Relationship between aerosol particles chemical composition and optical properties in the City of São Paulo

Abstract

Air quality in the São Paulo Metropolitan Area (SPMA) is determined mainly by local pollutants, especially vehicles. Over recent years, air quality has improved, with the exception of fine particulate matter (PM) and tropospheric ozone, which still have high concentrations, causing problems to human health and can influence the climate, changing the radiative balance of the atmosphere. Understanding the impacts of aerosols on the environment and climate depends on research and in conjunction with other parameters such as the optical properties of the particles. This study aims to characterize fine particulate matter (PM2.5) over 2 years of sampling at the School of Arts, Sciences and Humanities (EACH) of the University of São Paulo, located in the East Zone of the state capital, relating chemistry composition data and optical parameters, such as optical aerosol depth (AOD), Angstrom exponent (AE) and single scattering albedo (SSA), parameters provided by a solar photometer installed at EACH, which is part of AERONET worldwide network of photometers. Aerosol samplings will be performed using a Partisol sampler model 2025i (Fapesp 2012 / 24689-5 process) and a cascade impactor, and the characterization will be through the use of complementary techniques: gravimetry, X-ray fluorescence and ionic chromatography. The optical data in the atmospheric column are available from the AERONET website and surface (SSA) data will be collected using a nephelometer. AOD data derived from MODIS sensors on board the Terra and Aqua satellites will also be analyzed. In this research project we intend to use the different databases to arrive at results that complement each other and provide information in order to determine the main chemical characteristics of the emitted particles in the atmosphere of the SPMA and relate their optical properties, using surface and data integrated vertically in the atmospheric column, trying to show the relationship between techniques and instruments. At the end of the study, the sources of aerosols can be identified through the application of statistical models and also the determination of the dominant particles that contribute to changes in the radiative balance of the atmosphere, since the physicochemical characteristics of the particles are directly related to their potential interference in climate. (AU)