Size selective elemental concentration of aerosol particles using SR-XRF

MARIANA ACHAD; MARÍA LAURA LÓPEZ; SERGIO CEPPI; GUSTAVO G. PALANCAR; GERMÁN TIRAO; BEATRIZ M. TOSELLI

Campinas

Encuentro; 23ª Reunião Anual de Usuários; 2013

LNLS

Trace metals are ubiquitous in urban ambient air, with mass concentrations in the range of a few g m-3 down to less than a few ng m-3. To measure such low concentrations represents a challenge for chemical and physical analysis. In this study, ambient aerosols were collected in Córdoba (Argentina) from April 2010- June 2012, in 3-h intervals and four size fractions, using a SIOUTAS impactor (SKC). In addition, 24 h samples in the PM2.5 fraction were collected with the DPS-SKC impactor. Aerosol samples were excited with a monochromatic excitation beam at two different energies both, with and without the presence of air to obtain size-segregated elemental aerosol mass concentrations for Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu and Zn under the selected experimental conditions. The high sensitivity of SR-XRF allowed for very low detection limits for most of the above elements. The data obtained with this technique aims to illustrate that there is a considerable gain of relevant information when time resolution for measurements is increased from 1 day to 3 h. The individual size fractions of a specifc element seems to indicate di®erent short-term patterns although further analysis need to be performed. The aims of this work were: (1) to present detailed source apportionment results for PM2.5 and the minor fractions (with time resolution) measured in the city, and (2) to compare with samples collected from July 2009-April 2010 to verify possible seasonal and inter annual variability.