Evolution of hydrochemistry and isotopic characteristics in shallow alluvial aquifers of Poyang Lake Basin, Eastern China

Abstract The hydrochemical characteristics of shallow groundwater and the factors affecting them were analyzed using descriptive statistical analysis, Piper trilinear charts, Gibbs charts, and ion ratios, to help improve the groundwater quality of the Poyang Lake Plain. The results showed that the groundwater was weakly acidic, with an average pH of 6.27. was the main ion component, with high stability in the study area. The chemical ions in groundwater were mainly controlled by rock weathering, and Ca2+ and Mg2+ originated from the dissolution of carbonate, silicate, or evaporite. Cation exchange was an important driving factor in the formation of groundwater chemical components in the study area. The shallow groundwater and surface water in the region around Poyang Lake are replenished by precipitation, but both are more affected by evaporation. The large d-excess value indicated that the groundwater was greatly affected by water–rock interactions. The main source of is chemical fertilizer and levels were less affected by domestic sewage, which may be because the study area is a traditional agricultural area. Rock weathering, leaching, and human activities were the main driving factors for the evolution of the chemical characteristics of the groundwater in the study area. These results provide a technical reference and the basis for regional collaborative efforts to control groundwater and surface water pollution.