贵州草海水化学特征及离子来源分析

Hydrochemical Characteristics and Major Ion Sources of Lake Caohai in Guizhou Province

为明确草海水体化学的时空分布特征,揭示水-岩作用以及人类活动对水化学的影响,分别在枯水期和丰水期对草海湖水、河水及地下水进行系统采样,并通过Piper、Gibbs等水文地球化学方法分析水化学控制因素和主要离子来源。结果表明,草海水化学类型主要为HCO3-Ca和HCO3-SO4-Ca-Mg型。HCO3-、Ca2+为优势离子,分别占总阴离子、总阳离子的48%和44%,有明显河水与地下水输入特征。草海水化学过程主要受方解石、白云石等碳酸盐类风化和人为活动影响,同时还伴随有蒸发盐岩和硫酸盐岩(石膏和硬石膏)的溶解。草海水体HCO3-、Ca2+、Mg2+主要来自方解石和白云石等碳酸盐矿物风化,SO42-主要来源于硫酸盐岩溶解,K+、Na+、Cl-、NO3-主要受城市生活污水和农业面源污染影响。主成分分析显示碳酸盐岩、硫酸盐岩和硅酸盐岩等水-岩作用对草海水化学的贡献率约为51%,城镇生活污水、蒸发作用及生物作用的贡献率约为37%。

In order to clarify the temporal and spatial variation in the hydrochemistry of Lake Caohai,and to reveal the influence of water-rock interactions and the impact of human activities on the hydrochemistry,different water bodies,including Lake Caohai,rivers and ground water,were systematically sampled during the dry and wet seasons,and were subjected to the analysis of the controlling hydrochemical factors and main ion sources by methods such as Piper and Gibbs.The results indicate the hydrochemical types of Lake Caohai are mainly HCO3-Ca and HCO3-SO4-Ca-Mg,and HCO-3 and Ca2+,which account for 48%and 44%of total anion and total cation,respectively,are the dominant ions.The water of Lake Caohai has obvious characteristics of river and groundwater input.The hydrochemical process of Lake Caohai is mainly affected by the weathering of carbonate rocks,such as calcite and dolomite and so on,and the human activities.It’s also affected by the dissolution of evaporate and sulfate minerals (gypsum and anhydrite).Overall,HCO-23,Ca+,Mg2+in lake water of Caohai are mainly from the weathering of carbonate rocks such as calcite and dolomite;SO2-4is mainly derived from the dissolution of sulfate rocks;and K+,Na+,Cl-,NO-3 are mainly affected by the urban sewage and agricultural effluent.According to the principal component analysis,carbonate-sulfate and silicate rocks contribute about 51%to the hydrochemistry of Lake Caohai,while,urban sewage,evaporation and biological effects contribute another 37%.