No description available.

No description available.

Thesis advisor: Paul Davidovits / Aerosol particles are an important component of the Earth-Atmosphere system because of their influence on the radiation budget both directly (through absorption and scattering) and indirectly (through cloud condensation nuclei (CCN) activity). The magnitude of the raditaive forcing attributed to the direct and indirect aerosol effects is highly uncertain, leading to large uncertainties in projections of global climate change. Real-time measurements of aerosol properties are a critical step toward constraining the uncertainties in current global climate modeling and understanding the influence that anthropogenic activities have on the climate. The objective of the work presented in this thesis is to gain a more complete understanding of the atmospheric transformations of aerosol particles and how such transformations influence the direct and indirect radiative effects of the particles. The work focuses on real-time measurements of aerosol particles made with the Aerodyne Aerosol Mass Spectrometer (AMS) developed in collaboration with the Boston College research group. A key feature of the work described is the development of a lightscattering module for the AMS. Here we present the first results obtained with the integrated light scattering – AMS system. The unique and powerful capabilities of this new instrument combination are demonstrated through laboratory experiments and field deployments. Results from two field studies are presented: (1) The Northeast Air Quality Study (NEAQS), in the summer of 2004, conducted at Chebogue Point, Nova Scotia and (2) The Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign conducted in and around Mexico City, Mexico in March of 2006. Both field studies were designed to study the transformations that occur within pollution plumes as they are transported throughout the atmosphere. During the NEAQS campaign, the pollution plume from the Northeastern United States was intercepted as it was transported towards Europe. In this study, particles were highly processed prior to sampling, with residence times of a few days in the atmosphere. The MILAGRO campaign focused on the evolution of the Mexico City plume as it was transported north. During this study, regional and locally emitted particles were measured with residence times varying from minutes to days in the atmosphere. In both studies, the light scattering – AMS system provided detailed information about the density and composition of single particles, leading to important insights into how atmospheric processing transforms the particle properties. In Mexico City, the light scattering-AMS system was used for the first time as a true single particle mass spectrometer and revealed specific details about the atmospheric processing of primary particles from combustion sources.To quantify the radiative effects of the particles on climate, the processing and ultimate fate of primary emissions (often containing black carbon or soot) must be understood. To provide a solid basis for the interpretation of the data obtained during the field studies, experiments were conducted with a well characterized soot generation-sampling system developed by the Boston College research group. The laboratory soot source was combined with the light scattering – AMS system and a Cloud Condensation Nuclei Counter (CCNC) to measure the change in cloud-forming activity of soot particles as they are processed in the atmosphere. Because of the importance of black carbon in the atmosphere, several instruments have been developed to measure black carbon. In July of 2008, an intercomparison study of 18 instruments was conducted in the Boston College laboratory, with soot particles produced and processed to mimic a wide range of atmospherically-relevant conditions. Transformations in the physical, chemical, and optical properties of soot particles were monitored with the combined suite of aerosol instrumentation. Results from the intercomparison study not only calibrated the different instruments used in the study, but also provided critical details about how atmospheric processing influences the radiative effects of primary combustion particles. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Made available in DSpace on 2014-10-09T12:49:51Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:04Z (GMT). No. of bitstreams: 1 09826.pdf: 5905522 bytes, checksum: b0354cc2f21014da9657b88019b2b992 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:99/07068-0

Made available in DSpace on 2014-10-09T12:49:51Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:04Z (GMT). No. of bitstreams: 1 09826.pdf: 5905522 bytes, checksum: b0354cc2f21014da9657b88019b2b992 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:99/07068-0

Phase transitions and other intrinsic properties (shape, size, architecture) of molecularly structured aerosol particles are important for understanding their role in planetary atmospheres and for technical applications. By combining bath gas cooling with time resolved mid-infrared spectroscopy and modeling, information is obtained on dynamic processes and intrinsic properties of fluoroform and ethane aerosol particles. The distinct infrared spectral features of fluoroform aerosol particles make it a particularly suitable model system. Homogeneous crystallization rates of the sub-micron sized aerosol particles are determined (JV = 10⁸ - 10¹⁰ cm-³s-¹ or JS = 10³ – 10⁵ cm-²s-¹ at a temperature of T = 78 K), and the controversial question regarding volume versus surface nucleation in freezing aerosols is addressed. It is demonstrated that current state of the art measurements of droplet ensembles cannot distinguish between the two mechanisms due to inherent experimental uncertainties. The evolution of particle shape from spherical supercooled droplets to cube-like crystalline particles and eventually to elongated crystalline particles is recorded and analyzed in detail with the help of vibrational exciton model calculations. Phase behaviour of pure ethane aerosols and ethane aerosols formed in the presence of other ice nuclei under conditions mimicking Titan’s atmosphere provide evidence for the formation of supercooled liquid ethane aerosol droplets, which subsequently crystallize. The observed homogeneous freezing rates (JV = 10⁷ – 10⁹ cm-³s-¹) imply that supercooled ethane could play a similar role in ethane rich regions of Titan’s atmosphere as supercooled water does in the Earth’s atmosphere.

Phase transitions and other intrinsic properties (shape, size, architecture) of molecularly structured aerosol particles are important for understanding their role in planetary atmospheres and for technical applications. By combining bath gas cooling with time resolved mid-infrared spectroscopy and modeling, information is obtained on dynamic processes and intrinsic properties of fluoroform and ethane aerosol particles. The distinct infrared spectral features of fluoroform aerosol particles make it a particularly suitable model system. Homogeneous crystallization rates of the sub-micron sized aerosol particles are determined (JV = 10⁸ - 10¹⁰ cm-³s-¹ or JS = 10³ – 10⁵ cm-²s-¹ at a temperature of T = 78 K), and the controversial question regarding volume versus surface nucleation in freezing aerosols is addressed. It is demonstrated that current state of the art measurements of droplet ensembles cannot distinguish between the two mechanisms due to inherent experimental uncertainties. The evolution of particle shape from spherical supercooled droplets to cube-like crystalline particles and eventually to elongated crystalline particles is recorded and analyzed in detail with the help of vibrational exciton model calculations. Phase behaviour of pure ethane aerosols and ethane aerosols formed in the presence of other ice nuclei under conditions mimicking Titan’s atmosphere provide evidence for the formation of supercooled liquid ethane aerosol droplets, which subsequently crystallize. The observed homogeneous freezing rates (JV = 10⁷ – 10⁹ cm-³s-¹) imply that supercooled ethane could play a similar role in ethane rich regions of Titan’s atmosphere as supercooled water does in the Earth’s atmosphere.

Made available in DSpace on 2014-10-09T12:32:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:15Z (GMT). No. of bitstreams: 1 03182.pdf: 1972055 bytes, checksum: 9981ae33d320ed8dd71a0aaa2f020331 (MD5) / Tese(Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:32:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:15Z (GMT). No. of bitstreams: 1 03182.pdf: 1972055 bytes, checksum: 9981ae33d320ed8dd71a0aaa2f020331 (MD5) / Tese(Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-08-26T11:26:18Z No. of bitstreams: 0 / Made available in DSpace on 2016-08-26T11:26:18Z (GMT). No. of bitstreams: 0 / A água é um recurso essencial à vida, logo deve estar presente em quantidade e qualidade adequada para seu consumo. O presente estudo teve como objetivo avaliar a qualidade ambiental da represa Guarapiranga, Localizado em partes dos municípios de Cotia, Embu, Itapecerica da Serra, Juquitiba, São Lourenço da Serra e São Paulo e na área total do município de Embu Guaçu, este sistema tem significativa degradação em sua qualidade de água devido ao aporte de efluente doméstico e industrial aumentando o custo do tratamento e dificultando o acesso a água potável. Foram apresentados os resultados de 26 metais, 7 ânions, parâmetros limnológicos: pH, condutividade, temperatura, oxigênio dissolvido, transparência da água, obtidos a partir das amostras das coletas realizadas entre os anos de 2011 a 2013, em amostras de água na superfície, meio e fundo em 14 pontos e de sedimento de fundo nestes mesmos pontos sendo avaliando 26 metais. Os resultados de sedimento foram comparados com os valores de TEL e PEL e os resultados de água foram com os limites de estabelecidos pela resolução COMANA 357/2005. Os parâmetros limnológicos, condutividade, pH e oxigênio dissolvido ficaram fora do enquadramento da resolução do COMANA 357/05. Todas as espécies iônicas atenderam ao estabelecido pelo CONAMA 357/05, no entanto é observado um aumento das concentrações no decorrer das coletas. A serie nitrogenada assim com a relação Fe:P mostraram ser importantes parâmetros de controle do aporte da carga orgânica no reservatório. Dos 26 elementos analisados somente Al, Cu, Mn apresentaram concentrações fora do estabelecido pela resolução COMANA 357/05. Os sedimentos analisados os elementos químicos Cu, Cr, Zn apresentaram valores acima do TEL e do PEL. A partir dos resultados obtidos infere-se que o reservatório do Guarapiranga apresenta dois compartimentos distintos, um mais degradado que vai do ponto 05 a 14 que sofre os impactos da ocupação do seu entorno e um mais preservado que vai do ponto 01 a 05, sem tanta influência de ocupação urbana no seu entorno. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP