Polycyclic aromatic hydrocarbon contamination in marine sediments near Kitimat, British Columbia

Polycyclic aromatic hydrocarbons (PAHs), like many other hydrophobic organic contaminants, are rapidly sorbed to particles and incorporated within sediments in aquatic systems. The PAH composition within the sediments reflects the source(s) from which the PAHs were derived. However the "source signature" may be altered by postdepositional weathering or biodegradation. In the present study, variation in PAH composition was investigated in size-fractionated sediments and depth-fractionated sediments collected from a Canadian fjord contaminated with aluminum smelter derived PAHs. Multivariate analyses of PAH compositional data consistently showed that different sampling sites could he discriminated on the basis of their PAH composition, but smaller versus larger size fractions within a site could not. The composition of unsubstituted and alkyl-substituted PAHs in a sediment core primarily showed changes with depth that were attributable to enhancement of anthropogenic inputs in the upper core segments. No trends with sediment depth, associated with compound-specific weathering or biotransformation, were noted in the composition of anthropogenically generated PAHs. This may indicate a limited chemical and biological availability of the aluminum smelter derived PAHs.