黔西拖长江流域水化学演化特征及驱动因素

Characteristics and Driving Factors of Hydrochemical Evolution in Tuochangjiang River Basin,Western Guizhou Province

拖长江为黔西典型的矿业型岩溶山地小流域,研究其水化学演化特征及驱动因素,对当地经济社会发展和水资源科学管理均具有重要的意义.通过采集拖长江流域河水、泉水和矿井水样品,利用水化学图解、数理统计和绝对因子分析-多元线性回归受体模型(APCS-MLR),研究了拖长江流域河水溶质来源及其对河水水化学组分的贡献.拖长江流域河水pH值为7.30~8.31,TDS值为40~520 mg·L^(-1),TDS主要由Ca^(2+)、Na^(+)、HCO^(-)_(3)和SO_(4)^(2-)贡献.河水优势阳离子为Ca^(2+)和Na^(+),优势阴离子为HCO^(-)_(3)和SO_(4)^(2-),水化学类型从HCO_(3)-Ca过渡为HCO_(3)-Ca·Na和HCO_(3)·SO_(4)-Ca·Na型;矿井水主要为HCO_(3)-Na和HCO_(3)·SO_(4)-Na型.河水水化学组分受到岩石风化作用、阳离子交替吸附作用、矿物溶解和沉淀作用以及人类活动的综合影响,其中Ca^(2+)、Mg^(2+)和HCO^(-)_(3)主要来源于碳酸盐岩和硅酸盐岩的风化溶解,Na^(+)和SO_(4)^(2-)主要来源于矿业废水排放,Cl^(-)和NO^(-)_(3)则分别受到生活污水和农业活动的影响.APCS-MLR受体模型分析进一步显示,河水溶质主要有采煤废水排放、土壤矿物溶解、地质背景、农业活动和未知源这5种来源,对河水的贡献率分别为23.49%、35.04%、13.87%、7.96%和20.63%.矿业因子和土壤因子是河水溶质最重要的来源,二者是拖长江流域水化学演化的主要驱动因素.

Tuochangjiang River is a typical mining-type watershed in the karst mountainous area of western Guizhou province.The study of its hydrochemical evolution characteristics and driving factors is of great significance to the local economic development and the scientific management of water resources.The samples of river water,spring water,and mine water in the Tuochangjiang River Basin were collected,and the sources of solutes and their contribution to the chemical components of river water were discussed by means of hydrochemical diagrams,mathematical statistics,and the absolute principal component scores-multivariate linear regression model(APCS-MLR).The results showed that the pH of the river water ranged between 7.30 to 8.31,and the TDS value ranged between 40 to 520 mg·L^(-1),which was mainly contributed by Ca^(2+),Na^(+),HCO^(-)_(3),and SO_(4)^(2-).The dominant cations in river water were Ca^(2+) and Na^(+),the dominant anions were HCO^(-)_(3) and SO_(4)^(2-),and the main water chemistry transitioned from HCO_(3)-Ca to HCO_(3)-Ca·Na and HCO_(3)·SO_(4)-Ca·Na type,whereas that of the mine water was mainly the HCO_(3)-Na and HCO_(3)·SO_(4)-Na types.The chemical composition of river water was affected by rock weathering,exchange adsorption of anions,mineral dissolution and precipitation,and human activities,in which Ca^(2+),Mg^(2+),and HCO^(-)_(3) were mainly derived from the weathering and dissolution of carbonate and silicate rocks,Na^(+)and SO_(4)^(2-) were mainly from the discharge of mining wastewater,and Cl^(-) and NO^(-)_(3) were affected by domestic sewage and agricultural activities,respectively.APCS-MLR analysis further showed that the river water solutes mainly included five sources:discharge of mining wastewater,dissolution of soil minerals,geological background,agricultural activities,and unknown sources,and their contribution rates to river water were 23.49%,35.04%,13.87%,7.96%,and 20.63%,respectively.Mining factors and soil factors were the most important sources of solutes in the river water,and they were the main driving factors for the hydrochemical evolution of the Tuochangjiang River Basin.