Air synthesis review: polycyclic aromatic compounds in the oil sands region

Abstract

This air synthesis review presents the current state of knowledge on the sources, fates, and effects for polycyclic aromatic compounds (PACs) and related chemicals released to air in the oil sands region (OSR) in Alberta, Canada. Through the implementation of the Joint Canada–Alberta Oil Sands Monitoring Program in 2012 a vast amount of new information on PACs has been acquired through directed monitoring and research projects and reported to the scientific community and public. This new knowledge addresses questions related to cumulative effects and informs the sustainable management of the oil sands resource while helping to identify gaps in understanding and priorities for future work. As a result of this air synthesis review on PACs, the following topics have been identified as new science priorities: (i) improving emissions reporting to better account for fugitive mining emissions of PACs that includes a broader range of PACs beyond the conventional polycyclic aromatic hydrocarbons (PAHs) including, inter alia, alkylated-PAHs (alk-PAHs), dibenzothiophene (DBT), alk-DBTs, nitro-PAHs, oxy-PAHs including quinones and thia- and aza-arenes; (ii) improving information on the ambient concentrations, long-range transport, and atmospheric deposition of these broader classes of PACs and their release (with co-contaminants) from different types of mining activities; (iii) further optimizing electricity-free and cost-effective approaches for assessing PAC deposition (e.g., snow sampling, lichens, passive ambient sampling) spatially across the OSR and downwind regions; (iv) designing projects that integrate monitoring efforts with source attribution models and ecosystem health studies to improve understanding of sources, receptors, and effects; (v) further optimizing natural deposition archives (e.g., sediment, peat, tree rings) and advanced forensic techniques (e.g., isotope analysis, marker compounds) to provide better understanding of sources of PACs in the OSR over space and time; (vi) conducting process research to improve model capabilities for simulating atmospheric chemistry of PACs and assessing exposure to wildlife and humans; and (vii) developing tools and integrated strategies for assessing cumulative risk to wildlife and humans by accounting for the toxicity of the mixture of chemicals in air rather than on a single compound basis.

Secondary organic aerosol formation from α-pinene, alkanes and oil sands related precursors in a new oxidation flow reactor

“…The Alberta oil sands (OS) is a large unconventional crude oil deposit, which is extracted through both open-pit mining and in-situ steam assisted techniques. Considering the scale of OS oil production, a number of environmental concerns associated with OS air emissions have arisen, including the potential for ecosystem toxicity (Kirk et al, 2014;Harner et al, 2018) and acid deposition (Jung et al, 2011;Makar et al, 2018). Recent field measurements have shown that OS mining and processing facilities are a large source of volatile organic compounds (VOCs) (Simpson et al, 2010;Li et al, 2017).…”

Atmospheric change as a driver of change in the Canadian boreal zone1

“…The longterm deposition of these toxic pollutants either declined or remained stable with no significant increases detected in these studies. Considerably elevated deposition of non-Hg metals, as well as polycyclic aromatic compounds, occurred within the 50-km radius of oil sand facilities in the Athabasca Oil Sands region (e.g., Kelly et al 2009Kelly et al , 2010Bari et al 2014;Lynam et al 2015;Harner et al 2018). Their deposition in this region likely increased along with rising bitumen production since the mid-1980s (see Statistics Canada 2016).…”

Advances in science and applications of air pollution monitoring: A case study on oil sands monitoring targeting ecosystem protection

“…Two "integrating themes" were of interest across components: polycyclic aromatic compounds (PACs) and mercury. A summary on PAC integration (Harner et al 2018) is reported in this critical review. The issue of acid deposition was considered in an integrated manner, building upon a long monitoring history in this area (i.e., the Acid Rain Program beginning in the 1970s), and results are highlighted in this critical review (Makar et al 2018).…”

“…The Galarneau et al (2014) study of tailings pond water supported this finding, demonstrating that given known water concentrations, there is a potential for PAHs to partition into the air. Harner et al (2018) also highlighted that potential; in order for the inverse modeling of Parajulee and Wania (2014) to explain the observed ambient concentrations of phenanthrene, pyrene, and benzo[a]pyrene in 2009, their emissions would need to be 2-3 orders of magnitude higher than those reported in the NPRI and APEI databases. More recent emission estimates, also based on inverse modeling, but for a larger amount of ambient monitoring data (Schuster et al 2015), also concluded that PAH emissions are underestimated (Qiu et al 2018).…”

“…As PACs are a diverse class of compounds, their distribution is likely to undergo considerable change as they move from their specific source locations on the OS facilities to downwind areas. Quinones and nitrated compounds are believed to be the dominant end products from these reactions (Arey et al 1992;Keyte, Harrison, and Lammel 2013;Lundstedt et al 2007), and these compounds were measured at several ground sites within the surface-mineable region (Harner et al 2018). Separate measurements of the ambient gas-and particle-phase concentrations of seven unsubstituted PAHs and 19 corresponding quinones at the WBEA site south of Fort McKay, Alberta (AMS13), showed that the unsubstituted PAHs were predominantly found in the gas phase.…”