Application of water quality index and multivariate statistical analysis in the hydrogeochemical assessment of shallow groundwater in Hailun, northeast China

Due to the impact of human agricultural production and climate and environmental changes, the suitability of groundwater for drinking purposes has attracted widespread attention. In order to quantify the hydrochemical characteristics of groundwater in Hailun and evaluate its suitability for drinking purposes, 55 groundwater samples were collected and analyzed. The results show that groundwater in aquifers in the study area is weakly alkaline. The content is in the order HCO3-> Cl-> SO42- for anions, and Ca2+> Na+> Mg2+ for cations. Groundwater chemical type were dominated by HCO3-Ca center dot Mg, HCO3-Ca center dot Na, HCO3-Ca, and HCO3 - Ca center dot Mg center dot Na. The Gibbs plot, PCA, and CAI-1 index show that ion exchange, rock weathering and evaporation crystallization are the main reasons affecting the water chemical composition in Hailun. The analysis of water samples based on the WQI model revealed that about 69.09%, 25.45%, 1.81%, and 3.63% of the water samples were excellent, good, very poor, and unsuitable for drinking purposes, respectively. The spatial distribution map of water quality index show that most of the groundwater resources in the study area are not polluted and therefore suitable for drinking.