Heterocyclic Aromatics in Petroleum Coke, Snow, Lake Sediments, and Air Samples from the Athabasca Oil Sands Region

The
aromatic fractions of snow, lake sediment, and air samples
collected during 2011–2014 in the Athabasca oil sands region
were analyzed using two-dimensional gas chromatography following a
nontargeted approach. Commonly monitored aromatics (parent and alkylated-polycyclic
aromatic hydrocarbons and dibenzothiophenes) were excluded from the
analysis, focusing mainly on other heterocyclic aromatics. The unknowns
detected were classified into isomeric groups and tentatively identified
using mass spectral libraries. Relative concentrations of heterocyclic
aromatics were estimated and were found to decrease with distance
from a reference site near the center of the developments and with
increasing depth of sediments. The same heterocyclic aromatics identified
in snow, lake sediments, and air were observed in extracts of delayed
petroleum coke, with similar distributions. This suggests that petroleum
coke particles are a potential source of heterocyclic aromatics to
the local environment, but other oil sands sources must also be considered.
Although the signals of these heterocyclic aromatics diminished with
distance, some were detected at large distances (>100 km) in snow
and surface lake sediments, suggesting that the impact of industry
can extend >50 km. The list of heterocyclic aromatics and the mass
spectral library generated in this study can be used for future source
apportionment studies.