Hydrochemical characterizations and groundwater quality assessment in the coastal region of the Jiaodong peninsula, North China.

Groundwater resources constitute a primary water source in the coastal region of Jiaodong Peninsula (CRJP), serving as an essential foundation for socio-economic development and municipal water supply. This study sought to evaluate the hydrogeochemical properties of the CRJP's groundwater using 73 samples collected in 2017, comprehensively analyzing the chemical composition and environmental factors using mathematical statistics and hydrochemical techniques. The results demonstrate that groundwater in the CRJP possesses TDS values ranging from 262 to 28,160 mg/L, with a pH ranging between 6.4 and 8.5, characterizing a weakly alkaline water system. The cation order in groundwater is Na+ > Ca2+ > Mg2+ > K+, while the anionic sequence comprises Cl- > HCO3- > SO42- > NO3-. According to the Piper diagram, groundwater samples predominantly clustered into SO4·Cl-Ca·Mg and SO4·Cl-Na types. Additionally, significant spatial variations exist in the primary chemical components of groundwater. Hydrogeochemical characteristics within the region are influenced both by natural and human activities; natural elements include weathering of silicate rocks, gypsum and carbonate minerals dissolution, while human practices comprise industrial and mining activities, agricultural practices, and domestic waste discharge. The results from a health risk assessment show that non-carcinogenic risks posed by nitrate intake via drinking water are considerably high for infants in comparison to adults, teenagers, and children. Furthermore, certain regions within the CRJP show notable seawater intrusion effects on groundwater studied.