Deposition and source identification of nitrogen heterocyclic polycyclic aromatic compounds in snow, sediment, and air samples from the Athabasca Oil Sands Region

Abstract

Polycyclic aromatic compounds (PACs) canhave multiple sources in the Athabasca Oil Sands Region (AOSR). The current study was designed to identify andexplore the potential of nitrogen heterocyclic PACs (NPACs) as source indicators in snowpack, lake sediment and passiveair samples from the AOSR during 2014−2015. Sourcesamples including petroleum coke (petcoke), haul road dust,and unprocessed oil sands were also analyzed. Samples wereanalyzed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry, and liquidchromatography-high resolution Orbitrap mass spectrometry. Over 200 NPACs were identified and classified into at least24 isomer groups, including alkylated carbazoles, benzocarbazoles, and indenoquinolines. Levels of NPACs in environmentalsamples decreased with distance from the main developments and with increasing depth in lake sediments but were detectedwithin 50 km from the major developments. The composition profiles of several NPAC isomer classes, such asdimethylcarbazoles, showed that petcoke had a distinct distribution of NPACs compared to the haul road dust and unprocessedoil sands ores and was the most similar source material to near-field environmental samples. These results suggest that petcokeis a major contributing source for the identified NPACs and that these compounds have the potential to be used as sourceindicators for future research in the AOSR.