天津地区土壤环境中有机氯农药残留特征

通过对天津市辖区6种不同土地利用类型和2种灌溉类型的188个点位进行野外实地采样及定量分析,分析了天津市土壤环境中有机氯农药(OCPs)残留的空间分布特征及来源,系统研究了天津市六六六(HCHs)和滴滴涕(DDTs)各异构体单体在土壤中的残留水平、空间和剖面的分布特征,以及残留量今昔情况比较。结果表明:天津市土壤环境中HCHs和DDTs含量均可以达到国家一级标准。天津市HCHs污染空间分布特征为近郊区、滨海地区相对较重,市区次之,远郊区较轻;DDTs污染空间分布特征为近郊区、市区相对较重,远郊区次之,滨海地区较轻;不同的土壤利用类型中,城市绿地的OCPs残留量最高,清灌区和污灌区的OCPs残留量差异不大。剖面分析结果显示,有机氯农药的残留总量主要集中在0~30 cm的耕作层中。通过比较HCHs和DDTs的残留情况发现,DDTs的降解率高于HCHs,天津个别地区出现残留水平异常情况。

Residual Characters and Sources of Organochlorine Pesticides in Soils of Tianjin Area,China

The spatial distribution characteristics and the sources of organochlorine pesticides(OCPs)were studied according to the field sampling and quantitative analysis of OCPs of soils in 188 points with 6 land-use types and 2 irrigation types from Tianjin area. This article investigated the residual levels , spatial and profile distribution of the isomers of hexachloro- cyclohexane soprocide(HCHs) and dichlorodiphenyl trichloroethane(DDTs)firstly, and then made the comparison with the residues in the past. The results showed that the con-tents of HCHs and DDTs in the soil of Tianjin reached to class A of the national standard. The distribution characteristics of HCHs in soils from Tianjin indicated that the inner suburban district and the coastal region were the most polluted areas, downtown took the second place, and outer suburban district was the least polluted. The distribution characteristics of DDTs showed that the inner suburban district and the downtown were the most polluted area, outer suburban district took the second place, and the coastal region was the least polluted. In different land-use types, there was the highest OCPs residues in urban green area. And there was no significant differences of OCPs residues between irrigation area and sewage irrigation area. The results of profile analysis indicated that the total amount of OCPs was mainly found in the 0~30 cm of farming layer. Based on the comparison of the residues of HCHs with that of DDTs, the degradation rate of DDTs was higher than that of HCHs, and abnormal residual levels were found in some areas of Tianjin.