Characteristics and influencing factors of hydrochemistry and dissolved organic matter in typical karst water system

The unique hydrogeological conditions of karst area make the groundwater react rapidly to rainfall events, which makes the groundwater more susceptible to anthropogenic pollutions. The current study based on a combined excitation-emission matrix fluorescence spectroscopy and parallel factor analysis (EEM-PARAFAC) and geochemical–statistical investigation of water samples from the karst water system in Xintian County, Hunan Province, China, gives crucial information about the principal factors influencing karst water hydrochemistry and dissolved organic matter (DOM). The analyzed data revealed that both surface water and descending spring samples were within the Ca-Mg–HCO3 water type and dominated by humic-like fluorophore, and well water samples were within both the Ca–Mg–HCO3 and Na–HCO3 water types and controlled by protein-like fluorophore. The chemical compositions of surface water and descending springs were mainly influenced by the weathering of silicate, carbonate, and evaporate rocks and precipitation. In addition to be affected by the weathering of silicate, carbonate, and evaporate rocks and precipitation, the well water was also impacted by ion exchange and other activities like anthropogenic. The DOM in the karst water system was affected by allochthonous and autochthonous inputs as well as the chemical compositions of the water.