信江流域地下水水化学特征及形成机制

Hydro-chemical Characteristics and Formation Mechanism of Groundwater in Xinjiang River Basin

地下水质量是鄱阳湖水生态环境重要组成部分,研究地下水的水化学特征、形成机制对流域水资源合理开发利用和生态文明建设具有重要意义。利用Gibbs图解法、相关性分析法以及主成分因子分析方法等分析了鄱阳湖信江流域地下水的水化学特征和形成机制。结果表明:大气降水是地下水的主要补给来源,Ca~(2+)、Na~+、HCO~-_3是地下水中优势离子,受水文地质情况及人类活动影响流域内水化学类型主要以Ca-HCO_3、Ca-HCO_3·SO_4为主。地下水中离子主要来源于岩石风化,Ca~(2+)、HCO~-_3、Mg~(2+)主要来自碳酸岩风化,Na~+、SO_4~(2-)主要来自蒸发岩的溶解,NO~-_3、Cl~-主要来自人类活动,K~+主要来源于硅酸岩风化输入,人类活动的影响主要为工矿活动;同时Ca~(2+)、Na~+还受到阳离子交替吸附作用影响,阳离子交替吸附作用参与了地下水水文地球化学过程。碳酸岩、蒸发岩、硅酸岩、人类活动、大气降水对地下水溶质贡献率分别为29.6%、19.9%、12.1%、19%、19.4%。

Groundwater quality is an important part of Poyang lake water ecological environment. It is significant to study the hydro-chemical characteristics, material mechanism and water pollution of groundwater. Thus, the hydro-chemical characteristics and material source mechanism of groundwater in Xinjiang River basin were analyzed by methods of Gibbs graphic method, correlation analysis method and principal component factor analysis method. The result shows that precipitation is the main recharge source of groundwater. Ca2+, Na+, HCO-3 are the dominant ions in groundwater. The main hydro-chemical types are Ca-HCO3 and Ca-HCO3·SO4 due to the influence of hydro-geological conditions and human activities. Ions in groundwater mainly comes from rock weathering, Ca2+, HCO-3, Mg2+ mainly comes from carbonate weathering, Na+, SO42- mainly from the dissolution of evaporative rocks, NO-3 and Cl-mainly from human activities, and K+ mainly come from the weathering input of silicate rocks. The impact of human activities is mainly industrial and mining activities, and at the same time, Ca2+ and Na+ also affected by cation alternating adsorption. The contributions of carbonated rock, evaporative rock, silicate rock, human activity and atmospheric precipitation are 29.6%, 19.9%, 12.1%, 19% and 19.4%, respectively.