Carbon Dioxide (CO₂) sequestration requires that the injected CO₂ be permanently trapped in the subsurface and not leak from the target location. To accomplish this, it is important to understand the main mechanisms associated with CO₂ flow and transport in the subsurface once CO₂ is injected. In this work CO₂ seeps at the Crystal Geyser site were studied using modeling and simulation to determine how CO₂ geochemically reacts with formation brines and how these interactions impact the migration of CO₂. Furthermore different scenarios for CO₂ migration and seepage along the Grand Wash fault are studied and the possible outcomes for these different scenarios are documented. The GEM (Generalized Equation-of-State Model) from CMG Ltd. was used to perform the simulation studies. A 2-D model was built without geochemical reactions to mainly study the mechanism associated with dissolution of CO₂ gas. The process of CO₂ release from the brine as the fluid mixture flows up along the fault was modeled. Then, 3-D models with geochemical reactions were built for CO₂ migration corresponding to two different sources of CO₂ - deep crustal ₂ and CO₂-dissolved in groundwater. In both these cases, CO₂ reacted with the aqueous components and minerals of the formation and caused carbonate mineralization. In the case of deep crustal CO₂ source, there were vertical patterns of calcite mineralization simulated along the fault that indicated that calcite mineralization might be localized to isolated vertical flow paths due to vertical channeling of CO₂ from the crust. In the case of CO₂-dissolved groundwater flowing along the sandstone layers, calcite mineralization is spread over the entire fault surface. In this case, the groundwater flow is interrupted by the fault and there is vertical flow along the fault until a permeable sandstone layer is encountered on the other side of the fault. This vertical migration of CO₂-saturated brine causes a release in pressure and subsequent ex-solution of CO₂. As a result, modeling allowed us to establish difference in surface expression of CO₂ leakage due to two different CO₂ migrations scenarios along the fault and helped develop a scheme for selecting appropriate model for CO₂ leakage based on surface observation of travertine mounds. A key observation at the Crystal Geyser site is the lateral migration of CO₂ seep sites over time. These migrations have been confirmed by isotope studies. In this modeling study, the mechanism for migration of seep sites was studied. A model for permeability reduction due to precipitation of calcite was developed. It is shown using percolation calculations that flow re-routing due to permeability alterations can result in lateral migration of CO₂ seeps at rates comparable to those established by isotope dating. / text

L’utilisation d’outils microfluidiques pour la mise en œuvre de procédés sous-pression tels que des réactions chimiques, des synthèses de matériaux nano-structurés, ou en tant qu’outils de détermination de grandeurs physico-chimiques est une thématique de recherche récente. Quelques travaux précédents ont démontré l'intérêt des procédés supercritiques en microcanal pour la chimie organique et la synthèse de nanocristaux. Le développement de ces procédés est concomitant à la mise au point de dispositifs capables de résister à des conditions de pression et température élevées tout en étant compatibles avec l’utilisation de fluides supercritiques. Les avantages de ces fluides pour ce type de procédé sont une faible viscosité et une diffusivité élevée, ce qui offre des conditions de mélange favorables. Cependant, dans le même temps, les propriétés de transport – comme la masse volumique – sont très sensibles aux variations de température et de pression, qui ne peuvent être évités dans ces systèmes où les fluides sont en écoulement. Dans des systèmes diphasiques où le CO2 supercritique (PC = 74 bar) est utilisé en tant que solvant, les transferts thermique et de matière sont fortement influencés par la nature des écoulements. Dans un souci de maîtrise de ces procédés, la compréhension du comportement hydrodynamique, à la fois locale et globale, des fluides supercritiques en microcanal devient fondamentale. Dans cet objectif, un dispositif de microfluidique transparent et résistant à des pressions supérieures à la pression critique du CO2 a été développé. En adaptant une méthodologie propre à la lithographie molle, permettant la fabrication de puces microfluidiques pour des applications à pression atmosphérique, nous sommes parvenus à établir un protocole de fabrication de puces en verre et résine photosensible, viables pour une utilisation à plus de 100 bar en conditions CO2 supercritique. Grâce à ces dispositifs, des expérimentations d’ombroscopie ont pu être réalisées pour observer des écoulements composés de CO2 et d’éthanol dans le microcanal de section carrée de 200 x 200 µm à des pressions comprises entre 40 et 90 bar. Pour identifier et comprendre les phénomènes qui entrent en jeu lors de la création de l’écoulement à haute pression, une approche thermodynamique relative aux équilibres de phase est indispensable. En effet, la connaissance du diagramme de phase permet d’ores et déjà de représenter les zones d’équilibres thermodynamiques (pression, température et composition) pour lesquelles le mélange créé est monophasique liquide ou diphasique liquide-vapeur. L’illustration expérimentale par les séquences d’écoulement obtenues justifie la modélisation thermodynamique du diagramme de phase du binaire d’étude. Le régime d’écoulement de Taylor, obtenu spécifiquement à l’intérieur de la zone d’équilibre diphasique liquide-vapeur, est étudié. Ce régime est caractérisé par des bulles allongées entourées par un film liquide et séparées les unes des autres par une poche liquide. L’évolution des caractéristiques hydrodynamiques de ce régime – longueur de bulle, longueur de slug et vitesse de bulle – est étudiée en fonction des conditions opératoires, des débits et propriétés des fluides. L’objectif étant de repérer les similitudes avec les caractérisations à pression ambiante de la littérature et les particularités résultantes d’une manipulation à haute pression. Ce travail a été à l’origine de plusieurs avancées pour les communautés microfluidique et supercritique. Un nouveau protocole de fabrication à moindre coût de puces microfluidiques compatibles avec l’utilisation de CO2 supercritique et des méthodes de visualisation avancées est présenté. Une modélisation thermodynamique et une étude hydrodynamique expérimentale permettent de construire une carte d’écoulement des régimes biphasiques observés à haute pression ainsi qu’une caractérisation hydrodynamique du régime de Taylor à haute pression en microcanal. / The use of microdevices to run high pressure processes for chemical reaction, nanomaterial synthesis, or as analysis tools for determining physical properties have become of increasing interest in recent years. Several works in the literature have demonstrated the advantages of supercritical microfluidics for organic chemistry and complex nanomaterial synthesis. The development of pressure-resistant microfluidic chips, which also are compatible with the properties of supercritical fluids, is a key step in order to increase knowledge about these processes. Supercritical fluids have low viscosity and high diffusivity, which are advantageous for microprocesses since they facilitate mixing between species. However, the properties of these fluids are also very sensitive with small changes in pressure, temperature and composition. In twophase applications where supercritical CO2 may be used as solvent or reactant, these varying properties can result in very different flow patterns and hydrodynamics with pressure change. Since the hydrodynamics of such systems largely influence heat and mass transfer, the study of flow behavior under supercritical conditions in microchannel is fundamental. In pursuit of this objective, a transparent microdevice, which is suitable for experiments at pressures higher than critical pressure of CO2 (PC = 74 bar), has been developed in this thesis. Using a soft lithography method that is currently used to fabricate microfluidic chips for applications under ambient pressure, a methodology for fabricating a highly resistant chip made from glass and UV-curable polymer was developed. These chips can resist more than 100 bar in supercritical CO2 conditions. The microchips were then used to observe the flow behavior of a CO2-ethanol mixture created in a T junction microchannel (cross section: 200 x 200 µm) for pressures ranging from 40 to 90 bar using high-speed imaging. To identify and interpret phenomena that occur during the flow formation at high pressure, a thermodynamic approach was essential. Depending on the pressure, temperature and composition of the CO2-ethanol mixture, the flow at equilibrium can either be in the single phase liquid domain or in the two-phase liquid vapor domain, according to the phase diagram. Imaging experiments were conducted over the boundaries between the two-phase liquid vapor domain and the single phase liquid and the observed two-phase flow patterns and transitions confirm the predictions of the phase diagram. High-pressure CO2-ethanol Taylor flow, which was obtained in the twophase domain, was then studied. This flow pattern, which is characterized by elongated bubbles surrounded by a liquid film and separated from each other by liquid slugs, is well-known at low pressure and has been widely described in the literature. The objective here was therefore to compare the flow characteristics such as bubble length, slug length and bubble velocity obtained under high pressure operation with the behavior at low pressure. Differences coming from fluid characteristics or operating at high pressure were pointed . This work provides a variety of new results on high pressure microfluidics that will be of interest to both the microfluidics and the supercritical fluids communities. It presents a new protocol to fabricate low cost pressure-resistant microfluidic chips suitable for supercritical CO2 and advanced visualization methods. It also presents new findings obtained with this technology on map flow pattern at high pressure in correlation with thermodynamics approach and characterization of Taylor flow hydrodynamics under high pressure in microchannel.

LOBO, A. K. M. Photosynthesis regulation by sucrose metabolism under water deficit and source-sink alterations in sugarcane. 2016. 118 f. Tese (Doutorado em Bioquímica)-Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Anderson Silva Pereira (anderson.pereiraaa@gmail.com) on 2017-01-03T20:20:30Z No. of bitstreams: 1 2016_tese_akmlobo.pdf: 4541762 bytes, checksum: e3450d87e286b1a5213eb866921b6c94 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-01-09T21:32:52Z (GMT) No. of bitstreams: 1 2016_tese_akmlobo.pdf: 4541762 bytes, checksum: e3450d87e286b1a5213eb866921b6c94 (MD5) / Made available in DSpace on 2017-01-09T21:32:52Z (GMT). No. of bitstreams: 1 2016_tese_akmlobo.pdf: 4541762 bytes, checksum: e3450d87e286b1a5213eb866921b6c94 (MD5) Previous issue date: 2016 / Water deficit stress is the major limiting factor for plant growth and development, constraining food production. In order to survive in such dry conditions, many biochemical and physiological changes must be triggered by plants. In general, the responses to drought are loss of water content, reductions of stomatal conductance and photosynthesis and increase of carbohydrates. Soluble sugars play a key role in plant metabolism, acting as substrates and modulators of enzyme activity in carbon-related pathways and controlling the expression of different genes related to carbon, lipid and nitrogen routs. However, the mechanisms involved with photosynthesis down-regulation by drought and sugars in C4 plants are not fully understood. The aim of this study was to investigate how drought and source-sink perturbation regulate photosynthesis in sugarcane plants. Therefore, two studies were conducted with sugarcane plants with four months old cultivated under greenhouse conditions. In the first study sugarcane plants (cv. IACSP94-2094) were subjected to water deficit for 5 days (WD) with concomitant spraying of 50 mM exogenous sucrose (WD + Suc). While in the second study source-sink relationship was perturbed in two sugarcane cultivars (cv. IACSP94-2094 and cv. IACSP95-5000) by imposing partial darkness, spraying 50 mM exogenous sucrose and their combination for 5 days. The negative effects of WD in the gas exchange and photochemical parameters were aggravated by exogenous sucrose. Photosynthesis reductions were related to both stomatal and biochemical limitations, but exogenous sucrose intensified metabolic restrictions mainly through down-regulation of Rubisco initial activity and PSII effective quantum efficiency in drought-stressed plants. In addition, Rubisco activation state was decreased by WD + Suc, indicating perhaps that the activity of this enzyme was reduced by tight-binding inhibitors, such as sugars phosphates. Sucrose metabolism enzymes and sugars amount were also differently altered by WD and WD + Suc in leaves, sheath and stalk in WD and WD +Suc plants. Interestingly, Sucrose/hexose ratio decreased in both leaf and sheath whereas it was increased in stalk, suggesting that sucrose and related sugars were intensely metabolized and transported in drought-stressed plants. In well-watered conditions, photosynthesis was inhibited by sucrose spraying in both genotypes, through decreases in maximum Rubisco carboxylation rate (Vcmax), initial slope of A-Ci curve (k), stomatal conductance (gs) and ATP production driven by electron transport (Jatp). The partial darkness and sucrose spraying combination did not change photosynthesis in both genotypes. Significant increases in Vcmax, gs and Jatp and marginal increases in k were noticed when combining partial darkness and sucrose spraying compared with sucrose spraying alone. Altogether, these results suggest that CO2 assimilation impairment is aggravated by exogenous sucrose in drought-stressed plants. This limitation was mainly related to biochemical restrictions, specially associated with Rubisco initial activity and PSII quantum efficiency. In contrast, in vitro PEPCase activity and amount were increased in sucrose-treated plants, suggesting that C4 cycle efficiency was reduced in vivo by C3 cycle inhibition under drought conditions. Moreover, sucrose amount was increased in the stalk, suggesting the feedback regulation from stalk to source leaves in drought-stressed plants. Our data also revealed that increases in sink strength due to partial darkness offset the inhibition of sugarcane photosynthesis caused by sucrose spraying, enhancing the knowledge on endogenous regulation of sugarcane photosynthesis through the source-sink relationship. / A deficiência hídrica é o principal fator limitante para o crescimento e desenvolvimento das culturas. Para sobreviver nessas condições adversas, várias modificações bioquímicas e fisiológicas são desencadeadas pelas plantas. Em geral, os efeitos da seca em plantas são diminuição do status hídrico, reduções da condutância estomática, fotossíntese e crescimentos e aumentos nos níveis de carboidratos. Os açúcares solúveis desempenham papéis chave no metabolismo das plantas, atuando como substratos e moduladores da atividade enzimática em vias relacionadas com o carbono. Além disso, os açúcares controlam a expressão de genes associados com as rotas do metabolismo do carbono, lipídios e nitrogênio. Entretanto, os mecanismos envolvidos com a regulação negativa da fotossíntese por deficiência hídrica e açúcares em plantas C4 não estão totalmente entendidos. O objetivo deste estudo foi investigar como a deficiência hídrica e perturbações na relação fonte-dreno regulam a fotossíntese em plantas de cana-de-açúcar. Dois estudos foram conduzidos com plantas de cana-de-açúcar com quatro meses de idade cultivadas sob condições de casa de vegetação. No primeiro estudo, plantas de cana-de-açúcar (cv. IACSP94-2094) foram submetidas a deficiência hídrica por 5 dias (WD) com subsequente aplicação de sacarose exógena 50 mM (WD + Suc). Enquanto que no segundo estudo a relação fonte-dreno foi perturbada em duas cultivares de cana-de-açúcar (cv. IACSP94-2094 and cv. IACSP95-5000) pela imposição parcial de sombreamento, aplicação de sacarose exógena 50 mM e por suas combinações por 5 dias. Os efeitos negativos de WD nos parâmetros de trocas gasosas e fotoquímicos foram agravados por sacarose exógena. As reduções na fotossíntese foram relacionadas com limitações estomáticas e bioquímicas, porém a sacarose exógena intensificou as restrições bioquímicas principalmente por reduções na atividade inicial de Rubisco e eficiência quântica do PSII em plantas sob seca. Além disso, o estado de ativação de Rubisco foi inibido por WD + Suc, sugerindo que a atividade inicial dessa enzima foi possivelmente reduzida por inibidores que se ligam fortemente em seu sitio ativo, tais como açúcares fosfato. As enzimas do metabolismo de sacarose e a concentração de açúcares foram modificados diferentemente por WD e WD + Suc em folhas, bainha e colmo. Interessantemente, a relação sacarose/hexose decresceu em folhas e bainha, enquanto que no colmo essa relação aumentou, sugerindo que sacarose e outros açúcares relacionados foram intensamente metabolizados e transportados. Em condições irrigadas a fotossíntese foi inibida pela aplicação de sacarose nos dois genótipos, através de decréscimos da taxa máxima de carboxilação de Rubisco (Vcmax), inclinação inicial da curva A-Ci (k), condutância estomática (gs) e produção de ATP direcionada pelo transporte de elétrons (Jatp). A combinação de sombreamento parcial e sacarose não alterou a fotossíntese em ambos os genótipos. Significantes aumentos em Vcmax, gs, Jatp e k foram observados quando sombreamento parcial e sacarose foram combinados em comparação com plantas tratadas apenas com sacarose. Em conclusão, esses resultados sugerem que o impedimento da assimilação de CO2 é agravada por adição de sacarose exógena em plantas sob estresse hídrico. Essa limitação foi relacionada principalmente com restrições bioquímicas, especialmente associadas com reduções na atividade inicial de Rubisco e eficiência quântica do FSII. Em contraste, a atividade in vivo e concentração de PEPCase foram aumentadas em plantas tratadas com sacarose e estresse hídrico, sugerindo que a eficiência do ciclo C4 foi reduzida in vivo por inibições do ciclo C3 sob condições de seca. Além disso, o conteúdo de sacarose aumentou no colmo, indicando uma regulação de feedback do colmo para as folhas em plantas sob seca. Nossos dados revelam ainda que aumentos na força do dreno devido ao sombreamento parcial aliviaram os efeitos inibitórios na fotossíntese de cana-de-açúcar causados pela aplicação de sacarose, aumentando o conhecimento na regulação endógena da fotossíntese de cana-de-açúcar através da relação fonte-dreno.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Objetivando avaliar o comportamento das emissões de CO2 do solo em áreas mineradas do município de Santo Antônio de Pádua-RJ e sua correlação com a rizosfera, este presente estudo utilizou uma câmara fechada com sensor de infravermelho em três diferentes paisagens, a saber: A-1 (área reflorestada há 10 anos), A-2 (área desmatada) e A-3 (área em processo de recuperação). Em cada área foi instalada três cilindros para efeitos de repetição. O monitoramento foi realizado durante os meses representativos de cada estação do ano de 2013, sendo a análise realizada durante dois dias consecutivos. Concomitantemente as coletas de CO2 foram realizadas coletas de dados de temperatura e umidade do solo, sendo também avaliadas informações pedológicas através das análises de granulometria, porosidade, pH, carbono orgânico e matéria orgânica. Informações meteorológicas e microclimatológicas também foram extraídas através de uma estação meteorológica automática e através de sensores portáteis. Os resultados permitem concluir que existe uma variação sazonal dos fluxos de CO2, havendo uma tendência de máximos de emissão durante o verão e de mínimas durante o inverno, sendo o outono e a primavera marcados por valores medianos. A correlação das áreas entre os dois dias monitoramento indicam que as emissões foram semelhantes ao da análise em dia anterior, apresentando uma correlação significativa a 5% para A-1 e A-2 e de 1% para A-3. A-1 e A-2 apresentaram emissões de CO2 mais homogêneas que A-3, havendo, entretanto, um maior fluxo de CO2 durante o verão para todas as áreas. Os dados de MOS, COS e pH demonstraram não haver uma correlação direta com as emissões de CO2. Os dados de porosidade e densidade, porém, apontam para uma possível correlação com as menores emissões de CO2 em A-3 devido a menor porosidade e maior densidade de seus solos. A temperatura do solo foi a variável que mais se correlacionou com as emissões de CO2, havendo um índice igual a r =0,68 para A-1 e de r =0,74 para A-2, sendo que em A-3 esta correlação não foi significativa. A temperatura do ar demonstrou uma correlação somente na área descampada de A-2. No que se refere à correlação da umidade do solo não houve correlações diretas significativas, sendo que somente houve uma correlação negativa (r=-0,50) significativa a 5% em A-3 com a umidade do ar. O diagnóstico ambiental das áreas de monitoramento revela que estas possuem baixos indicadores de qualidade, sendo afetados também pela escassez hídrica da região durante oito meses do ano. A-1 apresenta os melhores indicadores biológicos, químicos e microclimáticos, seguidos por A-2 e A-3 que apresentam diversas deficiências e problemas em termos de estrutura e atividade biológica dos solos. Neste estudo permite-se concluir que áreas próximas, porém com características distintas podem produzir diferentes padrões de emissão de CO2, dificultando, portanto, estimativas globais de emissão de CO2. Os elementos mais associados às emissões de CO2 parecem estar relacionados à temperatura do solo e do ar, umidade do ar e estrutura do solo, havendo, entretanto, outros fatores que podem estar indiretamente relacionados e que exercem diferentes influências de acordo com o ambiente analisado. / Seeking evaluate the performance of CO2 emissions from soil in mined areas in the municipality of Saint Anthony of Padua - RJ and its correlation with the rhizosphere , the present study used a closed chamber with infrared sensor in three different landscapes , namely: A- 1 ( reforested area 10 years ago ) , a- 2 ( pasture) and A- 3 (area under recovery ) . In each area was installed three cylinders for the purpose of repetition. Monitoring was conducted during the months representing each season of the year 2013, with an analysis performed for two consecutive days. Simultaneously the analyses of temperature and soil moisture were performed, and also evaluated soil information by analyzing particle size , porosity, pH , organic carbon and organic matter information microclimatológicas and of weather were also extracted through sensors automatic and portable.The results indicate that there is a seasonal variation in CO2 fluxes , there is a trend of maximum emission during summer and minimum during winter , with autumn and spring marked by median values . The correlation among the areas two days indicate that monitoring emissions analysis were similar to the previous days, presenting a significant correlation to 5 % for A -1 and A -2 and A- 1 to 3 %. A- 1 and A- 2 had CO2 emissions more homogeneous than A- 3, there are, however, a greater flow of CO2 during the summer for all areas. MOS data, COS and pH showed no direct correlation with CO2 emissions. The porosity and density data, however, point to a possible correlation with the lowest CO2 emissions in A- 3 due to lower porosity and higher density of your soil. Soil temperature was the variable that was most associated with CO2 emissions, with an equal index for air = 0.68 A- 1 and r = 0.74 for A- 2, and A- 3 in this correlation was not significant. The air temperature showed a correlation only in the open area A- 2. With regard to the correlation of soil moisture no significant direct correlations, and only there was a significant negative correlation (r = -0.50) to 5 % in A- 3 with the humidity. The environmental assessment of the areas of monitoring shows that these have low quality indicators is also affected by water shortages in the region for eight months of the year. A- 1 shows the best biological, chemical and microclimatic indicators, followed by A-2 and A- 3 which have several deficiencies and problems in terms of structure and biological activity of soil. In this study, we conclude that nearby areas , but with distinct characteristics can produce different patterns of CO2 emission , thus hindering global estimates of CO2 emissions . Most elements associated CO2 emissions appear to be related to soil temperature and air temperature , humidity and soil , however , other factors that may be indirectly related and exert different influences according to the analyzed environment .

Rising carbon dioxide (CO2) concentrations in the atmosphere will increase the average pCO2 level in the world oceans, which will have a knock-on effect on the marine ecosystem. Coastal seagrass communities one of the most productive marine ecosystems are predicted to benefit from the increase in CO2 levels, but long-term effects of elevated CO2 on seagrass communities are less understood. Population reconstruction techniques was used to investigate the population dynamics of Cymodocea nodosa meadows, exposed to long term elevated CO2 at volcanic seeps off Greece and Italy. Effect of elevated CO2 was noticed on the growth, morphometry, density, biomass and age structure at CO2 seeps. Above to below ground biomass ratio of C. nodosa were higher at CO2 seeps than at reference sites. The plastochrome interval were similar at all CO2 seeps. The shoot age and shoot longevity of plants were lower at seeps than reference sites. The present recruitment (sampled year) of the seagrass were higher than long-term average recruitment of the communities near the seeps. Carbon to nitrogen ratios (%DW) of C. nodosa were higher in leaves at seeps. Annual leaf production was higher near the seeps. This study suggests increased production of C. nodosa under elevated CO2 levels, but other co-factors such as nutrients, trace metal toxicity must also be taken into consideration while predicting effects of future CO2 concentrations. Volcanic CO2 seeps are now being used as natural analogues for ocean acidification studies although these areas can be affected by trace element input and may alter ecosystem responses to gradient in carbonate chemistry. Here Fe and a range of trace elements (Cd, Co, Cu, Hg, Mn, Pb, Ni and Zn) were analysed from sediments and from the roots, rhizomes and leaves of seagrass at six CO2 seeps and reference sites off Greece and Italy. There were higher metal levels in sediment and seagrasses at all CO2 seeps than reference sites. Sediment Quality Guideline Quotient, a commonly used pollution index, indicated that some of the metals (Cd, Cu, Hg, Ni) were in high enough concentrations to have adverse biological effects, such as Cu at Ischia site and Hg at Vulcano. Higher accumulation of elements from sediments in roots and leaves at CO2 seeps were found from Bio Sediment Accumulation Factor index. There were higher levels of Cu, Fe, Mn and Zn in leaves and rhizomes for P. oceanica and higher levels of Cd, Co, Cu, Fe and Zn in C. nodosa compartments at CO2 seeps. Fe and Mn were found with positive correlation within sediment-roots and sediment-rhizomes, whereas Cd, Co and Pb were found with positive correlation in compartments of C. nodosa. In P. oceanica positive correlation were only observed for Cd within sediment-roots and plant compartments. Low pH and ocean acidification increased the concentration of elements at CO2 seeps than reference sites. Thus, caution is needed, when using volcanic seep systems as analogue for the effects of rising CO2, as metals can reach levels that are toxic to seagrass, masking any potential benefits of increased levels of carbon dioxide for seagrass productivity. Net community production (NCP) and community respiration (CR) were measured under air exposed and CO2 enriched conditions for intertidal Z. noltei meadows and unvegetated sediment communities during emersion in summer and winter seasons. Community production and respiration were measured in-situ using benthic chambers. CO2 flux under air and CO2 enriched conditions were measured over a series of short term incubations (30min) using an infra-red gas analyser. Incident photosynthetic active radiation (PAR) was recorded during the incubations covering the daily and seasonal variation. Linear regression model was used to test the effects of irradiance on net community production. NCP of Z. noltei community were higher under CO2 enriched conditions than air exposed conditions in both summer and winter seasons. There was no effect of CO2 on the CR rate of Z. noltei community in summer season. NCP of sediment community were higher in summer season and winter season under CO2 enriched conditions. Sediment CR rates were higher in winter than summer season. The light compensation point of Z. noltei and sediment community were lower in both seasons under CO2 enriched conditions. Seasonal budget of community production was higher in Z. noltei than sediment communities. A clear effect of PAR was noticed on the net community production of both communities. Higher PAR intensities resulted in higher NCP under CO2 enriched conditions for both communities. CO2 enrichment will have a positive effect on the intertidal communities during emersion.

Cette thèse s'attache à caractériser l'évolution dans le temps et l'espace des circulations de fluides le long des failles. Une approche multidisciplinaire et multi-échelle a été mise en place sur un exemple naturel dans la région du plateau du Colorado (Utah): du terrain à la modélisation et de la proche-surface au bassin. L'étude des minéralisations en proche surface et leur lien avec le transfert le long des failles a été effectuée sur des travertins récents. L'analyse isotopique et la datation U/Th des veines de travertins révèle des cycles de circulation de fluides enrichis en CO2 et de précipitation épisodiques de carbonates de calcium (travertin) correspondant à des cycles saisonniers ou climatiques (annuels et centennals) ainsi qu'à des cycles qui s'apparentent à des cycles sismiques de l'ordre du millier d'années. Ces données permettent de calibrer le volume de CO2 qui a fuit par la faille. Des zones de paléo-circulation, témoins de l'activité des failles sur le long-terme, sont observées sous forme de blanchiment chimique ("bleaching") des grès à l'affleurement, et ont été étudiées à l'échelle du bassin. Deux épisodes principaux de circulation de fluides le long des failles ont été distingués : une première circulation durant l'enfouissement maximum puis une seconde circulation le long des réservoirs et des failles, qui est reliée à des phénomènes tectoniques régionaux, compemporains de la remontée du Plateau du Colorado. La dernière circulation s'est découpée en plusieurs pulses avec des circulations de fluides de différente nature (tels que des saumures, des fluides riches en hydrocarbures ou en CO2) au cours du temps et le long des failles. / This work aims to characterise fluid flow along faults in time and space. Multi-disciplinary and multi-scale investigations of a natural analogue have been carried out in the Colorado Plateau area (Utak, USA), from fieldwork to numerical modeling. The study of Quaternary travertine calibrated the near-surface mineralization and their relationship with the faults. Stable Isotope measurements and U/Th datings of travertine veins revealed episodic cycles of CO2-fluid circulation and related calcium carbonate precipitation (travertine). These cycles may be linked with seasonal or climatic cycles (annual and centennial) and also with seismic cycles of millennial duration. Based on the obtained data, escaping CO2 volumes from the fault zone, with time have been calibrated. Chemical bleaching of the outcropping sandstones, linked with fluids paleo-circulation at depth, has been characterized at basin scale. Two main circulation events have been distinguished: a first circulation contemporaneous to maximum burial and a second along-reservoirs and faults circulation that could be linked with later regional tectonic events, contemporaneous of Colorado Plateau rusing. Pulses of different fluids (such as brines, fluids enriched in hydrocarbons or CO2) are linked in time and space with the last circulation.

O aumento da prevalência de lesões erosivas tem levado a um crescente interesse por medidas preventivas e para controle de tais lesões. Este estudo avaliou in vitro e in situ o efeito da associação de fluoretos à irradiação com laser de CO2 na permeabilidade do esmalte dental erodido. Para o experimento in vitro, foram selecionados oitenta fragmentos (n=10) de esmalte bovino (3x2x2 mm). Para formação de lesão de erosão, os espécimes foram submetidos a desafios ácidos iniciais duas vezes ao dia, durante dois dias, através de um regime alternado de erosão e remineralização. Para isso, os espécimes foram imersos individualmente em 20 ml de suco de laranja (pH 3,84) por 5 min sob agitação, enxaguados com água deionizada e armazenados em saliva artificial por 4 h. Os espécimes com as lesões de erosão pré-formadas foram divididos em 4 grupos para serem submetidos aos diferentes tratamentos: amina fluoretada (AmF), tetrafluoreto de titânio (TiF4), fluoreto de sódio (NaF) e placebo. Metade dos espécimes foi irradiada no modo contínuo com laser de CO2 ( λ= 10.6 µm; 2.0 W). Após a realização dos tratamentos, foram simulados novos desafios erosivos durante 2 dias, utilizando o mesmo protocolo descrito anteriormente. Terminadas as ciclagens, os espécimes foram preparados para a avaliação da permeabilidade, sendo submetidos ao método de coloração histoquímica. Uma vez obtidos os resultados do estudo in vitro, foi conduzido um experimento in situ constituído por um delineamento crossover, com duas fases de 5 dias cada. No estudo in situ, os fatores em estudo foram os tratamentos (TiF4 e placebo) e a aplicação do laser de CO2 (presente ou ausente.) Os fragmentos de esmalte bovino foram montados em dispositivo palatino para serem instalados nos participantes para a realização dos desafios erosivos, através da ingestão de 10 alíquotas de 25 ml cada, (9, 11, 13 e 15h). A avaliação da permeabilidade foi realizada conforme descrita para o estudo in vitro. Os dados foram analisados através da ANOVA e Tukey. No estudo in vitro, houve interação significativa entre fluoreto e laser (p=0,0152). Quando os géis fluoretados foram aplicados sozinhos, TiF4 promoveu menor permeabilidade do esmalte do que aquela observada após a aplicação do placebo, enquanto resultados intermediários foram encontrados para os géis de NaF e AmF. Redução na permeabilidade do esmalte foi observada quando a aplicação dos fluoretos foi associada à irradiação com laser de CO2 . No estudo in situ, houve efeito significativo da interação entre os fatores fluoreto e laser de CO2 (p = 0,0002). Em relação ao placebo, a aplicação do TiF4 reduziu significativamente a permeabilidade do esmalte, para substratos irradiados ou não. Mediante a aplicação do placebo, o laser foi capaz de reduzir significativamente a permeabilidade do esmalte, porém, quando se utilizou o TiF4, a aplicação do laser não implicou em redução da permeabilidade. Combinada à aplicação de gel fluoretado, a irradiação com laser de CO2 pode representar uma medida adjuvante no controle da permeabilidade do esmalte erodido. / The increased prevalence of erosive lesion has led to a growing interest of preventive means and to control such lesions. This study evaluated in vitro and in situ the effect of fluoride compounds combined with a CO2 laser on permeability of eroded dental enamel. To in vitro experiment, 80 bovine enamel slabs (n=10) were selected. To create erosion-like lesions, specimens were submitted to inicial erosive challenges, twice a day, during two days, through an alternating erosive and remineralizing regimen. For that, specimens were immersed in 20 ml of orange juice (pH 3.84) for 5 min under agitation, rinsed with deionized water and stored in artificial saliva for 4 h. Specimens with pre-formed lesions were divided into four groups to be treated with different fluoride gels: amine fluoride (AmF), titanium tetrafluoride (TiF4 ), sodium fluoride (NaF) and placebo. Half of the specimens were irradiated with CO2 laser ( λ= 10.6 µm; 2.0 W).Then, specimens were further cycled twice through the previously described erosive-remineralizing regimen. After cycled, specimens were subjected to permeability assessment. Once the results of in vitro study were obtained, an in situ experiment, consisting of a crossover design, with 2 phases of 5 days each, was performed. To in situ study, factors involved were treatments (TiF4 and placebo) and CO2 laser irradiation (present or absent). Bovine enamel slabs (n=10) were placed in palatal device to perform erosive challenges. Volunteers ingested orange juice as 250 mL volumes 4 times per day (9,11,13,15h). Permeability assessment was performed as described to in vitro study. Data were analyzed by ANOVA and Tukey. In vitro study demonstrated significant interaction between fluoride and laser (p = 0,0152). When fluoride gels were applied alone, TiF4 provided to enamel lower permeability than that observed following placebo application, while intermediate results were found to NaF and AmF gels. Reduction of enamel permeability was observed when fluorides were combined to CO2 laser irradiation. To in situ study, there was significant interaction between fluoride and laser (p=0,0002). When compared to placebo, TiF4 application reduced significantly enamel permeability, regardless of irradiation. Through application of placebo, laser was able to reduce significantly enamel permeability; however, when TiF4 was applied, laser irradiation did not decreased permeability. Combined to fluoride gel application, CO2 laser irradiation can represent an adjunctive way in controlling eroded enamel permeability.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Objetivando avaliar o comportamento das emissões de CO2 do solo em áreas mineradas do município de Santo Antônio de Pádua-RJ e sua correlação com a rizosfera, este presente estudo utilizou uma câmara fechada com sensor de infravermelho em três diferentes paisagens, a saber: A-1 (área reflorestada há 10 anos), A-2 (área desmatada) e A-3 (área em processo de recuperação). Em cada área foi instalada três cilindros para efeitos de repetição. O monitoramento foi realizado durante os meses representativos de cada estação do ano de 2013, sendo a análise realizada durante dois dias consecutivos. Concomitantemente as coletas de CO2 foram realizadas coletas de dados de temperatura e umidade do solo, sendo também avaliadas informações pedológicas através das análises de granulometria, porosidade, pH, carbono orgânico e matéria orgânica. Informações meteorológicas e microclimatológicas também foram extraídas através de uma estação meteorológica automática e através de sensores portáteis. Os resultados permitem concluir que existe uma variação sazonal dos fluxos de CO2, havendo uma tendência de máximos de emissão durante o verão e de mínimas durante o inverno, sendo o outono e a primavera marcados por valores medianos. A correlação das áreas entre os dois dias monitoramento indicam que as emissões foram semelhantes ao da análise em dia anterior, apresentando uma correlação significativa a 5% para A-1 e A-2 e de 1% para A-3. A-1 e A-2 apresentaram emissões de CO2 mais homogêneas que A-3, havendo, entretanto, um maior fluxo de CO2 durante o verão para todas as áreas. Os dados de MOS, COS e pH demonstraram não haver uma correlação direta com as emissões de CO2. Os dados de porosidade e densidade, porém, apontam para uma possível correlação com as menores emissões de CO2 em A-3 devido a menor porosidade e maior densidade de seus solos. A temperatura do solo foi a variável que mais se correlacionou com as emissões de CO2, havendo um índice igual a r =0,68 para A-1 e de r =0,74 para A-2, sendo que em A-3 esta correlação não foi significativa. A temperatura do ar demonstrou uma correlação somente na área descampada de A-2. No que se refere à correlação da umidade do solo não houve correlações diretas significativas, sendo que somente houve uma correlação negativa (r=-0,50) significativa a 5% em A-3 com a umidade do ar. O diagnóstico ambiental das áreas de monitoramento revela que estas possuem baixos indicadores de qualidade, sendo afetados também pela escassez hídrica da região durante oito meses do ano. A-1 apresenta os melhores indicadores biológicos, químicos e microclimáticos, seguidos por A-2 e A-3 que apresentam diversas deficiências e problemas em termos de estrutura e atividade biológica dos solos. Neste estudo permite-se concluir que áreas próximas, porém com características distintas podem produzir diferentes padrões de emissão de CO2, dificultando, portanto, estimativas globais de emissão de CO2. Os elementos mais associados às emissões de CO2 parecem estar relacionados à temperatura do solo e do ar, umidade do ar e estrutura do solo, havendo, entretanto, outros fatores que podem estar indiretamente relacionados e que exercem diferentes influências de acordo com o ambiente analisado. / Seeking evaluate the performance of CO2 emissions from soil in mined areas in the municipality of Saint Anthony of Padua - RJ and its correlation with the rhizosphere , the present study used a closed chamber with infrared sensor in three different landscapes , namely: A- 1 ( reforested area 10 years ago ) , a- 2 ( pasture) and A- 3 (area under recovery ) . In each area was installed three cylinders for the purpose of repetition. Monitoring was conducted during the months representing each season of the year 2013, with an analysis performed for two consecutive days. Simultaneously the analyses of temperature and soil moisture were performed, and also evaluated soil information by analyzing particle size , porosity, pH , organic carbon and organic matter information microclimatológicas and of weather were also extracted through sensors automatic and portable.The results indicate that there is a seasonal variation in CO2 fluxes , there is a trend of maximum emission during summer and minimum during winter , with autumn and spring marked by median values . The correlation among the areas two days indicate that monitoring emissions analysis were similar to the previous days, presenting a significant correlation to 5 % for A -1 and A -2 and A- 1 to 3 %. A- 1 and A- 2 had CO2 emissions more homogeneous than A- 3, there are, however, a greater flow of CO2 during the summer for all areas. MOS data, COS and pH showed no direct correlation with CO2 emissions. The porosity and density data, however, point to a possible correlation with the lowest CO2 emissions in A- 3 due to lower porosity and higher density of your soil. Soil temperature was the variable that was most associated with CO2 emissions, with an equal index for air = 0.68 A- 1 and r = 0.74 for A- 2, and A- 3 in this correlation was not significant. The air temperature showed a correlation only in the open area A- 2. With regard to the correlation of soil moisture no significant direct correlations, and only there was a significant negative correlation (r = -0.50) to 5 % in A- 3 with the humidity. The environmental assessment of the areas of monitoring shows that these have low quality indicators is also affected by water shortages in the region for eight months of the year. A- 1 shows the best biological, chemical and microclimatic indicators, followed by A-2 and A- 3 which have several deficiencies and problems in terms of structure and biological activity of soil. In this study, we conclude that nearby areas , but with distinct characteristics can produce different patterns of CO2 emission , thus hindering global estimates of CO2 emissions . Most elements associated CO2 emissions appear to be related to soil temperature and air temperature , humidity and soil , however , other factors that may be indirectly related and exert different influences according to the analyzed environment .

A descoberta de uma nova província petrolífera, conhecida como pré-sal, localizada no litoral brasileiro, representa um novo marco na produção de petróleo mundial. Dentre os vários desafios encontrados para exploração e produção dessa região, a presença de CO2 em grandes concentrações nos fluidos de alguns desses reservatórios tem sido um dos desafios de maior relevância para as empresas que exploram e produzem nessa área (FORMIGLI, 2007). Uma forma alternativa de sequestro do CO2 retirado do gás natural é a sua utilização como matéria prima ou co-alimentação para a síntese de produtos químicos, em especial aqueles com grande demanda de mercado. Um dos produtos que podem ser obtidos indiretamente a partir do CO2 é o petróleo sintético, produzido pelo processo conhecido como Gas-to-Liquids, ou GTL. Neste trabalho foi analisada a viabilidade técnica, econômica e potencial de captura de CO2, da produção de petróleo sintético, pelo processo GTL, offshore, a partir de dióxido de carbono (CO2) e metano (CH4), presentes na corrente de rejeito do tratamento do gás processado em uma plataforma de produção de petróleo e gás, através das reformas seca e a vapor, seguida da síntese Fischer-Tropsch. A partir de dados de literatura e com uso de simulador comercial de processos, a simulação do processo foi desenvolvida e diferentes alternativas para reaproveitamento das correntes residuais do processo foram analisadas, incluindo o reciclo e a queima dos efluentes combustíveis, assim como foram aplicadas técnicas de integração energética, otimização e análise econômica de processos. Os resultados indicaram que o processo, mássica e energeticamente integrado, na condição de menor emissão de CO2 e maior retorno financeiro, produziu petróleo sintético de forma técnica e economicamente viável. Os resultados indicaram ainda que o processo GTL, com as tecnologias utilizadas, não é indicado como método de captura de CO2 devido o fato de a geração desse componente para a produção de petróleo sintético ser duas vezes maior que a quantidade alimentada. / The discovery of a new oil province known as pre-salt, located in the Brazilian coast, represents a new frontier in the world\'s oil production. Among other challenges involved in the exploration and production in that region, the CO2 concentration at high levels in the fluids of some of those reservoirs has been the most relevant challenge for the companies that explore and produce in that area (FORMIGLI, 2007). An alternative to sequestering the CO2 extracted from natural gas is using it as a supply of raw material or as an input to the synthesis of chemical products, especially those with great market demand. One of the products that can be obtained indirectly from CO2 is synthetic fuel, produced by the process known as Gas-to- Liquids, or GTL. In this work the technical, economical and potential feasibility of CO2 capture is analyzed, as well as the production of synthetic fuel using the GTL process, offshore, from carbon dioxide (CO2) and methane (CH4), found in the waste chain of the gas treatment in an oil and gas production platform, through dry and steam reforming, followed by Fischer-Tropsch synthesis. Thus, based on literature data and on the use of a commercial process simulator, the simulation of the suggested process was developed and different alternatives to the reutilization of the waste chains were analyzed, including the recycling and burning of some effluent streams. Techniques of energetic integration, optimization and economic analysis of process have also been applied. The results indicated that the process, mass and energy integrated in the condition of lower CO2 emissions and greater financial return, produced synthetic oil in a technically and economically feasible way. The results also indicated that the GTL process, with the technologies used, is not suitable as a method for CO2 capture due to the fact that the generation of this component for the production of synthetic oil is two times greater than the amount fed.