Karla M. Longo

Large‐scale aerosol source apportionment in Amazonia

Aerosol particles were collected aboard two Brazilian Bandeirante EMB 110 planes, and the University of Washington Convair C-131A aircraft during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) field project in the Amazon Basin in August and September 1995. Aerosols were collected on Nuclepore and Teflon filters. Aerosol size distribution was measured with a MOUDI cascade impactor. Sampling was performed mostly over areas heavily influenced by biomass burning smoke. Particle-induced X ray emission (PIXE) was used to measure concentrations of up to 20 elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr, and Pb). Black carbon (BC) and gravimetric mass analysis were also performed. Instrumental neutron activation analysis (INAA) determined the concentrations of about 15 elements on the Teflon filters. Electron probe X ray microanalysis (EPMA) was used to analyze individual aerosol particles. The average aerosol mass concentration was 105 μg m−3, with a maximum of 297 μg m−3. Black carbon (BC) averaged 5.49 μg m−3, or 1–7% of the aerosol mass load. Five aerosol components were revealed by absolute principal factor analysis: (1) a biomass burning component (responsible for 54% of the aerosol mass and associated with BC, K, Cl, Zn, I, S, Br, Rb, aerosol mass concentration, and other elements); (2) a soil dust aerosol component (15.6% of the aerosol mass); (3) a natural biogenic component (18.7% of the aerosol mass and associated with P, K, S, Ca, Sr, Mg, Mn, Cu and Zn); (4) a second soil dust (5.7% of the aerosol mass and enriched in Si, Ti, and Fe); and (5) a NaCl aerosol component (5.9% of the aerosol mass with Na, Cl, Br, and iodine). Electron microscopy analysis of individual aerosol particles confirmed these five aerosol types. Organic material dominated the aerosol mass and the number concentration of airborne particles. Aerosol size distributions show that the fine mode accounts for 78% of the aerosol mass, centered at 0.33 μm aerodynamic diameter. The coarse mode accounts for 22% of the mass, centered at about 3.2 μm. Black carbon size distributions show a consistent picture, with a mass median diameter centered at about 0.175-0.33 μm aerodynamic diameter. This study suggests that for modeling the optical properties of aerosol in the Amazon Basin, it is essential to use a model that includes the optical and physical properties of at least two aerosol components other than the biomass burning aerosol, namely, natural biogenic aerosol and soil dust.

Impact on human health of particulate matter emitted from burnings in the Brazilian Amazon region

OBJECTIVE To analyze the impact on human health of exposure to particulate matter emitted from burnings in the Brazilian Amazon region. METHODS This was an ecological study using an environmental exposure indicator presented as the percentage of annual hours (AH%) of PM2.5 above 80 microg/m3. The outcome variables were the rates of hospitalization due to respiratory disease among children, the elderly and the intermediate age group, and due to childbirth. Data were obtained from the National Space Research Institute and the Ministry of Health for all of the microregions of the Brazilian Amazon region, for the years 2004 and 2005. Multiple regression models for the outcome variables in relation to the predictive variable AH% of PM2.5 above 80 microg/m3 were analyzed. The Human Development Index (HDI) and mean number of complete blood counts per 100 inhabitants in the Brazilian Amazon region were the control variables in the regression analyses. RESULTS The association of the exposure indicator (AH%) was higher for the elderly than for other age groups (beta = 0.10). For each 1% increase in the exposure indicator there was an increase of 8% in child hospitalization, 10% in hospitalization of the elderly, and 5% for the intermediate age group, even after controlling for HDI and mean number of complete blood counts. No association was found between the AH% and hospitalization due to childbirth. CONCLUSIONS The indicator of atmospheric pollution showed an association with occurrences of respiratory diseases in the Brazilian Amazon region, especially in the more vulnerable age groups. This indicator may be used to assess the effects of forest burning on human health.

Química atmosférica na Amazônia: a floresta e as emissões de queimadas controlando a composição da atmosfera amazônica

The understanding of the natural processes that regulate atmospheric composition in Amazonia is critical to the establishment of a sustainable development strategy in the region. The large emissions of trace gases and aerosols during the dry season, as a result of biomass burning, profoundly change the composition of the atmosphere in most of its area. The concentration of trace gases and aerosols increases by a factor of 2 to 8 over large areas, affecting the natural mechanisms of several key atmospheric processes in the region. Cloud formation mechanisms, for instance, are strongly affected when the concentration of cloud condensation nuclei (CCN) changes from 200-300 CCN/cc in the wet season to 5,000-10,000 CCN/cc in the dry season. The cloud droplet radius is reduced from values of 18 to 25 micrometers in the wet season to 5 to 10 micrometers in the dry season, suppressing cloud formation and the occurrence of precipitation under some conditions. Ozone is a key trace gas for changes in the forest health, with concentrations increasing from 12 parts per billion (ppb), at the wet season, to values as high as 100 ppb (in the dry season in areas strongly affected by biomass burning emissions). At this level, ozone could be damaging the vegetation in regions far from the emissions. The atmospheric radiation balance is also strongly affected, with a net loss of up to 70% of photosynthetic active radiation at the surface.

A convective kinematic trajectory technique for low-resolution atmospheric models

This paper presents a simple methodology to take into account the subgrid effects of wet convective processes to trace vertical motion of air parcels for low-resolution atmospheric models. Such models are used for wind field simulations that serve as input for trajectory models. Air parcels in moist convective regions can thus be vertically transported to the cumulus top level with the short timescale associated with cumulus updrafts. Two cases are presented: wet and dry seasons in Amazonia, showing the differences of trajectories followed by air parcels with and without the methodology. The implications for the interpretation of air chemistry measurements are discussed, and an example using LBA/CLAIRE data is used to point out the usefulness of the convective kinematic trajectory technique presented here.

Air pollution and hospital admissions for respiratory diseases in the subequatorial Amazon: a time series approach

The objective of the study is to evaluate the effect of the daily variation in concentrations of fine particulate matter (diameter less than 2.5 microm--PM2.5) resulting from the burning of biomass on the daily number of hospitalizations of children and elderly people for respiratory diseases, in Alta Floresta and Tangará da Serra in the Brazilian Amazon in 2005. This is an ecological time series study that uses data on daily number of hospitalizations of children and the elderly for respiratory diseases, and estimated concentration of PM2.5. In Alta Floresta, the percentage increases in the relative risk (%RR) of hospitalization for respiratory diseases in children were significant for the whole year and for the dry season with 3-4 day lags. In the dry season these measurements reach 6% (95%CI: 1.4-10.8). The associations were significant for moving averages of 3-5 days. The %RR for the elderly was significant for the current day of the drought, with a 6.8% increase (95%CI: 0.5-13.5) for each additional 10 microg/m3 of PM2.5. No associations were verified for Tangará da Serra. The PM2.5 from the burning of biomass increased hospitalizations for respiratory diseases in children and the elderly.

Associação entre material particulado de queimadas e doenças respiratórias na região sul da Amazônia brasileira

OBJETIVO: Investigar os efeitos de curto prazo da exposicao ao material particulado de queimadas da Amazonia na demanda diaria de atendimento ambulatorial por doencas respiratorias de criancas e de idosos. METODOS: Estudo epidemiologico com delineamento ecologico de series temporais. Os registros diarios de atendimento ambulatorial foram obtidos nas 14 unidades de saude do municipio de Alta Floresta, Mato Grosso, regiao sul da Amazonia brasileira, no periodo de janeiro de 2004 a dezembro de 2005. Informacao sobre os niveis diarios de material particulado fino foi disponibilizada pelo Instituto Nacional de Pesquisas Espaciais. Para controlar possiveis fatores de confusao (situacoes nas quais uma associacao nao causal entre exposicao e doenca e observada devido a uma terceira variavel), foram adicionadas ao modelo variaveis referentes a tendencia temporal, sazonalidade, temperatura, umidade relativa do ar, precipitacao pluviometrica e efeitos de calendario (como ocorrencia de feriados e finais de semana). Utilizou-se regressao de Poisson via modelos aditivos generalizados. RESULTADOS: Um incremento de 10 µg/m³ nos niveis de exposicao ao material particulado esteve associado a aumentos de 2,9 e 2,6% nos atendimentos ambulatoriais por doencas respiratorias de criancas no 6o e 7o dias subsequentes a exposicao. Nao foram encontradas associacoes significativas nos atendimentos de idosos. CONCLUSOES: Os resultados sugerem que os niveis de material particulado das queimadas na Amazonia estao associados a efeitos adversos a saude respiratoria de criancas.

Correlation between smoke and tropospheric ozone concentration in Cuiabá during Smoke, Clouds, and Radiation‐Brazil (SCAR‐B)

Ozone soundings launched from Cuiaba between August 16 and September 10, 1995, during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) experiment show an enrichment of tropospheric ozone when compared with average wet season values and also present a great variability in concentrations depending on the dominant circulation pattern. Smoke tracers, such as aerosol optical thickness, measured from a Sun photometer installed at the Instituto Nacional de Pesquisas Espaciais-Cuiaba site, and black carbon ground measurements, also show an enhancement of smoke during the same period. Although there is a connection between the enrichment of the tropospheric ozone around Cuiaba during the dry season and smoke from biomass burning, the correlation between ozone and smoke indicates different behavior in different periods. Trajectory analyses suggest that the strong ozone peak measured in the period between August 26 and 29, 1995, may be associated not only with direct biomass-burning emissions but also with urban/industrial emissions from big cities on the coast of Brazil and recirculation of old smoke. This view is confirmed by measurements made from the Cloud Lidar System instrument aboard the ER-2 aircraft.

Methane airborne measurements and comparison to global models during BARCA

[1] Tropical regions, especially the Amazon region, account for large emissions of methane (CH_4). Here, we present CH_4 observations from two airborne campaigns conducted within the BARCA (Balanco Atmosferico Regional de Carbono na Amazonia) project in the Amazon basin in November 2008 (end of the dry season) and May 2009 (end of the wet season). We performed continuous measurements of CH_4 onboard an aircraft for the first time in the Amazon region, covering the whole Amazon basin with over 150 vertical profiles between altitudes of 500 m and 4000 m. The observations support the finding of previous ground-based, airborne, and satellite measurements that the Amazon basin is a large source of atmospheric CH_4. Isotope analysis verified that the majority of emissions can be attributed to CH_4 emissions from wetlands, while urban CH_4 emissions could be also traced back to biogenic origin. A comparison of five TM5 based global CH_4 inversions with the observations clearly indicates that the inversions using SCIAMACHY observations represent the BARCA observations best. The calculated CH_4 flux estimate obtained from the mismatch between observations and TM5-modeled CH_4 fields ranges from 36 to 43 mg m^(−2) d^(−1) for the Amazon lowland region.

Emissões de queimadas em ecossistemas da América do Sul

THE VEGETATION fires in tropical areas of the Earth are important sources of pollutants to the atmosphere. In South America, during the winter months, an area, mainly of cerrado and forest ecosystems, of approximately 40 thousand square kilometers is burned annually. The biomass burning occurs primarily in Amazon and Central of Brazil regions, but through atmospheric transport these emissions results in a spatial distribution of smoke over an extent area, of about 4-5 millions of square kilometers, much higher than the area where the fires are concentrated. During the combustion process are emitted to the atmosphere gases pollutants and aerosol particles that interact efficiently with radiation, microphysics process, dynamic of cloud formation and the air quality. The effects of these emissions exceed, therefore, the local scale and affect regionally the composition and physical and chemical properties of the South America atmosphere and neighborhood oceanic areas, with potential impact in a global scale.

Airborne observations reveal elevational gradient in tropical forest isoprene emissions

Isoprene dominates global non-methane volatile organic compound emissions, and impacts tropospheric chemistry by influencing oxidants and aerosols. Isoprene emission rates vary over several orders of magnitude for different plants, and characterizing this immense biological chemodiversity is a challenge for estimating isoprene emission from tropical forests. Here we present the isoprene emission estimates from aircraft eddy covariance measurements over the Amazonian forest. We report isoprene emission rates that are three times higher than satellite top-down estimates and 35% higher than model predictions. The results reveal strong correlations between observed isoprene emission rates and terrain elevations, which are confirmed by similar correlations between satellite-derived isoprene emissions and terrain elevations. We propose that the elevational gradient in the Amazonian forest isoprene emission capacity is determined by plant species distributions and can substantially explain isoprene emission variability in tropical forests, and use a model to demonstrate the resulting impacts on regional air quality.