滴滴涕在我国典型POPs污染场地中的空间分布研究

在多年生产滴滴涕(DDT)的企业厂区内及周围布设采样点,采取不同深度的土壤进行分析,研究了POPs污染场地中DDT的空间分布规律.结果表明,生产厂区污染严重,在土壤表层,生产车间周围DDT的含量高达104mg·kg-1以上,离车间边界300m远处仍能检测到DDT,污染扩散范围与风向呈现一定相关性;在土壤深层,浓度随深度增加迅速降低,含量梯度变化最大为0.2～3m,3m以下土壤中浓度较小,10m深处浓度最高不超过8.89mg·kg-1.DDT的降解产物DDD和DDE在各个采样点均能检出,其降解率与含水率没有相关性.不同类型土壤中DDT的降解率存在很大差异,降解程度为粉砂(或粉土)＞黏土(或粉质黏土)＞杂填土.深层土壤中降解为DDD较为明显.(DDD DDE)/DDT比值显示,土壤中DDT为新输入的.

Spatial distribution of DDT in a typical contaminated site

Surface and profile distributions of DDT were studied at a typical pesticide contaminated site. Surface and profile soil samples were collected in and around a plant which had been used for long-term DDT production. The results show that DDT concentrations are higher than 104 mg·kg-1 in surface soil near the original production site, and could even be detected in soil 300 m away from the plant, indicating that this site has been greatly contaminated by DDT. Profile distribution showed that DDT concentration decreases with soil depth, especially from 0.2 to 3 m, and it was lower than 8.89 mg·kg-1 at 10 m. DDD and DDE, the decomposition products of DDT, were also detected in the soil. A relatively low (DDD+DDE)/DDT ratio might indicate that DDT was freshly added to this site. The decomposition rate of DDT varied among soil types, and it was highest in silty sand, followed by clay soil and miscellaneous fill soil.