运城盆地土壤中氟运移规律动态试验研究

A dynamic experimental study of the fluorine transport regularity in soil of Yuncheng Basin

针对运城盆地氟污染重点区域取土,借助土柱物理模型试验装置,进行了氟污染物在土壤中的迁移规律研究。得到了不同质地的土壤在连续输入不同污染物浓度条件下,土壤中氟离子浓度随时空变化的过程。结果表明,氟离子化学性质活泼,在土壤中迁移过程比较复杂,氟吸附过程中伴随羟基OH-的释放,故实验过程中土壤溶液pH值由中性过渡到碱性。由于受吸附和解吸作用的影响,表现在氟离子穿透曲线对称性不好,各测点浓度峰值沿程逐渐衰减,拖尾现象严重,垂向迁移距离非常有限,因此运城盆地土壤中的氟离子很难直接垂向淋滤到浅层地下水中,这与实测资料结果一致。

With the aid of soil column test models, the transport regularity of fluoride in different polluted fluoride soils of Yuncheng basin was studied. The curves of F- concentrations in different periods and at different positions were obtained in different soils under the condition of inputting fluoride contaminants continuously. Laboratory experiments reveal that the migration process of fluorine ion in soils is complex because of its active chemical properties. The pH values of the soil solution change from neutral to alkaline due to the release of OH-resulting from the adsorption in the course of the experiment. The breakthrough curve of the fluorine ion is asymmetric due to the adsorption and desorption, and the peak values of concentration decay gradually at different positions. The tail of the breakthrough curve is relatively long. The migration distance in vertical direction is comparatively short, and hence it is very difficult for the F- ion to migrate directly from soil to groundwater through eluviation. The results are consistent with the observation data.