饱和非饱和分层土壤中铁离子运移试验

Experimental study on migration of ferric ion in saturated-unsaturated layered soils

建立了由黏上、砂壤土、细砂组成的饱和非饱和分层大型土槽试验模型,以研究铁离子在饱和非饱和分层土壤中的迁移规律。结果表明,铁的迁移转化规律与分层土壤的分布顺序密切相关。同一时刻同一水平面上的点,离污染源越远,质量浓度越低;同一竖直剖面上的点,从上至下,质量浓度越来越高。铁在细砂、砂壤土、黏士中的迁移能力依次递减。水力梯度2.5%的条件下,铁在细砂层、砂壤土层、黏土层中运移1 m分别需要1 224 h、2 200 h、3 605 h。

This essay is inclined to present the findings of our experimental study on the migration of iron remnants in the saturated-unsaturated layered soils. Our study is different from the existing researches about the migration processes of ferric ion in groundwater in that the already existing studies mainly focus on the ferric ion concentration mechanisms, ferric ion distribution in groundwater, ferric ion migration processes in saturated soil iron, etc. Few of them are devoted to the study of the migration process of ferric ion in saturated-unsaturated horizontal layered soils. We have developed a saturated-unsaturated horizontal layered soil box experimental model, which is made up of clay, sandy loam and fine sand, with our aim focused on the migration process of ferric ion in saturated-unsaturated layered soils. The experimental results of our study show that： the migration process of ferric ion is closely related to the layered order of different soils; at the same time, the farther it is from pollution sources, the lower the concentration will be for the points on the same horizontal plane; and for the point on the vertical plane, the concentration becomes higher and higher from top to bottom. Therefore, the migration capability of ferric ion in the fine sand, sandy loam and clay tends to decrease gradually, and the migration velocities of ferric ion are respectively 1/1 224 m/h, 1/2 200 m/h and 1/3 605 m/h in fine sand, sandy soil and clay under the condition of hydraulic gradient 2.5%. And, therefore, it can be made sure that the experimental results presented in this paper will bring about imputes to improve our understanding of the migration processes of ferric ion in saturated and unsaturated layered soils, and also helps to lay a theoretic basis for better treatment of ferric ion pollution in the future.