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Some aspects of the distribution and fate of polycyclic aromatic hydrocarbon contamination in the Kitimat fjord system Simpson, Christopher David


The presence of polycyclic aromatic hydrocarbons (PAHs) in the environment is of concern because many PAHs are carcinogens, and PAHs are very persistent. In this thesis the distribution of PAHs has been investigated in the Kitimat fjord system, British Columbia, Canada. Total PAHs in the range 1-500 mg/kg were detected in sediments from the fjord system. Sediments with the highest PAH levels were collected from sites in close proximity to the aluminum smelter, and PAH levels in sediments declined with increasing distance from the smelter. The PAH composition in all samples was typical of combustion generated PAH mixtures. PAH composition and distribution as a function of sediment particle size was investigated. Sediments from two sites close to the aluminum smelter (CD2, CD3) showed a differential distribution of PAHs amongst various sediment particle size fractions (PSFs). At all other sites PAHs were uniformly distributed amongst the various sediment PSFs. At one site (CD3), the distribution of perylene and retene amongst PSFs was different from the distribution of the other PAHs examined. Total PAH levels were elevated in the upper sections of a sediment core, but declined to constant low levels (-30 ng/g) in the lower sections of the sediment core. The PAH composition in the upper part of the core was typical of combustion generated PAH mixtures. In contrast, perylene accounted for -70-80% of total (unsubstituted) PAHs in sections from the lower part of the core, pre-dating the operation of the aluminum smelter. The accumulation of PAHs by soft-shelled clams (Mya arenarid) collected from four beaches in the Kitimat fjord system was investigated. PAHs were detected in clams (0.8-5.7 mg/kg) and sediments (0.02-125 mg/kg) from all four beaches. The PAH composition was similar in both clams and sediments at each site. Biota-sediment accumulation factors (BSAFs) at Hospital Beach were significantly lower than predicted by the equilibrium partitioning (EP) theory, but BSAFs at the other three sites were within an order of magnitude of the EP predictions. Metabolism of pyrene and 1-hydroxypyrene by two species of bivalve mollusk, Mya arenaria and Protothaca staminea was studied under laboratory conditions. The metabolites identified included an hydroxypyrene isomer, pyrene-1-sulfate, and a sulfate conjugate of dihydroxypyrene. The metabolites formed indicate that the metabolic pathways used by the two mollusk species to metabolize pyrene are similar to the pathways vertebrates use to metabolize PAHs.

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