Polycyclic Aromatic Hydrocarbon Deposition in the Snowpack of the Athabasca Oil Sands Region of Alberta, Canada

In the Athabasca Oil Sands Region (AOSR) of Alberta, Canada, increased concentrations of polycyclic aromatic hydrocarbons (PAHs) in the regional ecosystems and downstream of oil sands development have been observed, presumably originating from various sources including those of oil sands and non-oil sands activities. In this study, we investigated the extent that oil sands activities contribute PAHs to the snowpack of the AOSR. The dominant groups of PAHs found in our snow samples were dibenzothiophenes, phenanthrenes/anthracenes, fluranthenes/pyrenes, chrysenes, and fluorenes. These PAHs were highly dominated by alkylated species, especially near oil sands operations. Aerial deposition of PAHs declined exponentially with increasing distance from the geographic center (GC), which was located close to Suncor and Syncrude’s oil sands operations. The higher aerial deposition at similar distances from GC in the N-S versus W-E directions reflects that PAH inputs from oil sands operations are clustered along the Athabasca River. Patterns of air parcel movements, derived from HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) modeling, closely matched patterns of aerial deposition, supporting that regional wind patterns influence the transport of PAHs emitted by oil sands operations in the AOSR. The source attribution techniques employed in this study revealed that sampling location influenced the characteristics of PAHs deposited. PAHs deposited at sites close to GC were associated with industrial activity, whereas the influences of other sources became increasingly apparent as distance increased from major oil sands areas.