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Principal components analysis (PCA) has been applied to a large data set of the concentrations of chlorinated dibenzo-p-dioxins and dibenzofurans in samples of crab hepatopancreas from British Columbia, Canada (B.C.). These samples have been collected since 1987 from locations in the vicinity of B.C. coastal mills and the principal B.C. harbors. PCA distinguishes harbor samples from mill samples, reveals differences between individual mill sites and reliably classifies the dioxin and furan congener patterns according to chlorine bleaching, digested polychlorinated phenol and pentachlorophenol wood preservative sources. PCA may also be used to assign sources to individual crab samples. Since 1987 both the proportion of toxic 2,3,7,8-chlorinated congeners and the overall dioxin and furan concentrations have generally decreased near B.C. mill sites. The mill-related tetrafurans have been removed faster than the hexadioxins, with the result that composition profiles and PCA projections have become more similar over time at the mill sites. Crab samples from B.C.’s harbors have lower proportions of the toxic 2,3,7,8-chlorinated congeners, but have shown less change over time.

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.

Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular 14C measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C24,26,28), plant wax FAs (C24,26,28), and n-alkanes (C27,29,31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these "old" terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C16,18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in 14C, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular 14C analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.

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. 210 Pb 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.

[1] As part of the International Polar Year research program, we conducted a survey of surface marine sediments from box cores along a section extending from the Bering Sea to Davis Strait via the Canadian Archipelago. We used bulk elemental and isotopic compositions, together with biomarkers and principal components analysis, to elucidate the distribution of marine and terrestrial organic matter in different regions of the North American Arctic margin. Marked regional contrasts were observed in organic carbon loadings, with the highest values (� 1m g Cm � 2 sediment) found in sites along Barrow Canyon and the Chukchi and Bering shelves, all of which were characterized by sediments with low oxygen exposure, as inferred from thin layers (

The present study characterizes the uptake and loss of persistent organic pollutants (POPs) in grizzly bears (Ursus arctos horribilis) by sampling and analyzing their terrestrial and marine foods and fecal material from a remote coastal watershed in British Columbia, Canada. The authors estimate that grizzly bears consume 341 to 1,120 µg of polychlorinated biphenyls (PCBs) and 3.9 to 33 µg of polybrominated diphenyl ethers daily in the fall when they have access to an abundant supply of returning salmon. The authors also estimate that POP elimination by grizzly bears through defecation is very low following salmon consumption (typically 100% for PCBs and organochlorine pesticides). Excretion of individual POPs is largely driven by a combination of fugacity (differences between bear and food concentrations) and the digestibility of the food. The results of the present study are substantiated by a principal components analysis, which also demonstrates a strong role for log KOW in governing the excretion of different POPs in grizzly bears. Collectively, the present study's results reveal that grizzly bears experience a vegetation-associated drawdown of POPs previously acquired through the consumption of salmon, to such an extent that net biomagnification is reduced.

On the morning of April 9, 2015, citizens in Vancouver (British Columbia, Canada) awoke to the sight and smell of oil on the shores of popular downtown beaches. Because the oil also had spread over the shallow seawater intakes for the Vancouver Aquarium, a preliminary screening of samples was performed as a prompt, first response to assess the risks to the Aquarium collection and guide the emergency operational response. A subsequent, more detailed examination for the presence of spilled oil in sediment, biota and water samples from the Vancouver Harbour region was then conducted based on the analysis of a large suite of alkanes, petroleum biomarkers, parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAH isomers. Most of the commonly applied biomarker ratios exhibit similar values for the spilled oil, Alberta oil (the main petroleum source for British Columbia), and pre-spill and un-oiled sediment samples. In contrast, alkyl PAH isomer ratios showed a clear distinction between the spilled oil and pre-spill samples, with the largest differences shown by isomers of the methyl fluoranthene/pyrene alkyl PAH series. This novel use of alkyl PAH isomers for fingerprinting petroleum helped to confirm the grain carrier MV Marathassa as the source of the oil that affected beach and mussel samples to document definitively the spread of the oil and to establish which samples contained a mix of the oil and hydrocarbons linked to historical activities. Finally, an initial evaluation of the biological risks of the MV Marathassa oil spill in Vancouver Harbour showed that oiled beach sediments had priority parent PAH concentrations that are likely to harm marine life.

We hypothesized that depleted fat reserves in grizzly bears (Ursus arctos horribilis) following annual hibernation would reveal increases in persistent organic pollutant (POP) concentrations compared to those present in the fall. We obtained fat and hair from British Columbia grizzly bears in early spring 2004 to compare with those collected in fall 2003, with the two tissue types providing contaminant and dietary information, respectively. By correcting for the individual feeding habits of grizzlies using a stable isotope-based approach, we found that polychlorinated biphenyls (sigmaPCBs) increased by 2.21x, polybrominated diphenylethers (sigmaPBDEs) increased by 1.58x, and chlordanes (sigmaCHL) by 1.49x in fat following hibernation. Interestingly, individual POPs elicited a wide range of hibernation-associated concentration effects (e.g., CB-153, 2.25x vs CB-169, 0.00x), resulting in POP pattern convergence in a PCA model of two distinct fall feeding groups (salmon-eating vs non-salmon-eating) into a single spring (post-hibernation) group. Our results suggest that diet dictates contaminant patterns during a feeding phase, while metabolism drives patterns during a fasting phase. This work suggests a duality of POP-associated health risks to hibernating grizzly bears: (1) increased concentrations of some POPs during hibernation; and (2) a potentially prolonged accumulation of water-soluble, highly reactive POP metabolites, since grizzly bears do not excrete during hibernation.

The type and flux of organic carbon (OC) delivered from the continents to the sea can both influence, and be influenced by, climate change on regional and global scales. In order to develop a more complete view of OC delivery in the climatically sensitive Arctic region, we measured the stable carbon and radiocarbon isotopic signatures of individual lipid biomarkers and products of kerogen pyrolysis from the surficial sediments of several sites on the Mackenzie Shelf and adjacent slope of the Beaufort Sea. Even carbon numbered fatty acids exhibit a trend of increasing 14C age with increasing chain length, from modern values for the nC14–nC18 homologues to several thousand years old for those ≥ nC24. Such depleted 14C values for longer-chain fatty acids likely reflect supply of vascular plant OC that has been pre-aged on the continents for several millennia prior to delivery to the Beaufort Sea. Their corresponding δ13C values support a C3 land plant source. The molecular distributions and 14C and 13C signatures of solvent-extractable alkanes point to at least two sources: higher plant leaf waxes and a 14C-‘dead’ component likely derived from erosion of organic-rich sedimentary rocks exposed within the Mackenzie River drainage basin. The δ13C and Δ14C values of n-hydrocarbon pyrolysis products from the corresponding demineralized sediments also suggest a mixed supply of ancient kerogen and pre-aged vascular plant-derived precursors to the Beaufort Sea. On a bulk level, the trend in sedimentary OC contents, C/N ratios, and δ13C values point to an overall decrease in the terrigenous input (mainly from the Mackenzie River) with increasing distance offshore, whereas bulk Δ14C measurements exhibit no trend suggesting a somewhat constant pre-aged component. A coupled molecular isotopic mass balance approach based on the lipid δ13C and Δ14C signatures is used to construct a budget of terrestrial, marine, and petrogenic OC burial on the shelf. Results indicate that roughly 40–50% of the carbon currently being buried in the Beaufort Sea is derived from the weathering of ancient sedimentary rock. The balance is composed of marine and terrestrial input, supporting the qualitative description of OC sources given by the bulk and molecular patterns above. This suggests that mass balances utilizing the δ13C and Δ14C signatures of biomarkers as endmembers can be used to semi-quantitatively deconvolve multiple sources of organic carbon in marine sediments.

An understanding of the carbon cycle within arctic sediments requires discrimination between the terrigenous and marine components of organic carbon, insight into the removal mechanisms for labile carbon during burial and appreciation of shelf-to-basin processes. Using a large data set of multiple molecular organic markers (alkanes, alkanols, sterols, saturated and unsaturated fatty acids, dicarboxylic acids), we apply (1) principal components analysis (PCA) to obtain a robust comparison of biomarker compositions in Arctic Ocean sediments, (2) geometric mean (GM) linear regression of the PCA variables to estimate the relative contributions of labile/marine and stable/terrigenous sources to each biomarker and (3) the slope of the GM regression of each biomarker with TOC to provide a novel measure of the removal rate of each biomarker relative to phytol. The PCA- and TOC-based indices generally increase together: biomarkers with very high TOC-based removal rates such as the saturated and unsaturated n-alkanoic acids generally have a high labile/marine content from PCA, while the sterols have low removal rates, but exhibit a range of labile/marine content values and the n-alkanes and n-alkanols have low values for both. A dominant feature of all PCA models examined is a progressive decrease in the autochthonous/marine biomarkers with each increase in sediment core depth, which points to a universal diagenetic alteration of organic carbon with depth in the cores. The PCA model also displays a shelf to basin trend that is non-diagenetic and implies the ongoing (centuries or more) delivery of long-chain n-alkanes, n-alcohols and n-alkanoic acids in a matrix that is pre-formed and well-preserved within the sediments. Terrigenous biomarker distributions within the PCA model suggest that atmospheric transport of plant waxes in aerosols and the water borne transport of very fine plant macerals likely have significant roles in the export of these vascular plant biomarkers to the basins. Biomarker ratios and profiles of the PCA-based labile/marine content with core depth indicate that the PCA model is more strongly influenced by the biomarker lability than the marine content, while increases in the marine content are largely responsible for the shifts in composition for near-surface core sections.

The provenance of organic matter in sediments from the Mackenzie River and Beaufort Shelf was investigated using the stable carbon and radiocarbon isotopic compositions of bulk organic matter and the stable carbon isotopic compositions of individual organic compounds, including lignin-derived phenols and lipid-derived fatty acids. Most river suspended sediments and shelf surface sediments contained organic carbon characterized by highly depleted Δ14C values that were consistent with average radiocarbon ages exceeding 7000 years. The stable carbon isotopic signatures of lignin phenols were uniformly depleted (−25≥δ13C≥−32‰), indicating the predominant contributions of C3 vascular plant sources. The isotopic compositions of C14 and C16 fatty acids exhibited important contrasts between the river (−36‰ to −40‰) and shelf (−25‰ to −29‰) sediments that were consistent with contributions from freshwater algae and/or vascular plants in the former and marine phytoplankton in the latter. Using 14C isotopic mass balance, the abundances of modern and ancient organic matter were quantitatively constrained. The fate of organic matter in the Beaufort Shelf was explored by normalizing these abundances to the specific surface area of sediments. Ancient organic carbon, which may include old pre-aged soil material as well as fossil bitumen or kerogen, accounted for the majority (∼70%) of the particulate organic matter exported by the Mackenzie River and deposited in surface sediments of the Beaufort Shelf. Modern organic carbon accounted for ∼30% in both river and shelf sediments, with significant contributions from vascular plant-derived materials in both river and shelf samples and from marine algae in the shelf sediments. Respiration (and/or leaching) of particle-bound marine organic matter dominates the carbon metabolism in the Mackenzie Delta/Beaufort Shelf region. However, land-derived pools, including modern carbon derived from vascular plants as well as ancient carbon also appeared to undergo a degree of post-depositional degradation prior to burial in the shelf. These novel source apportionments are reflected in an updated carbon budget for the study area.

A suite of organic biomarkers was examined in six sediment cores from two shelf-basin transects in the Chukchi and Beaufort Seas of the Arctic Ocean to compare the sources and preservation of organic carbon between the two differing depositional regimes. Profiles of polyunsaturated fatty acids (PUFAs) and several algal sterols reveal the dominance of marine carbon on the broad, shallow Chukchi Shelf and Slope, and suggest that episodic pulses of marine material may be incorporated relatively unaltered into sediments. Biomarker profiles show carbon from terrestrial sources is present throughout the Chukchi transect, but is of lesser importance and is degraded compared to that seen in the Beaufort Sea. In contrast, the narrow Beaufort Shelf system is greatly influenced by the Mackenzie River with terrestrial contributions to total organic carbon estimated as over 95% for the shelf area and approximately 65% farther offshore. An unexpected correlation between dinosterol and α-amyrin in shelf and slope sediments suggests that dinoflagellates may contribute significantly to phytoplankton abundance in areas of seasonal open water. At basin locations that are almost permanently covered with ice, sterol profiles reflect diatoms as the main source of marine carbon.

In the Fraser River Basin and the Strait of Georgia, a pristine hydrocarbon background is evident in older sediments and suspended sediments from remote regions. This natural background has been augmented over the past century by variable amounts of combustion PAHs and petroleum hydrocarbons derived from human activities, with impacts most evident near industrialised or highly populated regions. Traditional petroleum indicators, including alkane and alkyl PAH distributions and unresolved complex mixtures (UCMs), identify petroleum contamination in suspended particulates transported by the Fraser River and in modern sediments from lakes and rivers in the lower Fraser Basin and the Strait of Georgia. However, these markers have proven to be of limited quantitative use either because they overlap combustion PAH profiles or because they are prone to degradation in the environment. More specific and refractory petroleum markers such as the steranes, rearranged hopanes and tri- and tetracyclic terpanes are found where there are enhanced concentrations of traditional indicators, confirming previous assignments of petroleum contamination near industrial regions. Furthermore, the low or non-detectable quantities of these biomarkers in remote regions reinforce the conclusion that these areas remain pristine and suggest that these markers may provide useful indicators of any future contamination. Biomarkers of petroleum origin (reservoir location or age) do not provide incisive indicators of the origins of hydrocarbon contamination in the Fraser Basin but they have helped to narrow down the sources. In particular, the absence of structurally rearranged hopanes (25,28,30-trisnorhopane and 28,30-bisnorhopane) rules out contamination from Californian oils, while the presence of enhanced oleanane in samples from the lower Fraser River suggests a source in coal dust lost during railroad transportation to the coast.

Hydrocarbon data for dated sediment cores from Fraser Basin lakes and the Strait of Georgia in Canada reveal a pristine pre-industrial background that remains unaltered in modern sediments far from human activities. These pristine sediments contain polycyclic aromatic hydrocarbons (PAHs) from combustion (natural forest and prairie fires), and alkanes and PAHs from weathering of soils containing vascular plant remains and natural petroleum hydrocarbons, and algal production. At other locations examined, however, these natural loadings have been augmented over the past century by hydrocarbons from petroleum, the combustion of liquid (oil, gasoline) and solid (coal, wood) fuels and from processing of wood either directly from disturbed land and slash burning or indirectly through pulp mill effluent. Although contamination is clearest where there are nearby human activities, alkane profiles, PAH distributions and alkane unresolved complex mixtures suggest a widespread contamination from petroleum. Combustion products from human activities can also be identified, although with less source specificity than with the petroleum products. Regional emissions from anthropogenic combustion processes appear to support modern PAH increases within the Fraser River Basin and there is little evidence of inputs from global emissions. Principal components analysis using the new centred log ratio normalisation procedure to normalise data discriminates well between PAHs entering lakes from runoff or the atmosphere and PAH formed diagenetically within lake sediments, as well as between combustion and petroleum PAHs.

Hydrocarbon measurements have been made on dissolved, suspended particulate and sediment samples collected in 1987, 1993 and 1994 from the Mackenzie River delta and shelf and in 1993 from 10 smaller Northwest Territories and Nunavut rivers that drain into the Canadian Archipelago or Hudson's Bay. Suspended particulate samples from all rivers have a resolved higher alkane pattern with a well-defined odd–even predominance consistent with a major source in terrestrial, vascular plant material. Particulate samples from the 10 smaller rivers have alkane concentrations that are similar to the Mackenzie River during summer, but PAH (polycyclic aromatic hydrocarbon) concentrations are approximately 10 times lower for the parent PAHs and 100 times lower for alkyl PAHs. PAHs on suspended particulate from the Mackenzie River exhibit a uniform composition typical of mature petrogenic sources, while PAHs in the smaller rivers are typical of combustion. The virtual absence of petrogenic PAHs in the smaller rivers is the single most important difference between these and the Mackenzie River. During summer the alkane and PAH composition of suspended particulate in the Mackenzie River is sufficiently homogenous to estimate directly the hydrocarbon load from the particulate load. Mackenzie River particulates and sediments have the hopane and sterane ratios characteristic of immature bitumens, shales or coals from the Devonian Canol formation that outcrops in the lower Mackenzie River valley. The erosion of organic-rich rocks from this formation is likely the source of the refractory petrogenic material found in the Mackenzie River delta and shelf. Data are insufficient to determine whether the petrogenic lower alkanes and PAHs have the same source or whether more mature petroleum also contributes. Because sediment samples (suspended and bed) from the Mackenzie delta have natural PAH concentrations that exceed the level where adverse biological effects are expected to occur, there is an urgent need to establish whether these petroleum-derived PAHs are bioavailable and if they are inducing effects in bottom fish and other biota.

Parent and alkyl PAHs (51 compounds and alkyl homologues) have been quantified in suspended particulates and sediments (345 samples) from the Fraser River system, British Columbia, Canada. The best potential to distinguish natural and anthropogenic sources is exhibited by ratios of the principal mass 178, 202, 228 and 276 parent PAHs, 1,7/2,6+1,7-DMP (dimethylphenanthrene), the phenanthrene/anthracene and fluoranthene/pyrene alkyl PAH series and several less commonly applied PAHs (e.g. acephenanthrylene and pentaphene). Using these ratios we infer sources of PAH to the Fraser basin and evaluate the consistency of these source assignments and the suitability of various commonly applied PAH ratios as indicators. PAH ratios and total concentration data reveal a basin lightly impacted by a variety of sources in its remote regions, especially near roads, but heavily impacted in urban areas, particularly near Vancouver. Contamination sources shift from biomass (e.g. wood and grass) burning to vehicle emissions between remote and urban locations. Stormwater and wastewater discharges appear to collect PAH from urban areas and release them as point sources. In contaminated areas ratios are specific for combustion vs. petroleum sources, and some ratios (202 and 276) distinguish biomass or coal from liquid fossil fuel combustion. At lower concentrations multiple sources at times make interpretations based on a single ratio misleading and the higher mass ratios (228 and 276) may be most applicable to urban areas. In all cases the examination of a variety of PAH indicator ratios that encompass a range of masses is necessary for a robust interpretation.

Mill process changes and source controls instituted in the late 1980s at pulp and paper mills along the British Columbia (BC) coast produced dramatic reductions in both the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and the TEQ (2,3,7,8-TCDD toxic equivalents). Nevertheless, questions remained as to whether the sediments were acting as contaminant sources or sinks, whether crab uptake pathways have stayed the same since the mills ceased producing PCDD/Fs, and whether improvement was faster at some sites than others. To examine the processes governing the changes in PCDD/F composition, PCDD/F sources and compositional trends for the coastal BC sites were interpreted using sediment and crab PCA (principal components analysis) models and two indices based on the three main groups of PCDD/Fs that covary in all PCA models. One index measured the relative inputs of chlorine bleaching PCDFs and PCP (pentachlorophenol)-related PCDDs at each mill and harbor site whereas the other measured the relative inputs of PCP wood preservatives and pulp mill effluents. Results indicated that PCDFs produced during chlorine bleaching accumulate from sediments to crabs more readily than the PCDDs but that the chlorine bleaching TCDFs have generally decreased in importance at all mill sites. In the years just before 1995, little change was observed in either the proportion of toxic 2,3,7,8-chlorinated congeners or the PCDD/F concentrations, and the improvements seemed to have largely ceased by 1995. The lack of change in PCA composition for the harbors provided a further, disturbing indication that ecosystem recovery may have stalled. Results also implied that the main route of PCDD/Fs into crabs shifted from uptake via a pelagic food web incorporating effluent-borne PCDD/Fs associated with suspended particulate matter to uptake via a benthic food web.

Biota-sediment accumulation factors (BSAFs) for some chlorinated dibenzo- p -dioxin and dibenzofuran congeners (PCDD/Fs) in Dungeness crab (Cancer magister) hepatopancreas and associated sediments are concentration independent as required by equilibrium partition models. In particular 2, 3, 7, 8-tetrachlorodibenzo-p -dioxin (2, 3, 7, 8-TCDD), 2, 3, 7, 8-tetrachlorodibenzofuran, the 2, 3, 7, 8-substituted pentachlorodibenzofurans, and the non-2, 3, 7, 8-hexachlorodibenzofurans (HxCDFs) seem to fall into this group. The BSAFs for other isomers exhibit significant, nonlinear variations with sediment or crab PCDD/F concentrations. For some of these other isomers (e.g., the non-2, 3, 7, 8 TCDDs and possibility the 2, 3, 7, 8-substituted HxCDFs), association of a variable fraction of the total present with soot carbon may provide a satisfactory explanation for the concentration behavior. For the HxCDDs we propose that the nonlinear concentration behavior may arise from the thermodynamic properties of fluids confined in hydrophobic voids within particulate and colloidal material produced by the pulp mills. The nonlinear relationship between BSAFs and PCDD/F concentrations greatly complicates prediction of the potential for dioxin and furan bioaccumulation in crabs and the formulation of sediment quality criteria. We provide a nonlinear equation relating toxic equivalency and sediment concentrations.

Suspended sediments from the Mackenzie River Delta and surface sediments from the Beaufort Shelf were analyzed by alkaline CuO oxidation. In addition, elemental (percentage total organic carbon, inorganic carbon and silica) and stable carbon isotope compositions were determined for all samples. The carbon-normalized yields of over 60 different compounds derived from the oxidative hydrolysis of several biochemicals, including lignin, cutin, proteins, polysaccharides and lipids were quantified and subjected to principal component analyses (PCA). The results of these investigations indicate that most lignin and cutin products originate from non-woody angiosperm vascular vegetation such as that present in the tundra. For example, lignin-derived product compositions are characterized by relatively high syringyl:vanillyl and cinnamyl:vanillyl phenol ratios (exceeding 0.4 and 0.15, respectively). The compositions of these biomarkers, especially the elevated (0.5 to 1.5) acid:aldehyde ratios for vanillyl and syringyl phenols, also suggest that the land-derived organic matter (OM) exported by the Mackenzie River is highly degraded. Non-lignin CuO reaction products derived from proteins, polysaccharides and lipids display distributions that are consistent with a predominant marine (autochthonous) source. The composition of lipid-derived fatty acid products, which is in shelf sediments are dominated by hexanedecenoic acid, suggests a planktonic origin, likely from diatoms. The distribution of these biomarkers across the shelf indicates the presence of relatively fresh algal remains in at least one sample. The relationships between terrigenous biomarker concentrations and bulk 13 C/ 12 C ratios in surface sediments indicate that terrestrial organic carbon dominates in abundance (80% to 50% of total organic carbon) over much of the shelf. Marine/algal-derived carbon represents 20% to 50% of the total carbon in shelf sediments, with the largest fraction being present in the outer mid-shelf. The large variability in the yields of CuO biomarkers from the river suspended sediment samples highlights the heterogeneous nature of the particle load exported by the Mackenzie River. Such variability must be taken into account during the development of quantitative carbon budgets for the Beaufort Shelf.

Recent studies of contaminants under the Canadian Northern Contaminants Program (NCP) have substantially enhanced our understanding of the pathways by which contaminants enter Canada’s Arctic and move through terrestrial and marine ecosystems there. Building on a previous review (Barrie et al., Arctic contaminants: sources, occurrence and pathways. Sci Total Environ 1992:1–74), we highlight new knowledge developed under the NCP on the sources, occurrence and pathways of contaminants (organochlorines, Hg, Pb and Cd, PAHs, artificial radionuclides). Starting from the global scale, we examine emission histories and sources for selected contaminants focussing especially on the organochlorines. Physical and chemical properties, transport processes in the environment (e.g. winds, currents, partitioning), and models are then used to identify, understand and illustrate the connection between the contaminant sources in industrial and agricultural regions to the south and the eventual arrival of contaminants in remote regions of the Arctic. Within the Arctic, we examine how contaminants impinge on marine and terrestrial pathways and how they are subsequently either removed to sinks or remain where they can enter the biosphere. As a way to focus this synthesis on key concerns of northern residents, a number of special topics are examined including: a mass balance for HCH and toxaphene (CHBs) in the Arctic Ocean; a comparison of PCB sources within Canada’s Arctic (Dew Line Sites) with PCBs imported through long-range transport; an evaluation of concerns posed by three priority metals — Hg, Pb and Cd; an evaluation of the risks from artificial radionuclides in the ocean; a review of what is known about new-generation pesticides that are replacing the organochlorines; and a comparison of natural vs. anthropogenic sources of PAH in the Arctic. The reseArch and syntheses provide compelling evidence for close connectivity between the global emission of contaminants from industrial and agricultural activities and the Arctic. For semi-volatile compounds that partition strongly into cold water (e.g. HCH) we have seen an inevitable loading of Arctic aquatic reservoirs. Drastic HCH emission reductions have been rapidly followed by reduced atmospheric burdens with the result that the major reservoir and transport agent has become the ocean. In the Arctic, it will take decades for the upper ocean to clear itself of HCH. For compounds that partition strongly onto particles, and for which the soil reservoir is most important (e.g. PCBs), we have seen a delay in their arrival in the Arctic and some fractionation toward more volatile compounds (e.g. lower-chlorinated PCBs). Despite banning the production of PCB in the 1970s, and despite decreases of PCBs in environmental compartments in temperate regions, the Arctic presently shows little evidence of reduced PCB loadings. We anticipate a delay in PCB reductions in the Arctic and environmental lifetimes measured in decades. Although artificial radionuclides have caused great concern due to their direct disposal on Russian Shelves, they are found to pose little threat to Canadian waters and, indeed, much of the radionuclide inventory can be explained as remnant global fallout, which was sharply curtailed in the 1960s, and waste emissions released under license by the European reprocessing plants. Although Cd poses a human dietary concern both for terrestrial and marine mammals, we find little evidence that Cd in marine systems has been impacted by human activities. There is evidence of contaminant Pb in the Arctic, but loadings appear presently to be decreasing due to source controls (e.g. removal of Pb from gasoline) in Europe and North America. Of the metals, Hg provokes the greatest concern; loadings appear to be increasing in the Arctic due to global human activities, but such loadings are not evenly distributed nor are the pathways by which they enter and move within the Arctic well understood.

Sediment cores from the Fraser estuary, Vancouver Harbour and Strait of Georgia, suspended sediment samples from the Fraser River and sediment grabs from Vancouver Harbour have been analyzed for alkanes and parent and alkyl PAHs (polycyclic aromatic hydrocarbons). Principal components analysis (PCA) clearly distinguishes mixed sources by separating parent PAHs according to molecular size, and separating alkyl substituted PAHs from higher plant PAHs. We find the Fraser River to be the predominant source for natural and anthropogenic hydrocarbons to the Strait of Georgia. The natural hydrocarbon burden from the Fraser River is augmented principally by petroleum hydrocarbons and combustion PAHs from Vancouver. Contaminated sediments from Vancouver Harbour very likely have also been transported to a major ocean disposal site off the Fraser estuary. Petroleum alkanes, which dominate Fraser River suspended sediment samples, are lost by processes such as dissolution or microbial degradation during transport and sedimentation, while PAHs from the river are delivered essentially unchanged to sediments in the strait. Hydrocarbon composition undergoes little change with depth at a reference location in the Strait of Georgia, indicating that PAH inputs have changed very little since the early part of this century. In Vancouver Harbour the low rate of sediment accumulation coupled with surface mixing has led to the retention of contaminant PAHs within the surface mixed layer, while the rapid delivery of sediments from the Fraser River has buried contaminant PAHs from historical ocean disposal in the Strait of Georgia.

The Arctic Ocean accounts for 20% of the world's continental shelves. Because the Arctic is sensitive to global change, budgets of organic carbon for its shelves are of immediate interest. The Mackenzie Shelf of the Canadian Beaufort Sea is the best North American proxy for the enormous Eurasian Shelves (large area, large river input), and the only site for which a complete organic carbon budget can be attempted, due to an extensive data base. A mass balance for the Mackenzie Shelf has been constructed for sediments, terrestrial organic carbon, and primary produced carbon. We have considered allochthonous inputs from the Mackenzie River, from coastal erosion, from smaller rivers, from groundwater, from the atmosphere and import by ice. The Mackenzie River dominates the supply to the Beaufort shelf of inorganic sediment (127 Mt a −1 ) and paniculate and dissolved terrestrial carbon (2.1 Mt a −1 POC, 1.3 Mt a −1 DOC). The combined input from all other sources contributes only about 5% of the Mackenzie load. Using sediment accumulation data we estimate that about half of the sediment supply is trapped in the delta, about 40% on the shelf and the remainder escapes the shelf edge by various processes. Autochthonous primary production in the delta and on the shelf adds a further 3.3 Mt a −1 of particulate organic carbon. A box model has been constructed to account for sediment, terrestrial organic carbon and primary produced carbon. Whereas about 60% of the terrestrial POC is preserved in delta and shelf sediments, it appears that most (97%) of the primary produced carbon is recycled and not preserved in sediments. Confidence in the budget should be improved by focusing future research on the determination of modern sedimentation rates on the delta and shelf, measurement of organic carbon content of deltaic sediments, determination of primary production on the shelf, and determination of the relative proportions of terrestrial and marine organic carbon preserved in sediments.

Eight gravity cores collected from Alice Arm and Upper Observatory Inlet in British Columbia were analyzed for 210 Pb to determine the sediment accumulation rates. Sediment samples were also analyzed for Al, Ba, Cd, Cu, Fe, Mn, Pb, and Zn to establish the transport and fate of mine tailings in Alice Arm. Sediment accumulation rates ranged from 0.17 to 0.76 g cm −2 per year in Upper Observatory Inlet; in Alice Arm the accumulation rates ranged from 1.39 g cm −2 per year near the sill to above 2 g cm −2 per year in the upper sections of the arm. The significantly lower sedimentation rates in Observatory Inlet suggest that much of the sediment and mine tailings entering Alice Arm are trapped within the arm. Elevated Cd, Pb and Zn concentrations in the cores taken from Alice Arm indicate the presence of tailings from an open-pit molybdenum mine at the head of the Arm (Kitsault). Ba, Fe and Mn increase deep in cores from the head of Alice Arm, and a maximum in the Ba concentration around 1956 in a core from near the sill are probably associated with tailings disposed earlier into the Kitsault River at the head of the inlet (Dolly Varden mines). Post-1900 increases, particularly in Cu and Zn, for sediments from upper Observatory Inlet coincide with mining and smelting operations by Anyox at Granby Bay. Both the sediment accumulation rates and the sediment metal concentrations suggest that Alice Arm is an effective trap for most of the tailings supplied to it. The application of Principal Component Analysis on the metals data set shows a remarkably clear separation between Alice Arm (Cd, Pb, Zn) and Observatory Inlet (Cu, Zn) sediments; it appears that the submarine tailings discharge used by the most recent mine at Kitsault (Amax) deposited most tailings near the outfall and down the centre of the fjord.

Understanding the sources and pathways of pollutant transport to the Arctic is fundamental to our custody of this sensitive ecosystem. To achieve such an understanding, we need to go beyond a catalog of environmental concentrations. Sediments, which are a final sink for particle-active contaminants, can provide a valuable resource to assess fluxes and sources of contaminants. Here, we interpret PAH distributions from widely distributed Arctic marine sediments both as indicators of anthropogenic contribution and to illuminate transport pathways. We use principal components analysis (PCA) to reveal the potential sources of PAHs and their geochemistry in sediments from the Beaufort and Barents Seas. PCA distinguishes between natural and anthropogenic inputs and supports a direct linkage between anthropogenic emissions and Arctic contamination. In the Beaufort Sea, PAHs and triterpenes reflect strong Mackenzie River-dominated inputs of natural PAHs and petroleum which overwhelm anthropogenic sources. In the B...

The present study characterizes the uptake and loss of persistent organic pollutants (POPs) in grizzly bears (Ursus arctos horribilis) by sampling and analyzing their terrestrial and marine foods and fecal material from a remote coastal watershed in British Columbia, Canada. The authors estimate that grizzly bears consume 341 to 1,120 µg of polychlorinated biphenyls (PCBs) and 3.9 to 33 µg of polybrominated diphenyl ethers daily in the fall when they have access to an abundant supply of returning salmon. The authors also estimate that POP elimination by grizzly bears through defecation is very low following salmon consumption (typically2% of intake) but surprisingly high following plant consumption (100% for PCBs and organochlorine pesticides). Excretion of individual POPs is largely driven by a combination of fugacity (differences between bear and food concentrations) and the digestibility of the food. The results of the present study are substantiated by a principal components analysis, which also demonstrates a strong role for log KOW in governing the excretion of different POPs in grizzly bears. Collectively, the present study's results reveal that grizzly bears experience a vegetation-associated drawdown of POPs previously acquired through the consumption of salmon, to such an extent that net biomagnification is reduced.

Alkanes, hopane triterpenes, polycyclic aromatic hydrocarbons (PAHs), n -alcohols and sterols have been determined in the suspended particulate (> 0.7 μ m) and dissolved (Chromosorb T absorption) phases of samples from the Mackenzie River and shelf in winter, spring and summer. The dissolved phase carries a significant fraction of the alkanes and PAHs in winter and spring and is an important component of the hydrocarbon budget. However, dissolved alkanes and PAHs are only a minor component of the hydrocarbon budget when concentrations of suspended particulate are high during the open water season. At this time nearly all of the alkanes and parent PAHs are associated with the > 1.2 μ m particulate size fraction. The colloidal fraction is only a minor component of the PAHs in the Mackenzie River and nearshore, but a larger proportion of the PAH load is apparently borne by the finer particulate fractions in the marine regime. In all seasons the contribution to the dissolved phase decreases in the order diploptene, diagenetic hopanes, sterols and alcohols. Because petrogenic alkanes did not interfere in the higher alkane region, a seasonally independent terrigenous alkane equilibrium between the >0.7 μ m particulate reservoir and the dissolved fraction could be observed in the Mackenzie River and estuary. A dissolved phase odd-even predominance (OEP) is found wherever significant higher plant alkanes are present. The loss of this OEP on the mid shelf is most likely caused by a reduction in the particulate associated supply of terrigenous alkanes. The lower molecular-mass (up to 178), more water soluble PAHs predominate in the dissolved phase. Atmospheric PAHs are minor, occur most often in surface water and offshore samples and are present in greater amounts in the dissolved phase and fine particulate fractions.

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

We present the first sedimentary biomarker study encompassing the entire Arctic Ocean. A large data set of organic markers for terrigenous, petroleum and combustion inputs [alkanes, hopanes and steranes, parent and alkyl polycyclic aromatic hydrocarbons (PAHs)] is examined for patterns in space and time using principal components analysis (PCA) and partial least squares (PLS). Biomarker patterns reveal the central Arctic Ocean basin sediments to be compositionally distinct from those of the Mackenzie River/Beaufort Sea and Barents Sea, but similar to those of the Laptev Sea. PAH distributions reflected in PAH ratios and PCA projections demonstrate that Arctic Ocean sediment is dominated by natural inputs to the extent that anthropogenic combustion PAHs are not significant. We find only modest changes between the glacial and post-glacial sediments for atmospherically transported hydrocarbon biomarkers, while particle associated biomarkers were captured strongly at basin edges during the glacial period, and much more evenly transported across basins during the post-glacial period. The orders of magnitude decreases in particle associated petrogenic alkanes and PAHs in central basins during glacial times, coupled with the uniformity of most petrogenic biomarker parameters for most basin and shelf locations, reflect a massive reduction in ice transport that makes the margins the most likely source of petrogenic material for the Pleistocene/Holocene central Arctic basins. The proximity of large coal deposits of various maturity levels along the Lena River, the overlap in PAH and biomarker composition of the Laptev Sea and surficial sediments from the central Arctic Ocean and the location of the Laptev Sea at the origin of the main Transpolar Drift all point to eroded coals from the Lena River/Laptev Sea as the likely source of petrogenic hydrocarbons to the central Arctic Ocean. The ubiquitous presence of allochthonous coal in Arctic Ocean surface sediments provides a major constraint on the use of petrogenic biomarkers to infer the presence of subsurface petroleum reserves.

To study the largest source of river sediment to the Arctic Ocean, we have collected suspended particulates from the Mackenzie River in all seasons and sediments from the Mackenzie shelf between the river mouth and the shelf edge. These samples have been analyzed for alkanes, triterpenes and polycyclic aromatic hydrocarbons (PAHs). We found that naturally occurring hydrocarbons predominate in the river and on the shelf. These hydrocarbons include biogenic alkanes and triterpenes with a higher plant/peat origin, diagenetic PAHs from peat and plant detritus, petrogenic alkanes, triterpenes and PAHs from oil seeps and/or bitumens and combustion PAHs that are likely relict in peat deposits. Because these components vary independently, the season is found to strongly influence the concentration and composition of hydrocarbons in the Mackenzie River. While essentially the same pattern of alkanes, diagenetic hopanes and alkyl PAHs is observed in all river and most shelf sediment samples, alkane and triterpene concentration variations are strongly linked to the relative amount of higher plant/peat material. Polycyclic aromatic hydrocarbon molecular-mass profiles also appear to be tied primarily to varying proportions of peat, with an additional petrogenic component which is most likely associated with lithic material mobilized by the Mackenzie River at freshet. Consistent with the general lack of alkyl PAHs in peat, the higher PAHs found in the river are probably derived from forest and tundra fires. A few anthropogenic/pyrogenic compounds are manifest only at the shelf edge, probably due to a weakening of the river influence. We take this observation of pyrogenic PAHs and the pronounced source differences between two sediment samples collected at the shelf edge as evidence of a transition from dominance by the Mackenzie River to the geochemistry prevalent in Arctic regions far removed from major rivers.

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.

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; BSAFs1 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 (BSAFs500). 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.

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(2) 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(OW) (octanol-water partition coefficient) values compared to shallow samples (percent BDE-209 of total PBDE, 66 versus 32%; log K(OW) , 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.

[1] The Arctic Ocean is undergoing rapid loss in ice cover with yet unknown consequences for the cycling of organic material. Here we examine persistent terrigenous (land-based) alkane and polycyclic aromatic hydrocarbons with vascular plant, combustion, and petrogenic sources in seven cores collected from all major basins of the Arctic Ocean for insight as to how organic cycling at the Last Glacial Maximum compares to the present day. We find only modest changes between the glacial and postglacial sediments for atmospherically transported hydrocarbon biomarkers, demonstrating that glacial sea ice was not a barrier to atmospheric inputs. In stark contrast, particle-associated biomarkers were captured strongly at basin edges during the glacial period and much more evenly transported across basins during the postglacial period. Evidently the capture of organic matter shifted from the slopes to the shelves as the latter flooded during the Holocene, and the Transpolar Drift and Beaufort Gyre evolved from minor carriers of plant detritus from the glacial ocean margins to major modern transporters of shelf sediment to the basins. This suggests that changes in organic transport currently accompanying the loss of sea ice are likely to be very different from those that occurred at the end of the last glacial period.

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.

The allochthonous inputs of hydrocarbon to the Canadian Beaufort Shelf were studied by applying principal components analysis (PCA) to well-validated and rigorously blank-corrected samples. Incorporation of a wide range of perdeuterated n-alkanes and PAH into the analysis scheme ensured that only reliably quantified variables were used to interpret the hydrocarbon geochemistry. Application of PCA to Mackenzie River samples demonstrated a homogeneous system, from which we infer coupling or equilibrium between the river particulate hydrocarbons and the dissolved fraction. Particulate (particle size > 0.7 μm) hydrocarbon flux from the Mackenzie River is by far the most important terrestrially derived source of hydrocarbons to the Beaufort Sea. The Mackenzie River particulates have a distinct n-alkane signature which can be used to identify the riverine influence on the hydrocarbon geochemistry of the Beaufort Sea shelf. Based on one year's data, the flux of total alkanes is 440 ± 94 tonne/a, and PAH is 49 ± 8 tonne/a (uncertainties are one standard deviation of the sampling and analytical variation). The particulate flux exceeds the accompanying dissolved hydrocarbon flux by two orders of magnitude and has a strong seasonal cycle: winter contributes less than an estimated 0.6% of total annual flux. Deltaic silt from the western Mackenzie delta and the smaller amounts of detritus from coastal erosion of peat are minor hydrocarbon sources and contribute, in total, less than 10% to the budget for most alkanes. An important exception, with regard to shelf geochemistry, is the significant quantity of peat-derived higher plant n-alkanes.

The identity and form of dissolved organic matter in rivers and oceans are fundamental to the biogeochemical cycle of carbon. In particular, understanding the phase distribution of hydrocarbon compounds is a prerequisite to predicting the transfer between phases and the impact of anthropogenic inputs of fossil fuels to the aquatic environment. After rigorous blank-correction of each individual hydrocarbon component of dissolved and particulate hydrocarbon samples from the Mackenzie River, we obtained dissolved hydrocarbon measurements that were unquestionably above the mean blank. Equivalence of the dissolved and particulate hydrocarbon compositions indicates that the two fractions are coupled or at equilibrium in natural waters. Changes in individual hydrocarbon concentrations with sample volume suggest that the dissolved hydrocarbons may be distributed fractally in water.

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.

Sediment samples were collected to study the dispersion and fate of mineral oil hydrocarbons from the above-water discharge of oiled drill cuttings at two exploration well sites. At the shallow water (16 m), exposed location, the primary method of dispersion was wave action. Aliphatic hydrocarbon samples at times showed substantial weathering and concentrations decreased to ten times background at approximately 200 m from the wellhead. The oiled cuttings pile under the drill rig was observed to disappear within three months. At the deeper water (70 m) location, the dispersal mechanism was ocean (tidal) currents and the oiled cuttings appeared to be much more persistent. Hydrocarbon samples showed no significant weathering and aliphatic concentrations remained more than an order of magnitude above background 1500 m from the wellhead in the primary current direction. Concentrations three orders of magnitude above background were confined within 400 m, and four orders within 200 m. Aromatic hydrocarbon profiles at both well sites indicated a source other than the base oil.

Polycyclic aromatic hydrocarbon (PAH) concentrations in suspended particulate samples from the Mackenzie River delta and shelf sediments from the Beaufort Sea are higher than expected for a pristine area. Low concentrations of combustion PAHs indicate that anthropogenic inputs are low. Alkyl PAH distributions indicate that a significant component of the lower molecular weight parent (unsubstituted) PAH fraction is petrogenic. The majority of the high molecular weight PAHs, together with the petrogenic PAHs, have a principal source in the Mackenzie River. Despite the high PAH content, we consider the area still to be pristine. Although PAH concentrations are below the concentrations believed to induce toxic effects on biota, the high natural concentrations may make this region of the Arctic sensitive to additional PAHs from human activities. Key words: polycyclic aromatic hydrocarbon (PAH), Arctic, baseline, sediment, effects threshold, principal components analysis

Polychlorinated biphenyls and other persistent organic pollutants have been associated with immunotoxicity and outbreaks of (infectious) disease in marine mammals by rendering them vulnerable to infection by pathogens such as viruses and bacteria. In an immunotoxicological study of free-ranging harbor seals (Phoca vitulina), we obtained samples of blood and blubber from seal pups that were live-captured from two remote and two near-urban sites in British Columbia, Canada, and Washington state, USA. Using these samples, we quantified hematology, innate immune function, adaptive immune function, and polychlorinated biphenyl accumulation. While controlling for confounding factors (age, sex, and condition), univariate correlations between phagocytosis (r 2 = 0.30, p = 0.002), respiratory burst (r 2 =0.45, p= 0.000), T-lymphocyte function (r 2 = 0.16, p = 0.028), lymphocyte signaling (r 2 = 0.17, p = 0.025), and lymphocyte counts (r 2 = 0.29, p = 0.002), and polychlorinated biphenyl concentrations suggested chemical-associated immunotoxicity. Principal component analysis of immunological endpoints provided additional evidence of immunotoxic effects in seals. However, principal component analysis also identified a noncontaminant-related factor by distinguishing between seals inhabiting urban versus remote sites, with results being consistent with increased pathogen exposure. Elevated fecal coliform concentrations in water, and observations of terrestrial spill-over pathogens in local seals, further support the notion of biological pollution at these sites. Although our study highlights the role that environmental contaminants might play in rendering marine mammal populations vulnerable to disease through immunotoxicity, it also suggests that biological pollution represents an emerging conservation concern.

The harbor seal (Phoca vitulina) can serve as a useful indicator of food web contamination by persistent organic pollutants (POPs) because of its high trophic level, wide distribution in temperate coastal waters of the Northern Hemisphere, and relative ease of capture. In 1996 through 1997, we live-captured 60 harbor seal pups from three regions, spanning remote (Queen Charlotte Strait, BC, Canada), moderately industrialized (Strait of Georgia, BC, Canada), and heavily industrialized (Puget Sound, WA, USA) marine basins straddling the Canada-United States border. Biopsy samples of blubber were taken and analyzed for congener-specific polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) by using high-resolution gas chromatography-high-resolution mass spectrometry. Harbor seals in Puget Sound were heavily contaminated with PCBs, whereas seals from the Strait of Georgia had relatively high concentrations of PCDDs and PCDFs. Pattern evaluation and principal components analysis suggested that proximity to sources influenced the mixture to which seals were exposed, with those inhabiting more remote areas being exposed to lighter PCB congeners (those with lower Henry's law constant and K(ow)) that disperse more readily through atmospheric and other processes. Total toxic equivalents to 2,3,7,8-tetrachlorodibenzo-p-dioxin for the PCBs, PCDDs, and PCDFs suggest that Puget Sound seals are at greatest risk for adverse health effects, and that PCBs represent the class of dioxinlike contaminants of greatest concern at all sites.

Synchronous samples of sediment and Dungeness crab (Cancer magister) hepatopancreas, which were obtained for monitoring and assessment purposes at British Columbia, Canada, marine pulp mill sites between 1990 and 1995, were used to calculate biota-sediment accumulation factors (BSAFs) for individual chlorinated dibenzo-p -dioxin and dibenzofuran congeners (PCDD/Fs). The BSAFs for individual pairs of samples were highly variable, and no systematic trends were apparent in the observed accumulation factors over time, with crab size, with crab lipid concentration, with sediment percent organic carbon, or among mill sites or depositional environments. Composition and source differences in sedimentary PCDD/Fs, which are apparent as principal components analysis class separations in the sediment data set, also did not correlate with differences in BSAFs. This independence from environmental factors provides a valuable endorsement of the BASF concept for the formulation of aquatic effects-based sediment-quality criteria and human risk-assessment guidelines. However, BSAF values did exhibit a significant, nonlinear decrease with increasing log Kow and with sediment and crab PCDD/F concentrations. The correlation between BSAFs and sediment concentrations accounts for between 14 and 81% of the variability in the BSAF values. The PCDD/F congeners that are present in low concentrations and/or have reduced bioavailability are the congeners that have the strongest correlations between the BSAFs and the sediment PCDD/F concentrations. Congeners that are bioavailable to Dungeness crab exhibit poorer correlations between the BSAFs and sediment concentrations.

Comparaison des resines chromosorb T et XAD-2 pour l'extraction in situ d'alcanes et composes aromatiques polycycliques dans les eaux douces et de mer. Apres extraction les composes sont quantifies par spectrometrie de masse-chromatographie gazeuse