• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 213
  • 157
  • 30
  • 28
  • 20
  • 17
  • 4
  • 4
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 555
  • 555
  • 221
  • 197
  • 195
  • 185
  • 96
  • 93
  • 84
  • 70
  • 58
  • 55
  • 54
  • 47
  • 43
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Análise do material particulado atmosférico em uma região de São Carlos-SP / Analysis of atmospheric particulate matter in a region of São Carlos-SP

Válio, Vinícius Mori 29 May 2015 (has links)
O presente trabalho avaliou a qualidade do ar de uma área central da cidade de São Carlos-SP, mais precisamente no campus 1 da Universidade de São Paulo. Nessa região há grande movimentação de pessoas e veículos, principalmente durante o horário comercial. Esta avaliação foi feita com base na determinação de um dos parâmetros utilizados para verificar a qualidade do ar, o material particulado (MP) inalável em suspensão, ou seja, partículas que possuem diâmetro aerodinâmico menor ou igual a 10 μm e podem penetrar no sistema respiratório, sendo portanto, nocivas à saúde humana. O MP foi determinado em suas frações de 2,5 e 10 μm de diâmetro (MP10 e MP2,5). Duas metodologias diferentes foram utilizadas para determinar a concentração do material particulado em suspensão, fotometria por espalhamento de luz, através do equipamento ADR-1500 e gravimetria, através do PEM (Personal Enviromental Monitor). Os valores obtidos pelo método gravimétrico foram superiores aos resultados encontrados através da fotometria. As concentrações obtidas foram comparadas com os limites recomendados pela Organização Mundial da Saúde para o MP em suas frações de 2,5 e 10 μm, iguais respectivamente a 25 e 50 μg/m3. Além do material particulado foram obtidos dados para temperatura, umidade relativa e precipitação. As médias obtidas para as concentrações de MP10 e MP2,5, com o método gravimétrico, o qual fornece os resultados mais confiáveis, foram iguais respectivamente a 48,8 e 23,1 μg/m3, muito próximas portanto, de seus limites correspondentes. As menores concentrações obtidas para o MP10 foram, em sua maioria, verificadas em dias chuvosos, tanto através do PEM como do ADR. As concentrações de MP2,5, obtidas somente através do PEM, também apresentaram os menores valores em dias com chuva. Foi desenvolvido um modelo matemático que prevê o comportamento do MP10 durante as precipitações, evento este que se mostrou o mais importante na influência da concentração de material particulado atmosférico. / This study evaluated the air quality of a central area of the city São Carlos-SP, more precisely on the Campus 1 of the University of São Paulo. In this region there is a large movement of people and vehicles, manly during business hours. This evaluation was made based on determination of one parameter used to verify air quality, the inhalable particulate material (PM) suspended in the air, in other words, particles which have aerodynamic diameter less or equal to 10 μm and can penetrate in the respiratory system, therefore, harmful to human health. The PM was determined in its fractions from 2,5 and 10 μm of diameter (PM10 e PM2,5).). Two different methodologies were used to determinate the concentration of particulate suspended material, photometry by scattered light, using the equipment ADR-1500, and gravimetry, thru PEM (Personal Environmental Monitor). The data obtained from gravimetry were higher than the results found thru photometry. The concentrations found were compared to the limits recommended by World Health Organization for PM and its fractions of 2,5 and 10 μm, equal to 25 and 50 μg/m3. Besides PM, temperature, relative humidity and precipitation were measured. The average values for the concentrations of PM10 and PM2,5 , using gravimetry, which provide more reliable results, it were equal to 48,8 and 23,1 μg/m3, therefore really close to their corresponding limits. The lower concentrations seen for PM10 were, mostly, verified on rainy days, using PEM and ADR. The concentrations of PM2,5 , obtained just using PEM, also had the lowest values during rainy days. A mathematical model was developed to predict PM10 behavior during precipitations, this event has shown to have the most important influence on the concentration of atmospheric particulate matter.
32

Estudo da determinação do 1-Nitropireno em material particulado atmosférico /

Azevedo, Ricardo Cambiaghi January 2002 (has links)
Orientador: Mary Rosa Rodrigues de Marchi Santiago da Silva / Banca: Maria Olimpia de Oliveira Rezende / Banca: Alberto José Cavalheiro / Resumo: Os hidrocarbonetos policíclicos aromáticos nitrados (NHPAs) constituem a classe de compostos aromáticos que têm pelo menos um grupo nitro (-NO2) ligado à cadeia aromática de um hidrocarboneto policíclico aromático (HPA). Nos anos 70 a descoberta das propriedades mutagênicas destes compostos, presentes em material particulado atmosférico e na exaustão de motores a diesel, aumentaram o interesse científico sobre a ocorrência dos mesmos no ambiente. Estes compostos, como os HPAs, estão associados a fontes de combustão como automóveis, sistemas de aquecimento (baseados na queima de biomassa ou de combustíveis fósseis); queima de biomassa (cigarro, florestas, culturas agrícolas, etc), por causa disso pode-se prever que tenham uma distribuição abrangente no ambiente. Os NHPAs são produtos da reação dos HPAs com óxidos de nitrogênio na atmosfera, apresentando-se em concentrações muito baixas neste compartimento ambiental. A análise de NHPAs é muito difícil, principalmente pelos artefactos de amostragem e pela interferência analítica causada por HPAs e outros compostos. Assim sendo, a investigação de métodos alternativos que sejam sensíveis e seletivos são de extrema importância na determinação de NHPAs em amostras atmosféricas. Neste trabalho estudou-se um método para determinação de 1-nitropireno em material particulado proveniente da queima de cana-de-açúcar. O método inclui a redução do grupo nitro a amino, com posterior determinação por HPLC/fluorescência. O método proposto tem limite de detecção de 0,930ng mL-1 e limite de determinação de 1,250ng mL-1, apresentando recuperação entre 77,00 e 86,34%, para 5,00 e 50,00ng mL-1 respectivamente. / Abstract: Nitrated Polycyclic Aromatic Hydrocarbons (NPAHs) are the class of aromatic compounds with at least one nitro group (-NO2) enhanced to aromatic chain of a Polycyclic Aromatic Hydrocarbon (PAH). In 70's the discovery of mutagenic properties of these compounds present in atmospheric particulate matter and in gas exhaust of diesel motors are increased the scientific interess on occurrence of NPAHs into environment. These compounds, as PAHs, are associated with combustion sources as automobiles; harming systems (biomass and combustible based); burning of biomass (cigarette, florest, agricultural cultures, etc), because this they have a ubicous dissemination on environment. NPAHs are product of reaction of PAHs with nitrogen oxides on atmosphere, and they are present there at very low concentrations. The analysis of NPAHs in atmospheric samples is very difficult, because of artefacts of sampling process and PAH and other compounds interference on analytical determination. Because this, investigation of alternative methods sensitive and selective is necessary for NPAHs determination in atmospheric samples. In this work is studied a method for determination of 1-nitropyrene from particulate matter of sugar cane burning. The method include reduction of nitro group to amino, and analysis by HPLC/ Fluorescence. The proposed method has detection limit of 0, 930ng mL-1 and quantification limit of .1,250ng mL-1 showing recovery ranged between 77,00 and 86,34% for concentrations of 5,00 and 50,00ng mL-1, respectively. / Mestre
33

Quantificação e estimativa de material particulado no porto de Santos com suporte da técnica LIDAR / Quantification and estimative of particulate matter in the port of Santos with technical LIDAR

Salani, Maria Helena Gonçalves de Andrade 11 October 2018 (has links)
Um porto é uma organização dinâmica que possui áreas críticas que abrigam fontes emissoras de poluentes, como indústrias em seu entorno, modais terrestres (caminhões e trens), operações com carga e descarga de granéis agrícolas, fluxo de navios, entre outros. Neste estudo foi utilizada a modelagem desenvolvida em 2009 pela Current Methodologies in Preparing Mobile Source Port-Related Emission Inventories da Agência Americana de Proteção ao Meio Ambiente (US EPA), que estima os fatores de emissão de material particulado por navios considerando a energia, a característica e o tempo de atividade de cada embarcação, o fator de carga de propulsão e o fator de emissão para cada poluente. Para estimar as emissões fugitivas de material particulado provenientes de operações portuárias com milho, grãos de soja e farelo de soja foi utilizada a modelagem desenvolvida em 2006 pelo Group Emissions Factor US EPA, que considera o volume de carga movimentada, velocidade do vento, umidade do material e fator de tamanho das partículas. Os resultados, referente aos meses de maio e agosto de 2017, em conjunto com os dados coletados em 16 de maio de 2017 pela técnica LIDAR, indicam que as emissões de material particulado pelos navios têm sua maior taxa de emissão para MP10 (moda grossa). Para as emissões fugitivas em operações com grãos, os resultados mostraram que as maiores emissões são provenientes de operações de soja em grãos. Em suporte às modelagens, foi utilizada a técnica LIDAR (Light Detection And Ranging) de sensoriamento remoto que utiliza radiação luminosa, e está baseada na emissão de um feixe de radiação eletromagnética que permite a obtenção de medidas a distância através da radiação retroespalhada. O pulso de luz emitido para a atmosfera interage com as partículas e moléculas que agem como espalhadoras. Os dados coletados são inseridos no programa Mathematica, e os valores obtidos inseridos na plataforma PYTON gerando gráficos. Os dados foram coletados em 16 de maio de 2017, com medidas em diferentes horários e identificada a possível presença de material particulado (MP) na região do porto. O porto de Santos, está localizado no centro do litoral do estado de São Paulo, é o maior porto da América Latina e um dos principais conflitos nessa região são as emissões de material particulado. / A harbor is a dinamic organization that has critical áreas that contain pollutants sources such as insdutries in its surroundings, terrestrial modal (trucks and trains), operations with loading and unloading of agricultural bulk, ship flow, among others. This study used the model developed by the Current Methodologies in Preparing Mobile Source of the US Environmental Protection Agency (US EPA), which estimates the emission factors of particulate matter by ships considering the energy, characteristic and time of activity of each vessel, the propulsion load factor and the emission factor for each pollutant. To estimate fugitive emissions of particulate matter from port operations with corn, soybeans and soybean meal was used to model developed by Group Emissions Factor US EPA, which considers the volume of load handled, speed wind, humidity of the material and particle size factor. The results, referrinf to the months May and August of 2017, together with the data collected on May 16, 2017 by the LIDAR technique, indicate that emissions of particulate matter by ships have their highest emission rate for PM10 (coarse mode). For fugitive emissions of particulate matter in grain operations, the results showed that the highest emissions are from soybean grain operations. In support of modeling, It was used the LIDAR technology (Light Detection And Ranging) remote sensing which uses light radiation, and is based on the emission of an electromagnetic radiation beam that allows to obtain measurements at a distance by backscattering radiation. The pulse of light emitted into the atmosphere interacts with the particles and molecules that act as spreaders. The collected data are inserted into the Mathematica program and the values obtained are inserted into the PYTON platform generating graphs. The data were collected on May 16, 2017, with measurements at different times and identified the possible presence of particulate matter (PM) in the harbor region. The harbor of Santos, is located in the center of the coast of the state of São Paulo, is the bigger harbor in Latin America and one of the main conflicts in this region are emissions of particulate matter.
34

Abordagem metabolômica no estudo da exposição gestacional à poluição atmosférica / Metabolomics approach to the study of gestational exposure to air pollution

Faccio, Andréa Tedesco 17 September 2015 (has links)
Há fortes evidências dos efeitos negativos da exposição gestacional a poluentes atmosféricos. No entanto, mecanismos de atuação de poluentes não são bem compreendidos. Alterações fisiológicas anômalas na progenitora, durante o período de gravidez, podem causar mudanças permanentes na prole, que podem desencadear futuras doenças na vida adulta. Portanto, o estudo dessas alterações maternas é importante. A metabolômica é definida como a análise global do metaboloma de um organismo em experimentos comparativos, com o objetivo de observar mudanças relativas da abundância dos metabólitos, o aparecimento ou desaparecimento de metabólitos, e pode fornecer uma melhor compreensão dos mecanismos de funcionamento celular dos organismos a nível molecular. Nesse trabalho, um estudo experimental de exposição gestacional materna, ao material particulado fino (MP2,5), foi realizado, para avaliar os efeitos dessa exposição no metabolismo, por meio da análise metabolômica global da urina de camundongos fêmeas progenitoras expostas ao MP2,5 (grupo teste) ou a ar filtrado (grupo controle) durante a gestação. Um método cromatográfico e de preparo de amostra para metabolômica urinária por HILIC-MS foram otimizados. Para a otimização da condição cromatográfica, foram investigados a influência de aditivos, concentração de sal e pH da fase móvel, bem como, a rampa do gradiente. A melhor condição foi escolhida por meio da avaliação do formato de pico, da intensidade relativa e do CV do tempo de retenção para 15 m/z selecionados, assim como, pelo número total de molecular features e CV da intensidade desses molecular features. A melhor condição obtida apresenta 20 mmol/L de formiato de amônio em sua composição do solvente B da fase móvel e 95% acetonitrila e 5% solução aquosa 400 mmol/L de formiato de amônio na composição do solvente A. Para o preparo de amostra, foram examinados diferentes solventes orgânicos e suas misturas, para a precipitação de proteínas da urina. O isopropanol foi o solvente apresentou os melhores resultados para o preparo de amostra. Dessa forma, com o método analítico otimizado, as amostras de urina de camundongos fêmeas prenhas foram submetidas à analise metabolômica global por HILIC-MS. O metaboloma dos animais foi bastante alterado pela exposição gestacional ao material particulado. Observou-se alteração dos níveis de carnitinas, aminoácidos, peptídeos, entre outros. Há também indícios de que a poluição atmosférica alterou a microbiota intestinal dos animais, devido ao aumento de N-óxido de trimetilamina, um metabólito que também é relacionado ao processo de aterosclerose. Níveis de metabólitos relacionados ao metabolismo da histidina também foram alterados devido a exposição ao MP2,5. Níveis de carnitina e acilcarnitinas foram aumentados no teste, sugerindo alteração da produção de energia na mitocontria. / There are strong evidences regarding negative effects of gestational exposure to air pollution. However, the mechanisms of action of air pollutants are not well established. Maternal anomalous physiological changes during pregnancy may cause permanent changes in offsprings, that might initiate future diseases in adult life. Therefore, the study of those maternal changes during pregnancy is important. Metabolomics is defined as the global analysis of the metabolome of an organism in comparative studies, for the measurement of relative changes in the metabolite abundance, appearance or disappearance. Metabolomics might provide a better understanding of cellular functioning at the molecular level. In this work, an experimental study of maternal gestational exposure to fine particulate matter (PM2.5) was accomplished to evaluate the effects of this exposure to the metabolism, by an untargeted metabolomics analysis of urine from pregnant mice exposed to PM2.5 or to filtered air during pregnancy. A chromatographic and sample preparation methods for urinary untargeted metabolomics analysis by HILIC-MS were optimized. For the chromatography optimization, the influence of mobile phase additives, salt concentration and pH, as well as, the gradient ramp were investigated. The best condition was chosen by the evaluation of peak shape, relative intensity and retention time CV of 15 selected m/z, as well as, the total number of molecular features and the intensity CV of those molecular features. The best condition comprises of 20 mmol/L of ammonium formate as solvent B, and 95% acetonitrile and 5% 400 mmol/L of ammonium formate as solvent A, in the composition of the mobile phase. For the sample preparation, different solvents, along with, their mixtures were examined for the urine protein precipitation. Isopropanol was the solvent that presented the best results for sample preparation. Thus, after the analytical method optimized, urine samples from the progenitors were submitted to untargeted metabolomics analysis by HILIC-MS. The animals\' metabolome were significantly changed by the gestational exposure to particulate matter. It was observed changes in the levels of carnitines, amino acids, peptides, among others. There is some indication that the air pollution has altered the gut microbiota, due to the enhancement of trimethylamine N-oxide (TMAO), a metabolite that is also related to the atherosclerosis process. The level of metabolites related to histidine metabolism were also altered due to PM2.5 exposure. Carnitine and acylcarnitine levels were also increased in the test group, suggesting an altered energy production in the mitochondria.
35

Abordagem metabolômica no estudo da exposição gestacional à poluição atmosférica / Metabolomics approach to the study of gestational exposure to air pollution

Andréa Tedesco Faccio 17 September 2015 (has links)
Há fortes evidências dos efeitos negativos da exposição gestacional a poluentes atmosféricos. No entanto, mecanismos de atuação de poluentes não são bem compreendidos. Alterações fisiológicas anômalas na progenitora, durante o período de gravidez, podem causar mudanças permanentes na prole, que podem desencadear futuras doenças na vida adulta. Portanto, o estudo dessas alterações maternas é importante. A metabolômica é definida como a análise global do metaboloma de um organismo em experimentos comparativos, com o objetivo de observar mudanças relativas da abundância dos metabólitos, o aparecimento ou desaparecimento de metabólitos, e pode fornecer uma melhor compreensão dos mecanismos de funcionamento celular dos organismos a nível molecular. Nesse trabalho, um estudo experimental de exposição gestacional materna, ao material particulado fino (MP2,5), foi realizado, para avaliar os efeitos dessa exposição no metabolismo, por meio da análise metabolômica global da urina de camundongos fêmeas progenitoras expostas ao MP2,5 (grupo teste) ou a ar filtrado (grupo controle) durante a gestação. Um método cromatográfico e de preparo de amostra para metabolômica urinária por HILIC-MS foram otimizados. Para a otimização da condição cromatográfica, foram investigados a influência de aditivos, concentração de sal e pH da fase móvel, bem como, a rampa do gradiente. A melhor condição foi escolhida por meio da avaliação do formato de pico, da intensidade relativa e do CV do tempo de retenção para 15 m/z selecionados, assim como, pelo número total de molecular features e CV da intensidade desses molecular features. A melhor condição obtida apresenta 20 mmol/L de formiato de amônio em sua composição do solvente B da fase móvel e 95% acetonitrila e 5% solução aquosa 400 mmol/L de formiato de amônio na composição do solvente A. Para o preparo de amostra, foram examinados diferentes solventes orgânicos e suas misturas, para a precipitação de proteínas da urina. O isopropanol foi o solvente apresentou os melhores resultados para o preparo de amostra. Dessa forma, com o método analítico otimizado, as amostras de urina de camundongos fêmeas prenhas foram submetidas à analise metabolômica global por HILIC-MS. O metaboloma dos animais foi bastante alterado pela exposição gestacional ao material particulado. Observou-se alteração dos níveis de carnitinas, aminoácidos, peptídeos, entre outros. Há também indícios de que a poluição atmosférica alterou a microbiota intestinal dos animais, devido ao aumento de N-óxido de trimetilamina, um metabólito que também é relacionado ao processo de aterosclerose. Níveis de metabólitos relacionados ao metabolismo da histidina também foram alterados devido a exposição ao MP2,5. Níveis de carnitina e acilcarnitinas foram aumentados no teste, sugerindo alteração da produção de energia na mitocontria. / There are strong evidences regarding negative effects of gestational exposure to air pollution. However, the mechanisms of action of air pollutants are not well established. Maternal anomalous physiological changes during pregnancy may cause permanent changes in offsprings, that might initiate future diseases in adult life. Therefore, the study of those maternal changes during pregnancy is important. Metabolomics is defined as the global analysis of the metabolome of an organism in comparative studies, for the measurement of relative changes in the metabolite abundance, appearance or disappearance. Metabolomics might provide a better understanding of cellular functioning at the molecular level. In this work, an experimental study of maternal gestational exposure to fine particulate matter (PM2.5) was accomplished to evaluate the effects of this exposure to the metabolism, by an untargeted metabolomics analysis of urine from pregnant mice exposed to PM2.5 or to filtered air during pregnancy. A chromatographic and sample preparation methods for urinary untargeted metabolomics analysis by HILIC-MS were optimized. For the chromatography optimization, the influence of mobile phase additives, salt concentration and pH, as well as, the gradient ramp were investigated. The best condition was chosen by the evaluation of peak shape, relative intensity and retention time CV of 15 selected m/z, as well as, the total number of molecular features and the intensity CV of those molecular features. The best condition comprises of 20 mmol/L of ammonium formate as solvent B, and 95% acetonitrile and 5% 400 mmol/L of ammonium formate as solvent A, in the composition of the mobile phase. For the sample preparation, different solvents, along with, their mixtures were examined for the urine protein precipitation. Isopropanol was the solvent that presented the best results for sample preparation. Thus, after the analytical method optimized, urine samples from the progenitors were submitted to untargeted metabolomics analysis by HILIC-MS. The animals\' metabolome were significantly changed by the gestational exposure to particulate matter. It was observed changes in the levels of carnitines, amino acids, peptides, among others. There is some indication that the air pollution has altered the gut microbiota, due to the enhancement of trimethylamine N-oxide (TMAO), a metabolite that is also related to the atherosclerosis process. The level of metabolites related to histidine metabolism were also altered due to PM2.5 exposure. Carnitine and acylcarnitine levels were also increased in the test group, suggesting an altered energy production in the mitochondria.
36

Pollutants and immune regulation in the human airway : modulation of dendritic cell function by environmental particulate matter

Wildemann, Martha January 2018 (has links)
Ambient air pollution, including airborne particulate matter (PM) derived from combustion of fossil fuels (FF) or biomass (BM), has detrimental inflammatory effects on human health. Myeloid antigen presenting cells, including dendritic cells (DCs) regulate immune responses in the airway and sample inhaled PM. This study tests the hypothesis that PM interacts with multiple environmental sensing pathways in DCs with outcomes that depend on particle size and composition as determined by combustion source. The effects of different sized PM (< 10μm, PM10; < 2.5μm, PM2.5), derived from the combustion of FF or BM, on human monocyte-derived or ex vivo sputum DCs, were examined. DC activation status, cytokine production and aryl hydrocarbon receptor (AhR) signalling were assessed by flow-cytometry, multiplex ELISA and qRT-PCR, following exposure to PM. Pathway-specific antagonists were used to explore underlying mechanisms. Particle size and combustion source influenced the effects of PM on DCs. Irrespective of combustion source, PM10 but not PM2.5, induced MoDC maturation and stimulated production of inflammatory cytokines, including IL-1β and IL-18, indicative of inflammasome activation. These responses were dependent, at least in part, on TLR4 as was the induction of IDO by PM10. AhR signalling was induced by PM in both MoDC and ex vivo sputum DC. It was stimulated by both PM10 and PM2.5 and was induced more strongly by BM-derived PM. AhR activation was independent of DC maturation and TLR4 signalling. Additionally, BM- but not FF-derived PM increased NADH levels in DC suggestive of altered metabolism. Thus, PM induces a complex programme of DC activation, influenced by size and combustion source, which includes classical maturation, inflammasome dependent cytokine release and AhR signalling as well as potential metabolic changes. In the airway, exposure to different PM and the changes in DCs induced by them may lead to altered responses to inhaled antigen.
37

Long-range transport clusters, fine particulate matter (PM2.5) and soot concentrations of air masses in Cape Town, South Africa

Williams, John Peter January 2018 (has links)
>Magister Scientiae - MSc / Ambient air pollution is the biggest environmental threat to human health. According to the World Health Organisation (WHO), ambient air pollution kills millions of people worldwide every year. Airborne particulate matter (APM) affects more people than any other air pollutant and has been linked with various adverse health outcomes, especially fine fractions (commonly abbreviated to PM2.5). PM2.5 penetrates lung tissue to enter the cardiovascular system where it poses the greatest risk. Detailed ambient APM studies are rare in Africa. Such studies are needed to better understand the characteristics, origins and trends of particulate pollution. This study was conducted in Cape Town (the first of its kind for the area) as part of a bigger project on ambient PM2.5 and soot concentrations in South Africa. PM2.5 filter samples were collected at a fixed sampling site in the suburb of Kraaifontein from April 2017 to April 2018, yielding 121 days of data. PM2.5 mass concentration and absorption coefficient determinations were done using gravimetric analysis and smoke stain reflectometry (SSR). Mean PM2.5 concentration for the study period was 13.4 ± 8.1 μg.m-3 (range: 1.17-39.1 μg.m-3) that fell below the South African National Ambient Air Quality Standard (SA NAAQS) annual limit of 20 μg.m-3 but exceeded the WHO annual limit of 10 μg.m-3. Mean absorption coefficient for the same period was 1.38 ± 1.23 m-1.10-5 (range: 0.00-5.38 m-1.10-5) which did not exceeded any limits. Source-region analyses were performed using single, 24-hour backward trajectories and trajectory clusters derived from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Six single trajectories were identified; the most frequent were trajectories Atlantic-Ocean (38.8 %) and Indian-Ocean (26.4 %). Cluster analyses yielded three to four clusters per season. Dominating clusters were Atlantic-Ocean (61.8 %) and Indian-Ocean (29.5 %) and Inland (8.50 %). Contributions by local sources (within 40 km of the sampling site) to PM mass in samples far exceeded those of distant sources through long-range transport (LRT).
38

Morphological studies of model and native environmental surface films

Grant, Jacob Scott 01 May 2019 (has links)
The body of work in this dissertation focuses on the properties of an environmental thin film system, including the roughness and composition of the surface. The deposition of particles, such as airborne soil and plant pollen, from the atmosphere creates a thin film known as “environmental film” or “urban film” that covers virtually all of Earth’s solid surfaces. Environmental films have been shown to accumulate a variety of chemicals, including toxic pollutants. To investigate the means by which environmental films uptake chemicals, model films are made in the lab and real films are collected outside. Model films serve to mimic the properties of native films and allow for a simple analysis of a complex system. Native films serve to provide real field samples to analyze. The properties of model and native films are characterized using reflected light to determine what the film is made of and microscopes capable of imaging small particles. The results of the model film study indicate a model capable of reproducing the surface roughness and other properties of native films. This study serves as a platform with the goal of making model films that better mimic native films. The results of the native film study indicate successful imaging using microscopes capable of revealing the structure and chemical composition of the films. This imaging adds an important contribution to the field that has not previously been performed.
39

Analysis of metals in airborne particulate matter in eastern Iowa

Parker, Gavin James 01 August 2019 (has links)
Airborne particulate matter (PM) consists of solid and liquid particles suspended in air. PM causes many negative health effects when inhaled like exacerbations of asthma, chronic obstructive pulmonary disease (COPD), and premature death. The health impacts of PM depend on the physical size and chemical composition of the inhaled particles. Particles less than 2.5 micrometers can penetrate the deep lung and enter the bloodstream. Understanding the composition of PM helps study human exposures and evaluate PM sources to support control and mitigation strategies. This thesis examines PM in power plant emissions, in ambient air, and in homes, with an emphasis on characterizing hazardous metals. PM emissions from the University of Iowa power plant were examined during a transition away from coal. Biomass is a renewable fuel and when used in place of or co-fired alongside coal it directly reduces emissions of fossil CO2 and PM to the atmosphere. PM emissions were examined under two scenarios: the first was a stoker boiler that fired 100% renewable energy pellets. PM and metal emissions reduced by 59 and 80% respectively despite increases to polycyclic aromatic hydrocarbons (PAHs) that was attributed to emission of unburned carbon fuel. The second test was done in a circulating fluidized bed boiler firing 78% oat hulls, 17% coal, and 5% energy pellets. Decreases in PM, PAHs, and metal emissions were 32, 33, and 50%, respectively. Reductions in PM, PAHs, and metals when firing renewable fuels provide environmental advantages to local air quality while trying to eliminate the use of coal. Ambient air quality was examined downwind of the power plant. The levels of PM2.5 in Iowa City in 2016 ranged from 1.4-32.1 µg m-3 with an annual mean of 7.5 µg m-3. These levels are below the National Ambient Air Quality Standards (NAAQS) for 24-hours (35 µg m-3) and the annual average (12 µg m-3). On average, the analyzed metals accounted for 10.7 ± 5.3% of PM2.5. Potassium, calcium, and zinc were the most abundant metals (averaging 250 ± 10, 170 ± 40, and 11.2 ± 0.5 ng m-3, respectively) and are associated with geological sources and biomass burning. Metals associated with fossil fuel combustion such as arsenic, lead, or vanadium were observed at low levels (averaging 0.58 ± 0.01, 1.32 ± 0.03, and 0.19 ± 0.01 ng m 3, respectively). Harmful metals were at least an order of magnitude lower than the World Health Organization’s guideline concentrations in Iowa City PM2.5. Overall, the hazardous metals in ambient PM2.5 observed in Iowa City were not at concerning levels. The work in this chapter helps provide a metal speciation profile for future studies and these measurements can be used to assess future changes in PM2.5 metal concentrations. Indoor PM collected in homes of Eastern Iowa COPD patients was characterized for its metal content. COPD patients are at higher risk of developing respiratory infections, which cause acute exacerbations of COPD—the leading cause of mortality in COPD patients—and airborne PM increases risk of infection. From the 21 homes studied 6-87 mg of indoor PM was collected over 30 days in winter. Crustal metals such as magnesium, iron, and aluminum were the most concentrated in indoor PM, having mass fractions from 3000-25,000 ng mg-1. Toxic metals like vanadium and arsenic were at lower levels from 3-65 ng mg-1. Between homes the relative abundance of metals was similar, but the absolute abundance was highly variable. Analyzing indoor PM is essential since Americans on average spend 80% of their day indoors making it a significant environment for PM exposure. This chapter provides a chemical profile for different homes when studying the impact PM has on respiratory health. This thesis also provides new measurements of the chemical composition of PM at the point of emission, in ambient air, and within homes. Advancing knowledge of PM composition in different environments is vital in understanding its impacts on human health. Improvements to local air quality with reductions to PM and metal emissions were observed when firing alternative fuels. Ambient PM2.5 concentrations in Iowa City were lower than NAAQS levels and the composition of both ambient and indoor PM was evaluated. With greater understanding of PM composition, better control strategies can be studied and employed to improve local air quality.
40

Effects of Cache Valley Particulate Matter on Human Lung Cells

Watterson, Todd L. 01 May 2012 (has links)
During wintertime temperature inversion episodes the concentrations of particulate air pollution, also defined as particulate matter (PM), in Utah’s Cache Valley have often been highest in the nation, with concentrations surpassing more populated and industrial areas. This has attracted much local and national attention to the area and its pollution. The Cache Valley has recently been declared to be in non-attainment of provisions of Federal law bringing to bear Federal regulatory attention as well. While there is epidemiological evidence indicating that PM is detrimental to public health, there is much less information indicating by which biological and molecular mechanisms PM can exert harm. This study was undertaken to better understand the mechanisms by which ambient PM collected in the Cache Valley can be harmful to human lung cells. Cache Valley PM was found to be mildly cytotoxic only at concentrations that were much greater than physiologically achievable, and such concentrations were difficult to obtain with the limited amounts of captured ambient PM. The limited cytotoxicity was despite apparent PM-induced pro-apoptotic signaling such as caspase-3 upregulation, and activation of caspase-12 and calpain. Cache Valley PM was found to be stressful to cells, triggering endoplasmic reticulum stress and the unfolded protein response. Cache Valley PM was also found to be inflammogenic leading to activation of pro-inflammatory transcription factors, increases in the release of pro-inflammatory cytokines and chemokines, as well as the upregulation of the activating receptors of these cytokines. The proinflammatory effects and absence of apoptosis, despite pro-apoptotic signaling of the Cache Valley PM on human lung cells appeared to stem from increased activation of the central pro-growth protein Akt with subsequent inactivation of the tumor suppressor P-TEN. These findings have indicated novel mechanisms of PM-related cellular stress and inflammation contributing needed information on what may be underlying mechanisms of PM associcated illnesses.

Page generated in 0.272 seconds