Articles | Volume 14, issue 10
Atmos. Chem. Phys., 14, 5073–5087, 2014
Atmos. Chem. Phys., 14, 5073–5087, 2014

Research article 23 May 2014

Research article | 23 May 2014

An airborne assessment of atmospheric particulate emissions from the processing of Athabasca oil sands

S. G. Howell1, A. D. Clarke1,2, S. Freitag2, C. S. McNaughton1,*, V. Kapustin1, V. Brekovskikh1, J.-L. Jimenez3, and M. J. Cubison3,** S. G. Howell et al.
  • 1Department of Oceanography, University of Hawaii, Honolulu, Hawaii, USA
  • 2Department of Oceanography, University of Hawaii, Honolulu, Hawaii, USA
  • 3Cooperative Institute for Research in the Environmental Sciences and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado, USA
  • *now at: Golder Associates Ltd., Saskatoon, Saskatchewan, Canada
  • **now at: Tofwerk AG, Thun, Switzerland

Abstract. During the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign, two NASA research aircraft, a DC-8 and a P-3B, were outfitted with extensive trace gas (the DC-8) and aerosol (both aircraft) instrumentation. Each aircraft spent about a half hour sampling air around the oil sands mining and upgrading facilities near Ft. McMurray, Alberta, Canada. The DC-8 circled the area, while the P-3B flew directly over the upgrading plants, sampling close to the exhaust stacks, then headed downwind to monitor the aerosol as it aged. At short range, the plume from the oil sands is a complex mosaic of freshly nucleated ultrafine particles from a SO2- and NO2-rich plume, soot and possibly fly ash from industrial processes, and dust from dirt roads and mining operations. Shortly downwind, organic aerosol appears in quantities that rival SO4, either as volatile organic vapors condense or as they react with the H2SO4. The DC-8 pattern allowed us to integrate total flux from the oil sands facilities within about a factor of 2 uncertainty that spanned values consistent with 2008 estimates from reported SO2 and NO2 emissions, though there is no reason to expect one flyby to represent average conditions. In contrast, CO fluxes exceeded reported regional emissions, due either to variability in production or sources missing from the emissions inventory. The conversion rate of SO2 to aerosol SO4 of ~6% per hour is consistent with earlier reports, though OH concentrations are insufficient to accomplish this. Other oxidation pathways must be active. Altogether, organic aerosol and black carbon emissions from the oil sands operations are small compared with annual forest fire emissions in Canada. The oil sands do contribute significant sulfate and exceed fire production of SO2 by an order of magnitude.

Final-revised paper