Polycyclic aromatic hydrocarbons (PAHs), like many other hydrophobic o
rganic contaminants, are rapidly sorbed to particles and incorporated
within sediments in aquatic systems. The PAH composition within the se
diments reflects the source(s) from which the PAHs were derived. Howev
er the ''source signature'' may be altered by postdepositional weather
ing or biodegradation. In the present study, variation in PAH composit
ion was investigated in size-fractionated sediments and depth-fraction
ated sediments collected from a Canadian fjord contaminated with alumi
num smelter derived PAHs. Multivariate analyses of PAH compositional d
ata consistently showed that different sampling sites could he discrim
inated on the basis of their PAH composition, but smaller versus large
r size fractions within a site could not. The composition of unsubstit
uted and alkyl-substituted PAHs in a sediment core primarily showed ch
anges with depth that were attributable to enhancement of anthropogeni
c inputs in the upper core segments. No trends with sediment depth, as
sociated 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 alumin
um smelter derived PAHs.