Hydrochemical Characteristics and Genesis of Groundwater in Taoshan Granite Body, Yushan Uplift Area, South Jiangxi, China

Drawing upon an understanding of the distribution characteristics of groundwater in the Taoshan rock mass within the Yushan Uplift region of southern Jiangxi, this study utilizes mathematical statistics, ion ratio coefficients, factor analysis, and mineral dissolution equilibrium methods to characterize in detail the hydrochemical features of groundwater in humid mountainous areas. Furthermore, the study delves into the lithological source control and the primary natural mechanisms that underlie these characteristics. The results indicate that the average pH of groundwater in the study area is 7.13, classifying it as weakly alkaline. The dominant cations are Ca2+ and Na+, accounting for 61% and 26% of the total cations, respectively, while the dominant anion is HCO3−, constituting 91% of the total anions. The total dissolved solids (TDS) range from 37.93 mg/L to 228.16 mg/L, indicating low mineralization. The groundwater types are primarily HCO3-Ca·Na and secondarily HCO3-Ca. The groundwater type is mainly controlled by rock weathering, with the primary ion sources influenced by the weathering and dissolution of silicate rocks, supplemented by contributions from carbonate rock dissolution. Ion ratio analysis further confirms that the major ions in groundwater predominantly originate from the weathering of silicate minerals, with minimal influence from human activities. Na+, K+, and H2SiO3 are primarily derived from the weathering and dissolution of silicate rocks, while the weathering and dissolution of carbonate rocks (e.g., calcite) significantly contribute to Ca2+ and Mg2+. TDS shows significant positive correlations with Mg2+, SO42−, HCO3−, Na+, and Ca2+, with the most pronounced correlations observed between TDS and Ca2+ and HCO3−, exhibiting a correlation coefficient of 0.89. Factor analysis reveals that the first principal component has relatively high loadings for TDS, Ca2+, HCO3−, Mg2+, and SO42−. Additionally, among 45 natural spring water samples, 36 exhibit metasilicic acid (H2SiO3) concentrations exceeding 30 mg/L, meeting the standards for metasilicic acid mineral water and demonstrating significant potential for development and utilization.