Characterization of urban aerosol in Campinas, Sao Paulo, Brazil

A quantitative study was performed in Campinas, Brazil. Measurements were taken on an avenue with intense vehicle traffic in the city's downtown area from August 2003 to August 2004. A dichotomous sampler was employed for PM2.5 and PM10. Samples were collected for 24 h at 3-day intervals. In addition, seasonal variations were investigated, using a MOUDI cascade impactor and VOC adsorption tubes, during a specific 5-day period in the summer of 2003 (December) and the winter of 2004 (August). The polycarbonate filters were analyzed by gravimetry, Particle Induced X-ray Emission (PIXE), ion chromatography and reflectance, to identify the mass concentration, elemental composition, ions and elemental carbon mass, respectively. The quartz filters were analyzed by gravimetry and thermal combustion carbon analysis to identify the mass concentration and carbon mass. Results showed an annual mean of 20.85, 10.68 and 10.17 mu g m(-3) for PM10, PM2.5 and PM2.5-10, respectively. The cascade impactor provided mass distribution and revealed differences between the two seasons. The size distribution for chemical elements indicated soil-derived elements in the coarse fraction. PM winter concentrations were expected to be higher than those in summer, but that was not the case during the days of this study, when summer and winter concentrations were almost identical The PIXE analysis revealed metals and metal compounds, soil-derived elements, sulfates, carbonates, chlorides and other anthropogenic air-borne particles, supposing molecules in their usual composition. An analysis of the VOCs revealed benzene, toluene, m, p-xylene, n-hexane, 2-metilhexane and n-nonane. A mass balance analysis indicated different classes, among which elemental carbon was the most abundant, followed by organic carbon, soil elements and industrial sources. (C) 2007 Elsevier B.V. All rights reserved.