地下水回灌不仅能够弥补地下水资源的亏空，而且能够稀释净化受污染的地下水。根据北京水源四厂的回灌试验数据，利用PHREEQC模拟软件进行了水质混合模拟和水质预测研究。回灌试验对南井水质影响较大，北井和东井的水质基本没有变化；南井的水质由Ⅲ类水质提升为Ⅱ类水质，其氯化物、硫酸盐、硝酸盐和碳酸氢盐浓度在回灌结束时与回灌井的浓度非常接近；而钾、钙和镁的最终浓度略微低于回灌井中相应指标的浓度，可能是由于阳离子交换作用导致。混合模拟水质与其回灌实测水质数据具有很好的相关性，由此获得南井的模拟混合比与回灌时间的线性方程，其R2高达0.999。据此预测北井在相同的回灌条件下需要回灌11 d，其水质才能由最初Ⅳ类水质提升为Ⅱ类水质。本研究的水质预测方法能够有效提高地下水回灌的效率，对于地下水的精准回灌具有重要的指导意义。

Groundwater recharge can not only cover the deficit of groundwater resources,but also dilute and purify contaminated groundwater.The recharge experiments at Beijing Water Source No.4 Plant and the PHREEQC simulation software were used in this study for water quality mixing simulations and water quality prediction.The results showed that the recharge has a great impact on the water quality of South Well,but limited impacts on that of North Well and East Well.The water quality of South Well was upgraded from Class Ⅲ to Class Ⅱ.The chloride,sulfate,nitrate and bicarbonate were recharged and their the concentration.at the end were very close to those of the recharge wells.The final concentrations of potassium,calcium and magnesium were slightly lower than those of the recharge wells,probably due to cation exchanges.The simulated water quality of mixed water had a good correlation with the observations,and a linear equation of the simulation mixing ratio and recharge time of South Well were obtained.Its coefficient of determination (R2) was as high as 0.999.It predicted that the groundwater in Beijing needed 11 days to be recharged under the same conditions for the water quality being upgraded from the Class Ⅳ to Class Ⅱ.The water quality prediction method of this study can effectively improve the efficiency of groundwater recharge and has useful guideline for groundwater recharge prediction.

国家水体污染控制与治理科技重大专项“北京受水区饮用水安全保障技术研究与工程示范项目”