保守性离子在包气带层状土中运移规律研究

RESEARCH ON THE MIGRATION LAW OF CONSERVATIVE ION IN LAYERED SOIL UNDER UNSATURATED ZONE

为研究溶质在多层层状包气带土中运移规律,选取5种颗粒配比不同的土样填装成由粗及细和由细及粗两分层顺序相反的土柱,通过室内试验研究保守性Br-在两种不同结构层状土中基本运移规律。研究得出:当土体表层遭受浓度为200 g/L Na Br一次性污染,在15 mm/12 h降雨强度下,Br-在第1、2层土体浓度经历快速上升段、峰值段、下降段3个阶段变化,第3、4、5层土体浓度经历上升段、平稳下降段。试验结束时,Br-在由粗及细的土柱中分布较均匀,在由细及粗的土柱中集中在表层;溶质穿透整个土柱的时间,由粗及细结构比由细及粗结构提前96 h。结果表明,在截污性能和延缓溶质向地下水补给方面,由细及粗结构均要优于由粗及细的结构。

For studying solute migration law in layered soil under the unsaturated zone,this paper picked five kinds of soils from different particles ratio and then filled them into two group soil columns: From coarse to fine and the opposite,of which the hierarchical order was inverse. Via the laboratory experiment,the basic migration law of conservative Br-was uncovered under two types of layered soil. When the soil surface was polluted in the rainfall intensity of 15 mm /12 h,the Brconcentration of 1st and 2nd layers experienced three stages in the two sorts of soil structures: rising period rapidly,peak period and declining period. The soil concentration of 3rd,4th,and 5th layers had been through rising period and declining period stably. At the end of the test,Br-concentration was well-distributed in the columns from the coarse to fine,while it concentrated on the soil surface in the other one. Meanwhile,the time when the solute penetrated the entire soil column was about 96 h in advance composed of the structure from coarse to fine than the inverse. The structure from coarse to fine was better in the sewage entrapment performance and the solute delay to recharge the groundwater.