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The trophic magnification of polybrominated diphenyl ethers (PBDEs) and selected nonlegacy halogenated organic compounds (HOCs) was determined in the food web of Lake Ontario (ON, Canada). In all, 28 Br 3 -Br 8 -PBDEs and 24 HOCs (10 of which had not been targeted previously) were analyzed. Average concentrations of Σ 28 PBDEs in fish ranged between 79.7 ± 54.2 ng/g lipid weight in alewife (Alosa pseudoharengus) and 815 ± 695 ng/g lipid weight in lake trout (Salvelinus namaycush). For invertebrates, concentrations were between 13.4 ng/g lipid weight (net plankton; >110 μm) and 41.9 ng/g lipid weight in Diaporeia (Diaporeia hoyi). Detection frequency (DF) for HOCs was highest for anti-Dechlorane Plus (anti-DDC-CO), 1,3-diiodobenzene (1,3-DiiB), tribromo-methoxy-methylbenzene (ME-TBP), allyl 2,4,6-tribromophenyl ether (TBP-AE), pentabromocyclododecene (PBCYD), α+β-tetrabromocylcooctane (TBCO), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), and pentabromotoluene (PBT; DF for all = 100% in lake trout). Tetrabromoxylene (TBX), dibromopropyl 2,4,6-tribromophenyl ether (TBP-DBPE), and syn-DDC-CO were also frequently detected in trout (DF = 70-78%), whereas 2,3,4,5,6-pentabromoethyl benzene (PBEB) was detected only in plankton. Several HOCs were reported in aquatic biota in the Great Lakes (USA/Canada) for the first time in the present study, including PBCYD, 1,3DiiB, BATE, TBP-DBPE, PBT, α + β-TBCO, and ME-TBP. The Br 4-6 -BDEs (-47, -85, -99, -100, -153, and -154) all had prey-weighted biomagnification factors (BMF PW ) values >6, whereas BMF PW values for Br 7-8 -BDEs were <1. The highest BMF PW values of non-PBDEs were for TBP-DBPE (10.6 ± 1.34) and ME-TBP (4.88 ± 0.60), whereas TBP-AE had a BMF PW value of <1. Significant (p ≤ 0.05) trophic magnification factors (TMFs), both positive and negative, were found for Br 4-8- BDEs (BDE 196 = 0.4; BDE 154 = 9.5) and for bis(2,4,6-tribromophenoxy)ethane (BTBPE; 0.53), PBCYD (1.8), 1,3-DiiB (0.33), and pentabromobenzene (PBB; 0.25). Food chain length was found to have a significant influence on the TMF values. Environ Toxicol Chem 2019;38:1198-1210. © 2019 SETAC., (© 2019 SETAC.)

Long-term air monitoring data for POPs are required to determine the effectiveness of source reduction measures and factors controlling air concentrations. Air samples were collected between 1992 and 2012 at three sites with different geographical characteristics (Burnt Island, Egbert and Point Petre) in the Canadian Great Lakes Basin (GLB) using high-volume samplers and analyzed for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Spatial and temporal trends of gas-phase concentrations of OCPs, selected PCB congeners and ƩPCBs (84 congeners) were assessed. Egbert had the highest concentrations of some OCPs due to historical [dichlorodiphenyltrichloroethanes (DDTs), dieldrin, γ-hexachlorocyclohexane (γ-HCH)] and current (endosulfan) applications of these pesticides in the surrounding agricultural cropland. This shows that agricultural areas are a source of OCPs to the GLB. High o,p'-/p,p'-DDT ratios were determined and an increasing trend was observed at Point Petre and Burnt Island up to 2004; indicating that the GLB is influenced by dicofol-type DDT sources, which have higher o,p'-/p,p'-DDT ratios than technical DDT. Atmospheric PCB concentrations at Egbert and Point Petre are higher than those measured at Burnt Island, likely due to urban influence and greater populations. Loadings calculations suggest that the atmosphere is a source of α-endosulfan and p,p'-DDT to the lakes and the opposite is true for p,p'-DDE. Long-term decreasing trends were observed for both OCPs and PCBs; consistent with control measures implemented in North America. Atmospheric PCB concentrations are decreasing relatively slowly, with halflives in the range of 9-39 years. Chlordane, α-endosulfan, β-endosulfan, dieldrin, and DDT-related substances showed halflives in the range of 7-13 years. α-HCH and γ-HCH were decreasing rapidly in air, with halflives of 5 years. Long-term declining trends of PCBs and OCPs suggest that regulatory efforts to reduce emissions to the GLB environment have been effective, but emissions from primary and secondary sources might limit future declines., (Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.)

This study reports the history of contamination of American eels (Anguilla rostrata) from eastern Lake Ontario (LO) by persistent organic pollutants (POPs). Three groups of 10 large female eels captured in eastern LO in each of 1988, 1998, and 2008 were analysed for polychlorinated dibenzo-p-dioxins and furans, polychlorinated biphenyls, several organochlorine pesticides, and polybrominated diphenyl ethers. Mean concentrations were up to 3-fold lower in 2008 compared to previous years. When combined with the results of previous studies, these data show that concentrations of POPs in American eels have declined exponentially since the early 1980s by an average of 9.1±1.9% per year. Toxic equivalent (TEQ) concentrations of dioxin-like compounds (DLCs) were calculated from fish toxic equivalency factors. Assuming an efficient transfer of DLCs to their eggs, egg TEQs prior to 2000 exceeded the threshold for chronic toxicity to embryos of European eels (Anguilla anguilla) and lake trout (Salvelinus namaycush) (4-5 pg/g ww of TEQ). These results suggest that embryotoxicity of maternally-derived DLCs from LO eels, historically a major contributor to the spawning stock of American eels, could have impaired the reproductive and recruitment success of the species., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Loadings from Toronto, Canada to Lake Ontario were quantified and major sources and pathways were identified, with the goal of informing opportunities for loading reductions. The contaminants were polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs) and polycyclic musks (PCMs). Loadings were calculated from measured concentrations for three major pathways: atmospheric processes, tributary runoff, and wastewater treatment plant (WWTP) effluents. Although atmospheric deposition to the Great Lakes has received the greatest attention, this was the dominant loading pathway for PCBs only (17 ± 5.3 kg/y or 66% of total loadings). PCB loadings reflected elevated urban PCB air concentrations due to, predominantly, primary emissions. These loadings contribute to consumption advisories for nearshore fish. PBDE loadings to the lake, again from mainly primary emissions, were 48% (9.1 ± 1.3 kg/y) and 42% (8.0 ± 5.7 kg/y) via tributaries and WWTPs, respectively, consistent with emissions deposited and subsequently washed-off of urban surfaces and emissions to the sewage system. PAHs loadings of 1600 ± 280 kg/y (71%) from tributaries were strongly associated with vehicle transportation and impervious surfaces. PCM loadings were 83% (±140 kg/y) from WWTP final effluent, reflecting their use in personal care products. Opportunities for source reduction lie in reducing the current inventories of in-use PCBs and PBDE-containing products, reducing vehicle emissions of PAHs and use of PAHs in the transportation network (e.g., pavement sealants), and improving wastewater treatment technology.

This study examined the temporal and spatial trends in wet deposition of 19 legacy and emerging brominated flame retardants (14 polybrominated diphenyl ethers (PBDEs), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenylethane (DBDPE), hexabromocyclododecane (HBCD) and pentabromoethylbenzene (PBEB)) at 9 sites in the Canadian Great Lakes between 2004 and 2010. Concentrations of BDE-209 in wet deposition declined significantly. This indicates that the voluntary actions taken to phase out the use of BDE 209 in North America are having an immediate effect on its environment concentrations. The analysis also revealed the presence of 22 short-term high concentration events that dominated overall wet deposition loadings of current-use BFRs to the lakes. For instance, one sample in 2007 was responsible for 37% of the total loadings of HBCD to Lake Huron over the entire six-year sampling period. This questions the current paradigm of how we believe such pollutants enter the environment., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Several temperate freshwater eel stocks have experienced unsustainable declines, yet to be explained. The decline of lake trout (Salvelinus namaycush) in Lake Ontario has been linked to aryl-hydrocarbon receptor agonists such as polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), and polychlorinated naphthalenes (PCNs), and the question remains whether eels are affected similarly by these compounds. Concentrations of PCDD/Fs, dl-PCBs, and PCNs were determined in eels collected at seven locations in eastern Canada including L. Ontario, one location in New York, USA, and one location in Flanders, Belgium. Concentrations varied greatly among origins, indicating dissimilar historic loadings to local areas. The risk to eel reproduction was evaluated with 2,3,7,8-TCDD toxic equivalents, and increased by 10-fold from the least to most contaminated site. The risk to eel recruitment from dioxin-like compounds in American eel using available guidelines is low. The development of a more comprehensive model for eel recruitment risk assessment due to dioxin-like compounds, using eel-specific guidelines, is recommended. Toxic equivalents were 5-fold higher when based on mammalian toxic equivalency factors compared to fish values. About half of the eels captured in L. Ontario exceeded the Canadian guideline for fish consumption (20pg TEQ g(-1) ww), but there were no other exceedances in Canada. The current risk to eel consumers in Canada is low overall, except for highly urbanized and industrialized areas., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Mass defect is the difference between the nominal and exact mass of a chemical element or compound. An intrinsic property of polyhalogenated molecules is a uniquely negative mass defect, which readily distinguishes halogenated from non-halogenated compounds in a complex mass spectrum and can be visualized by constructing a mass defect plot. This study demonstrates the utility of the mass defect plot as a powerful tool to screen gas-chromatography (ultra)high-resolution mass spectrometry data for potentially toxic and bioaccumulative halogenated compounds in a Lake Ontario lake trout, an apex species in the Great Lakes environment. Our results indicate that the sample is contaminated with polychlorinated biphenyls, terphenyls, diphenylethers, as well as other chlorinated pesticides and flame retardants that are regulated and routinely analyzed by traditional target analyses. However, the mass defect plot also displays peaks which could be traced to the presence of as yet undiscovered contaminants. These include chlorinated polycyclic aromatic hydrocarbons as well as mixed halogenated analogues of the flame retardant Dechlorane 604. The identity of the latter class of compounds is supported by experiments with genuine standards.

The bioaccumulation of lipophilic contaminants such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) can result in a reduction in fitness and spawner quality in eels and may be a factor in Anguillid sp. population declines. Contaminant concentrations in eels have been studied extensively in Europe, but data for American eels are severely lacking. Concentrations of PCBs, OCPs, and PBDEs were determined in American eel from eastern Canada and New York, USA, along with European eel from Belgium. Principal component analysis revealed that eels captured in the St. Lawrence estuary were a mixture of upstream migrants from the St. Lawrence River watershed, and fish captured in local tributaries. Contaminant concentrations were dependent on origin, related to the local environment, and were lower than historic values. In Canada, concentrations of OCPs and PCBs in eel tissues were below the Canadian human consumption guidelines for contaminants in fish, indicating that the current risk to consumers is low. However, concentrations of PCBs, total DDT, and mirex in eels from L. Ontario and the upper St. Lawrence R. were above Great Lakes guidelines for the protection of piscivorous predators. Concentrations of penta-BDE homologs exceeded the Canadian guideline for environmental quality in over half of the eels in this study, but concentrations of the other homolog groups were below the guideline., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Exposure to perfluorooctane sulfonate (PFOS) may arise directly, from emission and exposure to PFOS itself, or indirectly via the environmental release and degradation of PFOS-precursors. Human serum enantiomer fractions (EFs) of 1m-PFOS have been shown to be nonracemic, suggesting that PFOS-precursors are a significant source of PFOS in humans, but little is known about the importance of PFOS-precursors in ecosystems. In the current work, concentrations of PFOS, perfluorooctane sulfonamide (PFOSA), PFOS isomer profiles, and EFs of 1m-PFOS were determined in Lake Ontario water, sediment, fishes and invertebrates. Concentrations of PFOS and PFOSA were highest in slimy sculpin and Diporeia, and concentrations of the two compounds were often correlated. 1m-PFOS was racemic in sediment, water, sculpin and rainbow smelt, but nonracemic in the top predator, lake trout, and all invertebrate species. Furthermore, EFs were correlated with the relative concentrations of PFOS and PFOSA in invertebrates. Overall, these empirical observations with a new analytical tool confirm previous suggestions that PFOS-precursors contribute to PFOS in the food web, likely via sediment. Implications are that future PFOS exposures in this ecosystem will be influenced by an in situ source, and that the apparent environmental behavior of PFOS (e.g., bioaccumulation potential) can be confounded by precursors.

Environment Canada recently developed a clean method suitable for sampling trace levels of metals in surface waters. The results of sampling for total mercury in the Laurentian Great Lakes between 2003 and 2009 give a unique basin-wide perspective of concentrations of this important contaminant and represent improved knowledge of mercury in the region. Results indicate that concentrations of total mercury in the offshore regions of the lakes were within a relatively narrow range from about 0.3 to 0.8 ng/L. The highest concentrations were observed in the western basin of Lake Erie and concentrations then declined towards the east. Compared to the offshore, higher levels were observed at some nearshore locations, particularly in lakes Erie and Ontario. The longer-term temporal record of mercury in Niagara River suspended sediments indicates an approximate 30% decrease in equivalent water concentrations since 1986., (Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.)

Concentrations of atrazine and metolachlor and stereoisomer fractions (SF = herbicidally active/total stereoisomers) of metolachlor were determined in 101 surface water samples collected from the five Laurentian Great Lakes in 2005-2006. Geometric mean (GM) concentrations of atrazine ranged from 5.5 to 61 ng L(-1), decreasing from lakes Ontario approximately Michigan approximately Erie > Huron > Superior, while metolachlor concentrations ranged from 0.28 to 14 ng L(-1) and showed similar trends among the lakes. Median SFs ranged from 0.527 (Superior) to 0.844 (Erie) with an overall value of 0.708, and were significantly different among the Great Lakes (p < 0.05), except for Michigan vs Huron and Michigan vs Ontario. The SF in Erie was closest to that of the dominant product in use, S-metolachlor (SF = 0.880), while Superior showed an SF similar to that of racemic metolachlor (SF = 0.500). The median SFs in lakes Ontario, Huron and Erie were significantly lower than the median SF in Ontario stream samples collected in 2006-2007. The lower SFs in lakes suggest in-lake stereoselective processing of metolachlor or hold-up of older racemic metolachlor residues.

A series of experiments were conducted among the laboratories participating in the Integrated Atmospheric Deposition Network (IADN) monitoring program to evaluate comparability of the reported persistent organic pollutant concentrations. This quality assurance activity is essential because a variety of methods are currently used for sample collection, extraction, and analysis by the IADN laboratories. The experiments included analyses of a common reference standard (CRS), analyses of split samples, and analyses of samples collected with co-located samplers at the Point Petre IADN measurement station. The analytes included polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs). For virtually all compounds, the laboratories produced generally comparable results for the CRS samples, the split samples and the co-location samples, although some differences were observed. Analysis of the methods may pinpoint areas where variations in the methods will result in the differences observed in the reported data. These differences can be due to the field sampling process, the analytical method, field blank values, or a combination of all these factors. This study points out the importance of QA activities at every step of an environmental monitoring process so that areas where improvements may be needed or where inconsistencies may exist can be identified.

The environmental ubiquity of perfluorooctane sulfonate (PFOS) is well-known. However, little is known about the environmental fate of individual PFOS isomers. In this study, we investigated the fractionation and the bioaccumulation of PFOS isomers in water, sediment and biota collected from Lake Ontario. A total of six isomers, three perfluoro-monomethyl-substituted compounds, and three perfluoro-dimethyl isomers in addition to the linear PFOS (L-PFOS) were detected in water, sediment and biota. L-PFOS represented a much higher proportion of total PFOS (sum of linear and branched) in all organisms (>88%) compared to its proportion in technical PFOS (77%). The predominance of L-PFOS suggests a reduced uptake of branched isomers, a more rapid elimination of the branched isomers and/or a selective retention of the L-PFOS. The PFOS isomer profile found in biota was very similar to sediment, even for pelagic organisms such as zooplankton, suggesting greater partitioning of L-PFOS to biota and to sediment. The bioaccumulation factor (BAF) for L-PFOS between lake trout (whole fish) and water was estimated to be 3.4 x 10(4) L/kg compared with 2.9 x 10(3) L/kg for the monomethyl-substituted group (MM-PFOS). The remarkable difference between L-PFOS and branched isomer BAFs is due to an enrichment of branched isomers in water. The trophic magnification factor of L-PFOS (4.6 +/- 1.0) was greater than MM-PFOS isomers (1.3 +/- 0.17 to 2.6 +/- 0.51), whereas dimethyl-PFOS showed no biomagnification. The results illustrate the important influence of molecular structure on the bioaccumulation of perfluoroalkyl sulfonates.

The majority of analytical results in the Greenland AMAP (Arctic Monitoring and Assessment Programme) are produced by laboratories that participate regularly in performance studies. This makes it possible to judge the quality of the results based on the objective measurements made by independent assessors. AMAP laboratories participated, while analysing the AMAP samples, in the QUASIMEME laboratory performance study programme, and in two other smaller laboratory performance study programmes. Here is a system presented where the laboratory performance studies are used to calculate a constant error and a proportional error for each analyte. The calculations are performed by the trial and error method that sets the proportional and the constant error so that the 95%, the 68.2%, and the 50% confidence limits fit as well as possible with the data. The constant error is roughly the same as the detection limit defined as the highest concentration where zero is inside the 95% confidence interval. The relative errors of the trace analyses, i.e. the relative deviation of the result obtained by the AMAP laboratory from the assigned value, are in most of the cases less than 25% which is regarded as acceptable by the QUASIMEME. Usually the errors, especially for trace elements, are less than 12.5%, while errors for trace organics below 1 microg kg(-1) may rise to 50% or more.

Planktonic copepods (Calanus glacialis and C. hyperboreus; n = 37) and water (n = 19) were collected to examine the spatial distribution and bioaccumulation of organochlorine contaminants (OCs) in the Alaskan and Canadian Arctic. The rank order of total OC (sigma OC) group concentrations in Calanus samples was toxaphene > or = sigma polychlorinated biphenyls (PCBs) > sigma hexachlorcyclohexane (HCH) > sigma DDT > sigma chlordane-related compounds (CHLOR) > sigma chlorobenzenes (ClBz). The dominant analyte was alpha-HCH in all water and zooplankton samples. The most abundant toxaphene congener in water and zooplankton samples was the hexachlorobornane B6-923. Organochlorine contaminant group concentrations in Alaskan zooplankton and water samples were lower than those in samples collected from sites in the eastern Canadian Arctic. Comparison of PCB and toxaphene congener profiles in zooplankton and water samples suggests that biotransformation by cytochrome P-4502B isozymes is low in Calanus, and limited phase I metabolism may occur. The log relationship of bioaccumulation factor (log BAF) versus octanol-water partition coefficient (log Kow) relationship was near 1:1 for OCs within the log Kow range of 3 to 6. A curvilinear model provided a better relationship between these two variables when OC compounds with log Kow > 6 were included. These results suggest that hydrophobic OCs (log Kow 3-6) in Calanus species are at equilibrium with the water concentrations and that physical partitioning, rather than biotransformation, is the major factor governing OC profiles in marine zooplankton.