Assessment of Alkylated and Unsubstituted Polycyclic Aromatic Hydrocarbons in Air in Urban and Semi-Urban Areas in Toronto, Canada.

22 alkylated polycyclic aromatic hydrocarbons (alk-PAHs) were characterized in ambient air individually for the first time in urban and semi-urban locations in Toronto, Canada. Five unsubstituted PAHs were included for comparison. Results from the measurements were used to estimate benzo[a]pyrene equivalent toxicity (BaPeq) of individual compounds in order to investigate the significance of a single compound in contributing to the overall toxic equivalency (TEQ) of air mixtures. To determine which compounds merit further investigation, BaPeq values of individual compounds were compared to the measured BaP toxicity. Our results showed that both unsubstituted and alkylated PAHs were more abundant in the urban area (38 and 30%, respectively). Benzo[a]pyrene levels at the urban location exceeded Ontario's 24 h guideline (40% of the events), and on average, it was 5 times higher than that at the semi-urban area. Gas-phase two- and three-ring compounds contributed up to 39% (urban) and 76% (semi-urban) of the TEQ of all compounds analyzed. Some alk-PAHs such as 7,12-dimethylbenzo[a]anthracene had a huge impact on the toxicity of urban air, and its BaPeq was on average 8 times higher than that of BaP. We emphasize that the toxic impact of alkylated and gaseous PAHs, which is not routinely included in many air monitoring programs, is significant and should not be neglected.

The effects of plume episodes on PAC profiles in the athabasca oil sands region.

Summer intensive air measurements of alkylated polycyclic aromatic compounds (Alk-PACs), nitrated polycyclic aromatic hydrocarbons (NPAHs), and oxygenated polycyclic aromatic hydrocarbons (OPAHs) was conducted during the summer of 2013 at an air monitoring site near the community of Fort McKay in the Athabasca oil sands region (AOSR). This study uses the ambient air measurements in conjunction with supplementary meteorological and air quality data from coordinated ground- and aircraft-based sampling over the same period to characterize diurnal variations and changes in the organic air pollutant profiles associated with the plume episodes. Principal component analysis showed a distinct PAC profile during plume episodes, driven mainly by higher fluorenone (FLO) and 9,10-anthraquinone (ANQ) concentrations. During the plume episodes (August 23-24), means of NPAHs and OPAHs concentrations were 120 and 2020 pg/m3, respectively, which were 2.7 and 2.5 times higher than those measured on the other days, while Alk-PACs did not reach maxima. The relative constancy of Alk-PACs during the plume episodes and baseline air quality periods likely reflects a continuous and broad emission of Alk-PACs from the oil sands mining activities. Only four OPAHs, including FLO, ANQ, benzo(a)fluorenone, and benzanthrone, exhibited higher average daytime than nighttime concentrations (p-value < 0.05). Categorizing air samples into clean and polluted conditions demonstrated that the polluted condition air samples were characterized by higher percent composition of alkylated fluorenes, FLO, MANQ, and photochemically-derived 1M4NN. A comparison of PAC profiles in air samples and oil sand ore samples suggests that the NPAHs were likely influenced by atmospheric formation while the OPAHs were impacted by a combination of primary sources and atmospheric formation. The strong correlations found between a number of NPAHs and OPAHs, and PM2.5 and NOx in this study could support the modelling of ambient air burdens of these compounds across the region.

Temporal trends of halogenated flame retardants in the atmosphere of the Canadian Great Lakes Basin (2005-2014).

Organic pollutants have been monitored in the atmosphere of the Great Lake Basin (GLB) since the 1990s in support of the Canada-US Great Lakes Water Quality Agreement and to determine the effectiveness of source reduction measures and factors influencing air concentrations. Air samples were collected between 2005 and 2014 at three sites with different geographical characteristics (Burnt Island, Egbert and Point Petre) in the Canadian GLB using high-volume air samplers and the air samples were analyzed for polybrominated diphenyl ethers (PBDEs) and several other non-PBDE halogenated flame retardants (HFRs). Spatial and temporal trends of total concentrations of HFRs were examined. BDE-47, BDE-99, and BDE-209 were the dominant PBDE congeners found at the three sites. For the non-PBDE HFRs, allyl 2,4,6-tribromophenyl ether (TBP-AE), hexabromobenzene (HBBz), pentabromotoluene (PBT), anti-dechlorane plus (anti-DDC-CO) and syn-dechlorane plus (syn-DDC-CO) were frequently detected. High atmospheric concentrations of PBDEs were found at the Egbert site with a larger population, while lower levels of PBDEs were detected at Point Petre, which is close to urban centers where control measures are in place. The strong temperature dependence of air concentrations indicates that volatilization from local sources influences atmospheric concentrations of BDE-28 and BDE-47 at Point Petre and Burnt Island, while long-range atmospheric transport (LRAT) was important for BDE-99. However, a weaker correlation was observed between air concentrations and ambient temperature for non-PBDE HFRs such as TBP-AE and HBBz. Atmospheric PBDE concentrations are decreasing slowly, with half-lives in the range of 2-16 years. Faster declining trends of PBDEs were observed at Point Petre rather than at Burnt Island. As Point Petre is closer to urban centers, faster declining trends may reflect the phase out of technical BDE mixtures in urban centers while LRAT influences the air concentrations at Burnt Island. The levels of syn-DDC-CO and anti-DDC-CO are decreasing at Point Petre and the levels of other non-PBDE HFRs such as TBP-AE, PBT and HBBz are increasing. Long-term declining trends of PBDEs suggest that regulatory efforts to reduce emissions to the GLB environment have been effective but that continuous measurements are required to gain a better understanding of the trends of emerging chemicals in the atmosphere of the GLB.

Atmospheric concentrations and loadings of organochlorine pesticides and polychlorinated biphenyls in the Canadian Great Lakes Basin (GLB): Spatial and temporal analysis (1992-2012).

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 Æ©PCBs (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, ß-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.