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PM14 Pesticides in Pacific Northwest (USA) Watersheds
(PM214) Biomagnification factors, target fish concentrations, and hazard quotients for bald eagles in the lower Columbia River.
Buck, J1, Tillitt, D2, 1 U.S. Fish and Wildlife Service, Portland, Oregon, USA2 U.S. Geological Survey-BRD, Columbia Environmental Research Center, Columbia, Missouri, USA
ABSTRACT- The lower Columbia River is an important resource for fish and wildlife, and persistent contaminants entering the system threaten reproduction of predators feeding at upper trophic levels. In 1994 and 1995, bald eagle (Haliaeetus leucocephalus) eggs were collected and apparent biomagnification factors (BMFs) were derived based on contaminant concentrations in eagle eggs and three species of prey fish collected in 1991. BMFs represented a field diet normalized to forage fish equivalents, given that eagles also forage on non-fish prey (primarily piscivorous and non-piscivorous birds). BMFs were used to develop target fish concentrations (TFCs), or the concentrations in fish estimated to be protective of upper trophic level species. In addition, the magnitude of contaminant concentrations in eagle eggs that exceeded guidance or reference levels was evaluated using hazard quotients (HQs). BMFs derived based on data from Columbia River bald eagle eggs and fish were fairly consistent among three river segments in the lower river, and the combined BMFs for the segments were 113 for polychlorinated biphenyls (PCBs), 75 for DDE, 2.8 for mercury, 16 for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), and 2 for 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF). The TFC values derived from the BMFs were 0.06 g/g for total PCBs, 0.04 g/g for DDE, 0.20 g/g for mercury, 0.9 pg/g for 2,3,7,8-TCDD, and 7.5 pg/g for 2,3,7,8-TCDF. HQs for lower Columbia River eagles were 1.3 for PCBs, 1.6 for DDE, 0.6 for mercury, and 1.5 for both 2,3,7,8-TCDD and TCDF. These values can be used by regulatory agencies in a basin-wide strategy (e.g., total maximum daily load programs) to 1) better control releases of bioaccumulative contaminants to the river and minimize impacts to fish-eating birds; 2) monitor changes in contaminants over time; and 3) better address contaminant uptake from sediment sources.
Key words: dioxin, Haliaeetus leucocephalus, DDE, trophic transfer
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