10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Fine Particles Sources in São Paulo: Evolution of Sources Identification for the Last 30 Years
MARIA DE FATIMA ANDRADE, Regina Maura Miranda, Luis Mendes Santos, Yann Marien, University of Sao Paulo
Abstract Number: 413 Working Group: Air Quality in Megacities: from Sources to Control
Abstract Brazil relies on hydroelectricity for more than 75% of its electricity and the transport sector is the main emitter of pollutants from the energy sector. This can be observed mainly in the capital cities of the country where the vehicular emissions are the main source of atmospheric aerosols. Brazil has two metropolitan areas with more than 10 million inhabitants (Sao Paulo and Rio de Janeiro). The Metropolitan Area of Sao Paulo (MASP) is the biggest metropolitan area of the country with more than 21 million inhabitants, corresponding to more than 11% of the total population of the country. The vehicular fleet, composed of more than 7 million units, is responsible for more than 97% of CO, 67.5% of NOx and 79% of HC emissions. The vehicles can run on ethanol, gasohol (gasoline with 25% ethanol) and diesel (or biodiesel). The fine particles (PM2.5) and ozone are the pollutants that present values above the air quality standards in compliance with the Sao Paulo State legislation. In the beginning of the 80´s the evaluation of atmospheric aerosols sources responsibility was mainly based on the application of the so called receptor models: chemical mass balance, factor analysis, principal component analysis and others. In MASP the receptor models started to be applied after initiating the capability of analyzing trace-elements components through x-Ray Fluorescent analysis. The receptor models showed the importance of the industrial sector and vehicular fleet in the 80´s and throughout the years there was a change in the sources impacts on the air quality. The changes were due to variations in economic situation, characteristics of the city evolving from industrialized to tertiary sector (commerce, services) which is now the dominant employer. The implementation of standards for pollutants emission by the vehicular fleet, the establishment of restrictions to the traffic of vehicles in the downtown area and the modification from fuel oil to electricity in the industries changed the drivers of the pollutants emission. Many uncertainties related to the source apportionment were due to the statistical methods. We did a historical analysis of the sources profile evolution comparing those profiles identified through Absolute Principal Component Analysis with Positive Matrix Factorization. To do this we recovered the oldest database available and remodeled the statistical analysis of the data. We observed that V and Ni, used as tracers for burning of fuel in industries, are not well correlated. Meanwhile, P and S, are now very well correlated and can be used as tracers for the mobile source, mainly diesel. We found the presence of these elements at the same ratio at bus terminals and trucks garage. The participation of the mobile source to total PM2.5 has increased from 40-45% in 80´s to 45-60% in 2013-2014. The combination of different receptor models continues to be the best practice to analyze the importance of the sources to the concentration of particulate matter. The air quality has not improved as expected due to the lack of coordination among urban, transport and traffic policies, resulting in more time for commuting in large cities, due to traffic congestion and the increase in the use of private cars.