An Update of PAHs Emissions and an Assessment of Oil Sands Sources Contributions to PAHs Ambient Concentrations in the Canadian Athabasca Oil Sands Region

This study first updates an existing emission inventory for 16 polycyclic aromatic hydrocarbons (PAHs) covering Athabasca oil sands region (AOSR) of Alberta, Canada using more recent knowledge. The updated emissions were then assessed by comparing dispersion model simulated ambient concentrations with available field measurements. Total emissions were further split into oil sands (OS) and non-oil sands (non-OS) sectors to conduct model sensitivity tests to quantify the contributions of OS sectors to ambient concentrations of PAHs. The estimated domain total annual emissions of the 16 PAH species (∑16PAHs) were 116.4 tonnes/year, of which 40.5 tonnes/year were emitted from ∑15PAHs and 75.9 tonnes/year from naphthalene. 72.6% of the total emissions were in the gas phase and the remaining in particle phase. Major source sectors include stationary point sources (43.3 tonnes/year), tailings ponds (19.9), residential and commercial sectors (15.5), fugitive dust (13.0), fuel combustion from mine fleet (11.7), local transportation (11.7), and controlled agriculture and forest burning (0.8). OS sources contributed 68% and 80% of the ∑15PAHs and naphthalene emissions, respectively. The differences between model-simulated concentrations and corresponding measurements ranged from -54% to 59% for ∑15PAHs (-9% on average) and from -81% to 151% (-3% on average) for naphthalene across 16 sites. OS sources contributed 67% and 74% to the domain-averaged ∑15PAHs and naphthalene ambient concentrations, respectively. OS sources had the greatest impact on ambient PAHs concentrations near tailings ponds and mine face, downwind of stationary point sources, and large areas north of Fort McKay. Non-OS sources had the greatest impact near cities, towns, and local highways.