有机污染物(菲)在弱透水层中的越流迁移特征

Cross-Flow Migration of Organic Pollutant(Phenanthrene) in Aquitard

采用高渗透压渗流试验装置,模拟已被污染的浅层地下水越流通过弱透水层污染深层地下水的过程,研究不同矿化度、不同pH条件下有机污染物（菲）通过饱和黏性土弱透水层时的质量浓度变化特征。结果表明：矿化度的增加有利于弱透水层吸附截留渗滤液中的菲;高矿化度水中的Na＋交替土层中的Ca2＋、Mg2＋,使水中的Ca2＋、Mg2＋质量浓度增加,与HCO-3、菲组合形成络合物;不同pH条件下,Ca2＋、Mg2＋、HCO-3对菲的迁移有阻滞作用,SO24-参与还原反应并可与菲形成络合物,对菲迁移有促进作用。菲在弱透水层中的迁移能力很弱,衰减率达82%~96%,高渗透压下菲的污染锋面迁移速度为0.714 m/d,pH=8时菲通过弱透水层的迁移质量浓度最小。控制渗滤液的pH、组分可有效阻止菲在弱透水层中的迁移。

A high osmotic pressure flow device was used to simulate the flow and contaminant transport processes through the aquitard.The concentration of the organic pollutant（phenanthrene） through saturation clay layer was studied with different degrees of mineralization and pH conditions.The results show that the increase of degree of mineralization can encourage the adsorption of phenanthrene leachate in the aquitard;sodium ions（Na＋） in high degree of mineralization water alternate calcium and magnesium ions（Ca2＋ and Mg2＋） in the soil layer,so that Ca2＋ and Mg2＋ in the water increase,HCO-3 participate the formation of complexes with phenanthrene.Under different pH conditions,the ions Ca2＋,Mg2＋,and HCO-3 retard the migration of phenanthrene.In the reductive reaction SO2-4 participates the formation of complexes with the phenanthrene.SO2-4 promotes the migration of phenanthrene.The migration ability of phenanthrene is very weak in the aquitard,the decay rate is 82%-96%;under hyper osmotic pressure,the migration speed of the phenanthrene front is about 0.714 m/d.When pH=8,the migration concentration of phenanthrene through the aquitard is the smallest.Control of leachate＇s pH and ion composition can effectively prevent the migration of phenanthrene through the aquitard.