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PT07 Contaminated Harbor and River Sediment
(PT122) Contributions of PCDD/Fs and Dioxin-like PCBs Sources in Rivers Flowing into the Tokyo Bay, Japan.
Kobayashi, N1, Masunaga, S1, Nakanishi, J1, 2, 1 Yokohama National University2 National Institute of Advanced Industrial Science and Technology
ABSTRACT- There are few reports which estimate quantitatively the contributions of sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like PCBs in an environmental medium. However, in order to develop effective countermeasures against dioxin pollution, information about contributions of different PCDD/F and dioxin-like PCB sources to the environmental medium is necessary. In this study, source identification of PCDD/Fs and dioxin-like PCBs are presented. PCDD/F and 12 dioxin-like PCB congeners were measured in 6 major rivers that flow into the Tokyo Bay. To estimate the contributions of sources to total TEQ (Toxic Equivalency) in river water, chemical mass balance (CMB) approach was used in this study. It was assumed that incineration emission and impurity of agrochemicals (PCP and CNP) are the sources of PCDD/Fs in Japan. And it was assumed that incineration emission and commercial PCBs (KC300, KC400, KC500 and KC600) are the sources of PCBs in Japan. In some rivers, it was estimated that more than 85% of total TEQ originated from combustion source. While, in other rivers, contribution of combustion source was less than 50%. Differences in the land use in the river basin might be reflected in the result of estimation. Moreover, TEQ of PCDD/Fs and dioxin-like PCBs transportation by each source were estimated, assuming that contributions of sources in the same river are constant in recent year. It was estimated that 7.8 g-TEQ (including 12 dioxin-like PCB congeners) were transported by sum of these 6 rivers in 2001. And it was estimated that combustion source accounted most for total TEQ (64%).
Key words: dioxin-like PCBs, PCDD/Fs, CMB approach, river water
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