废弃农药厂拆除过程对周边土壤DDTs污染影响

分4批次分别采集某废弃农药厂拆除前和拆除后周边土壤，研究土壤中DDTs含量、分布和组成的变化特征.结果表明，拆除1个月后，土壤中DDTs残留量（平均为334ng/g）明显大于拆除前（平均为97.0ng/g），之后土壤中DDTs的残留量明显下降.拆除前，周边土壤中以p，p'-DDE和p，p'-DDD为主，平均浓度分别为35.6和31.0ng/g；拆除后以p，p'-DDT为主要残留污染物，平均浓度为289ng/g，较拆除前（9.69ng/g）增长了28.9倍.来源分析表明，农药厂拆除前周边土壤中DDTs的污染主要受厂区内历史工业品DDTs生产和农田使用的三氯杀螨醇共同影响，而拆除过程周边土壤DDTs污染的贡献主要来自于厂区内工业品DDTs的挥发.在空间分布上，拆除前和拆除后整体上西部区域土壤的污染程度高于东部区域.

The effect of a pesticide plant demolition on the concentration of DDTs in its surrounding soils

The concentrations, distributions and compositions of DDTs in surrounding soils collected four times from a closed pesticides manufacturing plant were studied, respectively, before and after the demolition of the plant. The results showed that the concentrations of DDTs (average 334ng/g) in soils collected one month after the plant demolished were higher than those obtained (average 97.0ng/g) two months before the demolition. After that, a significant decrease was seen for the concentration of DDTs in surrounding soils. Before demolistion, p,p'-DDE (average 35.6ng/g) and p,p'-DDD (average 31.0ng/g) were the main congeners in surrounding soils, whilist p,p'-DDT(average 289ng/g) was the predominant congener in the soils after demolition, which was about 28.9tims of that detected in surrounding soils before the plant demolition. The historical production of technical DDT and usage of dicofol in surrounding agricultural soils were the main reasons for the concentrations of DDTs in surrounding soils, while the volatilization of technical DDTs was the main contribution for the concentration of DDTs in surrounding soils during the plant demolishing. The spatial distribution of DDT concentrations in surrounding soil is usually dominated by the wind, and the east wind is the prevailing wind direction in this area, which resulted in higher concentrations of DDTs in the western area than those in the eastern area both before and after the plant demolished.