长三角农田土壤中滴滴涕的污染特征与生态风险

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。低残留DDTs对土壤微生物的群落结构和多样性无显著影响(-0.25R0.25,0.307P0.979)。应用美国环保署(USEPA)方法评估了土壤中DDTs对人体的健康风险,其中致癌风险级别为非常低,对儿童和成人具有非致癌风险的样品比例分别为1.1%和0.7%。因此,长三角地区大多数点位农田土壤DDTs残留量较低,不会对生态环境和人体健康产生危害。

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

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 vegetable samples, and the concentrations were 9%-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