云南荞麦地流域地下水水化学特征及物质来源分析

为研究荞麦地流域地下水的水化学特征及物质来源,2017年7月在研究区共采集地下水的水样32个,综合运用聚类分析、因子分析和路径模型分析等方法,分析了荞麦地流域地下水水化学特征,并定性和定量探讨了荞麦地流域地下水水化学的物质来源.结果表明,研究区内水体整体呈弱碱性,Ca~(2+)、Mg~(2+)、SO_4~(2-)、HCO_3~-和N_3O~-等主要阴阳离子具有较高的空间变异性.通过聚类分析可知,研究区内地下水可分为两大类:A类和B类,分别具有两个子集:A_1、A_2、B_1和B_2,并且从A类地下水到B类地下水化学类型开始变得复杂,A类地下水水化学类型均为HCO_3-Ca型,B_1类地下水和B_2类地下水分别有HCO_3-Ca型、HCO_3-Na·Ca型、HCO_3-Na·Ca·Mg型和HCO_3-Ca型、HCO_3-Ca·Mg型、HCO_3-Na·Ca型各3类.为进一步探讨地下水水化学的影响因素,通过因子分析和路径模型分析可确定碳酸盐岩、人类活动、蒸发岩和硅酸盐岩是地下水的主要物质来源.其中人类活动的作用和MgSO_4型蒸发岩的溶解,是形成以碳酸盐岩为地下水化学组分的主要来源,同时具有多元地下水水化学特征的重要原因.

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.