Abstract: HCHs, DDTs and organophosphorus pesticides (OPPs) in 103 soil samples collected from Wutongqiao country Sichuan were analyzed to understand the spatial distribution characteristics of residual pesticide in soils of transitive zone from mountain to plain in Sichuan, employing the methods of GIS and geostatistical techniques. HCHs concentration in 94% soil samples was in the range of the 2nd level of National Soil Environment Quality Standard (GB15618-1995) (50~500μg.kg-1). Similarly, DDTs concentration in 70% soil samples accorded with the 1st level of National Soil Environment Quality Standard (GB15618-1995) (＜50μg.kg-1). Fenitrothion and bromohos were detected in 60.4% and 55.5% of all samples, which were higher than those of the rest of OPPs. The results indicated that residual HCHs and DDTs in soils of the study region were safe for agriculture, while residual OPPs were harmful for agriculture to a certain extent. Seen from the spatial distribution map of residual pesticide drawn by ArcGIS 9.0 software, obvious difference was found among different function zones and among towns, however, little difference was found among plains and between hilly region and plain. The diversity of pesticides in different function zone, nature villages and towns were more than those in different banks, mountain-hilly zone.

Key words: Wutongqiao country, residual pesticides, geostatistics, spatial distribution, assessment