岷江下游（五通桥段）土壤有机氯农药残留分布特征

CHARACTERISTICS IN DISTRIBUTION OF RESIDUAL ORGANOCHLORINE PESTICIDES IN SURFACE SOILS AT THE LOWER REACHES OF MINJIANG RIVER（WUTONGQIAO SECTION）

为了解岷江下游土壤污染特征，按功能分区和乡镇布点的方法，采集了岷江下游五通桥段103个表层土壤样品，检测其有机氯及其异构体代谢物含量，并应用Kriging插值法，研究了岷江下游土壤中有机氯农药残留分布特征。土壤中残留的HCHs和DDTs的异构体代谢物及总量均服从正态分布，并全部属于强变异。18．4％的土壤HCHs含量达到国家土壤环境质量标准（GB15618—1995）一级标准（〈50μg／kg），其余为二级标准（〈500μg／kg）；68．1％的土壤DDTs含量为国家土壤环境质量标准一级标准（〈50μg／kg）。土壤HCHs各代谢物含量呈块状分布，而HCHs总量相对较高的区域都分布在农业区（蔡金镇、冠英镇和石麟镇交界处）；DDT总量和p，p＇-DDT含量的高值区域出现在低山丘陵区（石麟镇）；p，p＇-DDD和p，p＇-DDE含量的高值区域出现在平原区（杨柳镇、竹根镇和西坝镇）。总体而言，研究区域存在一定程度的有机氯农药污染。

Residual organochlorine pesticide, and their isomers and metabolites in surface soils at the lower reaches of Minjiang River （Wutongqiao section） were detected in order to understand the distribution characteristics of soil pollution, employing the method of sampling and detecting 103 surface soils from different functional zones and towns combined with Kriging method in geostatistics. Residual HCHs and DDTs and their isomers and metabolites in soils distributed normally with strong variation. HCHs concentration in 18.4% soils was lower than the first level of National Soil Environment Quality Standard （GB15618- 1995） （〈50μg · kg^-1）, and the rest the second level （〈500μg · kg^-1）. Correspondingly, DDTs concentration in 68.1% soils were lower than 50 μg · kg^-1, which accorded with the first level of National Soil Environment Quality Standard. The contents of HCHs and their isomers and metabolites in soil distributed limpidly, while the total content of HCHs in soils were the highest in the agricultural zone （Caijin, Guanying and Shilin towns）. The hilly region （Shilin town） had the highest contents of total DDT and p,p＇- DDT, while the basin plain （Yangliu, Zhugen and Xiba towns） had the highest contents of p,p＇-DDD and p,p＇-DDE in soils. On the whole, soils in the studied region were contaminated to a certain extent by residual organochlorine pesticide.