我国南方主要城市土壤有机氯农药残留及分布特征

Residues and Distribution Character of Organochlorine Pesticides in Soil of Main Southern Cities of China

采用现场采样及室内分析方法，利用气相色谱仪采用ASE萃取技术，测定了我国南方主要城市土壤有机氯农药（OCPs）的残留量、残留物组成及垂直分布，并探讨了OCPs与总有机碳（TOC）以及有机氯农药组分之间的相关性。结果表明，南方主要城市土壤中残留有机氯农药主要是滴滴涕（DDTs）、六六六（HCHs）和六氯苯（HCB），三者占有机氯农药残留总量的97.30%，总有机氯农药类OCPs物质质量分数平均值为23.02 ng·g-1，其中DDTs占总有机氯农药类OCPs物质的58.95%，是南方主要城市土壤残留有机氯农药类的主要成分；氯丹（TC＋CC）、九氯（TN＋CN）硫丹（α-End＋β-End）残留量较低，是南方主要城市土壤中普遍存在的一类持久性有机污染物，没有对土壤质量造成危害；大部分土壤中DDT/（ DDE＋DDD ）均小于1，表明DDTs主要来自历史残留物；大部土壤中α-HCH/γ-HCH均小于1，并且较高的γ-HCH残留，表明南方主要城市土壤中HCH同系物之间发生相互转化，HCHs可能存在新的输入来源；OCPs物质及TOC含量均随土层深度的增加而降低，主要集中在土壤表层（0-5 cm），“表聚性”较为明显；土壤中TOC、DDT s、HCH s和HCB类农药与有机氯农药总含量之间显著相关（P〈0.05），在决定有机氯农药含量和分布上起着重要的作用。

The residues and distribution character of organochlorine pesticides in main southern cities of China were measured by gas chromatography and extracted by accelerated solvent extraction （ASE） adopting field sampling and laboratory analysis, and the correlations between OCPs and total organic carbon （TOC） among various OCPs components were discussed. The results showed that DDTs, HCH s and HCB were the dominant compounds, contributing 97.32%of the total OCPs, respectively. The total amount of pesticides OCPs was 23.02 ng·g^-1. DDTs was the primary compound in soil samples, accounting for 58.95%. In addition, chlordane （TC＋CC）, （TN ＋ CN） and endosulfan residue （α-End＋β-End） was low too, these pesticides OCPs made little harm to soils of main southern cities of China. The low ratios of w（DDT） tow （DDE ＋ DDD） （〈1） in the investigated samples possibly showed a long history of DDTs application, the relatively lowα-HCH/γ-HCH ratios indicated that fresh input was the current source of HCHs and HCH homologue had been changed from each other in main southern cities of China. In vertical direction, OCPs and TOC were decreased with increasing soil depth which mainly concentrated in 0-5 cm soil layer and showed an obvious“surface accumulation”. Correlation analysis revealed that TOC, DDTs, HCHs, and HCB had significant correlation with OCPs and had an important effect on the level and distribution of OCPs in the soils and sediments （P〈0.05）.