Avaliação do impacto de queima de biomassa nas propriedades físicas-químicas de aerossóis atmosféricos no Pantanal de Mato Grosso

• Autor(a) principal: Weber, Alfredo dos Santos
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFMT
• Texto Completo: http://ri.ufmt.br/handle/1/5507
• topic: Espectroscopia de energia dispersiva de raios-X; Dependência espectral de propriedades óticas; Modos de combustão; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA; X-ray dispersive energy spectroscopy; Spectral dependence of optical properties; Combustion modes

The Brazilian Pantanal is a complex landscape of great importance for the control of water flow in the Paraguay River Basin with growing agricultural and livestock production. The region has been impacted by deforestation and fires, emitting a crescent amount of biomass burning aerosols to the atmosphere with health and climate negative consequences. The physical-chemical and optical properties of aerosols at the Brazilian Pantanal were investigated to evaluate the impact of burning biomass at the dry season of 2012. This study focused on the analysis of meteorological and environmental events on the optical properties and the concentration of chemical elements of aerosols, relating the evolution of these characteristics in the dry season. Also, the aerosols were classified chemically and optically using Angstrom Matrix cluster analysis to verify the more common groups and the relation between chemical and optical characteristics. Changes in spectrum choice have also been assessed that effect the population of these optical groups Results indicate a dominance of coarse particles related to biogenics (P, K and Mg at coarse mode) and crustal elements (Al, Si, Ca and Fe) at the beginning of the dry season, and finer elemental carbon and biomass burning elements (S, Zn and K at fine mode) at the end of the season. Values of optical properties as Aerosol Optical Depth (AOD), Single Scattering Albedo (SSA) and Absorption, Scattering and Extinction Angstrom Exponents (AAE, SAE and EAE) were higher with the increase of biomass burning emissions during fires episodes. The optical classification shown a seasonally variation of more frequent groups, at the early dry season, species at low AAE e SAE were predominant has been labeled as Coated Large Particles and Biogenic, and in the advanced winter and beginning of Spring, the classes related to the elemental carbon as EC, OC/EC and Dust/EC with higher AAE and SAE. This is consequence of reduction of particle size and increase of organic and elemental carbon in the aerosols microstructure. There is a qualitatively relation between the optical and chemical classification, and the frequency of elemental and organic carbon groups was related qualitatively to the black carbon concentration at the filters. Changes in the choice between combinations of wavelengths for Absorption Angstrom Exponents can lead to very different results for long waves; however, there are no significant changes for short waves and between intermediate waves due to the chemical nature of the aerosols prevalent in the sampling. The scattering Angstrom exponent does not suffers from the same variation, with correlations always close to the ideal between spectral combinations. These results indicate that the aerosol composition and optical properties of the atmosphere during the dry season were impacted by land cover change, biomass burning, and fossil fuel emissions from Cuiaba, located more than 100 km away. These data highlight the importance of human impacts and long-range transport to the regional haze measured in the Northern Pantanal.