Diel and seasonal variations in the chemical composition of biomass burning aerosolReport as inadecuate

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1 MPIC - Max Planck Institute for Chemistry 2 Air Chemistry Group of the Hungarian Academy of Sciences 3 Institute of Materials and Environmental Chemistry CRC 4 Instituto de Fisica

Abstract : Fine aerosol particles were collected separately during daytime and nighttime at a tropical pasture site in Rondônia, Brazil, during the burning and dry-to-wet transition period in 2002. Total carbon TC and water-soluble organic carbon WSOC were measured by evolved gas analysis EGA. Based on the thermochemical properties of the fine aerosol, the relative amounts of the volatile and refractory compounds were estimated. It was found that the thermally refractory possibly higher molecular weight compounds dominated the TC composition. Their contribution to TC was higher in the daytime than in the nighttime samples. The relative share of WSOC also showed a statistically significant diel variation as did its refractory fraction. Anhydrosugars and phenolic acids were determined by GC-MS and their diel variation was studied. Based on the decrease of their relative concentrations between the biomass burning and transition periods and their distinctly different diel variations, we suggest that the phenolic acids may undergo chemical transformations in the aerosol phase, possibly towards more refractory compounds humic-like substances, HULIS, as has been suggested previously. These conclusions are supported by the results of the thermally assisted hydrolysis and methylation gas chromatography-mass spectrometry of the same filter samples.

Author: A. Hoffer - A. Gelencsér - M. Blazsó - P. Guyon - P. Artaxo - M. O. Andreae -

Source: https://hal.archives-ouvertes.fr/


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