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Descreve-se o método PIXE como uma técnica não destrutiva na análise quantitativa de traços de elementos em amostras de aerossol atmosférico. Fundamenta-se este método através do estudo da ionização de camadas internas de átonos por partículas carregadas e da secção de choque de produção de raios-X consequente do processo de ionização. A seguir são apresentados os conjuntos de impactadores em cascata utilizados pelo Grupo de Estudo de Poluição do Ar - IFUSP e pelo Grupo da FSU, na coleta de amostras de aerossol Atmosférico na cidade de Brasília, D.F.. São dadas. as características geométricas de cada conjunto e suas condições de funcionamento durante as amostragens. Discutem-se os resultados obtidos na análise PIXE das amostras provenientes dos dois conjuntos de impactadores procurando-se estabelecer correlações entre variações nas concentrações de mesmos elementos detectados nos dois conjuntos de impactadores. São discutidas possíveis causas que podem afetar o comportamento de dois conjuntos de impactadores e influir na análise de resultados obtidos pelo método PIXE. Para os casos em que há concordância nos resultados obtidos nas análises das amostras de aerossol atmosférico coletadas com impactadores em cascata e amostrador de filtro sequencial (apêndice 1) procura-se associar possíveis fontes de emissão de particulado na época das amostragens. Na complementação do método PIXE sugere-se a substituição do detector de Si (Li) por um espectrógrafo de cristal convexo. / The PIXE is described as a non destructive technique in the quantitative trace elimental analysis of aerossol atmospheric samples. The method is justified through the investigation of inner-shell ionization of atoms by charged particles and X-ray production cross section due the ionization process. Next are presented the sets of cascade impactors used during the aerossol sampling in Brasilia, Goiás, by the Group of Air Pollution Research - IFUSP and Air Chemistry Group - Oceanography Department - FSU. Dimensions of these two sets of impactors and conditions during the sampling are included in this work The results obtained from the analysis of the two sets of impactors are discussed correlating them with the variations in the amount of elements present in the samples. Possible causes changing the behavior of those impactors and can affect the analysis of results obtained by PIXE method are discussed. Results from impactors that are compatible with STREAKER analysis are interpreted according to possible emission sources of particulate matter in the atmosphere. In the implementation of PIXE apparatus the substitution of Si(Li) detector by a convex crystal X-ray spectrograph is suggested.

Spatial and temporal patterns of semi-volatile organic contaminant (SVOC) concentrations in air and precipitation were investigated at the urban scale in order to improve our understanding of emission sources and factors affecting intra-urban variability. Toronto, Canada was used as a case study. Advances were made in two methods used to examine intra-urban variability, namely passive air sampling and land use regression analysis. The study showed that these methods are useful for assessing local-scale variability, and that passive air sampler concentrations are most reliable when using homologue-specific sampling rates obtained from a co-located low volume sampler. The results of the spatially and temporally distributed sampling demonstrated that the highest atmospheric concentrations of SVOCs were associated with the highest density regions of the urban area. Temporal patterns of elevated concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in warm seasons were consistent with temperature-related emission processes such as volatilization and/or ventilation of indoor air. Spatial patterns in air concentrations were influenced by local sources on a scale of <5 km and were explained by factors related to human population activities such as building volume (PBDEs), population density (polycyclic musks, or PCMs), residential, commercial and transportation infrastructure (PAHs), and chemical inventory (PCBs). Industrial activities were not important factors. The link between elevated environmental concentrations and the in-use stock of banned chemicals, such as PCBs and PBDEs, suggest that efforts to control emissions and reduce environmental concentrations must address the removal of current use products, in addition to the bans on new uses of the SVOCs.

Spatial and temporal patterns of semi-volatile organic contaminant (SVOC) concentrations in air and precipitation were investigated at the urban scale in order to improve our understanding of emission sources and factors affecting intra-urban variability. Toronto, Canada was used as a case study. Advances were made in two methods used to examine intra-urban variability, namely passive air sampling and land use regression analysis. The study showed that these methods are useful for assessing local-scale variability, and that passive air sampler concentrations are most reliable when using homologue-specific sampling rates obtained from a co-located low volume sampler. The results of the spatially and temporally distributed sampling demonstrated that the highest atmospheric concentrations of SVOCs were associated with the highest density regions of the urban area. Temporal patterns of elevated concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in warm seasons were consistent with temperature-related emission processes such as volatilization and/or ventilation of indoor air. Spatial patterns in air concentrations were influenced by local sources on a scale of <5 km and were explained by factors related to human population activities such as building volume (PBDEs), population density (polycyclic musks, or PCMs), residential, commercial and transportation infrastructure (PAHs), and chemical inventory (PCBs). Industrial activities were not important factors. The link between elevated environmental concentrations and the in-use stock of banned chemicals, such as PCBs and PBDEs, suggest that efforts to control emissions and reduce environmental concentrations must address the removal of current use products, in addition to the bans on new uses of the SVOCs.

Assessments of the anthropogenic threats to savanna ecosystems are primarily focussed on land use change, bush encroachment, and biological invasions. There is, however, very little understanding as to the threats from atmospheric pollution. South Africa is the major emitter of CO2 on the African content while the Mpumalanga region bordering the Kruger National Park (KNP) is among the leading regions for nitrous oxide pollution in the world. It is not only increasing atmospheric pollution, but rainfall intensity is also predicted to increase for southern Africa. As savannas are nutrient limited, an increase in nitrogen deposition will have major consequences for vegetation structure and this can only be exacerbated by increased rainfall amounts. Current research suggests that these predicted increases in water and nutrients will result in increasing grass biomass and decreasing herbaceous species richness. The effects of global change drivers on savanna vegetation are also likely to propagate through to multiple trophic levels, with changes in vegetation structure cascading down to invertebrate assemblages. As invertebrates are ubiquitous, form the bulk of metazoan species diversity and biomass on earth, and play a pivotal role in many ecosystems, I discuss in the introductory chapter of this thesis why the influence of global change on these assemblages should not be ignored. In my first data chapter, Chapter 2, I examine the effect that increases in available nutrients and water may have on vegetation structure, and how this may cascade down to grasshopper and ant assemblages. I do this using a fully factorial experiment in KNP with nutrient and water additions where I assessed both herbaceous (forb and grass) and insect (ant and grasshopper) assemblages five years after resource additions began. My results show that there was a substantial increase in grass biomass while plant and insect species richness declined with water addition alone and that a combination of nutrients and water resulted in the greatest increases in grass biomass and concomitant decreases in plant and insect species richness. The effects of nutrient and water additions on the insect community assembly was primarily driven by a decrease in grasshopper species and ant abundance respectively. An analysis of ant functional traits showed that the rare ant species mediated the impact of the resource additions on the ant assemblage. Fire is inherent to savanna systems with profound effects on vegetation structure. There has, however, been relatively little research on the effects of fire on savanna invertebrate fauna. In Chapter 3 I look at the effect that fire may have on the vegetation and insect community assembly at my study site between five and eight months after the site had been burned. These results show an increase in grass biomass and decrease in plant and insect species richness with a combination of nutrients and water. My results also show that grasshopper biomass, abundance, and species richness decreased as herbaceous biomass decreased. While ant species richness decreased, ant abundance increased post-fire, primarily related to an increase in patches of bare ground. With global change, drought frequency is also expected to increase. The insect and grass assemblages, both on and off Macrotermes mounds, at two sites in the southern section of KNP had been sampled in a separate study in 2012. In Chapter 4 I describe a study where I resampled these mounds during the peak of the most severe drought in 30 years. The two sites differed in drought severity, one where the drought severity was very high and the other where severity was much lower. The objective was to determine the effects that drought may have on the grass and associated insect assemblages both on and off termite mounds. My results show that at the high severity site grass cover and biomass and grasshopper abundance decreased both on and off mounds. The overall reduction in habitat structure resulted in an increase in both ant abundance and species richness but the mound and matrix ant assemblages diverged during drought. Where the drought was less severe there was an increase in large mammal herbivores as animals moved out of the more affected areas. This increase in mammal herbivory was more evident on rather than off mounds resulting in grass biomass being lower on rather than off mounds. The cascading effect saw grasshopper abundance decrease on and increase off mounds. The mound and matrix ant assemblages did not respond to the comparatively smaller change in habitat structure. Finally, in the synthesis chapter I discuss my results in the broader context of how global change drivers such as increased nitrogen deposition may cascade down from plant to insect community assembly. At present there is very little understanding of the amounts of nitrogen being deposited in KNP or the effect that this may have. The results of my study would suggest that this increase in nitrogen deposition will have major consequences for vegetation structure and that this will cascade down to the insect assemblage. In mitigating for this, it is therefore essential that management in KNP adapt a monitoring protocol for nitrogen deposition, especially when considering that where N deposition is really high fire may not volatilise everything to allow the system to reset itself back to its original state. It is not only nitrogen deposition, but drought frequency is also likely to increase. In mitigation for this there should also be monitoring programmes to consider the effects of drought as animals may move from areas of high drought severity to areas where severity is lower. Such movement will increase grazing pressure on both low and high nutrient environments with cascading effects on vegetation structure and insect assemblages.

A poluição atmosférica é hoje uma questão que afeta as megacidades por todo o mundo. As partículas de aerossol participam do balanço radiativo, da formação de nuvens, da química atmosférica, e são prejudiciais à saúde da população exposta. A extensão e o rápido crescimento das megacidades têm levado à necessidade do desenvolvimento de ferramentas para o monitoramento da poluição do ar, urbana e regional, por sensoriamento remoto via satélites. Foram analisadas as propriedades ópticas dos aerossóis da região metropolitana de São Paulo com medidas obtidas por fotômetros da rede mundial AERONET (Aerosol Robotic Network) operada pela NASA. Foi desenvolvida uma nova metodologia para a determinação da espessura óptica das partículas de aerossol com alta resolução espacial de 1x1 km, sobre a região metropolitana de São Paulo, por satélite. Cinco modelos ópticos de aerossol, representativos da região, foram definidos como função do albedo simples. No comprimento de onda de 550 nm, os modelos possuem valores de albedo simples que variam de 0,83 a 0,93. Foram utilizadas medidas de radiâncias obtidas com o sensor MODIS (Moderate-Resolution Imaging Spectroradiometer), a bordo dos satélites Terra e Aqua da NASA. Extensos testes de sensibilidade foram realizados, analisando o papel do albedo simples, parâmetro de assimetria, refletância de superfície, vapor de água e outras propriedades na espessura óptica derivada. O algoritmo desenvolvido utiliza a propriedade de refletância crítica, que pode ser obtida pelo próprio sensor, para determinar o modelo de aerossol a ser empregado. Este procedimento permitiu a identificação mais precisa do modelo de aerossol, de forma dinâmica e interativa, reduzindo a incerteza na determinação da espessura óptica em alta resolução com o sensor MODIS. Os resultados de validação mostraram uma melhora significativa na comparação entre os produtos de espessura óptica obtidos com o sensor MODIS, quando comparado com as medidas de referência obtidas com radiômetros em superfície. Foram obtidos com esta metodologia mapas com a distribuição espacial de aerossóis com resolução de 1x1 km. Os estudos de casos também apresentaram a potencialidade do método em identificar o modelo de aerossol mais adequado, seja em eventos de poluição local, seja de transporte de poluentes de longa distância. Os modelos e procedimentos desenvolvidos podem ser aplicados a outras regiões urbanas, após as devidas validações. Como ferramenta complementar ao monitoramento ambiental de estações de superfície o produto apresentado pode-se tornar operacional e ser utilizado em rotina por órgãos de controle ambiental em megacidades, como, por exemplo, pela CETESB em São Paulo / Urban air pollution is a public concern in all megacities around the world. Aerosol particles are active participants in the atmospheric energy budget, cloud properties, atmospheric chemistry and have adverse effects on human health. The spatial extension and the high growth rate of the megacities show the need of the use of remote sensing technologies on urban air pollution monitoring. Optical properties of São Paulo aerosol particles were analyzed using global sun photometer measurements from the AERONET (Aerosol Robotic Network) operated by NASA. A new methodology was developed to retrieve aerosol optical thickness in 1x1 km resolution over São Paulo metropolitan area from satelites measurements. Five aerosol optical models representative of the region were defined as a function of the single scattering albedo. The single scattering albedo in 550 nm varied from 0,83 to 0,93 in the models. Radiances were used from MODIS (Moderate-Resolution Imaging Spectroradiometer) sensor on Terra and Aqua NASA platforms. Sensitivities studies have shown the importance of the single scattering albedo, assymmetry parameter, surface reflectance, water vapor and other properties in the aerosol optical thickness retrieval from space. The developed algorithm uses the critical reflectance aerosol property, that is obtainable from the sensor measurements, to identify the aerosol model to be used. This procedure allow a more precise and dynamic definition of the aerosol model, reducing the uncertainties in the aerosol optical thickness retrieved from the MODIS sensor. Validation results have shown a significant improvement in a comparison between aerosol optical thickness obtained from MODIS and from surface radiometers measurements. Aerosol optical thickness images with 1x1 km resolution were obtained with this methodology and shows that the increase in the resolution of the aerosol optical thickness provides a more effective monitoring of the aerosol distribution in São Paulo. The case studies have shown the potentiality of this methodology to identify an adequate aerosol model, for both local aerosol pollution and in the long distance transport of pollutants. The models and procedures developed in this work can be applied in other urban regions with the appropriate validation. The presented product can be operational and used as routine measurement by environmental agencies in megacities, as an example, for CETESB in São Paulo, as a complementary tool to the regular ground based particulate matter monitoring.

A poluição atmosférica é hoje uma questão que afeta as megacidades por todo o mundo. As partículas de aerossol participam do balanço radiativo, da formação de nuvens, da química atmosférica, e são prejudiciais à saúde da população exposta. A extensão e o rápido crescimento das megacidades têm levado à necessidade do desenvolvimento de ferramentas para o monitoramento da poluição do ar, urbana e regional, por sensoriamento remoto via satélites. Foram analisadas as propriedades ópticas dos aerossóis da região metropolitana de São Paulo com medidas obtidas por fotômetros da rede mundial AERONET (Aerosol Robotic Network) operada pela NASA. Foi desenvolvida uma nova metodologia para a determinação da espessura óptica das partículas de aerossol com alta resolução espacial de 1x1 km, sobre a região metropolitana de São Paulo, por satélite. Cinco modelos ópticos de aerossol, representativos da região, foram definidos como função do albedo simples. No comprimento de onda de 550 nm, os modelos possuem valores de albedo simples que variam de 0,83 a 0,93. Foram utilizadas medidas de radiâncias obtidas com o sensor MODIS (Moderate-Resolution Imaging Spectroradiometer), a bordo dos satélites Terra e Aqua da NASA. Extensos testes de sensibilidade foram realizados, analisando o papel do albedo simples, parâmetro de assimetria, refletância de superfície, vapor de água e outras propriedades na espessura óptica derivada. O algoritmo desenvolvido utiliza a propriedade de refletância crítica, que pode ser obtida pelo próprio sensor, para determinar o modelo de aerossol a ser empregado. Este procedimento permitiu a identificação mais precisa do modelo de aerossol, de forma dinâmica e interativa, reduzindo a incerteza na determinação da espessura óptica em alta resolução com o sensor MODIS. Os resultados de validação mostraram uma melhora significativa na comparação entre os produtos de espessura óptica obtidos com o sensor MODIS, quando comparado com as medidas de referência obtidas com radiômetros em superfície. Foram obtidos com esta metodologia mapas com a distribuição espacial de aerossóis com resolução de 1x1 km. Os estudos de casos também apresentaram a potencialidade do método em identificar o modelo de aerossol mais adequado, seja em eventos de poluição local, seja de transporte de poluentes de longa distância. Os modelos e procedimentos desenvolvidos podem ser aplicados a outras regiões urbanas, após as devidas validações. Como ferramenta complementar ao monitoramento ambiental de estações de superfície o produto apresentado pode-se tornar operacional e ser utilizado em rotina por órgãos de controle ambiental em megacidades, como, por exemplo, pela CETESB em São Paulo / Urban air pollution is a public concern in all megacities around the world. Aerosol particles are active participants in the atmospheric energy budget, cloud properties, atmospheric chemistry and have adverse effects on human health. The spatial extension and the high growth rate of the megacities show the need of the use of remote sensing technologies on urban air pollution monitoring. Optical properties of São Paulo aerosol particles were analyzed using global sun photometer measurements from the AERONET (Aerosol Robotic Network) operated by NASA. A new methodology was developed to retrieve aerosol optical thickness in 1x1 km resolution over São Paulo metropolitan area from satelites measurements. Five aerosol optical models representative of the region were defined as a function of the single scattering albedo. The single scattering albedo in 550 nm varied from 0,83 to 0,93 in the models. Radiances were used from MODIS (Moderate-Resolution Imaging Spectroradiometer) sensor on Terra and Aqua NASA platforms. Sensitivities studies have shown the importance of the single scattering albedo, assymmetry parameter, surface reflectance, water vapor and other properties in the aerosol optical thickness retrieval from space. The developed algorithm uses the critical reflectance aerosol property, that is obtainable from the sensor measurements, to identify the aerosol model to be used. This procedure allow a more precise and dynamic definition of the aerosol model, reducing the uncertainties in the aerosol optical thickness retrieved from the MODIS sensor. Validation results have shown a significant improvement in a comparison between aerosol optical thickness obtained from MODIS and from surface radiometers measurements. Aerosol optical thickness images with 1x1 km resolution were obtained with this methodology and shows that the increase in the resolution of the aerosol optical thickness provides a more effective monitoring of the aerosol distribution in São Paulo. The case studies have shown the potentiality of this methodology to identify an adequate aerosol model, for both local aerosol pollution and in the long distance transport of pollutants. The models and procedures developed in this work can be applied in other urban regions with the appropriate validation. The presented product can be operational and used as routine measurement by environmental agencies in megacities, as an example, for CETESB in São Paulo, as a complementary tool to the regular ground based particulate matter monitoring.

Foi avaliado quantitativamente o impacto que as atividades antropogênicas da cidade de Manaus causam na composição elementar dos aerossóis na Amazônia central. Para isso, foram amostrados aerossóis em três sítios experimentais entre 2014 e 2015: 1) ZF2, sítio com floresta preservada, 2) Hotel TIWA com impacto direto de emissões de Manaus e 3) Manacapuru sítio vento abaixo da cidade de Manaus. Dos filtros coletados obteve-se a concentração de diferentes componentes do material particulado (MP): Black Carbon Equivalente (BCe), elementos traço (Na até Pb), concentração de MP e carbono elementar e orgânico (EC e OC) separados em MP Fino (MPF, diâmetro menor que 2,5µm) e MP grosso (MPG, diâmetro entre 2,5µm e 10µm). A concentração média de MPF apresentou forte sazonalidade em todos os sítios com concentrações variando de 2,3±2,7µg/m³ para 5,5±2,7µg/m³ na ZF2 e 3,7±2,0µg/m³ para 11,0±7,6µg/m³ no TIWA na estação chuvosa e seca, respectivamente. Elementos traços associados a processos industriais e/ou veiculares apresentaram concentração média de aproximadamente 2 a 6 vezes maior no sítio TIWA que na ZF2. O balanço de massa indicou que entre 50% e 80% do MPF foi de matéria orgânica (MO), 15% a 20% foi de sulfato e de 8 a 20% de BCe. Comparações entre as concentrações de MO, indicaram aerossol mais envelhecido em Manacapuru. A aplicação da Análise de Componentes Principais Absoluta (ACPA) no MPF extraiu fatores regionais em todos os sítios: queima de biomassa, poeira mineral e aerossol marinho, além de fatores como poluição industrial e veicular nos sítios afetados pela pluma de Manaus. Além desses fatores encontrados pela ACPA, o método Positive Matrix Factorization (PMF) extraiu um fator biogênico no MPF e mais de um fator marinho para o MPG relacionados com o processamento do aerossol marinho. A concentração de MP extraído no TIWA para fatores diretamente relacionados com atividade antropogênica é em média de 905ng/m³ (MPF) e 1285ng/m³ (MPG). / This work quantitatively investigated the impact of anthropogenic emissions from Manaus City on the elemental composition of aerosol at Central Amazonia collecting particulate matter (PM) from 2014 to 2015 at ZF2, upwind of Manaus and TIWA and Manacapuru, downwind of Manaus. From the filters collected, different components of the PM were measured: equivalent Black Carbon (eBC), trace elements (Na to Pb), PM concentration and Elemental and Organic Carbon (EC and OC) with fine (FPM, diameter < 2.5um) and coarse (CPM, 2.5um < diameter < 10um) mode separated. At the dry season, FPM concentration was 5,5ug/m³ at ZF2 and 11,0ug/m³ at TIWA and for the CPM it was of 5,5ug/m³, 7,1ug/m³, respectively. During the wet season, reduction on the concentration of all sites at both modes was observed. Mass Balance Analysis showed that Organic Matter (OM) varied approximately from 50% to 80%, sulfate from 15% to 20% and eBC from 8% to 20% for the FPM. Comparisons between OM, obtained through spectrometry, and OC showed a more aged aerosol at Manacapuru than at TIWA. Absolute Principal Components Analysis (APCA) extracted three main factors at all sites for the FPM: biomass burning, marine aerosol and soil dust whilst PMF could also extract a biogenic factor. For the sites downwind of Manaus, factors related with anthropogenic emission were extracted. For the CPM three factors were identified at all sites: biogenic emission, soil dust and marine aerosol. PMF also found a second factor related with Cl depletion on marine aerosol. At the site TIWA both methods extracted a factor identified as pollution and PMF also found a factor related with vehicular emissions whilst at Manacapuru on APCA extracted a pollution factor. Direct anthropogenic emissions vehicular and pollution factors - at TIWA varies from 880ng/m³ (ACPA) to 930ng/m³ (PMF) in fine mode. In the coarse mode 790ng/m³ (APCA) to 1780ng/m³ (PMF).