氮迁移转化对地下水硬度升高的影响

城市地下水硬度升高是一个普遍的环境问题，研究表明地下水硬度高值区与硝酸盐污染在空间上的分布具有一致性。通过室内土柱试验和化学热力学模拟，讨论了污水入渗过程中氮迁移转化对水土系统钙镁迁移的影响。结果表明：在连续入渗条件下，阳离子交换作用是控制地下水硬度升高的主要过程；在间歇入渗条件下，硝化作用改变了土水系统的酸碱条件，使钙镁难溶盐溶解，导致地下水硬度升高。

EFFECTS OF NITROGEN TRANSFORMATION ON HARDNESS INCREMENT OF GROUNDWATER

Hardness increment of groundwater is a widespread environmental problem in urban areas of China. Investigation results show that high hardness regions of groundwater are distributed in space with high nitrate. With the help of laboratory and thermodynamic simulation, the relation of nitrogen transformation with calcium and magnesium variation during wastewater infiltration in soil water system is studied. The research results indicate that the nitrification makes the pH condition change and causes dissolution of some minerals bearing calcium and magnesium, like calcite and dolomite etc. in discontinuous infiltration condition and leads to the hardness increment of groundwater. And cation exchanges of calcium, magnesium and ammonium control the hardness increment of groundwater in continuous infitration condition.