太原市污灌区有机氯农药垂直分布特征及源解析

Vertical Distribution and Source Analysis of Organochlorine Pesticides in Sewage Irrigation Area,Taiyuan City

采用气相色谱-电子捕获检测器(GC-ECD)方法分析了太原市小店污灌区9个土壤剖面中有机氯农药(OCPs)的垂直分布特征.结果表明,OCPs主要积累在土壤上层0～30 cm,含量最大值为98.56 ng·g-1,其中六六六(HCHs)、滴滴涕(DDTs)、硫丹(endosulfans)和甲氧滴滴涕(methoxychlor)为主要污染物质,占总有机氯农药的85.1%,其它有机氯农药物质相对含量较少.绝大部分剖面土中OCPs含量随着深度增加而明显减少,β-HCH和DDE(o,p'-DDE+p,p'-DDE)在HCH农药和DDT农药中占主要成分.组分分析表明,清灌区和沼泽区中最近可能有新的DDT源输入,其它剖面土中HCH和DDT主要来自历史使用残留.研究区内绝大部分土壤为粉砂壤土;污灌区和清灌区中ΣOCPs含量与总有机碳(TOC)均表现出明显正相关性,但沼泽区和背景点与TOC相关性不显著.

Nine profile soil samples were collected from Xiaodian sewage irrigation area in Taiyuan city,and the concentrations of organochlorine pesticides（OCPs） were determined by gas chromatography coupled with electron capture detector（GC-ECD） to analyze the vertical distribution.The results showed that the OCPs were mainly accumulated in the surface soil layer（0-30 cm） with the maximum concentration of 98.56 ng·g-1,and HCHs,DDTs,endosulfans and methoxychlor were the predominant contaminants compared with other pesticides in the surface soil,which accounted for 85.1% in total OCPs.The concentrations of OCPs were clearly decreased with the increasing of the depth to the top layer in the most profile soils.β-HCH and DDE（sum of o,p′-DDE and p,p′-DDE） were the main contaminants in HCH pesticides and DDT pesticides,respectively.Composition analysis indicated that new DDT sources might be introduced into the groundwater irrigation and swamp area recently,and the main source of HCHs and DDTs was the residual of history use in other areas.Most profile soils were defined silt loam in study area.The correlations between the concentration of OCPs and the total organic carbon（TOC） were positively significant in sewage irrigation area and groundwater irrigation area,but they were not significantly correlated in swamp area and background area.