Chemical characterization and size distribution of atmospheric particles in urban area : preliminary study

The present work is a preliminary study with the aim of characterize lhe particle size and the chemical composition of aerosols in lhe Charqueadas County in Rio Grande do Sul State, Brazil, in order to better identify lhe sources responsible for alterations in lhe air quality. Seven filters were used for collecting material on thin nucleopore polycarbonate membrane (0,4 11m) during March/1996 to July/1996. X-ray energy dispersive scanning electron microscopy was used to determine the chemical composition of aerosol particles, and 21 elements were then analysed. Particle size distribution was measured by SEM-EDX analysis, and also by automated image technique. Nonhierarchical cluster analysis was applied to identify the types of particles present in lhe samples. This procedure resulted in lhe definition of 8 groups of particles containing Fe, Zn , Si, Al, S, Ca, Na and K, thal revealed lhe chemical heterogeneity of aerosols in Charqueadas County. The particle size analysis showed the predominance (around 80 % of ali analyzed particles) of lhe fraction