Source apportionment of time- and size-resolved ambient particulate matter

Size- and time-resolved particulate matter samples collected using eight-stage Davis Rotating-drum Universal-size-cut Monitoring (DRUM) impactors at the Washington-Dulles International Airport were analyzed for the elemental composition using synchrotron X-ray fluorescence. A physically realistic three-way factor analysis model consisting of the outer products of matrices (profiles) times a vector of mass contributions was applied to these data. The problem was solved using a weighted alternating least squares method. Five major emission sources: soil, road salt, aircraft landings, transported secondary sulfate, and local sulfate/construction were identified. The study shows that time- and size-resolved RDI data can assist in the identification of the airport emission sources and atmospheric processes leading to the observed ambient concentrations.