甲苯在毛细带中的垂向迁移过程及其环境要素响应

The vertical migration process of toluene in capillary zone and its response to environmental factors

为探究甲苯在非均质毛细带中的迁移规律及环境要素响应,采用一维土柱淋滤分层监测实验,模拟瞬时释放情境下甲苯从包气带进入毛细带到达含水层的迁移过程,同步监测pH值、DO、ORP等环境要素随甲苯迁移的变化规律,利用Pearson方法识别各环境要素与甲苯迁移的相关性.结果表明:甲苯在毛细带中迁移可分为4个阶段,即以重力作用为主导的浓度迅速上升阶段,受毛细带顶托作用迁移速度下降、浓度值缓慢上升阶段,受吸附作用甲苯浓度值明显下降阶段,稳定的污染分布形成阶段.pH值、DO和ORP等环境要素与甲苯迁移过程正相关性显著且呈现明显的阶段性,其中ORP与甲苯迁移规律最为接近,pH值次之,DO浓度与甲苯迁移规律偏差最大,尤其是上升阶段变化幅度最小.

In order to explore the migration law of toluene in heterogeneous capillary zone and the response of environmental factors,a one-dimensional soil column leaching experiment with multi-layered monitoring was used.This study simulated the migration process of toluene from the vadose zone to the aquifer under the instantaneous release situation,and the changes of pH,DO,ORP and other environmental factors with the migration of toluene were monitored synchronously.Through Pearson correlation analysis,the relationship between environmental factors and toluene migration was noticeable.The results showed that the migration of toluene in the capillary zone can be divided into four stages,namely,the rapid increase of concentration dominated by gravity;the migration rate decreased and the concentration increased slowly under the action of capillary zone jacking;the concentration of toluene decreased significantly under adsorption and the formation stage of stable pollution distribution.The environmental factors such as pH,DO and ORP were positively correlated with the migration process of toluene and showed obvious stages.Among them,the migration law of ORP was the closest to that of toluene,followed by pH,and the deviation between DO and migration law of toluene was the most obvious,especially in the ascending stage.