壤土夹层对苯和Br^-在均质细砂中运移影响的试验分析

Effect of Silty Loam Interlayer on Migration of Benzene and Br^- in Homogeneous Fine Sand

为研究粉质壤土夹层对苯和溴离子(Br-)在非饱和带中入渗的影响,采用成都市金牛区某施工基坑粉质壤土和河砂,验证不同土样对Br-和苯的吸附性,构建不同构型的土柱进行试验,并分析其运移规律。结果表明:Br-的吸附程度不会因土样中黏粒含量的增加而增加;土样对苯以线性吸附为主,黏粒含量越高吸附量越大,污染物的运移性越弱;示踪剂Br-的浓度对土样吸附苯的影响可忽略不计;均质砂土湿润锋推进呈现一定的非线性,夹层以上两种构型土柱进程近乎一致,进入分层后湿润锋推进速度明显减弱,说明夹层具有一定的减渗作用;夹层的存在减弱了Br-以及苯向下运移,并且粉质壤土对苯有一定的吸附净化作用。研究结果可供从事地下水有机污染研究的人员参考。

To study the influence of silty loam interlayer on the migration of benzene and Br-in unsaturated zone,we analyzed the laws of migration of Br-and benzene in different soil columns by examining the adsorption of Br-and benzene by silty loam and sand collected from a foundation pit in Jinniu District of Chengdu.Result showed that the adsorption of Br-did not increase with the climbing of clay content;the adsorption of benzene increased linearly with the increase of clay content,hence weakening the migration of contaminants.The impact of the concentration of tracer bromide ion on the adsorption of benzene by soil sample was negligible.Moreover,the advancing of wetting front in homogeneous sand was nonlinear,almost consistent above the silty loam interlayer in both soil columns;once entering the silty loam interlayer,the advancing of wetting front weakened evidently.The results indicate that silty loam interlayer has an inhibition effect on infiltration by weakening the migration of Br-and benzene downward and by adsorbing and purifying benzene.