Trends of Aerosol Particles in Buenos Aires

BAUMGARDNER, DARREL; BINIMELIS DE RAGA, GRACIELA; ULKE, ANA GRACIELA; TORRES BRIZUELA, MARCELA; CANCELADA, MAITE

Natal

Congreso; 13th Quadrennial iCACGP Symposium and 13th IGAC Science Conference on Atmospheric Chemistry; 2014

International Commission on Atmospheric Chemistry and Global Pollution, iCACGP

The longest continuous measurement campaign ever to be conducted in Buenos Aires was carried out in 2011 to determine certain characteristics of particulate pollution. This was a collaboration between universities in Mexico and Argentina. Measurements of particle mass (PM10), equivalent black carbon (eBC), condensation nuclei (CN) concentration and mass of particle bound poly aromatic hydrocarbons(PPAH) were made near the east central area of Buenos Aires from April 15 ?December 6, 2011. The light scattering and absorption coefficients were also measured from which the extinction coefficient and single scattering albedo were derived. Vertical profiles were made of aerosol backscattering using a ceilometer with a range of 7.5 km. Aerosol optical depth was measured with a nearby AERONETphotometer. Simultaneous measurements of wind and state variables were also made.The air mass history was determined every six hours using back trajectory analysis and the hourly boundary layer height was derived from the ceilometer profiles. Distinctive trends are detected in the CN, PPAH and eBC concentrations, increasing from fall to winter, with maxima at the winter equinox of 55000 cm-3, 500 ng m-3and 400 ng m-3 in CN, PPAH and eBC, respectively. The diurnal variations are related to the air mass origin prior to reaching the measurement site that was located on the roof of a university building at an altitude of 30 m a.s.l. Strong correlations between the CN, PPAH and eBC suggest that the majority of particles come from local combustion sources. The diurnal variations indicate that this source is from vehicular traffic, although the nearby power plant that uses fuel-oil, was another possible source of increased particle concentrations. Evaluation of the vertical profiles of backscattering show the daily growth and collapse of the mixed layer that are dependent upon the source of the air mass at the measurement site and the meteorological conditions. The highest particle concentrations are at times associated with a shallow mixed layer but this was not a consistent pattern.