巴中北部岩溶山区地下水化学特征及演化分析

Hydrochemical Characteristics of Karst Groundwater in the Mountains of Northern Bazhong City,China

为研究我国南、北岩溶发育过渡带地下水的水文地球化学特征及形成机制.采集巴中市北部双峰垭地区25组地下水样品,运用描述性统计分析、变异系数、Schoeller图、舒卡列夫分类、Piper图解、Gibbs与离子比例系数等方法对研究区岩溶水化学及分布特征进行分析,并探讨控制地下水化学演化的主要过程.结果表明,研究区南、北地下水存在一定的差异,北区地下水阴阳离子以HCO3-、Ca2+和Mg2+为主,水化学类型以HCO3-Ca·Mg型为主,南区地下水阴阳离子以HCO3-和Ca2+为主,水化学类型以HCO3-Ca型为主;地下水水文地球化学演化过程均受水-岩作用和阳离子交替吸附作用的控制,但对比之下南区蒸发结晶作用比北区更加强烈,北区大气降雨作用更加显著;气候与岩性的差异是导致研究区南、北部地下水化学存在差异的主要原因.

To study the hydrogeochemical characteristics and formation mechanism of groundwater in a karst development transition zone in southern and northern China,25 groundwater samples were collected from the Shuangfengya area in the northern part of Bazhong City.Descriptive statistics,coefficients of variation,Schoeller diagrams,Sukalev classification,Piper diagrams,and Gibbs and ion scale coefficients were used to analyze the karst water chemistry and distribution characteristics.The main processes controlling the chemical evolution of the groundwater are also discussed.The research shows that the degree of groundwater mineralization in the study area is generally low,with mostly neutral water and alkaline water.There are some differences in groundwater between the northern and southern regions;the anions and cations in the groundwater in the northern area were mainly HCO3-,Ca2+,and Mg2+,with HCO3-Ca·Mg being the main water chemistry type;the anions and cations in the groundwater in the northern area were mainly HCO3-,and Ca2+,and HCO3-Ca was the main water chemistry type.The chemical character of groundwater was controlled by rock weathering and alternate cation adsorption,and evaporation crystallization in the southern region was more significant than in the northern region.Furthermore,rainfall in the northern region had a more significant effect on groundwater geochemistry than in the south.The differences in climate and lithology between the northern and southern region are the dominant factors influencing the differences in hydrochemistry.