Chemical composition of aerosol in Sao Paulo, Brazil: influence of the transport of pollutants

Abstract

Sao Paulo is a Latin American megacity impacted by heavy traffic emissions and also affected by biomass burning and biogenic emissions. To better understand the sources of pollution during a highly polluted period, PM10 samples were collected in an intensive campaign in 2013. The concentrations of particulate matter, organic carbon (OC), elemental carbon (EC), biomass burning tracers (levoglucosan, mannosan, and galactosan), water-soluble ions, and polycyclic aromatic hydrocarbons (PAHs) were determined to identify the main sources affecting the air quality. The PAHs results were compared to an intensive campaign done in 2012. Backward air masses trajectories were used in other to investigate the influence of remote sources. The average benzo[a]pyrene equivalent index (BaPE) values represented a higher cancer risk in 2013 samples than in 2012; the diagnostic ratios indicated vehicular emissions for both campaigns but fresher particles emission for 2013 campaign. During the 2013 campaign, the samples presented good correlations between OC and EC with monosaccharides, suggesting an influence of biomass burning on the carbonaceous species. Levoglucosan to mannosan ratio indicated the influence of sugarcane burning; the backward air masses trajectories suggested transport of aerosol from the sugarcane production region in 60 % of the sampling days.