Aluminum smelter-derived polycyclic aromatic hydrocarbons and flatfish health in the Kitimat marine ecosystem, British Columbia, Canada

Abstract

From 2000–2004 a monitoring study was conducted to evaluate the impacts of aluminum smelter-derived polycyclic aromatic hydrocarbons (PAHs) on the health of fish in the marine waters of Kitimat, British Columbia, Canada. These waters are part of the historical fishing grounds of the Haisla First Nation, and since the 1950s the Alcan Primary Metal Company has operated an aluminum smelter at the head of the Kitimat Arm embayment. As a result, adjacent marine and estuarine sediments have been severely contaminated with a mixture of smelter-associated PAHs in the range of 10,000–100,000ng/gdrywt. These concentrations are above those shown to cause adverse effects in fish exposed to PAHs in urban estuaries, but it was uncertain whether comparable effects would be seen at the Kitimat site due to limited bioavailability of smelter-derived PAHs. Over the 5-year study we conducted biennial collections of adult English sole (Parophrys vetulus) and sediment samples at the corresponding capture sites. Various tissue samples (e.g. liver, kidney, gonad, stomach contents) and bile were taken from each animal to determine levels of exposure and biological effects, and compare the uptake and toxicity of smelter-derived PAHs with urban mixtures of PAHs. Results showed significant intersite differences in concentrations of PAHs. Sole collected at sites nearest the smelter showed increased PAH exposure, as well as significantly higher prevalences of PAH-associated liver disease, compared to sites within Kitimat Arm that were more distant from the smelter. However, measures of PAH exposure (e.g., bile metabolites) were surprisingly high in sole from the reference sites outside of Kitimat Arm, though sediment and dietary PAHs at these sites were low, and fish from the areas showed no biological injury. PAH uptake, exposure, and biological effects in Kitimat English sole were relatively lower when compared to English sole collected from urban sites contaminated with PAH mixtures from other sources. These findings indicate that while smelter-associated PAHs in Kitimat Arm appear to be causing some injury to marine resources, they likely have reduced bioavailability, and thus reduced biological toxicity, compared to other environmental PAH mixtures.