Polychlorinated Dibenzo-p-dioxins and Dibenzofurans : Their Concentrations and Profiles in Sediments in the Tama River, Japan

Sukeo Onodera^a Masakazu Sugimoto^a Tsuyoshi Takagi^a and Kazuo Tanaka^b

^aFaculty of Pharmaceutical Sciences, Tokyo University of Science, 12 Ichigaya- funagawara-machi, Shinjuku-ku, Tokyo 162-0826, Japan and ^bMS Application Laboratory, Application and Research Center, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-0021, Japan

Surface sediments were collected from eight sampling points, representing upper, mid- and downstream regions, of the Tama River, to obtain background information on the polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/ DF) levels, profiles and transport in this river. The sediment profiles of PCDD/DF were strongly dependent on the sampling points, with total PCDD/DF levels ranging from 27.0 to 231.6 pg/g dry weight (mean value, 90.7 pg/g) and the I-TEQ values ranging from 0.05 to 2.8 pg/g (mean value, 1.2 pg/g). Two maxima in the PCDD/DF concentrations were observed for the sediment samples taken from stations 3 (midstream) and 7 (upstream) in this river, although none for the samples from downstream (industrial area). Sediment samples taken from the midstream near waste water discharges and a municipal solid waste (MSW) incinerator plant showed high TEQ values of 0.5 to 1.2 and 13.0 pg/g, respectively, indicating a potential PCDD/DF source in this river. In contrast, the PCDD/DF concentrations in the sediment samples taken from five tributaries flowing into the midstream region were very low, indicating no PCDD/DF impact into the studied areas. These data suggest a multiplicity of sources ranging from agricultural activities to urban activities such as emission gas from MSW incinerators and effluents from wastewater treatment plants.