Hydrochemical Characteristics and Potential Health Risk Assessments of Groundwater Resources in the Yinchuan Plain, China

Groundwater quality is a critical factor constraining the sustainable and healthy development of the economy, particularly in regions with scarce water resources. Given the combined influences of natural processes and human activities, understanding the hydrochemical evolution and pollution status of groundwater in the Yinchuan Plain is essential for effective groundwater resource management in this area. This study collected 94 phreatic groundwater samples and integrated traditional hydrochemistry methods, the entropy-weighted water quality index (EWQI), and the human health risk assessment (HHRA) model to analyze the hydrochemical characteristics, water quality, and sulfate- and nitrate-related health risks in the Yinchuan Plain. The results revealed that the groundwater chemical types shifted from an HCO3-Ca type and mixed type to a Cl-Na type along the groundwater flow path. Rock weathering and evaporation were identified as the main factors influencing groundwater chemistry. SO42− concentrations were largely controlled by gypsum dissolution and evaporation. The EWQI assessment showed that 31.91% of samples were not suitable for drinking. Poor quality samples were primarily concentrated in the Huinong county, Pingluo county, Helan county and the southern part of the Litong district. Additionally, high integrated weights of HCO3−, K+, NO3−, pH, SO42− and Na+ pointed their high information content and variability in the groundwater dataset. Furthermore, long-term exposure to elevated sulfate and nitrate concentrations may pose potential health risks. The potential health risks for pregnant women and breastfeeding women were found to be higher than those for individuals over 10 years of age, warranting increased attention from both society and the academic community. This study aims to provide a basis for identifying priority monitoring areas, prioritizing key groundwater contaminants, and developing targeted pollution control measures. Integrating groundwater-quality monitoring, pollution-source control, and sustainable groundwater-use planning can support the long-term protection and sustainable utilization of groundwater resources in the Yinchuan Plain.