蛤蟆通河流域地下水化学特征及控制因素

为研究蛤蟆通河流域水化学特征及主要离子来源,2017年先后采集地下水样品59组,综合运用数理统计、Piper三线图、Gibbs模型和离子比等方法,分析了蛤蟆通流域地下水的水文地球化学特征,并探讨了蛤蟆通流域的水化学演化规律及主要离子来源.结果表明,该区地下水阳离子以Ca~(2+)为主,占阳离子总量的质量分数为22. 1%～72. 4%,平均为48. 7%;阴离子以HCO_3~-为主,占阴离子总量的质量分数为35. 3%～97. 5%,平均为80%; TDS介于93. 3～521. 1 mg·L~(-1),平均值为219. 1 mg·L~(-1),均为淡水;地下水类型以HCO_3-Ca、HCO_3-Ca·Mg和HCO_3-Ca·Na型水为主;地下水样品均分布在Gibbs模型左中部,说明该流域水化学离子组成受岩石风化作用控制;通过离子来源分析,该区主要离子来源于硅酸盐岩和碳酸盐岩的风化溶解.

Major Ionic Features and Possible Controls in the Groundwater in the Hamatong River Basin

In order to study the major ion chemistry and controls of groundwater, 59 groundwater samples were collected and their major ions measured in the Hamatong River Basin. The hydrogeochemical characteristics of groundwater in this basin were analyzed by means of mathematical statistics, Piper triangular diagrams, Gibbs figures, and ionic relations, and the water chemical evolution and ion sources of the Hamatong River Basin were determined. The results showed that Ca²⁺ was the main cation in the groundwater, accounting for 22.1% to 72.4% of the total cations, with an average value of 48.7%. HCO₃^- was the main anion, accounting for 35.3% to 97.5% of the total anions, and with an average value of 80%. Total dissolved solids concentration ranged from 93.3 mg·L^-1 to 521.1 mg·L^-1 with a median value of 219.1 mg·L^-1. The hydrochemical types of groundwater are HCO₃-Ca, HCO₃-Ca·Mg, and HCO₃-Ca·Na. Chemical weathering rates of carbonates and silicates were estimated, and the chemical composition of groundwater samples located in the middle of Gibbs model indicated that the major chemical process of groundwater was controlled by rock weathering. Silicate weathering is believed to significantly contribute to dissolved solute compositions, and carbonate weathering played an important role as the source of dissolved ions.