成层土壤中氨氮入渗迁移试验研究

Migration and permeation of ammonia in multilayered soils

垃圾填埋场渗滤液是造成土壤和地下水污染的重要来源,其中氨氮含量非常高,是垃圾渗滤液的主要污染物之一。为了寻求垃圾填埋场防渗与污染控制设计的理论依据,把握氨氮在地基中的迁移机理,将垃圾填埋场渗滤液的运移概化为渗滤液在垂直方向上的不同性质成层土壤中入渗迁移。通过大型土柱室内试验,研究了设有黏土防渗层的饱和-非饱和成层土壤中氨氮入渗迁移规律。提出了氨氮在黏土防渗层及非饱和黏土层中的吸附特性及在迁移过程中发生的三氮转化反应规律。氨氮质量浓度随土柱深度的增加而逐渐减少。在还原环境中,氨氮转化为亚硝酸盐和硝酸盐的比例很小,硝化细菌活动性不强。总结了影响氨氮迁移和转换的影响因素,土壤的性质(成分)对氨氮的吸附作用影响最显著。

The present paper is inclined to introduce its authors＇ study on the mechanism of leachate migration and permeation of the landfill as the result of the vertical infiltration and permeation of the leachate through different layers. It is just for this purpose, we have generalized likely mechanisms of the ammonium-nitrogen contents in the saturated-unsaturated layered soils through a series of large-scale soil column experiments in hoping to clarify the adsorption characteristics Of ammonium-nitrogen in the anti-seepage layer and unsaturated clay layer while emphasizing the ammonium-nitrogen transformation in the course of permeation, At the same time, we have also analyzed the relevant factors affecting such a process. As a matter of, fact, landfill leachate pollution has been becoming an ever threatening pollution .source likely to cause-serious soil and groundwater contamination, which has made ammonium-nitrogen one of the main pollutants because of very high content in landfill leachate. Though some protection techniques such as setting clay layer have been adopted in recent years, it becomes clear that such measures are not in the position to prevent leachate pollution from the very bettom of the＇ problem. It comes just from this rudimental need that we suggest the need of exploration of the migration and penetration mechanism＇ of the leachate to change the current civil engineering practice merely based on the seepage prevention experiences.