title: A multiple lines of evidence approach for the ecological risk assessment of an accidental bitumen release from a steam assisted gravity drainage (SAGD) well in the Athabasca oil sands region.
abstract: To assess the ecological impacts of two independent accidental bitumen releases from two steam assisted gravity drainage (SAGD) wells in the Athabasca oil sands region, a multiple lines of evidence (LOE) approach was developed. Following the release in 2010, action was taken to minimize environmental impact, including the selective removal of the most highly impacted vegetation and the use of oil socks to minimize possible runoff. An ecological risk assessment (ERA) was then conducted based on reported concentrations of bitumen related contaminants in soil, vegetation, and water. Results of biological assessments conducted at the site were also included in the risk characterization. Overall, the conclusion of the ERA was that the likelihood of long-term adverse health effects to ecological receptors in the area was negligible. To provide evidence for this conclusion, a small mammal sampling plan targeting Southern red-back voles (Myodes gapperi) was carried out at two sites and two relevant reference areas. Voles were readily collected at all locations and no statistically significant differences in morphometric measurements (i.e., body mass, length, foot length, and adjusted liver weight) were found between animals collected from impact zones of varying levels of coverage. Additionally, no trends corresponding with bitumen coverage were observed with respect to metal body burden in voles for metals that were previously identified in the source bitumen. Hepatic ethoxyresorufin-O-deethylase (EROD) activity was statistically significantly elevated in voles collected from the high impact zones of sites compared to those collected from the reference areas, a finding that is indicative of continued exposure to contaminants. However, this increase in EROD was not correlated with any observable adverse population-wide biological outcomes. Therefore the biological sampling program supported the conclusion of the initial ERA and supported the hypothesis of no significant long-term population-wide ecological impact of the accidental bitumen releases.
authors.affiliation: Intrinsik Health Sciences Inc., 6605 Hurontario Street, Suite 500, Mississauga, Ontario L5T 0A3, Canada.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Berger
authors.affiliation: Intrinsik Environmental Sciences Inc., 6605 Hurontario Street, Suite 500, Mississauga, Ontario L5T 0A3, Canada.
authors.forename: Melissa Whitfield
authors.initials: MW
authors.lastname: Aslund
authors.affiliation: Omnia Ecological Services, 722 27th Avenue NW, Calgary, Alberta T2M 2J3, Canada.
authors.forename: Greg
authors.initials: G
authors.lastname: Sanders
authors.affiliation: Omnia Ecological Services, 722 27th Avenue NW, Calgary, Alberta T2M 2J3, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Charlebois
authors.affiliation: Stantec Consulting Ltd., 200-835 Paramount Drive Stoney Creek, Ontario L8J 0B4, Canada.
authors.forename: Loren D
authors.initials: LD
authors.lastname: Knopper
authors.affiliation: Intrinsik Environmental Sciences Inc., 736 - 8th Avenue SW, Suite 1060, Calgary, Alberta T2P 1H4, Canada. Electronic address: kbresee@intrinsik.com.
authors.forename: Karl E
authors.initials: KE
authors.lastname: Bresee
mesh_terms: D000818:Animals; D003411:Arvicolinae / Q000378:metabolism; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D006838:Hydrocarbons / Q000032:analysis*; D061329:Oil and Gas Fields; D018570:Risk Assessment; D013227:Steam; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004785:Environmental Pollutants; D006838:Hydrocarbons; D013227:Steam; D014874:Water Pollutants, Chemical; C006647:asphalt; D019363:Cytochrome P-450 CYP1A1
keywords: Bitumen; Ecological risk assessment; Ethoxyresorufin-O-deethylase; Red-backed voles; Steam assisted gravity drainage