First Results
from the Oil Sands Passive Air Monitoring
Network for Polycyclic Aromatic Compounds
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Abstract
Results are reported from an ongoing
passive air monitoring study
for polycyclic aromatic compounds (PACs) in the Athabasca oil sands
region in Alberta, Canada. Polyurethane foam (PUF) disk passive air
samplers were deployed for consecutive 2-month periods from November
2010 to June 2012 at 17 sites. Samples were analyzed for polycyclic
aromatic hydrocarbons (PAHs), alkylated PAHs, dibenzothiophene and
its alkylated derivatives (DBTs). Relative to parent PAHs, alkylated
PAHs and DBTs are enriched in bitumen and therefore considered to
be petrogenic markers. Concentrations in air were in the range 0.03–210
ng/m<sup>3</sup>, 0.15–230 ng/m<sup>3</sup> and 0.01–61
ng/m<sup>3</sup> for ∑PAHs, ∑alkylated PAHs and ΣDBTs,
respectively. An exponential decline of the PAC concentrations in
air with distance from mining areas and related petrogenic sources
was observed. The most significant exponential declines were for the
alkylated PAHs and DBTs and attributed to their association with mining-related
emissions and near-source deposition, due to their lower volatility
and greater association with depositing particles. Seasonal trends
in concentrations in air for PACs were not observed for any of the
compound classes. However, a forest fire episode during April to July
2011 resulted in greatly elevated PAH levels at all passive sampling
locations. Alkylated PAHs and DBTs were not elevated during the forest
fire period, supporting their association with petrogenic sources.
Based on the results of this study, an “Athabasca PAC profile”
is proposed as a potential source marker for the oil sands region.
The profile is characterized by ∑PAHs/∑Alkylated PAHs
= ∼0.2 and ∑PAHs/∑DBTs = ∼5