Polycyclic aromatic compounds in ambient air in the surface minable area of Athabasca oil sands in Alberta (Canada)

This study characterizes concentrations and describes the spatiotemporal patterns of ambient air polycyclic aromatic compounds (PACs) between 2011 and 2015 in the Athabasca oil sands region (AOSR). 24-hour integrated ambient air samples were collected at multiple sites and analyzed for 110 PACs. Alkylated polycyclic aromatic hydrocarbons (alk-PAHs) formed the majority of the PACs in air and correlated with unsubstituted PAHs, suggesting common emission source(s) and/or origin. Concentrations of individual PACs varied spatially and seasonally. Temporal variability of PAC concentrations was evident, however based on Seasonal Mann-Kendall test a monotonic increase in concentrations at the monitored sites was not significant at p < 0.05. PAC concentrations measured during wildfire events (which were excluded from the trend analysis above) were the highest and were enriched in higher molecular weight alk-PAHs. This enrichment in alk-PAHs has not been previously reported and is believed to be a unique phenomenon for the Athabasca region. Sulfur and petroleum coke stockpiles, mining and bitumen processing were identified as potential sources of PACs near the main production operations, while mining and diluent naphtha production stood out as possible sources at a site 16 km north of the main open-pit mining area.

Automated summary

This study characterized the concentrations and spatiotemporal patterns of ambient air polycyclic aromatic compounds in the Athabasca oil sands region between 2011 and 2015. Alkylated polycyclic aromatic hydrocarbons were found to be the majority of PACs in air, with concentrations varying spatially and seasonally. PAC concentrations measured during wildfire events were the highest and enriched in higher molecular weight alk-PAHs.