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Bisphenol A (BPA) is an industrial chemical that has been identified by some jurisdictions as an environmental concern. In 2010, Canada concluded that this substance posed a risk to the environment and human health, and implemented actions to reduce its concentrations in the environment. To support these activities, a multimedia analysis of BPA in the Canadian environment was conducted to evaluate spatial and temporal trends, and to infer mechanisms influencing the patterns. BPA was consistently detected in wastewater and biosolids across Canadian wastewater treatment plants (WWTPs) and in landfill leachate. In addition, BPA concentrations were significantly higher in surface water downstream compared to upstream of WWTPs in three of five urban areas evaluated. However, application of biosolids to Canadian agricultural fields did not contribute to elevated BPA concentrations in soil, earthworms, and European Starling (Sturnus vulgaris) plasma one and two years post-treatment. Spatial trends of BPA concentrations in surface water and sediment are influenced by human activity, with higher concentrations typically found downstream of industrial sources and WWTPs in urban areas. BPA was detected in bird plasma at locations impacted by WWTPs and landfills. However, spatial trends in birds were less clear and may have been confounded by metabolic biotransformation. In terms of temporal trends, BPA concentrations in surface water decreased significantly at 10 of 16 monitoring sites evaluated between 2008 and 2018. In contrast, recent temporal trends of BPA in six sediment cores were variable, which may be a result of biotransformation of the flame retardant tetrabromobisphenol A to BPA. Overall, our study provides evidence that Government of Canada actions have been generally successful in reducing BPA concentrations in the Canadian environment. Our results indicate that long-term monitoring programs using surface water are more effective than other media for tracking and understanding future environmental trends of BPA., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2020. Published by Elsevier B.V. All rights reserved.)

Hexabromocyclododecane (HBCDD) is a high concern environmental pollutant due to its persistent, bioaccumulative, and toxic properties. The spatial distribution of HBCDD was investigated in top predator fish (lake trout, walleye, or brook trout) collected in 2013 ( n = 165) from 19 sampling sites and in 2015 ( n = 145) from 20 sites across Canada. HBCDD was measurable in at least one sample at each sampling site regardless of sampling year with the exception of walleye from the south basin of Lake Winnipeg (2013). Sampling sites in or near the Laurentian Great Lakes had greater ΣHBCDD concentrations compared to locations to the west or east. The greatest mean ΣHBCDD concentration was 72.6 ng/g lw in fish from Lake Huron-Goderich (2015). Regardless of the sampling sites, α-HBCDD was the dominant congener followed by γ-HBCDD, whereas β-HBCDD was barely detectable. In fish from the same waterbody there were comparable α/γ isomer concentration ratios. The greatest ratio was 20.8 in fish from Lake Ontario, whereas the lowest ratio was 6.3 for fish from Lac Memphrémagog (Québec) likely related to more recent emissions of a technical HBCDD mixture. Temporal trends of HBCDD in lake trout from Lake Ontario showed a significant decreasing trend for γ-HBCDD with a half-life estimate of 10 years over a 36-year period (1979-2015), and for α-HBCDD with a half-life of 11 years over the years of 2008 to 2015. The proportion of α-HBCDD to ΣHBCDD increased significantly during 1979 to 2015. The present study provided novel information on the isomer-specific HBCDDs in Canada freshwater fish.

The identification, persistence, accumulation and trophic transfer of 25 polybrominated diphenyl ether (PBDE) congeners, 23 non-PBDE halogenated flame retardants (NPHFRs), 4 polybrominated-diphenoxybenzenes (PB-DiPhOBzs) and 6 methoxylated (MeO-) PB-DiPhOBzs were investigated in predator and prey fish collected in 2010 from sites in the North American Great Lakes of Ontario (n = 26) and Erie (n = 39). Regardless of locations or species, 20 PBDEs and 12 NPHFRs were quantifiable in at least one of the 65 analyzed samples, and polybrominated-1,4-diphenoxybenzenes (PB-DiPhOBzs) and MeO-PB-DiPhOBzs were not detectable in any of analyzed samples. Among the FRs, the greatest concentrations were the ∑PBDE, ranging from 1.06 (Rainbow Smelt, Lake Erie) to 162 (Lake Trout, Lake Ontario) ng/g wet weight (ww), which was followed by mean HBCDD concentrations ranging ND to 17.3 (Lake Trout, Lake Ontario) ng/g ww. The remaining FRs were generally not detectable or at sub-ppb levels. In most of cases, FR concentrations in samples from Lake Ontario were greater than those from Lake Erie. Strong and significant positive linear relationships occurred between log-normalized FR concentrations (ww or lipid weight (lw)) and ages of the top predator Lake Trout (n = 16, from Lake Ontario), and the estimated FR doubling ages (T 2 ) were 2.9-6.4 years. For Walleye from Lake Erie, significantly positive linear relationships were also observed for some FRs, but the linear relationships generally became negative after FR concentrations were normalized with lipid weight. This study provides novel information on FR accumulation in aquatic organisms, and for the first time, significant positive linear relationships are reported between log-normalized FR concentrations (lw or ww) and ages of Lake Trout from the Great Lakes.

With the phase-out and regulation of some flame retardant chemicals, the production and usage of organophosphate triester flame retardants (OPFRs) has increased in recent years. In the present study, 14 OPFRs (either chlorinated, brominated or non-halogenated) were analyzed in egg pools of 10-13 individual herring gull eggs from five colonial nesting sites for 11 years spanning 1990-2010, (for a total of n=55 egg pools) in the Laurentian Great Lakes of North America (Chantry Island, Fighting Island, Agawa Rocks, Toronto Harbour and Gull Island). OPFR profiles varied slightly between colony sites and collection years. For all five sites tris(2-chloroisopropyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl) phosphate (TBOEP) were detected, while triphenyl phosphate (TPHP) was only quantifiable in eggs from Chantry Island and Gull Island collected in 2008 and 2010. For the 2010 egg pools, the ΣOPFR concentrations were generally low and ranged from 2.02 to 6.69 ng/g wet weight (ww). ΣOPFR concentrations in 2010 were significantly higher (p<0.05) than they were between 1990 and 2004 (4.06 vs. 1.55 ng/g ww, respectively). In a pilot examination of Great Lakes aquatic food webs, 2010-collected alewife and rainbow smelt (major herring gull fish prey) and lake trout from western Lake Erie and Ontario, only contained TBOEP at low to sub ng/g ww concentrations. These results demonstrate that low to sub-ppb concentrations of at least three OPFRs, TCIPP, TCEP and TBOEP, have been persistent in herring gull eggs from the Great Lakes for at least the past 20 years, probably bioaccumulate mainly via the fish diet, and are transferred to the eggs of exposed herring gulls., (Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.)

Freshwater mussels are frequently found in rivers receiving effluent from wastewater treatment plants (WWTP), and there is strong evidence that poor water quality is deleterious to freshwater mussel populations. WWTPs are among the main sources of pharmaceuticals and personal care products (PPCPs) in surface waters. We monitored 145 PPCPs in wild and caged mussels both upstream and downstream of the Kitchener WWTP in the Grand River, Ontario, as well as 118 PPCPs in water samples. Our objectives were to characterize the seasonal changes in PPCP concentrations in water, to calculate bioaccumulation factors (BAFs) of PPCPs in mussels, and to determine the chemical and physical properties of PPCPs driving the bioaccumulation. Seventy PPCPs were detected in water, and concentrations were highest in the summer or early fall, which corresponded to low river flow. Forty-three PPCPs from many pharmaceutical classes were detected in mussel tissues, including stimulants, a contrasting agent, anti-inflammatory drugs, anti-bacterial agents, antibiotics, antidepressants, antihistamines, progestins, and illicit drugs such as cocaine and amphetamines. The BAFs ranged from 0.66 for metformin to 32,022 for sertraline. Using partial least squares to predict BAFs based upon chemical properties, log KOC, Log KOW, and fugacity ratio (sediment) all had similar and positive loadings with BAFs (R(2)X = 0.70; caged mussels). BAFs of PPCPs in mussels were predictable from fugacity models that estimate bioconcentration factors using log KOW. Our study demonstrated that mussels readily bioaccumulate PPCPs, in a manner consistent with expectations based upon BCF models and the chemical characteristics of each compound., (Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.)

Environmental contamination and regulation of longer-chain perfluoroalkyl substances (PFASs) such as perfluorooctanesulfonate (PFOS) has given rise to the increased use of shorter-chain PFASs as alternatives in new products, although confirmation of their presence in the environment remains limited. In this study, the PFAS alternative, perfluoro-1-butane-sulfonamide (FBSA), was identified for the first time in biota in homogenate samples of fish by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-ToF-MS) and quantified by ultra high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-QQQ-MS/MS). In one flounder (Platichthys flesus) muscle sample from the Western Scheldt, The Netherlands, FBSA concentration was at 80.12 ng/g wet weight (w.w.) and was exceeded only by PFOS. FBSA was also detected in 32 out of 33 samples of freshwater fish collected (2009-2010) from water bodies across Canada. In lake trout (Salvelinus namaycush) from northern Canada (e.g., Lake Kusawa (Yukon Territory), Great Bear Lake (Northwest Territories and in the Arctic), and Lake Athabasca (northern Alberta)), the concentrations of FBSA ranged from below method detection limit (<0.01 ng/g w.w) to 0.44 ng/g w.w. and were much lower than those reported for lake trout from the more urbanized and industrialized Laurentian Great Lakes sites (3.17 ± 1.53 ng/g w.w.). In three species of fish purchased from a supermarket in Ottawa (ON, Canada), FBSA concentrations were the lowest of all fish and ranged from < MLOD to 0.29 ng/g w.w. and 0.03 to 0.76 ng/g w.w. in muscle and liver, respectively. FBSA is a bioaccumulative contaminant in fish in Canada and possibly in The Netherlands. It is likely sourced from new alternative perfluorobutane-based products, as well as other shorter chain perfluoroalkyl-based products.

Short and medium chain polychlorinated n-alkanes (sPCAs and mPCAs) were measured in top predatory fish from nine freshwater bodies across Canada in 2010-2011. Maximum sPCA concentrations were measured in brook trout from Kejimikujik Lake in Nova Scotia (10±8 ng g(-1) wet weight) while the lowest concentrations were found in lake trout from Kusawa Lake in the Yukon (2±3 ng g(-1) wet weight). The presence of sPCAs in fish from these sites is strongly suggestive of long range atmospheric transport, given the absence of known point sources. The highest mPCA concentrations (11-12 ng g(-1) wet weight) were found in lake trout from Lakes Huron, Erie and Ontario. These results showed that fish from sites impacted mostly by atmospheric sources contained higher concentrations of sPCAs than mPCAs while the opposite was observed in sites impacted by industrialization. C12H20Cl6, C12H19Cl7, C14H24Cl6 and C14H23Cl7 were the most abundant homologue groups observed. Lake trout from Lake Huron showed a markedly different sPCA homologue profile, characterized by higher abundances of C11H15Cl9 and C12H17Cl9, indicating local sources. Principal components analysis of sPCA homologues abundances showed that C12H20Cl6, C12H19Cl7, C11H18Cl6, C11H17Cl7 were associated with lakes influenced by atmospheric sources while C11H16Cl8, C12H18Cl8, C11H15Cl9, C12H17Cl9 were associated with sites influenced by urban/industrial sources. Finally, concentrations of sPCAs in Lake Ontario lake trout collected in 2011 decreased 6.6-fold compared to 2001, however no significant differences were observed for mPCAs., (Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.)

Whole body homogenates of Lake Trout (Salvelinus namaycush) or Walleye (Sander vitreus) collected from Canadian lakes were screened for organophosphate flame retardant (OPFR) and organosiloxane compounds. Six OPFR and five siloxane compounds were detected above quantitation limits in at least one individual fish from sampled lakes. The OPFRs, tris(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl) phosphate (TBOEP), were most frequently quantified with concentrations ranging from <0.07 to 9.8 ng/g (ww). Levels of TBOEP were highest in fish from the Great Lakes region while TCEP was detected only in fish from the northernmost lakes in our network. Concentrations of the cyclic siloxanes, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6), were above quantitation limits in all fish. D5 was the most abundant siloxane across all sampling locations with the highest concentrations (45-719 ng/g ww) observed in Lake Trout from the western end of Lake Ontario near the mouth of the Niagara River., (Copyright © 2014. Published by Elsevier Ltd.)

During the bitumen extraction from the oil sands of Alberta, large volumes of process water containing naphthenic acids are stored in tailing ponds. The naphthenic acids along with other components in the processed waters are known to be toxic in aquatic environments. In view of the complex matrix and the toxicity of the processed waters, there is a need for complementary analytical techniques for comprehensive characterization of the naphthenic acid mixtures. This study reports the online gas chromatographic separation of naphthenic acid mixtures prior to ultrahigh resolution mass spectrometry detection, using electron and chemical ionization. Two oil sands processed water samples and two groundwater samples were characterized to evaluate the performance of the instrumental technique. The high mass resolution of the system enabled visualization of the data using Kendrick mass defect plots. The addition of gas chromatographic separations enabled visualization of the data as unique compound class elution fingerprints. The technique is demonstrated to be a valuable tool for chemical fingerprinting of naphthenic acids.

We examine the concentrations and food web biomagnification of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) using aquatic biota collected from Lake Erie. Concentrations of cVMS in biota were within the range reported for other studies of cVMS in aquatic biota. Trophic magnification factors (TMF) were assessed in various food web configurations to investigate the effects of food web structure. TMF estimates were highly dependent on the inclusion/exclusion of the organisms occupying the highest and lowest trophic levels and were >1 for D4 and D5, indicating biomagnification, in only 1 of the 5 food web configurations investigated and were <1 in the remaining 4 food web configurations. TMF estimates for PCB180 were also dependant on food web configuration, but did not correspond with those obtained for cVMS materials. These differences may be attributed to environmental exposure and/or lipid partitioning differences between PCB180 and cVMS., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

In Canada, perfluoroalkyl acids (PFAAs) have been the focus of several monitoring programs and research and surveillance studies. Here, we integrate recent data and perform a multi-media assessment to examine the current status and ongoing trends of PFAAs in Canada. Concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and other long-chain perfluorocarboxylates (PFCAs) in air, water, sediment, fish, and birds across Canada are generally related to urbanization, with elevated concentrations observed around cities, especially in southern Ontario. PFOS levels in water, fish tissue, and bird eggs were below their respective Draft Federal Environmental Quality Guidelines, suggesting there is low potential for adverse effects to the environment/organisms examined. However, PFOS in fish and bird eggs tended to exceed guidelines for the protection of mammalian and avian consumers, suggesting a potential risk to their wildlife predators, although wildlife population health assessments are needed to determine whether negative impacts are actually occurring. Long-term temporal trends of PFOS in suspended sediment, sediment cores, Lake Trout (Salvelinus namaycush), and Herring Gull (Larus argentatus) eggs collected from Lake Ontario increased consistently from the start of data collection until the 1990s. However, after this time, the trends varied by media, with concentrations stabilizing in Lake Trout and Herring Gull eggs, and decreasing and increasing in suspended sediment and the sediment cores, respectively. For PFCAs, concentrations in suspended sediment, sediment cores, and Herring Gulls generally increased from the start of data collection until present and concentrations in Lake Trout increased until the late 1990s and subsequently stabilized. A multimedia comparison of PFAA profiles provided evidence that unexpected patterns in biota of some of the lakes were due to unique source patterns rather than internal lake processes. High concentrations of PFAAs in the leachate and air of landfill sites, in the wastewater influent/effluent, biosolids, and air at wastewater treatment plants, and in indoor air and dust highlight the waste sector and current-use products (used primarily indoors) as ongoing sources of PFAAs to the Canadian environment. The results of this study demonstrate the utility of integrating data from different media. Simultaneous evaluation of spatial and temporal trends in multiple media allows inferences that would be impossible with data on only one medium. As such, more co-ordination among monitoring sites for different media is suggested for future sampling, especially at the northern sites. We emphasize the importance of continued monitoring of multiple-media for determining future responses of environmental PFAA concentrations to voluntary and regulatory actions., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

Perfluoroalkyl contaminants (PFCs) were determined in Lake Ontario Lake Trout sampled annually between 1997 and 2008 in order to assess how current trends are responding to recent regulatory bans and voluntary phase-outs. We also combined our measurements with those of a previous study to provide an updated assessment of long-term trends. Concentrations of PFCs generally increased from the late 1970s until the mid-1980s to mid-1990s, after which concentrations either remained unchanged (perfluorooctane sulfonate (PFOS) and perfluorocarboxylates) or declined (perfluorodecanesulfonate (PFDS)). The temporal trends were assessed using three models, quadratic, exponential rise to maximum, and two-segment linear piecewise function, and then evaluated for best fit using Akaike Information Criteria. For PFOS and perfluorocarboxylates, the exponential rise to maximum function had the best fit. This is particularly interesting for PFOS as it suggests that although concentrations in Lake Ontario Lake Trout may have stopped increasing in response to voluntary phase-outs in 2000-2002, declines have yet to be observed. This may be due to continuing input of PFOS from products still in use and/or slow degradation of larger precursor molecules. A power analysis of PFOS suggested that 15 years of data with a within-year sample size of 10 is required to obtain sufficient power (80%) to detect a 5% decreasing trend. However, the length of the monitoring program had a greater influence on the ability to detect a trend compared to within-year sample size. This provides evidence that additional sampling years are required to detect a response to bans and phase-outs, given the variability in the fish data. The lack of observed declines of perfluorocarboxylate residues in fish may be expected as regulations for these compounds were only recently enacted. In contrast to the other compounds, the quadratic model had the best fit for PFDS. The results of this study emphasize the importance of long-term monitoring for assessing the effectiveness of bans and phase-outs on PFCs in the environment.

Annual and weekly mercury (Hg) concentrations, precipitation depths, and Hg wet deposition in the Great Lakes region were analyzed by using data from 5 monitoring networks in the USA and Canada for a 2002-2008 study period. High-resolution maps of calculated annual data, 7-year mean data, and net interannual change for the study period were prepared to assess spatial patterns. Areas with 7-year mean annual Hg concentrations higher than the 12 ng per liter water-quality criterion were mapped in 4 states. Temporal trends in measured weekly data were determined statistically. Monitoring sites with significant 7-year trends in weekly Hg wet deposition were spatially separated and were not sites with trends in weekly Hg concentration. During 2002-2008, Hg wet deposition was found to be unchanged in the Great Lakes region and its subregions. Any small decreases in Hg concentration apparently were offset by increases in precipitation., (Published by Elsevier Ltd.)

We performed dynamic linear modeling analysis on fish contaminant data collected from the Ontario Ministry of the Environment and Environment Canada to examine long-term trends of total mercury (THg) and polychlorinated biphenyls (PCBs) in Lake Erie. Several sport fish species (walleye, smallmouth bass, rainbow trout) with differences in their diet habits, food competition strategies and foraging patterns are characterized by weakly increasing trends of their THg levels in Lake Erie after the mid- or late 1990s. Similarly, our analysis shows that the decline rates of the PCB body burdens in white bass, smallmouth bass, freshwater drum and whitefish have slowed down or have switched to weakly increasing rates over the last decade. Our analysis also provides evidence that the rainbow trout and coho salmon PCB concentrations have been decreasing steadily but the associated rates were fairly weak. The systematic shifts in energy trophodynamics along with the food web alterations induced from the introduction of non-native species, the new role of the sediments as a net contaminant source, and the potentially significant fluxes from the atmosphere stand out as some of the hypotheses proposed to explain the limited Lake Erie response in recent years to the various contamination mitigation strategies., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The risk of mercury (Hg) exposure to humans and wildlife from fish consumption has driven extensive mercury analysis throughout the Great Lakes Region since the 1970s. This study compiled fish-Hg data from multiple sources in the region and assessed spatiotemporal trends of Hg concentrations in two representative top predator fish species. Walleye (Sander vitreus) and largemouth bass (Micropterus salmoides) were chosen for the trend analysis because they had more Hg records (63,872) than other fish species that had been sampled from waters throughout the region. Waterbody types were inland lakes (70%), the Great Lakes, impoundments, and rivers. The compiled datasets were analyzed with a mixed effects statistical model having random effects of station, year, and fish length; and fixed effects of year, tissue type, fish length, habitat, and season. The results showed a generally declining temporal trend in fish-Hg for the region (1970-2009), with spatial trends of increasing Hg concentration from south to north and from west to east across the region. Nonlinearity was evident in the general downward trends of Ontario walleye, with a shift to an upward trend beginning in the 1990s. Only ongoing monitoring can reveal if this upward shift is an oscillation in a long-term decline, a statistical anomaly, or a sustained declining temporal trend in regional fish-Hg concentrations.

A nationwide study was conducted to examine concentrations of polybrominated diphenyl ethers (PBDEs) in top predatory fish, with a focus on lake trout (Salvelinus namaycush), across Canada, and to explore possible influences of food web processes. Concentrations of the three most abundant PBDE homolog groups (tetra-, penta-, and hexa-PBDEs) were, for the most part, higher in Great Lakes and Lake Champlain fish compared with fish from other systems. The Canadian Federal Environmental Quality Guideline for the penta-homolog was exceeded in 70% of the fish examined. However, virtually no guideline exceedances were found for other congeners. In general, PBDE-47 (a representative lower brominated congener) was significantly and positively correlated with fish length, weight, age, lipid content, and stable isotopes of nitrogen and carbon. Significant differences in the slopes of the PBDE-47/covariate relationships between sites prevented concentrations from being adjusted using an analysis of covariance (ANCOVA). However, plots showed that elevated concentrations of PBDE-47 in Great Lakes and Lake Champlain fish remained after accounting for the influence of covariates. In contrast, for PBDE-183 (a representative higher brominated congener), the relationships between fish concentrations and covariates were not consistent, which could be a result of biotransformation being more important in controlling its bioaccumulation. The data from the current study show an overall disconnect between fish PBDE concentrations and likely loadings, which may be caused by differences in food web processes between systems. Continued long-term fish contaminant monitoring is needed to evaluate potential risk to fish and their consumers. However, we also recommend sediment sampling and focused food web studies to provide information on PBDE inputs to the systems and mechanisms of biomagnification, respectively., (Copyright © 2011 SETAC.)

The temporal trends of total mercury (THg) in four fish species in Lake Erie were evaluated based on 35 years of fish contaminant data. Our Bayesian statistical approach consists of three steps aiming to address different questions. First, we used the exponential and mixed-order decay models to assess the declining rates in four intensively sampled fish species, i.e., walleye (Stizostedion vitreum), yellow perch (Perca flavescens), smallmouth bass (Micropterus dolomieui), and white bass (Morone chrysops). Because the two models postulate monotonic decrease of the THg levels, we included first- and second-order random walk terms in our statistical formulations to accommodate nonmonotonic patterns in the data time series. Our analysis identified a recent increase in the THg concentrations, particularly after the mid-1990s. In the second step, we used double exponential models to quantify the relative magnitude of the THg trends depending on the type of data used (skinless-boneless fillet versus whole fish data) and the fish species examined. The observed THg concentrations were significantly higher in skinless boneless fillet than in whole fish portions, while the whole fish portions of walleye exhibited faster decline rates and slower rates of increase relative to the skinless boneless fillet data. Our analysis also shows lower decline rates and higher rates of increase in walleye relative to the other three fish species examined. The food web structural shifts induced by the invasive species (dreissenid mussels and round goby) may be associated with the recent THg trends in Lake Erie fish.

A number of initiatives have curtailed anthropogenic mercury emissions in North America over the last two decades; however, various factors, including long-range transport of global emissions, may complicate the response of fish mercury levels to remedial actions. Since the Great Lakes of North America are together the largest surface freshwater body in the world and are under the influence of many complicating factors, trends of mercury in fish from the Great Lakes can reflect the overall impact of mercury management actions at local, regional, and perhaps global scales. Here we present a comprehensive view of mercury trends in Canadian Great Lakes fish using two large (total 5807 samples), different (fillet and whole fish), and long-term (1970s-2007) monitoring data sets. The spatial differences in lake trout and walleye mercury levels during this period have generally been within a factor of 2-3 with Lakes Erie and Superior having the lowest and highest concentrations, respectively. These spatial differences have diminished in the recent years (2000-2007). The concentrations have generally declined over the three decades (mid-1970s to 2007); however, in recent years, the concentration trends are flat in Lake Ontario walleye and appear to be increasing in Lake Erie walleye. There was a mismatch in the Lake Ontario lake trout and walleye temporal trends, which shows the importance of considering more than one fish species for proper spatial/temporal trend assessments.

Surface water samples were collected from 55 sites in the Great Lakes Basin and analyzed for the presence of perchlorate using HPLC/MS/MS with an isotopically enriched internal standard. Sites included areas impacted by heavy industry, urbanization, agriculture and atmospheric deposition. Perchlorate was detected at several of the sites at concentrations close to the method detection limit (0.2 microg/l). Despite these low concentrations, its presence was confirmed by sample concentration and determination of the isotopic ratio of perchlorate. The presence of perchlorate at two of the sites was related to a fireworks display which had occurred prior to sampling. The other detections of perchlorate were in rivers/creeks draining watersheds which had high density livestock and crop farming activity. We suspect the two are related. To our knowledge, these are the first reported concentrations of perchlorate in Canadian surface waters.

Objectives: We address marine and terrestrial mammal blubber, liver, muscle, kidney, heart, tongue, maktak and maktaaq (epidermis and blubber from bowhead, beluga whales, respectively), and fish muscle and livers, as commonly consumed tissues in subsistence communities across northern Alaska in the context of organochlorine (OC) contamination of store-bought foods. Human exposure to contaminants from biota, as part of a subsistence diet, has been superficially evaluated in numerous studies (focused on liver and blubber), but are limited in the type of tissues analyzed, and rarely consider the contaminants in the alternatives (i.e., store-bought foods)., Study Design: Concentrations from published literature on selected persistent organochlorine contaminants (OCs) in eight tissues of the bowhead whale and other biota (1) were compared to store-bought foods evaluated in this study., Results: As expected, store-bought foods had lower concentrations of OCs than some tissues of the marine mammals (especially blubber, maktak, and maktaaq). However, blubber is rarely eaten alone and should not be used to give consumption advice unless considered as a portion of the food item (i.e., maktak). This study indicates that the store-bought food alternatives have detectable OC concentrations (e.g., < 0.01 to 22.5 ng/g w.w. for hexachlorobenzene) and, in many cases, have greater OC concentrations than some subsistence food items. Many wildlife tissues had OC concentrations similar to those quantified in local store-bought food., Conclusions: Switching from the traditional diet to western store-bought foods will not always reduce exposure to OCs. However, raw blubber-based products are clearly more contaminated with OCs due to lipid content. A detailed profile of traditional/country foods and western foods consumed by subsistence communities of northern Alaska is required to address chronic exposure in more detail for the diverse sources of foods (subsistence use and commercially available) and the widely varying concentrations of contaminants reported therein. This should be combined with biomonitoring people dependent upon subsistence foods. Further assessment of essential and non-essential elements, emerging contaminants (e.g. brominated flame retardants), etc. should be conducted in order to improve our understanding of the differences and similarities between wildlife and store-bought foods.

Bowhead whale (Balaena mysticetus; n = 5) blubber, liver, muscle, kidney, heart, diaphragm, tongue, and uncooked maktak (bowhead whale epidermis and blubber) were collected during subsistence hunts at Barrow, AK, USA (1997-1999) to measure concentrations of persistent organochlorine contaminants (OCs). The exposure of humans to OCs via bowhead whales and other biota [fish, ringed (Phoca hispida) and bearded seals (Erignathus barbatus), and beluga whale (Delphinapterus leucas)] as part of a subsistence diet was evaluated. Concentrations of OCs in bowhead whale tissues were correlated with lipid content (P < 0.001) and were less than levels in other marine mammals reported herein, reflecting the lower trophic status of this cetacean. The relative proportions of hexachlorobenzene (HCB) and sum (Sigma) concentrations of chlordane components (SigmaCHL), DDT-related compounds (SigmaDDT), and polychlorinated biphenyls (SigmaPCB) were not statistically different among the tissues analyzed (P < 0.05). However, relatively higher proportions of hexachlorocyclohexane isomers (SigmaHCH), particularly beta-HCH, were observed in bowhead whale heart and diaphragm (P < 0.03). Based on Canadian and World Health Organization daily intake guidelines, "safe" human consumption rates of bowhead whale tissue and other marine biota were calculated. The most restrictive limits (mean value) for daily consumption for bowhead and beluga whale were 302 and 78 g for maktak and maktaaq (beluga whale epidermis and blubber), respectively. The tolerable daily intake limits of dioxin-like compounds from the consumption of bowhead whale blubber and liver were calculated to be 199 g (approximately 600 g for maktak) and 2222 g, respectively. A detailed profile of traditional/country foods consumed by subsistence communities of northern Alaska is required to address chronic exposure in more detail. Overall, bowhead whale tissues and other biota from northern Alaska are safe to consume at, or below, the levels calculated.

The present study examines the effects of exposure to oil sands on the early life stages (ELS) of fathead minnows (Pimephales promelas). Sediments within and outside natural oil sand deposits were collected from sites along the Athabasca River (AB, Canada). The ELS toxicity tests were conducted with control water, natural oil sands, reference sediments, and oil-refining wastewater pond sediments. Eggs and larvae were exposed to 0.05 to 25.0 g sediment/L and observed for mortality, hatching, malformations, growth, and cytochrome P4501A induction as measured by immunohistochemistry. Natural bitumen and wastewater pond sediments caused significant hatching alterations and exposure-related increases in ELS mortality, malformations, and reduced size. Larval deformities included edemas, hemorrhages, and spinal malformations. Exposure to reference sediments and controls showed negligible embryo mortality and malformations and excellent larval survival. Sediment analyses using gas chromatography-mass spectrometry revealed high concentrations of alkyl-substituted polyaromatic hydrocarbons (PAHs) compared to unsubstituted PAHs in natural oil sands (220-360 microg/g) and oil-mining wastewater pond sediments (1,300 microg/g). The ELS sediment toxicity tests are rapid and sensitive bioassays that are useful in the assessment of petroleum toxicity to aquatic organisms.

The enantiomeric composition of seven chiral PCB congeners was measured in the Lake Superior aquatic food web sampled in 1998, to determine the extent of enantioselective biotransformation in aquatic biota. All chiral PCB congeners studied (CBs 91, 95, 136, 149, 174, 176, and 183) biomagnified in the Lake Superior aquatic food web, based on biomagnification and food web magnification factors greater than unity. PCB atropisomers were racemic in phytoplankton and zooplankton, suggesting no biotransformation potential toward PCBs for these low trophic level organisms. However, Diporeia and mysids had significantly nonracemic residues for most chiral congeners studied. This observation suggests that these macrozooplankton can stereoselectively metabolize chiral congeners. Alternatively, macrozooplankton obtained nonracemic residues from feeding on organic-rich suspended particles and sediments, which would imply that stereoselective microbial PCB biotransformation may be occurring in Lake Superior sediments at PCB concentrations far lower than that previously associated with such activity. Widely nonracemic PCB residues in forage fish (lake herring, rainbow smelt, and slimy sculpin) and lake trout suggest a combination of both in vivo biotransformation and uptake of nonracemic residues from prey for these species. Minimum biotransformation rates, calculated from enantiomer mass balances between predators and prey, suggest metabolic half-lives on the order of 8 yr for CB 136 in lake trout and 2.6 yr for CB 95 in sculpins. This result suggests that significant biotransformation may occur for metabolizable PCB congeners over the lifespan of these biota. This study highlights the potential of chiral analysis to study biotransformation processes in food webs.

Bowhead whale (Balaena mysticetus) blubber (n = 20) and plasma (n = 19) samples were collected during the 1997 to 2000 Inuit subsistence harvests in Barrow, Alaska, USA, to quantify the concentrations of methylsulfone (MeSO2)-containing and hydroxylated (OH) polychlorinated biphenyl (PCB) metabolites in this cetacean. The distribution of MeSO2-PCBs in blubber was dominated by 4-MeSO2-substituted congeners, the most abundant being 4-MeSO2-CB-70, 3'-MeSO2-CB-132, and 4-MeSO2-CB-64. Mean (+/- 1 standard error) sum (sigma) MeSO2-PCBs concentrations in blubber were low (6.23 +/- 0.81 ng g(-1) lipid normalized) compared to concentrations previously reported in other marine mammals. However, similar ratios of MeSO2-PCB metabolites to parent PCB congeners among marine mammals suggest that cytochrome P450 2B-like biotransformation and other necessary enzyme-mediated processes and mechanisms that influence the formation and clearance of MeSO2-PCBs exist in the bowhead whale. Pentachlorophenol was the most abundant halogenated phenolic compound quantified in bowhead plasma (1.55 +/- 0.19 ng g(-1) wet wt). Despite indirect evidence for arene epoxidation of the biphenyl moiety inferred from MeSO2-PCB formation, sumOH-PCB concentrations in bowhead plasma were low (1.52 +/- 0.31 ng g(-1) wet wt) compared to humans and marine mammals and were comprised of only two detectable OH-PCB congeners (4'-OH-CB-130 and 4-OH-CB-187). Further research is required to elucidate the toxicokinetics and distribution of OH-PCBs in this cetacean.

Enantiomeric ratios (ERs) and enantiomeric fractions (EFs) of a number of chiral organochlorine pesticides and PCB atropisomers were measured by chiral gas chromatography/mass spectrometry (GC/MS) in five standard (SRM) and certified (CRM) reference materials: SRM 1588a (organics in cod liver oil), SRM 1945 (organics in whale blubber), Marine Mammal Quality Assurance Exercise Control Material IV (NIST IV, organics in whale blubber), CRM trout, and CRM EC-5 (sediment). Target analytes were cis- and trans-chlordane, heptachlor exo-epoxide, oxychlordane, U82, MC5, MC6, MC7, o,p'-DDT, and PCB congeners 91, 95, 136, 149, 174, 176, and 183. Measured ERs and EFs are in close agreement with the few literature values reported for some of these analytes in SRMs and CRMs. Chiral PCB ERs and EFs measured by one-dimensional chiral GC/MS were similar to values measured using multidimensional chiral GC/MS. Non-racemic chiral compositions are in agreement with known uptake and biotransformation in the respective environmental matrices. These values should aid in the quality assurance/quality control methodologies for chiral environmental chemistry using standardized reference materials.

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.

A variety of commercial surfactants were tested to determine their effect on polychlorinated biphenyl (PCB) transformation by Pseudomonas LB400. Initial tests determined that most surfactants were fully or partially able to solubilize the PCB congeners 2,5,2'-chlorobiphenyl (CBP), 2,4,2',4'-CBP, 2,3,5,2',5'-CBP and 2,4,5,2',4',5'-CBP, at concentrations above the surfactants' critical micelle concentration (CMC). Surfactants were also found to have no negative effect on bacterial survival, as cell numbers were the same or higher after incubation in the presence of surfactants than after incubation without surfactants. A comparison of the extent of biotransformation of single PCB congeners by the bacterium revealed that, at surfactant concentrations above the CMC, the presence of an anionic surfactant promoted while nonionic surfactants inhibited PCB transformation, compared to a control with no surfactant. The rates of transformation of PCB congeners were also higher in the presence of the anionic surfactant compared to the control. The inhibitory effects of a nonionic surfactant, Igepal CO-630 at a concentration above its CMC, on transformation of 2,4,5,2',5'-CBP could be eliminated by diluting the surfactant/PCB solution to a concentration close to the surfactant CMC.

Resting cells of Pseudomonas strain LB400, grown on biphenyl, transformed 80, 50 and 17% of Aroclor 1242, 1254, and 1260, respectively. Resting cells grown on glucose or glycerol also transformed these polychlorinated biphenyl (PCB) mixtures to the extent of 60, 35, and 9% for Aroclors 1242, 1254, and 1260, respectively. Time courses of the transformation of the separated individual congeners in the Aroclors were plotted and used to determine the transformation rate constants (k). By analysis of the rate constants, it was concluded that the order of degradation of the different congeners in an Aroclor were similar regardless of the growth substrate. In general, k values for the conversion of a particular congener were lower for cells grown on glucose or glycerol compared with cells grown on biphenyl. Generally, k values for the transformation of the same congener in different Aroclors were not the same: rate constants had highest values for the congener in Aroclor 1242 and lowest values in Aroclor 1260. The data allowed congeners to be grouped according to their relative rates of degradation. The ratio of k values for transformation of individual congeners in Aroclors by cells grown on biphenyl and glucose were not constant.