Aerosol composition and source apportionment in Santiago de Chile

Santiago de Chile, Sao Paulo and Mexico City are Latin American urban areas that suffer from heavy air pollution. In order to study air pollution in S antiago area, an aerosol source apportionment study was designed to measure ambient aerosol composition and size distribution for two downtown samplin g sites in Santiago. The aerosol monitoring stations were operated in Gotuz o and Las Condes during July and August 1996. The study employed stacked fi lter units (SFU) for aerosol sampling, collecting fine mode aerosol (dp < 2 mu m) and coarse mode aerosol (2 < dp < 10 mu m) on polycarbonate filters. Aerosol mass (PM10 mass of particles smaller than 10 mu m) and black carbo n concentration were also measured. Particle-Induced X-ray Emission (PIXE) was used to measure the concentration of 22 trace elements at levels below 0.5 ng m(-3). Quantitative aerosol source apportionment was performed using Absolute Principal Factor Analysis (APFA). Very high aerosol concentration s were observed (up to 400 mu g/m(3) PM10). The main aerosol particle sourc es in Santiago are resuspended soil dust and traffic emissions. Coarse part icles account for 63% of PM10 aerosol in Gotuzo and 53% in Las Condes. A ma jor part of this component is resuspended soil dust. In the fine fraction, resuspended soil dust accounts for 15% of fine mass, and the aerosols assoc iated with transportation activities account for a high 64% of the fine par ticle mass. Sulfate particle is an important component of the aerosol in Sa ntiago, mainly originating from gas-to-particle conversion from SO2. In the Gotuzo site, sulfates are the highest aerosol component, accounting for 64 .5% of fine mass. Direct traffic emissions are generally mixed with resuspe nded soil dust. It is difficult to separate the two components, because the soil dust in downtown Santiago is contaminated with Pb, Br, Cl, and other heavy metals that are also tracers for traffic emissions. Residual oil comb ustion is observed, with the presence of V, S and Ni. An aerosol components from industrial emissions is also present, with the presence of several he avy metals such as Zn, Cu and others. A factor with molybdenum, arsenic, co pper and sulfur was observed frequently, and it results from emissions of c opper smelters. (C) 1999 Elsevier Science B.V. All rights reserved.