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TitleSources of polycyclic aromatic hydrocarbons (PAHs) to northwestern Saskatchewan lakes east of the Athabasca oil sands
AuthorAhad, J M E; Jautzy, J J; Cumming, B F; Das, B; Laird, K R; Sanei, H
SourceOrganic Geochemistry vol. 80, 2015 p. 35-45, https://doi.org/10.1016/j.orggeochem.2015.01.001
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20130393
PublisherElsevier
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceAlberta; Saskatchewan
NTS74C/09; 74C/10; 74C/11; 74C/12; 74C/13; 74C/14; 74C/15; 74C/16; 74D/09; 74D/10; 74D/11; 74D/12; 74D/13; 74D/14; 74D/15; 74D/16; 74E/01; 74E/02; 74E/03; 74E/04; 74E/05; 74E/06; 74E/07; 74E/08; 74F/01; 74F/02; 74F/03; 74F/04; 74F/05; 74F/06; 74F/07; 74F/08
AreaFor McMurray; Fort McKay
Lat/Long WENS-112.0000 -108.0000 57.5000 56.5000
Subjectsfossil fuels; geochemistry; bitumen; core samples; fires; isotope geochemistry; mining activities; bituminous sands; aromatic hydrocarbons; oil sands; carbon isotopes; bitumen; retene; Rock-Eval
Illustrationslocation maps; tables; plots; geochemical plots
ProgramCoal & Oil Resources Environmental Sustainability, Environmental Geoscience
AbstractThe past several decades have witnessed a significant expansion of mining activities in the Athabasca oil sands region, raising concerns about their impact on the surrounding boreal forest ecosystem. To better understand the extent to which distal sites are impacted by oil sands-derived airborne contaminants, we examine sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and dated sediment cores from Saskatchewan lakes situated 100-220 km east-northeast of the main area of bitumen mining activities. The concentrations and fluxes of both parent and alkylated PAHs are low and show considerable variability over the past 70-100 years. Small yet discernible increases in PAH concentrations and fluxes occurred over the past 30 years, a trend which coincides with the rapid growth in bitumen production. However, several lines of evidence point to wildfires as the principal source of PAHs to these lakes: (1) the significant co-variations in most cores between retene (1-methyl-7-isopropyl phenanthrene) and other groups of parent and alkylated PAHs, (2) the similarity in compound specific d13C signatures of the parent PAHs phenanthrene and pyrene in recently deposited surficial sediments and those corresponding to time intervals considerably pre-dating the large scale development of the oil sands and (3) the discernible up-core increases in the proportion of refractory carbon (i.e., char) in Rock-Eval 6 data. The collective evidence points to softwood combustion from boreal forest fires as the principal source of retene in sediments and the general increase in forest fire activity in this region over the past several decades as the source of refractory carbon. Mining activities associated with the Athabasca oil sands are thus not considered a major source of PAHs to these lakes.
Summary(Plain Language Summary, not published)
Polycyclic aromatic hydrocarbons (PAHs) are a group of organic contaminants found naturally in Athabasca oil sands bitumen that are released to the environment through various sources, including non-mining-related ones (e.g., forest fires). To better understand the extent to which distal sites are impacted by oil sands-derived airborne contaminants, here we examine historical trends in PAHs in dated sediment cores from four Saskatchewan lakes situated ~100 to 190 km east-northeast of the main area of bitumen mining activities. The concentrations and fluxes of PAHs were low and showed considerable variability over the past 70 to 100 years. The main control on PAH inputs in these lakes is attributed to local and regional forest fires, with a more limited role from Athabasca oil sands mining operations.
GEOSCAN ID293462