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TitleSource apportionment of background PAHs in the Peace-Athabasca Delta (Alberta, Canada) using moluecular level radiocarbon analysis
AuthorJautzy, J JORCID logo; Ahad, J M EORCID logo; Hall, R I; Wiklund, J A; Wolfe, B B; Gobeil, C; Savard, M MORCID logo
SourceEnvironmental Science & Technology (ES & T) vol. 49, issue 15, 2015 p. 9056-9063,
Alt SeriesEarth Sciences Sector, Contribution Series 20140273
PublisherAmerican Chemical Society (ACS)
Mediapaper; digital; on-line
File formatpdf
NTS74J; 74G
AreaPeace-Athabasca Delta
Lat/Long WENS-111.7500 -110.7500 58.7500 58.2500
Subjectsenvironmental geology; hydrogeology; fossil fuels; hydrocarbons; aromatic hydrocarbons; environmental studies; environmental impacts; watersheds
Illustrationslocation maps; plots
ProgramEnvironmental Geoscience Coal & Oil Resources Environmental Sustainability
Released2015 07 09
AbstractThe 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.
Summary(Plain Language Summary, not published)
The accumulation of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) in the Peace-Athabasca Delta (PAD) is a key issue associated with the rapid development of Canada¿s oil sands industry. Forest fires and erosion of naturally occurring bitumen outcrops are two important sources for PAHs delivered to the PAD. Consequently, any attempt to examine the impact that mining activities has on this environment requires a detailed understanding of the PAH background. Using a dated sediment sequence from an oxbow lake situated in the PAD, we utilized molecular level natural abundance radiocarbon (14C) measurements to discriminate sources of alkylated PAHs (fossil versus modern biomass). We report PAH concentrations naturally exceeding the sediment quality guidelines and associated with flooding events. This research allowed us to characterize and quantify the relative contributions of the background sources in the Peace section of the PAD (90% bitumen, 10% forest fire).

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