A study of elemental contents in atmospheric aerosols in Mexico City

Abstract

Samples of airborne particulate matter with sizes between 0 and 15 µm in Mexico City were analyzed in order to evaluate its elemental composition. Samples were collected during one week in August 1990, using a Stacking Filter Unit (SFU), resulting in the separation between particles having sizes 2.5 to 15 µm (coarse), and smaller than 2.5 µm (fine). The collection period was from 6:00 to 12:00 hrs. Analyses with proton Induced X-ray Emission (PIXE) allowed the quantification of elements with atomic number greater than 10; Proton Elastic Scattering Analysis (PESA) gave information on hydrogen contents; and elemental carbon (soot) was measured by means of the Laser Integrating Plate Method (LIPM). Also, the gravimetric mass of the deposited matter was measured. The results permit then the possible identification of sources of the measured elements, with the help of Cluster Analysis. Moreover, the comparison of the gravimetric mass with the mass reconstructed from the elemental analysis supports the values obtained in the latter.