Characterisation and source identification of PM10 aerosol samples collected with a high volume cascade impactor in Brisbane (Australia)

PM10 (particulate matter with aerodynamic diameter < 10 mu m) samples of Br isbane air were collected and fractionated into six size fractions (< 0.5, 0.5-0.61, 0.61-1.3, 1.3-2.7, 2.7-4.9 and 4.9-10 mu m) with a high volume ca scade impactor. The chemical composition of the samples was analysed by tec hniques including Ion Beam Analysis. On average, 42% of the aerosol mass is in the > 2.7-mu m size fraction, with the <0.5-mu m size fraction also con tributes 41% of the aerosol mass. The composition of the < 1.3-mu m aerosol s is significantly different to that of the > 1.3-mu m aerosols. The aeroso l mass and concentrations of chemical components related to human activitie s show a bimodal size-distribution pattern, with most of the mass in the ac cumulation range (< 0.65 mu m). The size geometric mean of aerosol mass is 0.96 mu m in the samples collected from an industrial/residential site, and is 1.74 mu m in the samples collected from a suburban site. The size geome tric mean of concentrations of chemical components related to human activit ies ranges from 0.16 to 0.57 mu m. The concentrations of crustal matter and sea salt show a unimodal size-distribution pattern, and with geometric mea ns of 3.73 and 4.12 mu m, respectively. Four source factors were resolved b y multivariate analysis techniques for the size-fractionated aerosol sample s, namely the soil, sea salt, organics and vehicular exhausts factors. The source fingerprints of the factors vary in the size ranges and have implica tions on the formation and dispersal processes of the particles. On average , the soil and sea salt factors contribute more than 80% of the aerosol mas s in the > 2.7-mu m fractions, while the organics and vehicular exhausts fa ctors explain almost all the aerosol mass in the < 0.61-mu m fractions. (C) 2000 Elsevier Science B.V. All rights reserved.