Dioxins in aquatic sediment and soil in the Kanto region of Japan: major sources and their contributions.
Major sources of dioxins (tetra- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans) were quantitatively identified, and the contributions of each source were estimated in aquatic surface sediment and soil in the Kanto region of Japan, where a major part of the municipal, industrial, and agricultural activities in Japan take place. Detailed chromatographic peak-specific data corresponding to all dioxin compounds were used throughout the analysis to achieve source specificity. Four major sources were identified by using principal component analysis. Three of them were combustion processes, impurities in pentachlorophenol, and impurities in the diphenyl ether herbicide CNP. One, characterized by polychlorinated dibenzo-p-dioxins with 1,2,6,9-chlorine substitution, remained unattributed to any known source or transformation process. The composition of the unattributed source resembled those reported in sediment samples free from anthropogenic impacts. Contributions from the four major sources were estimated by using a mass balance receptor model, and the source contributions to each homologue varied among samples. Tokyo Bay sediment was characterized by the highest relative contribution from pentachlorophenol impurities in the region. The unattributed source contribution was most prominent in the Lake Kasumigaura sediment. The results indicated considerable contributions in aquatic surface sediment in the studied region from dioxin impurities in herbicides used in the past.
Sakurai
Takeo
T
National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. tsakurai@nies.go.jp
D000383:Agriculture; D004147:Dioxins / Q000032:analysis*; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry; D017745:Incineration; D007564:Japan; D012989:Soil Pollutants / Q000032:analysis*; D014873:Water Pollutants / Q000032:analysis*
D004147:Dioxins; D006540:Herbicides; D012989:Soil Pollutants; D014873:Water Pollutants