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

Abstract

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.