Long-Term Monitoring of Atmospheric Aerosols in the Amazon Basin: Alta Floresta and Rondônia - aerosol source identification and apportionment
Maria Lúcia
Antunes, UNESP - Unidade Diferenciada Sorocaba/Iperó, malu@sorocaba.unesp.br
(Presenting)
Paulo
Artaxo, Instituto de Física da USP, artaxo@if.usp.br
Long term continuous sampling of atmospheric aerosols was carried out at two different sites in the Amazon Basin: Alta Floresta (9°52´32´´S, 56°05´10´´W) and Rondônia (10°44´54´´S, 62°12´57´´W) from 1992. These sites are heavily affected by biomass burning emissions. Fine and coarse mode aerosol particles were collected using stacked filter units (SFU). Elemental analysis was performed with Particle Induced X-ray Emission (PIXE). Soot carbon and gravimetric mass analysis were also performed. Multivariate statistical techniques were used to study the relationship between aerosol elemental concentrations. At the Alta Floresta and Rondônia sites, during the dry season, a strong component of biomass burning is observed. Concentrations in excess of 600 µg/m3 were measured during the peak of the dry season. For fine mode particles, we observed an average of 63 µg/m3 (Alta Floresta) and 33 µg/m3 (Rondônia). The elemental composition is dominated by organic compounds that accounts for about 70% of the aerosol mass. The major trace element present are K, S, Ca, Si, Fe, Al and Mg with other minor trace elements such as P, Zn, Cl. Potassium and chlorine concentration in Alta Floresta site is higher than Rondônia site, because of predominance of deforestation emissions. Absolute Principal Factor Analysis (APFA) has derived absolute elemental source profiles. APFA showed three aerosol particles components for both sites: biomass burning (soot, fine mode mass concentration, K, Cl), soil dust ( Al, Ca, Ti, Mn, Fe) and natural biogenic aerosol.