, and sewage irrigation). Groundwater salinity originates mainly from the dissolving of gypsum and anhydrite and from anthropogenic inputs rather than from the weathering, precipitation, and dissolution of calcite, dolomite, and aragonite.