Abstract
A field program was conducted to determine the transformation of sulfur dioxide to particulate sulfate in the emissions from oil sands extraction plants near Fort McMurray, Alberta. Measurements were made under cold winter conditions during March and December 1983 and warm summer conditions during June 1984. The transformation rates of SO2 to SO4 were determined by tracking a single parcel of air emitted from the stack using an instrumented aircraft. Two methods were employed: the aerosol excess volume production and chemical analysis of particles collected on filters. The conversion rate varied from 0 to 2.81 percent per hour in the winter and 0 to 6.01 percent per hour in the summer. The significant oxidation of SO2 to SO4 observed during wintertime and early morning periods in the summer, and the considerable amounts of excess aerosol volume production of particles larger than 1.0 μm suggest that heterogeneous conversion may be appreciable close to the emission source, when the SO2 and aerosol concentrations are high and the aerosol surface is wet.