POLYCHLORINATED DIHENZO-P-DIOXIN AND DIBENZOFURAN CONCENTRATION PROFILES IN SEDIMENT AND FISH TISSUE OF THE WILLAMETTE BASIN, OREGON

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) are highl y hydrophobic compounds that have been implicated as carcinogens and, more recently, as estrogen disrupters. An occurrence and distribution study of these compounds in the Willamette Basin, Oregon, was conducte d by the U.S. Geological Survey as part of the National Water-Quality Assessment Program. Bed sediment was collected from 22 sites; fish tis sue was collected from eight sites. PCDD/F were found to be ubiquitous in Willamette Basin sediment. A distinct homolog profile, dominated b y octachlorodibenzo-p-dioxin, was observed in sediment throughout the basin. The PCDD homolog profile was consistent at all sites, regardles s of total PCDD/F concentration, presence of point sources, subbasin s ize, geographic location or land use. Principal components analysis re vealed a gradient among the homolog profiles that showed increasing do minance of highly chlorinated congeners where human and industrial act ivity increased. Tissue and bed sediment obtained from the same site d id not have similar PCDD/F concentrations or homolog profiles. Fish ti ssue showed enrichment in less chlorinated congeners and congeners wit h chlorine substitutions in the 2, 3, 7 and 8 positions.