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Yunker M.B.,7137 Wallace Dr. | McLaughlin F.A.,Canadian Department of Fisheries and Oceans | Fowler M.G.,Geological Survey of Canada | Fowler B.R.,Axys Analytical Ltd.
Organic Geochemistry | Year: 2014

Significant reserves of oil and gas have been predicted for Hecate Strait, a pristine, semi-enclosed sea on the continental shelf adjacent to British Columbia, on the west coast of Canada. To establish a baseline for the natural background of hydrocarbons in sediment prior to any further offshore oil and gas development or increase in oil tanker traffic in the Hecate Strait region, three sediment box cores were collected along a west to east transect across southern Hecate Strait in September 2003. 210Pb measurements established that the bottom sections date to ~1920, pre-1800 and ~1870, respectively, which predate any significant industrial development on the coast. Alkane and polycyclic aromatic hydrocarbon (PAH) concentrations are low in most sediment samples and both the concentrations and fluxes differ little between surface and bottom core sections. PAH profiles exhibit a dominance of alkyl PAHs for each alkyl PAH homologous series with varying amounts of parent (unsubstituted) PAHs, while alkane chromatograms show no unresolved complex mixture (UCM), and there is little change in composition between present day and pre-1800 sediments for most parameters. Principal components analysis (PCA) models, and PAH and biomarker ratios indicate that composition patterns are consistent with low and varying natural petrogenic and pyrogenic inputs, with little or no anthropogenic input. The most likely primary source of petrogenic PAHs to the sediments is Cenozoic lignites from the Skonun Formation, which outcrops on Haida Gwai and underlies most of Hecate Strait. Two subsurface sections (deposited in ~1990 and ~1930) in the core from Milbanke Sound, on the east side of the transect, have elevated concentrations for the alkyl phenanthrene/anthracenes and dibenzothiophenes with no UCM, and most likely also have a source in immature coal. This study suggests that the Hecate Strait environment has low hydrocarbon concentrations, with an apparent minor role for oil seeps and a likelihood that most of the petrogenic PAH sources are shales or immature coals with limited PAH bioavailability. If these characteristics are representative of Hecate Strait sediments overlying the Queen Charlotte Basin, it may mean that biota are likely unadapted to the presence of oil and thus would be more sensitive to exposure to oil from an oil spill than those in a more impacted environment. © 2014 Elsevier Ltd. Source

Yunker M.B.,7137 Wallace Dr. | Macdonald R.W.,Canadian Department of Fisheries and Oceans | Ross P.S.,Vancouver Aquarium Marine Science Center | Johannessen S.C.,Canadian Department of Fisheries and Oceans | Dangerfield N.,Canadian Department of Fisheries and Oceans
Organic Geochemistry | Year: 2015

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 C3 and C4 naphthalenes, C2 and C3 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. © 2015 Elsevier Ltd. Source

Yunker M.B.,7137 Wallace Dr. | Perreault A.,Capital Regional District | Lowe C.J.,Capital Regional District
Organic Geochemistry | Year: 2012

Previous studies have suggested that coal from the 1891 shipwreck of a collier off Victoria, BC, Canada is responsible for elevated parent (unsubstituted) PAH concentrations in sediments near deep marine outfalls from Esquimalt and Victoria in the Strait of Juan de Fuca. To resolve this question, we analysed a comprehensive suite of resolved and unresolved complex mixture (UCM) alkanes, tricyclic terpane, hopane and sterane biomarkers, and parent and alkyl polycyclic aromatic hydrocarbons (PAHs) in samples of coal, wastewater and sediments. Composition patterns, principal components analysis (PCA) models and PAH and biomarker ratios all indicate that coal from the collier does not make a dominant contribution to any sediment sample. Mass balance calculations based on the n-C 24 content and 24/4 tetracyclic terpane to 26/3R tricyclic terpane ratio in coal provide a particularly good match between predicted and observed alkyl PAH concentrations for sediments with high alkyl naphthalenes and phenanthrene/anthracenes and low UCM, but the predicted coal contribution substantially underestimates the measured parent PAHs for all sediment samples. Methylbenz[a]anthracene/chrysene profiles for sediments with a dominance of parent PAHs are very close to coal tar, with a marked predominance of methylbenz[a]anthracenes and the possible 10-methylbenz[a]anthracene as a major constituent, while the methylchrysenes predominate in coal. Hence, coal from the collier could account for most alkyl PAHs in the sediments, but dredged sediment containing pyrolised coal waste from a former coal gas plant in Victoria Harbour is a more likely source for the samples with elevated parent PAHs. PAH ratios indicate that these sources are superimposed on combustion PAHs introduced by a combination of atmospheric deposition and delivery via stormwater and the outfalls. Parent PAH distributions also suggest that PAHs in wastewater that originate from oils and soot in liquid fossil fuel combustion are dispersed and degraded, while the larger wood char particles (containing PAHs more protected from degradation) settle closer to the outfalls. Overall, results suggest that PAHs have predominant sources in wood combustion, coal and possibly coke, with a likelihood of much lower bioavailability than would be expected from wastewater dominated by oils and soot from vehicle combustion. © 2012 Elsevier Ltd. Source

Harris K.A.,Canadian Department of Fisheries and Oceans | Harris K.A.,University of Victoria | Yunker M.B.,7137 Wallace Dr. | Dangerfield N.,Canadian Department of Fisheries and Oceans | Ross P.S.,Canadian Department of Fisheries and Oceans
Environmental Pollution | Year: 2011

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. © 2010 Published by Elsevier Ltd. Source

Yunker M.B.,7137 Wallace Dr. | Lachmuth C.L.,Canadian Department of Fisheries and Oceans | Cretney W.J.,13 909 Carolwood Dr. | Fowler B.R.,Axys Analytical Ltd. | And 3 more authors.
Marine Environmental Research | Year: 2011

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. © 2011 Elsevier Ltd. Source

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