Polychlorinated naphthalenes, -biphenyls, -dibenzo-p-dioxins, and -dibenzofurans in double-crested cormorants and herring gulls from Michigan waters of the Great Lakes

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), and biphenyls (PCBs) were measured in eggs of double-crested cormorants and herring gulls collected from Michigan waters of the Great Lakes. Concentrations of PCNs in eggs of double-crested cormo rants and herring gulls were in the ranges of 380-2400 and 83-1300 pg/g, we t wt, respectively. Concentrations of 2,3,7,8-substituted PCDDs and PCDFs w ere 10-200 times less than those of PCNs in eggs whereas those of total PCB s (380-7900 ng/g, wet wt) were 3-4 orders of magnitude greater. While the p rofile of PCB isomers and congeners between double-crested cormorants and h erring gulls was similar, the PCN isomer profile differed markedly between these two species. PCN congeners 66/67 (1,2,3.4,6,7/1,2,3,5,6,7) accounted for greater than 90% of the total PCN concentrations in herring gulls, wher eas their contribution to total PCN concentrations in double-crested cormor ants ranged from 18 to 40% (mean, 31%). The ratios of concentrations of PCD Ds to PCDFs were greater in herring gulls than in double crested cormorants collected from the same locations, suggesting the ability of the former to metabolize PCDF congeners relatively rapidly. 2,3,7,8-Tetrachlorodibenzo-p -dioxin (TCDD) equivalents (TEQs) contributed by PCNs in double-crested cor morant and herring gull eggs were 2-3% of the sum TEQs of PCBs, PCDDs, PCDF s, and PCNs. PCB congener 126 (3,3',4,4',5-PeCB) accounted for 57-72% of th e total TEQs in double-crested cormorant and herring gull eggs.