First Results from the Oil Sands Passive Air Monitoring Network for Polycyclic Aromatic Compounds

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(3), 0.15-230 ng/m(3) and 0.01-61 ng/m(3) 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.

Stability of polycyclic aromatic compounds in polyurethane foam-type passive air samplers upon O3 exposure

“…(Schuster et al, 2015) A pipet was used to distribute 320 ng of the individual PACs in 0.5 ml of isooctane evenly onto a cleaned PUF disk. The spiked PUFs were air-dried in a fume hood for 5 min to allow solvent to evaporate before being placed in the flow tube chamber.…”

“…(Schuster et al, 2015) Briefly, PUFs were spiked with the labeled recovery PAH surrogates and extracted with pressurized liquid extraction using petroleum ether and acetone (75:25, v:v; 2 cycles). The extracts were evaporated under a purified N 2 stream with a Turbovap II (Biotage, NC).…”

“…Passive air sampling has been widely used in air monitoring for persistent organic pollutants (POPs) (Bartkow et al, 2004;Harner et al, 2006;Jaward et al, 2004;Schuster et al, 2015) as it is convenient, inexpensive, and does not require electricity to operate. Chemicals, both gas-phase and particulate-phase, are passively accumulated in sampling media being deployed for months at a time.…”

“…The sampling media include semipermeable membrane devices (SPMDs), polyurethane foam (PUF) disks, and XAD resin. Given that they are easy to handle, polyurethane foam (PUFs) disks are commonly used in a number of air monitoring programs, (Jaward et al, 2004;Klanova et al, 2006;Motelay-Massei et al, 2005;Pozo et al, 2004;Schuster et al, 2015) including the Joint Canada/Alberta Implementation Plan on oil sands Monitoring (JOSM) by Environment Canada and Alberta Environment and Sustainable Resource Development.…”

“…The PACs being monitored include parent polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (alkPAHs), dibenzothiophene (DBT) and alkylated DBTs. (Schuster et al, 2015) Released from pyrogenic (e.g. combustion processes) and petrogenic (e.g.…”