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TitlePetrogenic organic carbon and PAHs in snow deposited on Athabasca oil sands region lakes
AuthorAhad, J M E; Pakdel, H; Gammon, P R; Savard, M M
SourceAmerican Geophysical Union (AGU) Fall Meeting 2017, New Orleans, LA, USA - abstract volume; 2017, 1 pages
Year2017
Alt SeriesNatural Resources Canada, Contribution Series 20170312
PublisherAmerican Geophysical Union (AGU)
MeetingAmerican Geophysical Union (AGU) Fall Meeting 2017; New Orleans, LA; US; Fall 2017
Documentbook
Lang.English
Mediapaper; on-line; digital
File formathtml
ProvinceAlberta
AreaAthabasca oil sands region
SubjectsHealth and Safety; fossil fuels; geochemistry; oil sands; bituminous sands; health hazards; heavy metals contamination; pollution; pollutants; coke; aromatic hydrocarbons; hydrocarbons; radiocarbon dates; snow
ProgramSources, Environmental Geoscience
LinksAbstract - Résumé
AbstractFugitive dust associated with surface mining activities is one of the principal vectors for transport of airborne contaminants in Canada's Athabasca oil sands (AOS) region. The two main sources for mining-related dust - unprocessed oil sand and petroleum coke (petcoke) - contain high levels of bitumen-derived organic contaminants such as polycyclic aromatic hydrocarbons (PAHs). Here, we report the radiocarbon (14C) contents of solvent-extractable organics in snow particulates deposited during the winter of 2016-17 on fourteen lakes across the AOS region to quantify the contribution of anthropogenic dust transported directly to these ecosystems. Concentrations of parent and alkylated PAHs were determined in both dissolved and particulate fractions of snow. Radiocarbon isotope ratios (delta-14C) ranged from -805 to -177 pmil, indicating a significant contribution of petrogenic or fossil (i.e., delta-14C = -1000 pmil) carbon in snowpack dust at some sites. More negative delta-14C values were generally found in samples containing higher levels of particulate matter and at lakes closer to the geographic center of AOS mining operations. Concentrations of PAHs > 2 rings were significantly higher in the particulate phase and in samples with the largest petrogenic carbon components. Relatively high levels of PAHs at some distal sites associated with less negative delta-14C values pointed to an important modern carbon contribution, potentially ash originating from the ~ 1.5 million acre 2016 Fort McMurray wildfire. As demonstrated here, fugitive dust in snow covering AOS region lakes can contain significant petrogenic organic carbon and high levels of PAHs, particularly in areas close (i.e., < 25 km) to the center of AOS mining operations. The spring snowmelt thus provides a direct pathway for mining-related contaminants to lake sediments.
Summary(Plain Language Summary, not published)
Fugitive dust associated with surface mining activities is a main source of airborne contaminants in Canada's Athabasca oil sands (AOS) region. This dust contains high levels of bitumen-derived organic contaminants such as polycyclic aromatic hydrocarbons (PAHs). Bitumen is millions of years old and contains no radiocarbon (14C). As a result, 14C is a useful marker for determining the amount of petrogenic (i.e., fossil) organic carbon in environmental samples. In this study, we measured the 14C contents of snow dust deposited to the surface of fourteen AOS region lakes. We report a significant contribution of petrogenic carbon in snowpack dust at some sites, with a greater petrogenic component generally found at lakes closer to the geographic center of AOS mining operations and in samples containing higher levels of particulate matter and PAHs. Our study demonstrates that the spring snowmelt provides a direct pathway for mining-related contaminants to lake sediments.
GEOSCAN ID306371