PIXE ANALYSIS OF ATMOSPHERIC AEROSOLS FROM A SIMULTANEOUS 3-SITE SAMPLING DURING THE AUTUMN OF 1993 IN MEXICO-CITY

A simultaneous three site aerosol sampling was performed during the au tumn of 1993 in Mexico City. Stacked filter units of the Davis design were used to collect atmospheric aerosol samples, providing two sample s per unit and separating particles into ''coarse'' and ''fine'' accor ding to size. The samples were taken simultaneously at three different sites from 6:00 to 12:00 h, on seven alternate days. Elemental concen trations of aerosol contents were determined by PIXE analysis performe d both at the Florida State University and at the ININ facilities. 18 elements were found systematically in most of the samples, including S , Cl and heavy metals. Fine mass concentrations of sulfur were more ab undant than coarse mass concentrations at all three sites. Enrichment factors and correlation matrices were computed to identify possible po llutant sources.