Elemental analysis of particulate matter and source identification in Lisbon

A Gent PM10 air sampler with stacked filter units was used to collect size-fractionated aerosol samples in Lisbon between October 1993 and January 1995. Sampling was made on a twice-a-week basis (one weekend day and one midweek day). The filter loads were measured by gravimetry and elemental analyses were carried out by PIXE and INAA techniques. The complementarity of the techniques allowed the determination of the concentrations of 22 elements in more than 30% of all samples. Monitoring of NO, NO2, CO and SO2 concentrations was also performed. Time variations for both total particulate mass and elemental concentrations are presented Weekend and midweek data are compared. Enrichment factors were calculated for the fine and coarse fractions and the ratios between the two fractions were derived. Principal components analysis was applied to the identification of aerosol sources. Correlations were found between the gases and coarse particle elemental concentrations. A tendency for a concentration increase in the total suspended particle mass was observed at the end of each year. The concentration pattern for the rare earth elements measured was altered owing to the activity of a nearby refinery. (C) 1998 John Wiley & Sons, Ltd.