有机质对污染土壤中DDTs热脱附行为的影响

Impact of organic matter on thermal desorption of DDTs in contaminated soils

采用2种不同性质土壤(黑土和棕壤)作为供试土壤,利用DDT农药自配滴滴涕类(DDTs,包括p,p′-DDT、o,p′-DDT、p,p′-DDD、p,p′-DDE)污染土壤。采用热脱附方法,研究了原土及去有机质后土壤中DDTs在300℃,6个停留时间(5、10、20、30、40和50 min)下的去除率以及脱附后土壤中DDTs的残留情况。结果表明,有机质的存在能够显著提高p,p′-DDT在土壤中的脱附效率(P<0.05),降低其在土壤中的残留浓度。同时,对p,p′-DDE的转化和脱附也有显著影响。但是对o,p′-DDT和p,p′-DDD在土壤的脱附并不存在显著影响。同时,有机质对DDTs在土壤中的去除率影响显著。

Two different soils,black earth and brown earth,were chosen as test samples.They were both mixed with DDT pesticide（known as DDTs,including p,p′-DDT、o,p′-DDT、p,p′-DDD and p,p′-DDE）.Under six gradually increase levels of residue times,5,10,20,30,40 and 50 min,respectively,thermal desorption technology was adopted to study the removal rates and residual concentrations of DDTs in soils at 300 ℃.The results showed that the removal of p,p′-DDT could be significantly enhanced by organic matter.In addition,organic matter could remarkably influence the transformation and desorption of p,p′-DDE.By contrast,it had little impact on the removal of o,p′-DDT and p,p′-DDD.Moreover,there were significant differences in the removal rates of DDTs in soils before the removal of organic matter and after that.