[Chemical Characteristics of Groundwater and Material Sources Analysis in Buckwheat Field, Yunnan Province]

In order to study the hydrochemistry characteristics and material sources of groundwater in the Buckwheat basin, we collected 32 groundwater samples in the study area in July 2017. The chemical characteristics of groundwater were analyzed by cluster analysis, factor analysis, and path model analysis. Meanwhile, we qualitatively and quantitatively assessed the sources of groundwater hydrochemistry in the Buckwheat basin. The results showed that the groundwater in the study area was weakly alkaline, and the major ions such as Ca²⁺, Mg²⁺, SO₄^2-, HCO₃^-, and NO₃^- had high spatial variability. According to the clustering analysis, the groundwater in the study area can be divided into two categories, namely, class A and class B, and these have the following two subsets:A₁, A₂, B₁, and B₂. From A to B, the chemical types of groundwater become more complex. The hydrochemistry types of class A were all of the HCO₃-Ca type, while those of class B₁ were HCO₃-Ca, HCO₃-Na·Ca, and HCO₃-Na·Ca·Mg, and those of class B₂ were HCO₃-Ca, HCO₃-Ca·Mg, HCO₃-Na·Ca. In order to further explore the influence factors of groundwater hydrochemistry, we determined that carbonate rocks, human activities, evaporite rocks, and silicate rocks were the main material sources of groundwater through factor analysis and path model analysis. Among all of the above factors, the dissolution of magnesium sulfate evaporite and the actions of human activities were found to be important reasons for the formation of carbonate rocks, which served as the main sources of groundwater chemical components and diverse hydrochemistry characteristics.