Source apportionment of background PAHs in the Peace-Athabasca Delta (Alberta, Canada) using molecular level radiocarbon analysis.

• Published in: Environmental Science & Technology
• Main Authors: Jautzy, Josué, Ahad, Jason M. E., Hall, Roland I., Wiklund, Johan A., Wolfe, Brent B., Gobeil, Charles, Savard, Martine M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2015
• Subjects: aromatic hydrocarbons; deforestation; environmental impact; fire hazards; fires; forestry; fossil fuel deposits; oil sands; petroleum deposits; watersheds; Canada; Peace-Athabasca Delta; Peace River
• Online Access: https://espace.inrs.ca/id/eprint/3865/; https://doi.org/10.1021/acs.est.5b01490

The downstream accumulation of polycyclic aromatic hydrocarbons (PAHs) in the Peace-Athabasca Delta (PAD), an ecologically important landscape, is a key issue of concern given the rapid development of the oil sands industry in Northern Alberta, Canada. In addition to PAHs derived from industrial activity (i.e., oil sands mining) within the Athabasca watershed, however, forest fires and erosion of fossil fuel deposits within both the Athabasca and Peace watersheds are two potentially important natural sources of PAHs delivered to the PAD. Consequently, evaluating the environmental impact of mining activities requires a quantitative understanding of natural, background PAHs. Here, we utilize molecular-level natural-abundance radiocarbon measurements on an amalgamated sediment record from a Peace River flood-susceptible oxbow lake in the northern Peace sector of the PAD to quantitatively discriminate sources of naturally occurring alkylated PAHs (fossil and modern biomass). A radiocarbon mass balance quantified a predominantly natural petrogenic source (93% petrogenic, 7% forest fire) for alkylated PAHs during the past ~50 years. Additionally, a significant petrogenic component determined for retene, a compound usually considered a biomarker for softwood combustion, suggests that its use as a unique forest fire indicator may not be suitable in PAD sediments receiving Peace watershed-derived fluvial inputs.