Trends in the Distribution of PCBs Compared to PACs in Sediments and Mussels of Halifax Harbour

Abstract

Abstract Surficial sediments and blue mussels (Mytilus edulis) were collected around the perimeter of Halifax Harbour. Samples were analyzed for the presence of polychlorinated biphenyls (PCBs), ranging from mono- to decachloro congeners, and results compared to the presence of polycyclic aromatic compounds (PACs). The objective was to explore the relationship between contaminant profiles in sediments and in mussels, and the possibility of deducing their sources, patterns of deposition, circulation and bioavailability. IUPAC hexachlorobiphenyls 138/158/160/163 (unresolved) and 153/132/168 were the most abundant congeners in both sets of matrices, ranging in concentration between <0.5 to 46 and 4.5 to 25.5 ng/g (dry weight) in sediments and mussels, respectively. PCBs profiles point to a combination of commercial sources superimposed on some weathering. Biota-sediment accumulation factors (BSAF, concentration in mussels, dry weight/concentration in sediments, dry weight, and lipid/TOC normalized) varied throughout the harbour and per congener. Some similarities were observed between the most contaminated sites previously analyzed for PACs and presently analyzed for PCBs, while BSAF were highest at the entrance to the harbour, for PACs and PCBs.