Geochemical Characteristics and Controlling Factors of Chemical Composition of Groundwater in a Part of the Nanchang Section of Ganfu Plain

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This work aims to investigate the hydrochemical characteristics and formation mechanisms of shallow groundwater in a part of the Nanchang section of Ganfu plain. The hydrochemical data from 90 groundwater samples were interpreted by the methods of mathematical statistics, Piper diagrams, Gibbs plots, ratio graphs of ions, and geochemical modeling. The results show that shallow groundwater is weakly acidic, the average concentration of cation in groundwater decrease in Ca2+ > Na+ > Mg2+ > K+, and the abundance is in the order HCO3− > NO3− > SO42− > Cl− for anions. The hydrochemical type of groundwater was dominated by HCO3-Na·Ca·Mg, HCO3·Cl-Na·Ca·Mg, and HCO3-Na·Ca. Moreover, the main controlling factor of groundwater hydrochemistry is water-rock interactions. Na+ and K+ mainly originate from the dissolution of halite. Ca2+ and Mg2+ are mainly controlled by carbonate dissolution, while the main anions come from the dissolution of evaporite and carbonate. The groundwater chemical evolution is affected by the dissolution and precipitation of the mineral phase and cation exchange.