Hydrochemistry characters and hydrochemical processes under the impact of anthropogenic activity in the Yiyuan city, Northern China

Water resource is a valuable resource for human beings to survive and maintain social stability and development. However, in recent years, the process of urbanization has been accelerated, and many cities and towns have presented groundwater pollution. To investigate the spatial distribution of hydrochemical components in urban areas after groundwater pollution and the hydrogeochemical effects on surrounding areas, using multifarious methods such as classical statistics, geostatistics, saturation index, and stable isotopes, the hydrogeochemical effects along groundwater flow were analyzed and deduced. The results show that the main ions of the groundwater in the Yiyuan are Ca2+ and HCO3−, it is mainly low-salinity fresh water, and the hydrochemistry type is mainly HCO3–Ca·Mg type. Groundwater pollution in urban areas increases the content of inorganic and organic matter in groundwater, the main ions affected are NO3−, Cl−, Ca2+, and SO42−, and their concentrations increased by 12.3, 22.3, 7.6, and 12.3 mg/L, respectively. In the city, negative cation exchange occurs mainly, after leaving the city, cation exchange occurs mainly. The results of the saturation index calculation indicate that groundwater pollution has little effect on the dissolution and precipitation of minerals. After leaving the town, denitrification, desulphurization, and cation exchange occurs in the underground aquifer, which reduces the concentration of pollutants in the groundwater. The study suggests that a variety of hydrogeochemical processes play an important role in the spontaneous reduction of some pollutant concentrations in groundwater away from the pollution source, while the concentration of other substances may rise.