THE CONGENER PROFILES OF PCDD/DFs AND DIOXIN-LIKE PCBs IN SOIL ANIMALS FROM JAPANESE FALLOW

Introduction In recent years, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and nonand monoortho-substituted polychlorinated biphenyls (dioxin-like PCBs) have received considerable attention because of their extreme persistence, bioaccumulation and toxic potential to wildlife. The concentrations of these compounds in wildlife were reported in recent years 1, . And particularly PCDD/DFs were detected at extremely high concentrations in raptors; in spite of the general low soil concentrations. Therefore, the mechanisms of bioaccumulation especially for terrestrial wildlife should be investigated. But very few researches have been done in this area. Almost all the PCDD/DFs in terrestrial field exist in soil because of their high adsorption affinity to soil organic fraction. The soil organisms, on the other hand, which constitute soil ecosystem, feed on soil. The soil ecosystem is the starting point of terrestrial food web. The soil animals intake pollutants in soil and passes them through other biota to raptors . Thus, concentrations of PCDD/DFs of soil animals should be measured and the accumulation characteristics in soil ecosystem should be clarified. In Japan, the two main sources of PCDD/DFs were combustion and agrochemicals such as pentachlorophenol (PCP) and chloronitrofen (CNP) . The emissions from agrochemicals were far greater than those from combustion sources in the past, and they still remain in the rice field soil. However, there is no report for soil animals in rice field, so rice field was chosen as target of study.