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  • 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.
21

Chemical and physical characterization of aerosols from the exhaust emissions of motor vehicles

Lim, McKenzie C. H. January 2007 (has links)
The number concentration and size distribution of particles in Brisbane have been studied extensively by the researchers at The International Laboratory for Air Quality and Health, Queensland University of Technology (Morawska et al., 1998, 1999a, 1999b). However, the comprehensive studies of chemical compositions of atmospheric particles, especially with regard to the two main classes of pollutants (polycyclic aromatic hydrocarbons and trace elements), that are usually of environmental and health interest, have not been fully undertaken. Therefore, this thesis presents detailed information on polycyclic aromatic hydrocarbons (PAHs) and elemental compositions of vehicle exhausts and of urban air in Brisbane. The levels of polycyclic aromatic hydrocarbons (PAHs) and elements in three of Brisbane's urban sites (Queensland University of Technology, Woolloongabba and ANZ stadium sites) were measured. The most common PAHs found in all sites were naphthalene, phenanthrene, anthracene, fluoranthene, pyrene and chrysene while Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Si, Sn, Sr and Zn were the most common elements detected in the total suspended particles and fine particle (PM2.5). With the aid of multivariate analysis techniques, several outcomes were obtained. For example: -- Major human activities such as vehicular and industrial sources were the most contributing pollution sources in Brisbane. However, these two sources have different influential strength on the compositions of the polycyclic aromatic hydrocarbons and trace inorganic elements found in the urban air. -- Woolloongabba bus platform was the most polluted site on the basis of the elemental and PAH compositions in its air samples while QUT site was the worst polluted site in terms of PM2.5 elemental contents. These results demonstrated that the impact of traffic related pollutants on Brisbane's urban air is significant. This led to the investigations of the direct emissions of pollutants from exhaust vehicular source in the second part of this research work. The exhaust studies included the investigations of PAHs, trace inorganic elements and particles. At the time of the study, the majority of vehicles in Brisbane used low sulfur diesel (LSD) fuel or unleaded petrol (ULP). However, the importance of vehicles using ultra low sulfur diesel (ULSD) and liquefied petroleum gas (LPG) is constantly growing. Therefore, the exhaust emission studies on chassis dynamometer from heavy duty non-catalyst-equipped buses powered by LSD and ULSD with 500 ppm and 50 ppm sulfur contents respectively as well as passenger cars powered by ULP and LPG were explored. The outcomes of such studies are summarized as follows: -- Naphthalene, acenaphthene, acenaphthylene, anthracene, phenanthrene, fluorene, fluoranthene and pyrene were frequently emitted by the buses powered by LSD and ULSD. However, buses powered by ULSD emitted 91% less PAHs than those powered by LSD. On the other hand, Mg, Ca, Cr, Fe, Cu, Zn, Ti, Ni, Pb, Be, P, Se, Ti and Ge were found in measurable quantities in the exhaust of the buses. The emissions of the elements were found to be strongly influenced by the engine driving conditions of the buses and fuel parameters such as sulfur content, fuel density and cetane index. -- Naphthalene, fluorene, phenanthrene, anthracene, pyrene, chrysene, benzo(a)anthracene and benzo(b)fluoranthene were predominantly emitted by ULP and LPG cars. On the average, the total emission factors of PAHs from LPG cars were generally lower than those of ULP cars, but given the large variations in the emission factors of cars powered by the same type of fuel, differences in the emission factors from both car types were statistically insignificant. In general, platinum group elements and many other elements were found in the exhausts of cars powered by both fuels. Emissions of inorganic elements from the cars were dependent on the type and the mileage of the cars. For example, ULP cars generally emitted higher levels of Cu, Mg, Al and Zn while LPG cars emitted higher level of V. In addition, cars with higher mileages were associated with higher emissions of the major elements (Zn, Al, Fe, V and Cu). -- Buses powered by ULSD usually emitted fewer particles, which were generally 31% to 59% lower than those emitted by LSD powered buses. Similarly, cars powered by LPG emitted less particles from those powered by ULP fuel. However, more nanoparticles (those with aerodynamic diameters of less than 50 nm) were emitted by LPG powered cars than their ULP counterparts. Health effect assessment of the exhaust PAHs was evaluated in terms of benzo(a)pyrene toxicity equivalent (BAPeq). The potential toxicities of PAHs emitted by ULSD powered buses were generally lower than those emitted by their LSD counterparts. A similar trend with lower emissions of PAHs from LPG cars than from ULP cars was observed when otherwise identical passenger cars were powered by LPG and ULP fuels. In summary, this thesis has shown that the majority of airborne particles found around Brisbane have anthropogenic origins, particularly vehicle emissions, and that fuel or lubricant formulations and engine operating conditions play important roles in the physical and chemical characteristics of pollutants emitted by vehicles. The implications of these results on worldwide strategies to reduce the environmental and health effects of particles emitted by motor vehicles were discussed. In this regard, direct emission measurements from vehicles powered by LSD, ULSD, ULP and LPG unveiled the relative environmental benefits associated with the use of ULSD in place of LSD to power diesel engines, and of LPG in place of ULP to power passenger cars.
22

Characterization and sources of atmospheric particles in different population density environments / Πηγές και χαρακτηρισμός ατμοσφαιρικών σωματιδίων σε περιοχές διαφορετικής πυκνότητος πληθυσμού

Πικριδάς, Μιχαήλ 06 December 2013 (has links)
In order to reduce uncertainty of atmospheric particle emissions and to examine the mechanism of new particle formation from precursor gases, measurements were conducted in a megacity (Paris, France), an urban area (Patras, Greece) and a remote location (Finokalia, Greece). At Finokalia, the composition of particles with diameter smaller than 1 μm (PM1) depended on air mass origin. The highest concentrations, and most frequent, were observed when air masses were coming from Europe. Organic aerosol was found to be 80% water soluble and the increased organic to elemental carbon ratio correlated with ozone concentration. These findings indicate that particulate matter (PM) at Finokalia was not emitted near the site but was transported from source regions hunderd of kilometers away and thus the area can be considered as a background of Europe. At Finokalia, atmospheric nucleation was observed more frequently during winter when sunlight intensity was below average and favored by air masses that crossed land before reaching the site. This behavior was explained by ammonia involvement in the nucleation process. PM1 was mainly acidic during summer and consumed all available ammonia, contrary to winter when, due to the lower sunlight intensity, particles were neutral and ammonia was available. During both seasons nucleation would only occur if particles were neutral which resulted in higher frequency of events during winter. Air masses that crossed land before reaching the site were enriched with ammonia, thus it was more likely for nucleation to occur. Number size distributions were monitored in Paris, France at fixed and mobile ground stations along with airborne measurements. The Paris plume was identified at a distance of at least 200 km from the city center and the number concentration was found to increase even by a 3-fold when air masses crossed Paris. During summer nucleation was observed approximately half of the campaign days; when the condensational sink was lower than average contrary to winter when no event was identified due to higher sink. Increased number concentration was observed at an altitude outside of the Paris plume simultaneously with new particle formation observed on the ground and was attributed to that phenomenon. At Patras, the legislated by E.U. daily PM10 standards were found to be violated. Exceedances were more frequent (58 of a total of 75) during the colder months (October to March) of the year. The warmer months (April to September) 80% of the PM2.5 was transported from other areas. Contrary during the colder months the contribution of transported PM reduced to 70% during autumn and 50% during winter, when the highest concentrations were observed on average. Local traffic contributed approximately 15% during winter and the remaining 35% was primarily due to domestic heating. PM2.5 and PM1 concentrations were found to exceed 100 μg m-3 on several occasions during nighttime due to domestic heating, either diesel or biomass combustion. Potassium, a tracer of biomass combustion, correlated well (R2=0.79) with PM2.5 during winter indicating a biomass source. Potassium concentrations were higher within the urban premises than a rural area located 36 km away from the city, indicating that at least a portion of the biomass combustion related PM2.5 were emitted locally. / Με σκοπό την μείωση της αβεβαιότητας των εκπομπών ατμοσφαιρικών σωματιδίων (ΑΣ) καθώς και διευκρίνισης του μηχανισμού σχηματισμού ΑΣ από την οξείδωση πρόδρομων αερίων, μετρήσεις πεδίου έλαβαν χώρα σε μία μεγαλούπολη (Παρίσι, Γαλλία), μία αστική περιοχή (Πάτρα, Ελλάδα) και σε μία απομακρυσμένη τοποθεσία (Φινοκαλιά, Ελλάδα). Στην Φινοκαλιά, η σύσταση των σωματιδίων με διάμετρο μικρότερη από 1 μm (ΑΣ1) εξαρτιόταν από την προέλευση των αερίων μαζών. Τις υψηλότερες συγκεντρώσεις εμφάνιζαν οι αέριες μάζες από τη Ευρώπη, που ήταν και οι πιο συχνές. Οργανικές ενώσεις των ΑΣ, εμφάνιζαν, υψηλή διαλυτότητα στο νερό (80%) και αυξημένο λόγο οργανικού προς στοιχειακό άνθρακα που συσχετιζόταν θετικά με τις συγκεντρώσεις όζοντος. Όλα τα παραπάνω υποδεικνύουν πως τα ΑΣ στην περιοχή της Φινοκαλιάς μεταφέρονταν από γειτονικές περιοχές εκατοντάδες χιλιόμετρα μακριά και συνεπώς η περιοχή μπορεί να θεωρηθεί ως σταθμός υποβάθρου για την Ευρώπη. Στην Φινοκαλιά, το φαινόμενο της ατμοσφαιρικής πυρηνογένεσης ήταν συχνότερο τους χειμερινούς μήνες, όταν η ένταση φωτός ήταν χαμηλότερη, και σε αέριες μάζες που παρέμεναν σημαντικό χρόνο πάνω από την στεριά πριν φτάσουν στον σταθμό. Αυτή η συμπεριφορά εξηγήθηκε με την συμμετοχή της αμμωνίας στην διαδικασία της πυρηνογένεσης. Τα ΑΣ1 το καλοκαίρι ήταν κατά κανόνα όξινα και κατανάλωναν όλη την διαθέσιμη αμμωνία σε αντίθεση με τον χειμώνα, όπου εξαιτίας της χαμηλότερης έντασης φωτός, τα ΑΣ1 ήταν ουδέτερα και υπήρχε διαθέσιμη. Και στις δύο περιόδους η πυρηνογένεση λάμβανε χώρα μόνο όταν τα σωματίδια ήταν ουδέτερα, το οποίο είχε ως αποτέλεσμα υψηλότερη συχνότητα του φαινομένου τους χειμερινούς μήνες. Οι αέριες μάζες όταν παρέμεναν πάνω από στεριά εμπλουτίζονταν με αμμωνία, αυξάνοντας την πιθανότητα πυρηνογένεσης. Κατανομές μεγέθους αριθμού μετρήθηκαν στο Παρίσι, Γαλλίας σε επίγειους σταθμούς, σταθερούς και κινητούς, καθώς και σε υψόμετρο. Ο θύσανος του Παρισιού ταυτοποιήθηκε σε απόσταση τουλάχιστον 200 km από την πόλη και οι συγκεντρώσεις αριθμού ΑΣ αύξαναν ακόμα και κατά 300% όταν οι αέριες μάζες προέρχονταν από το Παρίσι. Το καλοκαίρι πυρηνογένεση έλαβε χώρα τις μισές μέρες της δειγματοληψίας, όταν η διαθέσιμη επιφάνειας συμπύκνωσης ήταν χαμηλή, ενώ το χειμώνα, επειδή η διαθέσιμη επιφάνεια ήταν υψηλότερη, δεν ταυτοποιήθηκε το φαινόμενο. Αυξημένες συγκεντρώσεις αριθμού ΑΣ ταυτοποιήθηκαν εκτός του θυσάνου του Παρισιού ταυτόχρονα με πυρηνογένεση στο έδαφος και αποδόθηκαν σε αυτό το φαινόμενο. Στην Πάτρα τα θεσμοθετημένα από την Ε.Ε. ημερήσια όρια ΑΣ10 βρέθηκαν να παραβιάζονται. Οι υπερβάσεις ήταν πιο συχνές (58 από τις 75) τους ψυχρούς μήνες (Οκτώβριο - Μάρτιο). Τους θερμούς μήνες (Απρίλιο - Σεπτέμβριο) το 80% των ΑΣ2.5 μεταφέρονταν από άλλες περιοχές. Αντίθετα τους ψυχρούς μήνες η συνεισφορά από μεταφερόμενα ΑΣ μειωνόταν στο 70% το φθινόπωρο και 50% το χειμώνα, όταν και οι συγκεντρώσεις ΑΣ2.5 ήταν κατά μέσο όρο οι υψηλότερες στην περιοχή. Η τοπική κυκλοφορία συνείσφερε περίπου 15% τον χειμώνα ενώ ένα σημαντικό κομμάτι από το υπόλοιπο 35% οφειλόταν στην οικιακή θέρμανση. Συγκέντρωση ΑΣ2.5 και ΑΣ1 ίση ή μεγαλύτερη των 100 μg m-3 μετρήθηκε κατ'επανάληψη τις νυχτερινές ώρες των χειμερινών μηνών εξαιτίας της οικιακής θέρμανσης, είτε με πετρέλαιο είτε με καύση βιομάζας Η καύση βιομάζας υποδεικνύεται από την συσχέτιση (R2=0.79) των συγκεντρώσεων ΑΣ2.5 με τις συγκεντρώσεις καλίου, ένα δείκτη καύσης βιομάζας. Οι συγκεντρώσεις αυτού του δείκτη βρέθηκαν υψηλότερες μέσα στον αστικό ιστό από μία αγροτική περιοχή 36 km μακριά από την Πάτρα, αποκλείοντας την αποκλειστική μεταφορά ΑΣ2.5 καύσης βιομάζας από γειτονικές περιοχές.
23

Avaliação dos efeitos do material particulado proveniente da queima da plantação de cana-de-açúcar sobre a morbidade respiratória na população de Araraquara - SP. / Evaluation of the effects of particulate matter deriving from sugar cane plantation burning on the respiratory morbidity of the Araraquara city population.

Marcos Abdo Arbex 10 May 2002 (has links)
Desde o início do século passado, estudos na literatura médica documentaram uma significativa associação entre poluição atmosférica decorrente da emissão de combustíveis fósseis e morbimortalidade na raça humana, inclusive para níveis de poluentes no ar considerado como seguro para a saúde da população exposta. Na década de 70, durante a crise do petróleo o governo brasileiro implementou um programa chamado Proálcool com o objetivo de produzir um combustível alternativo, renovável, e não poluente: o etanol, derivado da cana-de-açúcar. Esse programa culminou com uma grande produção de veículos movidos a álcool a partir da década de 80, e um grande incremento da cultura da cana-de-açúcar na região central do Estado de São Paulo. Com a crescente utilização do álcool como combustível em veículos automotores houve uma melhora na qualidade do ar nos grandes centros urbanos. Existe, porém, o contraponto: a cana-de-açúcar é uma cultura agrícola singular, uma vez que, por razões de produtividade e de segurança, a colheita é realizada após a queima dos canaviais, o que gera uma grande quantidade de elemento particulado negro denominado "fuligem da cana". Esse material particulado modifica as características do meio ambiente nas regiões onde a cana-de-açúcar é cultivada, colhida e industrializada. A queima da biomassa é a maior fonte de emissão de material particulado e de gases tóxicos no planeta, e não havia na literatura médica qualquer trabalho, que relacionasse a poluição atmosférica em conseqüência da queima desse tipo especifico de biomassa, com a saúde humana. Esse estudo epidemiológico de séries temporais avalia a associação entre o material particulado coletado durante a queima de plantações de cana-de-açúcar e um indicador de morbidade respiratória em Araraquara (SP). Entre 26 de maio e 31 de agosto de 1995, o número diário de pacientes que necessitaram inalações em um dos principais hospitais da cidade foi quantificado, e utilizado para estimar a morbidade respiratória. Para estimar o nível da poluição do ar foi quantificado diariamente o peso do sedimento do material particulado proveniente da fuligem da cana-de-açúcar, obtido por sedimentação simples, em dois pontos da cidade, um localizado no centro e o segundo na zona rural. A associação entre o peso do sedimento e o número de pacientes que necessitaram de terapia inalatória, foi avaliada pelo modelo aditivo generalizado da regressão de Poisson com controle para sazonalidade, temperatura e dias da semana. Encontrou-se uma associação positiva significante e dose dependente entre o número de terapia inalatória e o peso do sedimento. Um aumento de 10 mg no peso do sedimento está associado a um risco relativo de terapêutica inalatória de 1,09 (1-1,19). Nos dias mais poluídos o risco relativo de terapêutica inalatória é de 1,20 (1,03-1,39). Esses resultados indicam que a queima das plantações da cana-de-açúcar pode causar efeitos deletérios à saúde da população exposta. / This times series epidemiological study was designed to evaluate the association between particulate matter collected during sugar cane plantation burning and an indicator of morbidity respiratory in Araraquara, São Paulo State, Brazil. From May 26th to August 31st, 1995, the daily number of patients that received inhalation therapy in one of the main hospitals of the city was recorded and used as a morbidity respiratory estimation. In order to estimate air pollution levels the daily sediment weight from sugar cane particulate matter was measured after collected by simple sedimentation process, in two strategic points of the city: one in a central area and the other in a peripheral area. The association between the sediment weight and the number of patients who received inhalation therapy was evaluated by means of generalized additive Poisson regression models controlled for seasonality, temperature and days of the week. A positive significant and dose-dependent relationship was found between the number of inhalation therapy and the sediment weight. The relative risk of inhalation therapy associated with an increase of 10 mg in the sediment weight was 1.09 (1 - 1.19), and the relative risk of an inhalation therapy was 1.20 (1.03 -1.39) in the most polluted days. These results indicate that sugar cane plantations burning may cause deleterious health effects in the exposed population.
24

Geoprocessamento de dados meteo-oceonogr?ficos (cor do oceano e temperatura da superf?cie do mar) aplicado ao monitoramento ambiental na costa setentrional do Rio Grande do Norte

Ferreira, Anderson Targino da Silva 14 October 2009 (has links)
Made available in DSpace on 2015-03-13T17:08:24Z (GMT). No. of bitstreams: 1 AndersonTSF_1_60pdf.pdf: 1582556 bytes, checksum: e1053ad83e14cdcdf0d10a9b5dcbdbbf (MD5) Previous issue date: 2009-10-14 / Orbital remote sensing has been used as a beneficial tool in improving the knowledge on oceanographic and hydrodynamic aspects in northern portion of the continental shelf of Rio Grande do Norte, offshore Potiguar Basin. Aspects such as geography, temporal and spatial resolution combined with a consistent methodology and provide a substantial economic advantage compared to traditional methods of in situ data collecting. Images of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's AQUA satellite were obtained to support systematic data collections related to the campaign of environmental monitoring and characterization of Potiguar Basin, held in May 2004. Images of Total Suspension Matter (TSM) and values of radiance standard were generated for the calculation of concentrations of total suspension matter (TSM), chlorophyll-a and sea surface temperature (SST). These data sets were used for statistical comparisons between measures in situ and satellite estimates looking validate algorithms or develop a comprehensive regional approach empirically. AQUA-MODIS images allowed the simultaneous comparison of two-dimensional water quality (total suspension matter), phytoplankton biomass (chlorophyll-a) variability and physical (temperature). For images of total suspension matter, the generated models showed a good correlation with the field data, allowing quantitative and qualitative analysis. The images of chlorophyll-a showed a consistent correlation with the in situ values of concentration. The algorithms adjusted for these images obtained a correlation coefficient fairly well with the data field in order that the sensor can be having an effect throughout the water column and not just the surface. This has led to a fit between the data of chlorophyll-the integration of the average sampling interval of the entire water column up to the level of the first optical depth, with the data generated from the images. This method resulted in higher values of chlorophyll concentration to greater depths, due to the fact that we are integrating more values of chlorophyll in the water column. Thus we can represent the biomass available in the water column. Images SST and SST measures in situ showed a mean difference DT (SST insitu - SST sat) around -0.14 ? C, considered low, making the results very good. The integration of total suspension matter, chlorophyll-a, the temperature of the sea surface (SST) and auxiliary data enabled the recognition of some of the main ways to fund the continental shelf. The main features highlighted were submerged canyons of rivers Apodi and A?u, some of the lines and beachrocks reefs, structural highs and the continental shelf break which occurs at depths around -60 m. The results confirmed the high potential for use of the AQUA-MODIS images to environmental monitoring of sea areas due to ease of detection of the field two-dimensional material in suspension on the sea surface, temperature and the concentration of chlorophyll-a / O sensoriamento remoto orbital tem sido utilizado como ferramenta vantajosa na melhoria do conhecimento sobre os aspectos hidrodin?micos e oceanogr?ficos na por??o norte da plataforma continental do Estado do Rio Grande do Norte, regi?o offshore da Bacia Potiguar. Aspectos como a cobertura geogr?fica e resolu??es temporal e espacial, somados a uma metodologia consistente garantem uma substancial vantagem e economia em rela??o aos m?todos tradicionais de coletas de dados in situ. Em apoio ?s coletas sistem?ticas referentes ? campanha de caracteriza??o e monitoramento ambiental da Bacia Potiguar, realizada em maio de 2004, foram obtidas imagens do sensor Moderate-Resolution Imaging Spectroradiometer (MODIS) instalado a bordo do sat?lite AQUA da NASA. Foram gerados imagens de material partitulado em suspens?o e valores de radi?ncias normalizadas para o calculo de concentra??es do material particulado em suspens?o (MPS), clorofila-a e temperatura da superf?cie do mar (TSM). Estes conjuntos de dados foram utilizados para compara??es estat?sticas entre medidas in situ e estimativas por sat?lite buscando validar algoritmos globais ou desenvolver uma abordagem regional empiricamente. As imagens AQUA-MODIS permitiram a compara??o bidimensional simult?nea da qualidade da ?gua (material particulado em suspens?o, da biomassa fitoplanct?nica (clorofila-a) e variabilidade f?sica (temperatura). Para as imagens de material particulado em suspens?o, os modelos gerados apresentaram uma boa correla??o em rela??o aos dados de campo, permitindo uma an?lise quantitativa e qualitativa dessas imagens. As imagens de clorofila-a apresentaram correla??o consistente com os valores das concentra??es in situ. Os algoritmos ajustados para essas imagens obtiveram um coeficiente de correla??o razoavelmente bom em rela??o aos dados de campo, tendo em vista que o sensor possa estar tendo influ?ncia de toda a coluna d ?gua e n?o apenas da superf?cie. Esse fato levou a um ajuste entre os dados de clorofila-a da integra??o das m?dias dos intervalos de coleta de toda a coluna ?gua at? o n?vel da primeira profundidade ?ptica, em rela??o aos dados gerados das imagens. Tal m?todo resultou em valores mais altos de concentra??o de clorofila para maiores profundidades, devido ao fato de se estar integrando mais valores de clorofila na coluna d ?gua. Dessa maneira pode-se representar a biomassa dispon?vel na coluna d ?gua. As imagens TSM e as medidas de TSM in situ mostraram uma diferen?a m?dia v DT (TSM insitu TSM sat) em torno de -0,14 ?C, considerada baixa, tornando os resultados muito bons. A integra??o de imagens de sedimentos em suspens?o, de clorofila-a e de temperatura da superf?cie do mar possibilitaram o reconhecimento de algumas das principais formas de fundo da plataforma continental. As principais fei??es destacadas foram os canyons submersos dos rios Apodi e A?u, algumas das linhas de beachrocks e recifes, altos estruturais e a quebra da plataforma continental que ocorre a profundidades em torno de 60 m. Os resultados confirmaram o alto potencial de uso das imagens AQUA-MODIS no monitoramento ambiental de ?reas oce?nicas devido ? facilidade na detec??o do campo bidimensional material em suspens?o na superf?cie do mar, de temperatura e da concentra??o de clorofila-a

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