Distribution and Bioaccumulation of Chlorinated Diphenyl Ethers in a Contaminated Embayment of Lake Ontario

Polychlorinated diphenyl ethers (PCDEs) are halogenated aromatic hydrocarbons that have structural similarities to polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans. PCDEs have been detected in piscivorus fish, fish eating birds and humans, but little is known about the transfer of these compounds through aquatic ecosystems. At sampling stations in the contaminated area of Whitby Harbour on the north shore of Lake Ontario, mean concentrations of total PCDE congeners in sediment were between 622 and 1,929 ng/g dry weight. Analysis of semipermeable membrane devices (SPMDs) deployed at several stations around the harbor indicated that PCDEs were distributed homogeneously in the water. Mean total PCDE concentrations in biota were as high as 672 ng/g wet weight (105 μg/g lipid) in white sucker (Catostomus commersoni) and 791 ng/g wet weight (55 μg/g lipid) in brown bullheads (Ameiurus nebulosus). The patterns of 45 PCDE congener analytes differed among the SPMDs, sediment, and biota, but between invertebrates and fish the congener patterns were relatively homogeneous. Bioamagnification factors (BMFs) calculated for total PCDEs in a simple benthic food chain (oligochaetes to white suckers) and a simple pelagic food chain (plankton to pumpkinseed) indicated that there was biomagnification, with BMFs < 50 on a lipid-normalized basis and BMFs < 5 on a wet weight basis. For individual PCDE congeners, there was a slight trend to increasing BMFs with increasing chlorine substitution.