粉煤灰浸出液入渗土壤过程中的水岩作用研究

为明确粉煤灰浸出液对地下水环境的影响,依据饱水土柱试验,利用质量平衡模型,对比研究了灞桥电厂粉煤灰浸出液和清水入渗土壤过程中的水岩作用.研究表明,虽然粉煤灰浸出液和清水入渗土柱的渗出液水化学特征存在明显差异,但入渗水的水质对渗出液的时间变异性影响较小.矿物的溶解沉淀作用及Ca-Na离子交换等水岩作用对浸出液和清水入渗过程中的化学反应及水化学形成产生重要影响.高浓度的粉煤灰浸出液比清水溶解了土壤中更多的可溶盐,使土壤的渗透系数增大,增加了地下水污染风险.

On the water-rock interactive function of fly-ash leachate during its infiltration into soil

The present paper is aimed to disclose the water-rock interactive effect of fly-ash leachate on the groundwater quality. For this purpose, we have performed the saturated sandy loam column correlation experiment in the laboratory condition in 12 days. By using the experiment with the fly-ash leachate in Baqiao power plant and clean water as the contrast media, we have studied the mechanism of water-rock interactive infiltration through the soil. The hydro-chemical simulation study has been focused on the analysis of the chemical characteristics of the leachate derived from the column A and column B, which may account for the reaction mechanism of the water-rock interaction of the leachate in the soil. Remarkable difference has been found as the experimental results between the hydro-chemical components of fly-ash leachate and the quality of clean water;however, little variation can be detected due to the infiltration or the clean water infiltration through the soil. The geochemical modeling approach has been used to predict the chemical reaction in the water-rock interaction to the water composition by PHREEQC software. Thus, it can be said that the simulation seems likely to lead to the following probabilities: water-rock interaction of dissolution/deposition of the mineral in the soil and the Ca-Na cation exchange may have important effect on the chemical reaction in the process of the fly-ash leachate or clean water infiltration through soil, in which different chemical reactions may account for the product of different hydro-chemical components in the leachate. As the same time, fly-ash leachate tends to result in more water than the clean water in the process of infiltration through the sandy loam column. Since in 12 days, it is possible for the fly-ash leachate to dissolute more dissoluble salt than the clean water, the permeability coefficient is likely to get bigger during the fly-ash leachate infiltration through the soil than during the clean water infiltration through the sandy loam. Thus, it can be concluded that bigger permeability coefficient in the fly-ash field is likely to account for the pollution hazard of the groundwater when the fly-ash leachate infiltrates into it with the time going on.