Hydrochemical components evolution and suitability assessment of groundwater in Emei-Jiajiang Plain of Southwestern China

To investigate the hydrochemical formation mechanisms of groundwater in Emei-Jiajiang Plain and to analyze the sources of hydrochemical components, traditional hydrochemical diagram methods, mathematical statistics, the Absolute Principal Component Scores-Multiple Linear Regression model (APCS-MLR), and the Positive Matrix Factorization model (PMF) were used. Based on the inorganic component contents of 19 Quaternary groundwater samples, the hydrochemical characteristics of Quaternary groundwater, the contribution rates of hydrochemical component sources, and water quality status were analyzed. The results show that: The hydrochemical composition of groundwater is mainly controlled by rock weathering, with carbonates and silicates being important sources of groundwater ionic components, and the dissolution of carbonate is comprehensively controlled by H ₂ CO ₃ and H ₂ SO ₄ . Human activities have exerted a certain impact on the groundwater in the study area, mainly from domestic sewage and agricultural sewage. Both the APCS-MLR and PMF results indicate that natural sources, mixed sources from of industrial and agricultural activities, agricultural activities, and domestic sewage are the main factors affecting the groundwater in the study area. The groundwater quality in the study area is generally good. Entropy Weight Water Quality Index (EWQI) evaluation results show that most areas are suitable for direct human consumption, with a low potential non-carcinogenic risks, and suitable for irrigation, only local sites have health risks and are not suitable for irrigation.