桂林会仙湿地表层土壤中有机氯农药污染现状

为了解会仙湿地表层土壤中有机氯农药（OCPs）的残留现状，于2019年11月，根据不同土地利用类型，在桂林会仙湿地18个点位分别采集了不同深度的表层土壤样品，采用GC-ECD法对土壤中24种OCPs进行检测分析，对其残留特征、可能来源和生态风险进行了相关研究。结果表明，研究区土壤中24种OCPs检出率均高于80%，总OCPs含量范围为3.56~69.7 ng·g^-1，均值为14.0 ng·g^-1，与其他研究区相比，OCPs残留量处于较低水平，其中主要组分为滴滴涕（DDTs）和甲氧滴滴涕（MXC）。农用地土壤中OCPs残留量较高，且OCPs在0~10 cm深度残留量高于其他深度。研究区土壤中OCPs主要来源于工业DDTs等传统农药的历史残留。生态风险评价结果表明研究区土壤中六六六（HCHs）生态风险较低，DDTs存在一定的生态风险。

Status of organochlorine pesticide pollution on surface soil of Huixian wetland in Guilin, China

In order to better understand the status of organochlorine pesticide(OCP)pollution on surface soil of Huixian wetland, surface soil samples of different depths from different types of land uses were collected from 18 sites in Huixian wetland in November 2019. 24 OCPs in soil were detected by GC-ECD, and their residual characteristics, sources, and ecological risks were analyzed. The detection rates of OCPs were above 80%, and the total concentrations of 24 OCPs ranged from 3.56 ng·g^-1 to 69.7 ng·g^-1, with a mean value of 14.0 ng·g^-1. Compared with the soil of other studied areas, the residues of OCPs in Huixian wetland were at a lower level, while dichlorodiphenyltrichloroethanes(DDTs)and methoxychlor (MXC)accounted for a higher proportion of OCPs. The distribution of OCPs was characterized by a high residue in agricultural soil and soil with a depth of 0~10 cm. The historical residues of industrial DDTs and other traditional pesticides were the main sources of OCPs in the soil; however, new input could not be ignored. Results of ecological risk assessment indicated that the ecological risk of HCHs in soil was low; however, DDTs might have some potential ecological risk impact on the studied area.