长三角农田土壤中滴滴涕的污染特征与生态风险

Contamination Characteristics and Ecological Risks of DDTs in Agricultural Soils from the Yangtze River Delta of China

以长江三角洲地区农田土壤为研究对象,分析了土壤和蔬菜中滴滴涕（DDTs）的残留水平和空间分布特征,评估了DDTs对土壤生态和人体健康的潜在风险。结果显示,长三角地区农田土壤中DDTs含量范围为〈0.2～3 520 ng·g-1,平均63.8 ng·g-1,主要残留在土壤耕作层（0～30 cm）。土壤中DDTs及其代谢产物残留量较低,98.5%的点位土壤符合《中国土壤环境质量标准》的二级标准。15%的蔬菜样品中检出DDTs,其浓度为相应土壤DDTs浓度的9%～18%,土壤残留的DDTs通过食物链进入人体导致的健康风险很小。

This study revealed the contamination status and spatial distribution of DDTs in agricultural soils from the Yangtze River Delta of China, and estimated the associated health and ecological risks. The overall residues of DDT,DDD and DDE were in the range of 0.2 ～ 3 520 ng·g-1（average： 63.8 ng·g-1）. The majority of DDTs resided in the tillage layer（0 ～ 30 cm）. The concentrations of DDTs in 98.5% of the samples were under the stringent grade II limits of the Environmental Quality Standard for Soil（GB-15618-1995） of China. Uptake of DDTs in vegetables from soil was investigated. DDTs were only detected in 15% of all the vegetable samples, and the concentrations were9%-18% of those in the corresponding soils. To reveal the variations in diversity of soil microbial community induced by DDTs, the phospholipid fatty acid（PLFA） analysis was carried out. The results show that the DDTs concentrations are not significantly correlated with the diversity of microbial community（-0.25 R 0.25, 0.307 P 0.979）. Moreover, the majority of the samples were of very low carcinogenic risks, with only 1.1% and 0.7% of the samples posing non-cancer risks to adults and children, respectively. Thus the residues of DDTs from most soils pose low or negligible threat to ecosystem and human health.