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Polychlorinated biphenyl (PCB) biomagnification was characterized in a harbor seal food web in the Strait of Georgia, British Columbia, Canada. Trophic magnification factors (TMFs) for PCBs averaged 3.6, with a range of 0.7 to 9.4. The TMFs for individual congeners correlated with log KOW ( r2 = 0.56, p < 0.001), reflecting the role that physicochemical properties play in driving the biomagnification of PCBs in marine food webs. However, TMFs differed among PCB structure activity groups, clearly indicating an additional role for metabolic transformation of certain PCBs. The known feeding preferences of harbor seals enabled the calculation of trophic level-adjusted biomagnification factors (BMFTL) for PCBs in this species, which averaged 13.4 and ranged from 0.2 to 150.6. Metabolic transformation in seals explained some of the variation in congener-specific biomagnification, with lower BMFTL values for PCB congeners with meta- and parachlorine unsubstituted positions. Principal components analysis revealed the distinct roles played by trophic level, log KOW, and metabolic transformation in explaining the notable differences in PCB patterns among harbor seals, their pups, and their prey. In the present study, the authors estimate there to be approximately 76 kg of PCBs in the biota of the Strait of Georgia, of which 1.6 kg is retained by harbor seals. Environ. Toxicol. Chem. 2012; 31: 2445-2455. © 2012 SETAC [ABSTRACT FROM AUTHOR]

The Strait of Georgia (British Columbia, Canada) is a hydrologically complex inland sea with a rich abundance and diversity of species of aquatic life. Marine sediments, as both a sink for hydrophobic contaminants and a potential source for aquatic food webs, were collected from 41 sites throughout the 6,900-km Strait of Georgia. The congener-specific concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), including BDE-209, were measured. Urban harbors represented hotspots for both PCBs and PBDEs, whereas PBDEs were also found at high concentrations near municipal outfalls. Patterns of PCB distribution were consistent with historical point source emissions in urban areas and environmental distillation toward lighter profiles in remote sites over time. The single congener BDE-209 dominated the PBDEs, accounting for 52% of the average total concentration. However, nonurban deep-water sediment PBDE profiles were both heavier and had higher concentration-weighted average log K (octanol-water partition coefficient) values compared to shallow samples (percent BDE-209 of total PBDE, 66 versus 32%; log K, 9.5 versus 8.2, respectively). Collectively, our results suggest that although source signals largely explain PCB and PBDE hotspots in the Strait of Georgia, the combination of physicochemical properties and environmental processes drive divergent compositional fates for the PCBs and the heavier PBDEs in the sediments of the Strait of Georgia. Environ. Toxicol. Chem. 2011; 30:1522-1532. © 2011 SETAC [ABSTRACT FROM AUTHOR]

We measured persistent organic pollutant (POP) concentrations in chinook salmon (Oncorhynchus tshawytscha) in order to characterize dietary exposure in the highly contaminated, salmon-eating northeastern Pacific resident killer whales. We estimate that 97 to 99% of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dichlorodiphenyltrichloroethane (DDT), and hexachlorocyclohexane (HCH) in returning adult chinook were acquired during their time at sea. Highest POP concentrations (including PCBs, PCDDs, PCDFs, and DDT) and lowest lipids were observed in the more southerly chinook sampled. While feeding by salmon as they enter some more POP-contaminated near-shore environments inevitably contribute to their contamination, relationships observed between POP patterns and both lipid content and δ13C also suggest a migration-related metabolism and loss of the less-chlorinated PCB congeners. This has implications for killer whales, with the more PCB-contaminated salmon stocks in the south partly explaining the 4.0 to 6.6 times higher estimated daily intake for ΣPCBs in southern resident killer whales compared to northern residents.We hypothesize that the lower lipid content of southerly chinook stocks may cause southern resident killer whales to increase their salmon consumption by as much as 50%, which would further increase their exposure to POPs. [ABSTRACT FROM AUTHOR]

-Current regulatory paradigms have favored a shift from persistent pesticides that amplify in aquatic food webs to pesticides with reduced persistence and bioaccumulative potential (low log KOW). Although these new generation pesticides preferentially partition away from food web-associated lipids, aquatic biota may nonetheless be exposed to them via other environmental compartments. To characterize pesticide patterns in coho salmon (Oncorhynchus kisutch) habitat, we studied two salmon-bearing watersheds (agricultural and urban) in British Columbia, Canada's Fraser River valley and one in a remote area of the province's central coast. The agricultural and remote sites exhibited pesticide patterns dominated by current-use pesticides, whereas the urban site was largely dominated by legacy organochlorine pesticides. When adjusted to trans-chlordane concentrations across environmental matrices, correlations were observed between water to sediment ratios for the pesticides and their octanol:water partitioning coefficients (log KOW; r² = 0.48, p < 0.0001); between air to water ratios and Henry's Law coefficients (r² = 0.55, p < 0.0001); and between fish to water ratios and log KOW (r² = 0.74, p < 0.0001). These relationships underscore the importance of physicochemical properties in determining the fate of pesticides in freshwater salmon habitat, and highlight the need for research on the nature of health risks associated with exposure where little or no accumulation occurs. [ABSTRACT FROM AUTHOR]