TEMPORAL VARIATIONS IN ELEMENTAL CONCENTRATIONS OF ATMOSPHERIC AEROSOLS IN MEXICO-CITY

Measurements are reported of elemental concentrations of airborne part iculates in Mexico City and their time variation over a one-week perio d in the spring of 1988. Proton-induced X-ray emission analysis (PIXE) was used to analyse the atmospheric aerosols which were bombarded wit h 2.5 MeV protons from the 12 MV tandem Van de Graaff accelerator at t he Instituto Nacional de Investigaciones Nucleares, ININ. Variations i n the elemental concentrations were observed over the time period stud ied. An intercomparison was made in the case of the element lead with PIXE results obtained at the Crocker Nuclear Laboratory (CNL), Univers ity of California for the same set of samples. Excellent agreement was obtained both for the time variation of the relative concentration an d the absolute lead concentrations. These results give added confidenc e to the protocol adopted at ININ.