Orientadora: Ivanise Guilherme Branco / Banca: Cassia Roberta Malacrida Mayer / Banca: Izabel Cristina Freitas Moraes / Resumo: O alginato, presente na parede celular das algas marinhas pardas, apresenta coloração marrom, sendo necessário seu branqueamento para melhor aceitabilidade do mercado consumidor. O gás ozônio (O3) tem mostrado grande potencial de aplicabilidade como agente clareador mais sustentável. O presente estudo visa a otimização, utilizando a análise de superfície de resposta, dos parâmetros de clareamento (tempo, fluxo de oxigênio e temperatura), utilizando ozônio como agente branqueador, sobre os parâmetros colorimétricos (porcentagem de transmitância e índice de luminosidade), composição química (razão entre os ácidos manurônico (M) e gulurônico (G) M/G) e propriedades reológicas (viscosidade dinâmica, viscosidade intrínseca e massa molar) do alginato de sódio extraído de algas pardas (Sargassum spp.). Nas condições otimizadas de clareamento também foi verificada a influência da ozonização sobre a atividade antioxidante do alginato. O tempo é a variável independente que apresentou maior influência nas respostas, seguido da temperatura e fluxo de oxigênio. A condição otimizada encontrada foi um tratamento com fluxo de oxigênio de 2 L/min por 35 minutos à 25oC. A amostra clareada na condição otimizada apresentou capacidade antioxidante maior que a amostra comercial, indicando que o processo de clareamento por ozonização pode ser menos prejudicial aos compostos bioativos. Além disso, os antioxidantes naturais presentes no alginato de sódio aqui estudado podem agregar valor aos produtos que utilizam esse composto em preparações alimentícias / Abstract: Alginate is a polysaccharide which can be found in the cell wall of brown algae. Its original color is brown that is why a bleaching process is needed to improve this visual impairment. The ozone gas (O3) has shown a great potential as a more sustainable bleaching agent. The present study aims the optimization of bleaching parameters (time, oxygen flow rate and temperature) of sodium alginate from brown seaweeds (Sargassum spp.) using ozone gas as the bleaching agent on the colorimetrics parameters (percent transmittance and index of luminosity), chemical compositon (mannuronic (M) and guluronic (G) acid ratio M/G) and rheological properties (intrinsic viscosity, dynamic viscosity and molar mass). Once it was found the optimal conditions of bleaching, it was also verified the influence of ozonation on antioxidant activity of sodium alginate. The findings point out that ozonation time is the independent variable that most affects the responses, followed by the temperature and oxygen flow rate. The optimized bleaching conditions were determinated with an oxygen flow rate at 2 L/min, during 35 min at 25oC. The bleached sample on the optimized conditions presented a higher antioxidant capacity than the commercial sodium alginate sample, highlighting that the discoloration by ozone might be less harmful to bioactive compounds. Besides, natural antioxidants of sodium alginate can add value to products that use this compound in food preparations / Mestre

It has been shown by Schlesinger and Mintz (1979) that the UCLA general circulation model (GCM) is able to simulate the observed negative correlation between the total amount of ozone in a vertical atmospheric column (the total ozone) and the eastward-propagating synoptic disturbances in the troposphere, with the total ozone maxima and minima located respectively at the troughs and ridges of the tropospheric waves. The goal of the present study was to understand how the GCM simulated this observed relationship. Our analysis shows that the transient-eddy total ozone disturbances were an omnipresent feature of the GCM January simulation in the northern hemisphere midlatitudes, just as they are in nature. It is also found that the transient-eddy total ozone disturbances in the northern hemisphere midlatitudes were closely related to the transient-eddy geopotential heights there throughout the entirety of the simulation. Furthermore, the correlations between these two quantities are negative up to the 72 mb level and attain their largest negative values at the 300 mb level. The analysis also shows that the transient-eddy disturbances in the stratosphere are out of phase with their counterparts in the troposphere, in accord with what would be expected from Dines compensation. In the GCM simulation there is a well-defined positive correlation between the total ozone and the ozone content in each of the model layers in the upper troposphere and lower and middle stratosphere. It is found that although layers 5-8 (19.3-150 mb) contain the largest percentage of the total ozone, it is predominantly layers 6-9 (37.3 -300 mb) that make the largest contribution to the temporal variations of total ozone. In accordance with the observations, a strong negative correlation is found between the simulated total ozone and the height of the simulated tropopause. However, changing the height of the tropopause cannot in itself change the total ozone, but rather only its partitioning between the stratosphere and the troposphere. Our analysis clearly shows that it is the ozone convergence and divergence in an atmospheric column, not the photochemical ozone production and destruction, which are responsible for the synoptic increases and decreases of total ozone. / Graduation date: 1988

Tropospheric ozone pollution is a world-wide problem, based on studies reported from locations as diverse as India, Hong Kong, Taiwan, South Korea, Germany, Spain, Greece, Canada, and the United States. Ozone is a serious pollutant in the troposphere due to its adverse effects on the health of plants, and on the respiratory systems, eyes, and mucous membranes of humans. Due to the seriousness of the issue, the ozone problem in the Atlanta, Georgia metropolitan area was investigated. A review of the literature revealed a research deficiency, since no environment-to-circulation analysis of the ozone problem in the Atlanta metropolitan area could be found. Therefore such a study was conducted, in order to determine how high ozone days in Atlanta were related to atmospheric patterns and meteorological variables. Statistical analysis of radiosonde data, and data from eleven air quality monitoring stations in metropolitan Atlanta, for the summer months of 2000-2003, revealed a relationship between high ozone days and both high- and low- pressure patterns, as well as between high ozone days and higher temperature and lower dew point temperature. The data revealed two groups of stations differentiated by geography, and also suggested transport of precursor chemicals as a factor at some stations. This research may assist policy-makers as well as policy-implementers in elucidating associations or mechanisms that can assist efforts to reduce tropospheric ozone concentrations in the Atlanta area.

Graduation date: 1991

En cette fin du XXe siècle où les faillites de l'environnement nous interpellent; alors que la diminution de la couche d'ozone, la pollution urbaine et la perturbation des conditions climatiques hypothèquent l'existence biologique de l'humanité, on parle de plus en plus de lois applicables à la gestion de l`environnement. Leur contexte appartient à des cadres spatiaux et juridiques qui se calquent sur les limites politiques, administratives des états et regroupements régionaux. Là où existent les lois sur la gestion de l'environnement, leur application intégrale n'est point garantie. De puissants groupes de pression et des influences politiques complaisants imposent volontiers un silence destructeur. On constate par ailleurs que l'approche qui inspire le pluralisme politique ainsi reconnu se voulant répressive, soulève des interrogations. Qu'est-ce que 'environnement et comment fonctionne-t-il? N'est-il pas important de reconsidérer le cadre théorique des rapports entre l'homme et l'environnement? Pourquoi parler de la gestion de l'environnement dans un contexte juridique? La loi Naturelle structure les géosystèmes environnementaux. Lorsqu'ils connaissent la moindre rupture d'équilibre, un processus de recherche de l'équilibre perdu se déclenche. Ainsi se comprend le principe de l'interpellation de la Terre, planète vivante, à l'endroit de l'humanité.

CHRONOS, AURAMS et GEM-AQ sont trois modèles de simulation de la qualité de l'air à l'échelle régionale développés et utilisés par différentes institutions canadiennes. Ils reproduisent, avec différents degrés de complexité, les interactions physico-chimiques présentes dans l'atmosphère. Bien que CHRONOS et AURAMS aient déjà prouvé leurs capacités à reproduire des épisodes intenses de pollution, les évaluations réalisées ne permettent pas une comparaison directe de leurs performances respectives. GEM-AQ, quant à lui, est en phase d'évaluation par ses concepteurs. Les objectifs de ce projet consistaient à réaliser la première intercomparaison de ces trois modèles sur une période commune et sur un même domaine d'évaluation, puis de caractériser les écarts pour identifier leurs origines. À l'aide d'analyses appropriées, nous avons comparé les niveaux d'ozone simulés, du 6 juillet au 31 août 2004, par les modèles avec 607 sites de mesure des réseaux de surveillance de la qualité de l'air canadiens et américains. Les sites de mesure sélectionnés ont été répartis selon cinq secteurs qui couvrent la moitié est de l'Amérique du nord et qui caractéristisent des régimes météorologiques différents. Nous avons rencontré des difficultés avec GEM-AQ pour effectuer les simulations qui n'ont pas pu être résolues par manque de temps. Nous avons donc limité l'intercomparaison à deux modèles. Nous avons montré que CHRONOS et AURAMS reproduisaient la variation des niveaux horaires d'ozone observés, avec des coefficients de corrélation moyens respectifs de 0.71 et 0.66. Cependant, les deux modèles ont surestimé leurs amplitudes sur l'ensemble du domaine hormis sur la péninsule floridienne où celles-ci ont été similaires. Les surestimations sur les niveaux horaires ont été de 30 à 50% en moyenne pour CHRONOS alors que celles d'AURAMS ont rarement excédées 20%. Nous avons constaté que les écarts évoluaient selon un cycle nycthémère plus influencé par les données d'émissions, notamment celles qui décrivent les émissions biogéniques, que par les paramétrages qui décrivent les processus photochimiques. Par ailleurs, les différences entre les moyennes d'ozone observées et simulées ont également présenté une caractéristique spatiale; Les différences les plus importantes ont été retrouvées sur un secteur commun aux deux modèles. Celui-ci recouvre l'essentiel de la chaîne des Appalaches et son versant occidental. Cette particularité soulignerait l'influence de la définition géographique des émissions sur la simulation des niveaux d'ozone. Nous avons également observé que l'évolution de la couche de mélange simulée par le modèle météorologique GEM pourrait être à l'origine d'une surestimation notable des niveaux d'ozone en fin d'après-midi. Finalement, nous avons identifié les influences que peuvent avoir la couverture et la résolution d'une grille sur les niveaux d'ozone simulés. Ainsi, les moins bonnes performances d'AURAMS ont été retrouvées au voisinage de sa limite ouest et dans les régions où les effets locaux peuvent fortement influencer le comportement des polluants troposphériques. Dans ce contexte, nous avons montré la pertinence potentielle d'une évaluation de modèle qui reposerait sur la comparaison du niveau d'ozone simulé dans une cellule par rapport à la moyenne des niveaux observés par les stations présentes dans cette cellule. Pour caractériser l'influence des émissions sur la simulation des niveaux d'ozone, nous avons réalisé une étude de sensibilité d'AURAMS où nous avons successivement modifié les émissions biogéniques puis anthropiques. Cette étude nous a permis d'associer les émissions biogéniques à la surestimation des niveaux d'ozone simulés; Nous avons également observé que les derniers inventaires d'émission canadien et américain ont réajusté à la baisse les émissions d'oxydes d'azote associés au trafic matinal. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Évaluation de modèle, CHRONOS, AURAMS intercomparaison Ozone, Caractérisation des écarts.

Interactions between societal, natural, and infrastructure systems can be beneficial or harmful to society. Society benefits from natural systems by being provided with the basic necessities of life (air, water, and food). However, events such as stratospheric ozone depletion demonstrate that society ultimately can be harmed by societal impacts on natural systems. Domain knowledge is developed from observation of natural, societal, and infrastructure systems. Domain knowledge is contained within scientific knowledge and engineering knowledge. Scientific knowledge is gained through structured observation and rigorous analysis of natural and societal systems. Engineering knowledge is partially developed from scientific knowledge and is used to manipulate natural and societal systems. Technology is the application of engineering knowledge. In the past two centuries scientific and engineering knowledge have produced technologies that affect the interaction between societal and natural systems. Although scientists and engineers are in positions to advise on policies to address problems involving societal/natural system interactions, their contributions are not always fully utilized. This research examines feedback mechanisms that describe societal, natural, and infrastructure system interaction to develop an improved understanding of the dynamic interactions between society, natural systems, infrastructure systems, scientific and engineering knowledge, technology, and public policy. These interactions are investing through and opposing case study analysis performed using computer simulation modeling. The stratospheric ozone depletion study represents a case in which domain experts successfully influenced public policy. The U.S. civilian nuclear power study represents a case in which domain experts were less successful in influencing public policy. The system dynamics methodology is used to construct these two highly integrated models of societal-natural system interaction. Individual model sectors, based on existing theory, describe natural/infrastructure systems, knowledge and technology development, societal risk perception, and public policy. The work reveals that the influence of scientists and engineers in the public policy is due in part to their ability to shift dominance between causal feedback mechanisms that seek to minimize societal risk from natural systems and feedback mechanisms that seek to minimize the economic risk of increased regulations. The ability to alter feedback mechanism dominance is not solely dependent upon scientists and engineers ability to develop knowledge but to a larger extent depends on their ability to interact with policy makers and society when describing issues involving natural and infrastructure systems.

Houston-Galveston-Brazoria area is in severe non-attainment status for ozone compliance. Source-oriented mechanistic modeling was used to determine the major sources of VOCs that contributes to ozone formation during the Texas Air Quality Study (TexAQS) from August 16, 2000 to September 7, 2000. Environmental Protection Agency (EPA)?s Community Scale Air Quality Model (CMAQ) version 4.6 was used as a host model to include a revised Statewide Air Pollution Research Center (SAPRC99) photochemical mechanism with source-oriented extensions to track the contributions of Volatile Organic Compounds (VOCs) emissions from diesel engines, biogenic sources, highway gasoline vehicles, fuel combustion, off-highway gasoline engines, solvent utilization and petrochemical industries to ozone formation in the atmosphere. Source-oriented emissions needed to drive the model were generated using a revised Sparse Matrix Operator Kernel Emissions (SMOKE) model version 2.4. VOC/NOx ratios are found to be a critical factor in the formation of ozone. Highest ozone formation rates were observed for ratios from 5-15. The contributions of VOC to ozone formation were estimated based on the linear relationship between the rate of NO to NO2 conversion due to radicals generated from VOC oxidation and the rate of net ozone formation. Petroleum and other industrial sources are the largest anthropogenic sources in the urban Houston region and contribute to 45% of the ozone formation in the HGB area. Highway gasoline vehicles make contributions of approximately 28% to ozone formation. Wildfires contribute to as much 11% of ozone formation on days of high wildfire activity. The model results show that biogenic emissions account for a significant amount of ozone formation in the rural areas. Both highway and off-highway vehicles contribute significantly to ozone formation especially in the downwind region. Diesel vehicles do not contribute significantly to ozone formation due to their low VOC emissions.

Kaohsiung is a densely populated harbor city, in which the density of motor vehicles is also high. Since the temperature and sunlight is also relatively high in Southern Taiwan, tending to transform ambient volatile organic compounds to ozone thus causes high ozone events. This study measured the concentrations of 63 hydrocarbon (HC) species from C2 to C15 simultaneously at the Nan-Chie and Hsiung-Kong sites in Kaohsiung city during the morning (07-10), the afternoon (13-16), and the evening (18-21) periods on three successive days in winter 2004. Results show that the most abundant species of Kaohsiung¡¦s air is toluene (43.01-60.95 £gg/m3), followed by i-pentane, 1,2,4-trimethylbenzene, benzene, n-butane, propane, and acetylene, in the range 9.55-16.93 £gg/m3, while the concentrations of halocarbons is 0.17-4.12 £gg/m3. Alkanes (44.7-45.9%) represent the largest proportion of the total HC, followed by aromatics (35.4-36.8%), alkenes (10.5-10.9%) and halocarbons (3.6-3.9 %). The OFP (ozone formation potential) of HC species were evaluated based on the MIR (maximum incremental reactivity). Results show that aromatics (45.9-54.3%) represent the largest proportion of the OFP, followed by alkenes (17.7-37.5%), and alkanes (16.5-23.6%). The results from the factor analyses show the major sources of ambient HC in Kaohsiung city are the vehicle exhausts, industrial processes, solvent evaporations, combustion exhausts, and petrochemical processes.

Ozone is a powerful oxidant which can be use for bacterial inactivation, deodorizing, and bleaching. In aquatic farms, it can improve larvae hatching and keep water quality under control. The primary object of this research is to investigate the influence of ozone solubility by the concentrations chloride¡]Cl-¡^and bromide¡]Br-¡^in seawater. The indigo colorimetric method was used to detect the variation of total residual oxidants¡]TROs¡^after ozonation. The bacteriocidal effects of ozone with added Cl- or Br- were tested on three common marine fish pathogens. The results showed that the ozone solubility in reverse osmosis¡]RO¡^treated water was about 2.3 mg/L, and rapidly decreased to 0.5 mg/L when ozonation stopped. The process of ozonation in seawater from start to equilibrium, the TROs concentration could reach 8.5 mg/L and then decreased slowly to a stable concentration of about 6 mg/L. When Cl- was added in RO water, the TROs concentration varied from 2 to 3.5 mg/L, and rapidly disappeared after stop ozonation. It was concluded that Cl- could not effectively increase ozone solubility in seawater. In contrast, adding Br- in RO water not only efficiently increased the solubility of ozone but also maintained the TROs concentrations after stop ozonation, and the TROs concentrations were proportional to the Br- concentrations. The same trends were also observed in seawater added with Br-. In the bacteriocidal effect of ozone, compare with pure seawater, adding of Br- in seawater could effectively reduce the TROs concentrations needed to completely inhibit each pathogen. Such practice may be extended to aquatic farms to eliminate or reduce the bacterial pathogens in seawater.