Temporal and Spatial Trends of Polycyclic Aromatic Compounds in Air across the Athabasca Oil Sands Region Reflect Inputs from Open Pit Mining and Forest Fires

Abstract

Results of a passive air monitoring study for polycyclic aromatic compounds (PACs) in the Athabasca oil sands region (AOSR) in Alberta, Canada, are reported. Polyurethane foam disk passive air samplers were deployed for consecutive 2-month periods from November 2010 to January 2016 at 15 sites. Samples were analyzed for polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (alkPAHs), and dibenzothiophene and its alkylated derivatives (DBTs). Concentrations in air were in the ranges of 0.3–43, 0.15–460, and 0.04–130 ng/m3 for ∑PAHs, ∑alkPAHs, and ∑DBTs, respectively. The increase in the levels of PACs in air at most sites was small but statistically insignificant over this 5-year period, which is consistent with expectations as in situ bitumen extraction techniques have become predominant over open pit mining in the area. Significant increases in PAC levels were observed at a site that is within a few kilometers of open pit mining that expanded over the study period. The 5-year regional trend for PACs in air provides a baseline against which planned future open pit mining projects (e.g., Teck Frontier) can be assessed for impact. Seasonal trends in concentrations in air were observed for more volatile PACs; concentrations in air were higher in winter than in summer. These trends were not observed for less volatile compounds. Two major forest fire episodes from April to July 2011 and during June and July 2015 resulted in greatly elevated levels for PAH and a small subset of alkylated PAHs but not for the majority of alkPAHs and DBTs. Increases in regional PAH concentrations associated with forest fire periods were consistent with estimates based on published emission factors for PAHs for wood combustion. Although forest fires are likely to be an important source of PAH concentrations in air across the AOSR, alkPAHs and DBTs appear to be primarily associated with emissions from oil sands mining operations. Air quality guidelines for alkPAHs and DBTs are still lacking.

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

“…Consistent with the spatial pattern in air concentrations (Schuster et al 2019), deposition occurs on a gradient, with higher deposition near oil sands production activity. Spatial patterns of PAC deposition have been explored using a variety of methods, including snow (Manzano et al 2016), bulk deposition collectors (Bari, Kindzierski, and Cho 2014), lichen (Graney et al 2017;Landis et al 2019), moss sampling (Zhang et al 2016), and a passive dry deposition sampler (Jariyasopit et al 2018).…”

“…These include resuspended dust from mine faces, unpaved roads, and petroleum coke storage piles, as well as volatilization from tailings ponds (Figure 13). Schuster et al (2019) documented the long-term concentrations of the three PAC classes across 15 sites in the OS region covering the period 2010-2016. These passive data serve as a key baseline for assessing the impact of future and expanded mining projects in the region on ambient levels of PACs.…”

“…combustion emission factors for alk-PAHs and the DBTs, complicating assessment of the contribution from the OS industry to their levels in water, sediment, and biological compartments (Schuster et al 2019).…”

Characteristics and Influencing Factors of Polycyclic Aromatic Hydrocarbons Emitted from Open Burning and Stove Burning of Biomass: A Brief Review

“…The concentrations of PAHs in other regions during the open-burning period also show massive increases; concentrations increase approximately 2.80–9.54 times compared to those in the non-burning period [ 41 , 66 , 67 ], indicating that the open burning of crop residues significantly increases the ambient concentration of PAHs, which can cause severe health effects. Unlike the artificial burning of crop straw, the open burning of biomass in sparsely populated areas is dominated by forest and grassland fires, which increase the local level of PAHs and their load in long-range transport [ 68 , 69 , 70 , 71 ]. Wang et al estimated that the annual emission of PAHs from bushfires/wildfires in Australia ranged from 160 to 1100 Mg/year with a median of 700 Mg/year [ 72 ].…”

Estimation of Atmospheric Dry and Wet Deposition of Particulate Elements at Four Monitoring Sites in the Canadian Athabasca Oil Sands Region

“…The Oil Sands Monitoring (OSM) Program, a collaborative effort of the governments of Canada and Alberta together with Indigenous communities and industries, is aimed at enhancing the understanding of the cumulative environmental effects of oil sands industries in the AOSR through monitoring a large number of atmospheric pollutants, including acidifying pollutants (Griffin et al, 2019;McLinden et al, 2020;Shephard et al, 2015;Whaley et al, 2018), polycyclic aromatic compounds (Cheng et al, 2018;Galarneau et al, 2014;Schuster et al, 2015Schuster et al, , 2019Zhang et al, 2015), mercury (Kirk et al, 2014;Wasiuta et al, 2019;Willis et al, 2018) and particulate elements (Mamun et al, 2021) at multiple sites. More than 40 different particulate elements were measured, but only in air and not in precipitation, and only at four sites.…”