Caracterização fisico-química de aerossóis no experimento Goamazon2014/15: a interação entre emissões urbanas de Manaus com emissões naturais da floresta
Atmospheric aerosols play an important role in human-induced climate change because of their effects on solar insolation and cloud processes. The direct and indirect effects of aerosols on Amazonian climate have been studied in recent years. The Amazonian forest is linked to the mechanisms that c...
| Autor principal: | Silva, Glauber Guimarães Cirino da |
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| Grau: | Tese |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/12681 http://lattes.cnpq.br/4792139391237534 |
| Resumo: |
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Atmospheric aerosols play an important role in human-induced climate change because of their
effects on solar insolation and cloud processes. The direct and indirect effects of aerosols on
Amazonian climate have been studied in recent years. The Amazonian forest is linked to the
mechanisms that control atmospheric concentration of critical trace gases and particles, changing
the physical chemical and biological properties of this environment. The natural biogenic sources
emitted by vegetation are linked to the mechanisms of cloud microphysics and precipitation
production, to the atmospheric radiation balance and to nutrient cycling, which in turn may affect
important processes in the ecosystem. However, the sharp population growth of large urban
centers in the Central Amazon has interfered with these mechanisms in a still unknown way. The
understanding of these natural processes that regulate the atmospheric composition in Amazonia
is an essential step for the establishment of a sustainable development strategy in the region.
Here, we show for the first time the impact of urban emissions of the Manaus on the chemical
and physical composition of natural aerosols in the Central Amazon. Using emission ratios of
inert chemical species and a simulated set of air masses back-trajectories over the experimental
sites, the chemical signature of the pollution plume was determined and thus the effects
generated on the physico-chemical properties of aerosols, downwind of the city. An increase
corresponding to 8 to 10 and 2 to 4 multiplicative factors in the total particle concentration (CN),
black carbon (BC) and ozone (O3) when compared to natural forest conditions. On the average it
was observed that the Manaus urban plume emission affects areas downwind with particle
number usually above 3000-4000 cm-3 and BC concentrations often above 1000 ngm-3. The SO2
concentrations are in the range of 0.20-0.30 ppbv during the wet season, but can reach up to 0.60
ppbv in the dry season, contributing greatly to the fine fraction and greater increase scattering. A
significant increase of around 40% in the concentration of organic aerosols (OA) attributed to the
formation of secondary organic aerosol during transportation 4-6h between experimental sites
was found. Also, a clear evolution in the distribution of particle size of ~ 50-100nm (Aitken to
accumulation mode), and up to 30% reduction in the total concentration of aerosols (CN) was
found, attributed here, especially to the formation of secondary organic aerosols (SOA),
condensation of inorganic materials and of organic oxidation products. In addition to the changes
in the chemical composition of natural aerosol of the pristine forest, various optical properties
have also been changing with potential effects on the ecosystem. Absorption and scattering
coefficients increased by multiplicative factors 3.0 and 1.8 in respect to the pristine forest
conditions, respectively. The SSA, that is a key parameter in determining the climatic effects of
aerosols, is strongly altered and reduced by about 10-15% under the direct influence of the city's
emissions. The observed changes in the characteristics of the population of aerosols downwind
the city (size distribution, quantity and chemical composition) may be changing significantly
important properties of clouds, such as albedo and precipitation, thus contributing to impacts on
the hydrological cycle and changes in radiative transfer rates, with consequences (indirect) still
unknown for photosynthesis rates. |