Search

Polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) concentrations and profiles in paired sediment-plankton samples were determined along a 500 km transect in coastal British Columbia, Canada. PCB and PBDE levels in sediment were both greater in the industrialized Strait of Georgia than in remote northern sites and exhibited parallel spatial trends. In plankton, recent-use PBDE levels were higher near-source, while levels of legacy PCBs were uniform across sites. Principal component analysis of 95 PCB congeners illustrated the influence of proximity to source (Le., latitude) on congener patterns for both matrices (sediment, r2 = 0.52, p - 0.012; plankton, r2 = 0.59, p = 0.016). The PCB pattern in plankton grew lighter with latitude, but the opposite pattern in sediments suggested that temperature-related fractionation, sediment processes, and basin-wide oceanography had divergent effects on each matrix. Biotasediment accumulation factors (BSAFs) were greater for PBDEs than PCBs, but spatial profiles were similar; PCBs and PBDEs were near equilibrium in remote atmospherically driven sites (BSAF = 1.7 and 1.3) but accumulated preferentially in sediments at source-driven sites (BSAF = 0.2 and 0.4). The influences of particle-binding and hydrophobidty on the aquatic fate of PCBs and PBDEs was evident by the strong influence of log KqW on congener-specific BSAFs (PCBs, r2 = 0.18 p < 0.001; PBDEs, r2 = 0.61 p < 0.001). While biotic uptake of PCBs has become spatially uniform in coastal BC because of dilution over time, biomagnification of PBDEs remains higher in industrialized waters. [ABSTRACT FROM AUTHOR]

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]

Sediment-associated hydrocarbons can pose a risk to wildlife that rely on benthic marine food webs. We measured hydrocarbons in sediments from the habitat of protected sea otters in coastal British Columbia, Canada. Alkane concentrations were dominated by higher odd-chain n-alkanes at all sites, indicating terrestrial plant inputs. While remote sites were dominated by petrogenic polycyclic aromatic hydrocarbons (PAHs), small harbour sites within sea otter habitat and sites from an urban reference area reflected weathered petroleum and biomass and fossil fuel combustion. The partitioning of hydrocarbons between sediments and adjacent food webs provides an important exposure route for sea otters, as they consume ∼25% of their body weight per day in benthic invertebrates. Thus, exceedences of PAH sediment quality guidelines designed to protect aquatic biota at 20% of the sites in sea otter habitat suggest that sea otters are vulnerable to hydrocarbon contamination even in the absence of catastrophic oil spills. [Copyright &y& Elsevier]

In order to distinguish between ‘local’ and ‘background’ sources of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in coastal British Columbia (Canada) air, we collected samples from two sites: a remote site on western Vancouver Island, and a near-urban site in the Strait of Georgia. Seasonally-integrated samples of vapor, particulate, and rain were collected continuously during 365 days for analysis of 275 PCB and PBDE congeners. While deposition of the legacy PCBs was similar at both sampling sites, deposition of PBDEs at the remote site amounted to 42% (10.4 mg/ha/year) of that at the near-urban site. Additional research into atmospheric circulation in the NE Pacific Ocean will provide more insight into the transport and fate of priority pollutants in this region, but trans-Pacific delivery of PBDEs to the west coast of North America may underlie in part our observations. For example, approximately 40% of >12,000 ten-day back trajectories calculated for the remote site originated over Asia, compared to only 2% over North America. [Copyright &y& Elsevier]

Abstract: We previously reported in vivo induction of cytochrome P450 1A (CYP1A) by β-naphthoflavone in skin and liver biopsies of captive harbour seals (Phoca vitulina richardsi). The present study evaluated CYP1A expression (immunoblot analysis and ethoxyresorufin O-deethylase activity-EROD) in harbour seals using two study designs: i) skin and liver biopsies from 20 harbour seal pups captured from coastal British Columbia (BC, Canada) and temporarily housed in captivity; and ii) skin biopsies from 42 free-ranging harbour seals captured and sampled on-site in multiple locations in BC and Washington State (USA). Toxic Equivalency Quotients (TEQs) were calculated for polychlorinated biphenyl, polychlorinated dibenzo-p-dioxin, and polychlorinated dibenzofuran residues measured in blubber from a subset of study animals (n =30). CYP1A data from the seal pups held temporarily in captivity show that CYP1A protein levels were greater in liver than skin and that CYP1A protein and EROD activity were correlated in skin and liver. However, analysis of free-ranging seals from different sites revealed that blubber organochlorine TEQ values did not correlate with skin CYP1A levels. CYP1A protein levels and EROD activities in skin of seal pups from the BC locations and from Puget Sound were relatively low, possibly reflecting contaminant levels that were not high enough to elicit a response, a small sample size, or methodological limitations. Our results show that CYP1A measurements in skin show promise as a biomarker of contaminant exposure, but that refinements to techniques and a larger sample size are needed. [Copyright &y& Elsevier]

Marine coastal areas of British Columbia, Canada are subject to a gradient of increasing anthropogenic sources from pristine areas in the north to the more urbanised areas of the south. Along the gradient, the relative contributions of polycyclic aromatic hydrocarbons (PAHs) from multiple natural and anthropogenic sources are not well understood, but concerns linger about bioavailability and consequent risks to marine biota. Composition patterns and principal components analysis (PCA) models for surface sediment and core samples collected along this transect indicate that samples from the urbanised Vancouver area have the highest proportions of tricyclic terpane, hopane and sterane biomarkers, UCM (unresolved complex mixture), the alkyl fluoranthene/pyrene and benz[ a ]anthracene/chrysene series and most parent PAHs. Those from Hecate and Queen Charlotte Straits and other locations in the Strait of Georgia have, on the other hand, higher proportions of the resolved alkanes, and petrogenic alkyl naphthalene, fluorene, dibenzothiophene and phenanthrene/anthracene series. PAH ratios clearly indicate a predominance of combustion sources for the four ring and higher parent PAHs for all the sediments. Most samples have values close to the biomass/solid fuel and liquid fuel combustion borderline for ratios of the major PAHs, but liquid fuel combustion input dominates closer to urbanised locations. Ratios also suggest similar pyrogenic and petrogenic inputs between central Hecate Strait and reference sediments from Hecate Strait through to Queen Charlotte Strait, which indicates that biomass combustion and immature coal formations are the major putative respective sources for the reference areas. Alkyl PAH ratios for the C 3 and C 4 naphthalenes, C 2 and C 3 phenanthrenes and 3- and 2-methylchrysene, reflecting terrigenous/vascular plant sources and petroleum maturity, exhibit marked differences between Comox bituminous coal and Alberta Sweet Mixed Blend (ASMB) oil and reveal that the petrogenic input in all of the sediments is non-biodegraded. Ratios of these alkyl PAHs with multiple substituents indicate that the sediment samples in the northern Strait of Georgia closest to the Comox coal field receive relatively constant input of eroded coal, while those in the southern Strait of Georgia and Vancouver Harbour show a composition closest to ASMB oil. PAHs associated with liquid fossil fuel combustion and petroleum discharges adjacent to urbanised areas are expected to be fully bioavailable to marine food webs, while the char from biomass combustion and coal from immature deposits in more remote areas would have limited bioavailability. This implies that biota in remote areas of Hecate Strait/Queen Charlotte Sound are likely not adapted to the presence of oil and thus would be more sensitive to exposure to spilled oil than those in the more impacted environments in southern British Columbia. [ABSTRACT FROM AUTHOR]

Abstract: The question of polycyclic aromatic hydrocarbon (PAH) bioavailability and its relationship to specific PAH sources with different PAH binding characteristics is an important one, because bioavailability drives PAH accumulation in biota and ultimately the biochemical responses to the PAH contaminants. The industrial harbour at Kitimat (British Columbia, Canada) provides an ideal location to study the bioavailability and bioaccumulation of sediment hydrocarbons to low trophic level biota. Samples of soft shell clams (Mya arenaria) and intertidal sediment collected from multiple sites over six years at various distances from an aluminium smelter and a pulp and paper mill were analysed for 106 PAHs, plant diterpenes and other aromatic fraction hydrocarbons. Interpretation using PAH source ratios and multivariate data analysis reveals six principal hydrocarbon sources: PAHs in coke, pitch and emissions from anode combustion from the aluminium smelter, vascular plant terpenes and aromatised terpenes from the pulp and paper mill, petroleum PAHs from shipping and other anthropogenic activities and PAHs from natural plant detritus. Harbour sediments predominantly contain either pitch or pyrogenic PAHs from the smelter, while clams predominantly contain plant derived PAHs and diterpenes from the adjacent pulp mill. PAHs from the smelter have low bioavailability to clams (Biota-Sediment Accumulation Factors; BSAFs <1 for pitch and coke; <10 for anode combustion, decreasing to ∼0.1 for the mass 300 and 302 PAHs), possibly due to binding to pitch or soot carbon matrices. Decreases in PAH isomer ratios between sediments and clams likely reflect a combination of variation in uptake kinetics of petroleum PAHs and compound specific metabolism, with the importance of petroleum PAHs decreasing with increasing molecular weight. Plant derived compounds exhibit little natural bioaccumulation at reference sites, but unsaturated and aromatised diterpenes released from resins by industrial pulping processes are readily accumulated by the clams (BSAFs >500). Thus while most of the smelter associated PAHs in sediments may not be bioavailable to benthic organisms, the plant terpenes (including retene, totarol, ferruginol, manool, dehydroabietane and other plant terpenes that form the chemical defence mechanism of conifers) released by pulp mills are bioavailable and possess demonstrated toxic properties. The large scale release of plant terpenes by some of the many pulp mills located in British Columbia and elsewhere represents a largely undocumented risk to aquatic biota. [Copyright &y& Elsevier]

We document the abundance, composition and distribution of microplastics in sub-surface seawaters of the northeastern Pacific Ocean and coastal British Columbia. Samples were acid-digested and plastics were characterized using light microscopy by type (fibres or fragments) and size (<100, 100-500, 500-100 and >1000 μm). Microplastics concentrations ranged from 8 to 9200 particles/m(3); lowest concentrations were in offshore Pacific waters, and increased 6, 12 and 27-fold in west coast Vancouver Island, Strait of Georgia, and Queen Charlotte Sound, respectively. Fibres accounted for ∼ 75% of particles on average, although nearshore samples had more fibre content than offshore (p<0.05). While elevated microplastic concentrations near urban areas are consistent with land-based sources, the high levels in Queen Charlotte Sound appeared to be the result of oceanographic conditions that trap and concentrate debris. This assessment of microplastics in the NE Pacific is of interest in light of the on-coming debris from the 2011 Tohoku Tsunami., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

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 delta13C 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 sigmaPCBs 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.

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 K(OW)). 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 K(OW); 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 K(OW) (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.

Biomarkers of organochlorine exposure, such as the induction of cytochrome P450 1A (CYP1A), can be used to assess the impact of environmental contaminants on the health of free-ranging marine mammal populations. The objective of the present study was to measure CYP1A in skin and liver biopsies obtained from live harbour seals (Phoca vitulina). Twelve harbour seal pups, aged three to five weeks, were captured from the Fraser River estuary, British Columbia, Canada, and temporarily held in captivity. Skin ( approximately 60 mg) and liver ( approximately 40 mg) biopsies, obtained while seals were under general anaesthesia, yielded sufficient tissue for the measurement of CYP1A by immunoblot analysis and ethoxyresorufin O-deethylase activity. A short-term exposure experiment, in which harbour seals (n=3) were treated orally with beta-naphthoflavone (BNF), resulted in increased hepatic and cutaneous CYP1A protein levels, consistent with observations in other mammals. This study is the first to measure CYP1A in skin and liver biopsies from live harbour seals and to report in vivo BNF-associated CYP1A induction in a marine mammal. The results demonstrate that microsamples collected using minimally-invasive techniques can provide toxicologically-relevant information form marine mammals.