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Análise de sistemas fotovoltaicos conectados à rede no âmbito do mecanismo de desenvolvimento limpo : estudo de caso dos projetos da chamada N° 13 da ANEEL / Analysis of the grid-connected photovoltaic systems within the framework of the clean development mechanism : a case report of the strategic projects callLopes, Davi Gabriel, 1981- 24 August 2018 (has links)
Orientador: Carla Kazue Nakao Cavaliero / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T10:55:11Z (GMT). No. of bitstreams: 1
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Previous issue date: 2013 / Resumo: Atingir o desenvolvimento sustentável é algo relativo e difícil de ser mensurado, haja vista a complexidade do tema e as discussões em diversas esferas institucionais, porém o passo para se discutir esse tema no âmbito da geração de energia elétrica passa necessariamente pelas emissões de gases de efeito estufa (GEEs). Isso porque o Mecanismo de Desenvolvimento Limpo (MDL) está consolidado em esfera mundial como uma ferramenta que mensura e aponta os possíveis benefícios socioambientais de atividades de projetos executados em países em desenvolvimento que utilizam, por exemplo, fontes de energia renováveis. Assim, a presente tese busca inserir os Sistemas Fotovoltaicos Conectados à Rede (SFCR) nesse contexto e utiliza a Chamada Estratégica nº 13 da ANEEL (Chamada 13) para avaliar quantitativamente a sua contribuição para a redução das emissões de CO2e. A partir da estimativa da energia elétrica gerada pelos 13 projetos aprovados nessa Chamada, realizada com o Software PVsyst 6.1.0, e da aplicação da metodologia aprovada pela UNFCCC, adequada às condições de geração, foi estimada a emissão evitada de CO2e com a inserção dessa energia na rede do Sistema Interligado Nacional (SIN). Além disso, descreveu-se e analisou-se a contribuição desses projetos para o desenvolvimento sustentável, avaliação indispensável para qualquer projeto de MDL. Dentre os resultados encontrados verificou-se que a geração de energia elétrica total é de 25.619 MWh/ano e que a Chamada 13 pode evitar emissões de 6.285 tCO2e/ano, usando o ano base 2011; e 11.229 tCO2e/ano, no ano base 2012. Os projetos de SFCR podem colaborar para o desenvolvimento sustentável gerando 454 "empregos solares" diretos, aumentando direta e indiretamente a renda da população local, contribuindo para a capacitação tecnológica nacional e auxiliando diversos setores da economia brasileira que fazem parte da cadeia dos SFCR. Ao final, visando aplicar os resultados obtidos, preencheu-se o Documento de Concepção do Projeto (DCP), exigido para a submissão das atividades de projeto no âmbito do MDL, com os dados da Usina Solar de Tanquinho/CPFL, um dos 13 projetos aprovados na Chamada 13 e que foi adotado como projeto de referência para as estimativas realizadas nessa tese / Abstract: Achieving sustainable development is relative and difficult to measure, given the complexity of the issue and the discussions in institutional spheres, but the first step to discuss this topic in power generation necessarily involves the estimation of greenhouse gases emissions (GHGs). That is partly because the Clean Development Mechanism (CDM) is a global tool consolidated that measures and indicates the possible social and environmental benefits of project activities implemented in developing countries that use renewable energy sources, for example. Thus, within the context describe above, this thesis has the objective to analyze the Grid-Connected Photovoltaic Systems of the Strategic Call n°13 from ANEEL to quantitatively evaluate its contribution to the reduction of emissions of CO2e. The estimation of electrical power generated by the 13 projects approved in this Call was held with the PVsyst Software 6.1.0, and then the methodology adopted by UNFCCC was applied to estimate avoided emissions of CO2e in the National Grid. Furthermore, the contribution of these projects to sustainable development was described and analyzed, which is an evaluation indispensable for any CDM project. Among the findings it was determined that the total electricity generation is 25,619 MWh/year and that can avoid emissions of 6,285 tCO2e/year , if using the base year 2011, and 11,229 tCO2e/year, if using base year 2012. The Grid-Connected Photovoltaic Systems projects can contribute to sustainable development by direct generating 454 "solar employments", as well as indirect jobs increasing the income of local people, encouraging the national technological capability and helping various sectors of the Brazilian economy. Finally, the results were applied and the Project Design Document (PDD) was filled in with data from the Solar Power Plant of Tanquinho/CPFL, one of 13 projects approved on Call 13. This document is required for project activities under the CDM, and it was adopted as the reference design for the estimates made in this thesis / Doutorado / Planejamento de Sistemas Energeticos / Doutor em Planejamento de Sistemas Energéticos
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Avaliação de opções e custos de mitigação das emissões de GEE utilizando a cana-de-açúcar / Assessment of options and costs of GHG emissions mitigation using sugarcane biomassPereira, Tássia Penha, 1987- 24 August 2018 (has links)
Orientadores: Joaquim Eugênio Abel Seabra, Manoel Regis Lima Verde Leal / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T13:24:02Z (GMT). No. of bitstreams: 1
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Previous issue date: 2014 / Resumo: Em 2011 a cana-de-açúcar foi confirmada como a fonte renovável primária mais importante para a oferta interna de energia no Brasil (15,7% suplantando os 14,7% da energia hidráulica). Atualmente, as formas de energia resultantes do processamento da cana são o etanol e a eletricidade. Com o aumento da mecanização uma quantidade considerável de biomassa se torna disponível na lavoura. Algumas usinas já tentam recuperar economicamente parte dessa biomassa para uso como combustível suplementar ao bagaço, estendendo o período de geração de energia para além do período de colheita. Adicionalmente, há um esforço em pesquisa em desenvolvimento para se ter alternativas para o aproveitamento do material lignocelulósico da cana (bagaço e palha) integrando processos tecnológicos e, assim, utilizar a biomassa como matéria-prima para a obtenção de artigos de maior valor agregado. Diante dessas opções, há a preocupação em saber qual forma de conversão da biomassa é mais eficiente não só do ponto de vista técnico-econômico, mas também ambiental. A Avaliação de Ciclo de Vida (ACV) é uma técnica que pode ser usada para analisar a eficiência e sustentabilidade de alternativas quando comparadas com tecnologias convencionais. Neste trabalho, seis cenários tecnológicos para conversão da biomassa da cana-de-açúcar foram confrontados quanto ao potencial de mitigação de gases de efeito estufa (GEE) e aos respectivos custos de mitigação: ciclo a vapor (Rankine) e sistema BIG-GT, para a geração de energia excedente durante todo o ano; síntese de combustíveis, para produção de etanol e álcoois superiores; conversão bioquímica a partir da hidrólise enzimática para produção de etanol; pirólise lenta para a produção de biocarvão (utilizado como condicionador de solo); e produção de peletes para exportação para a Europa. Tais cenários foram comparados com a configuração mais comum de uma destilaria de etanol na nova expansão do setor brasileiro. Análises de incertezas e de sensibilidade também foram realizadas. Os resultados mostram que a peletização da biomassa é a opção tecnológica mais promissora devido ao bom potencial de mitigação (23 t CO2eq/ha.a) e baixo custo (-7 R$/t CO2eq). A pirólise lenta, apesar da grande incerteza, apresenta o segundo melhor potencial de mitigação (21 t CO2eq/ha.a) através do sequestro promovido pelo biocarvão, porém é a alternativa mais onerosa (260 R$/t CO2eq). De forma geral, dentre as opções investigadas, aquelas mais viáveis economicamente são as que apresentam os menores potenciais de redução de emissões de GEE / Abstract: In 2011 sugarcane was confirmed as the main renewable source in the domestic energy supply in Brazil (15.7% against 14.7% from hydropower). Currently, the energy products resulting from sugarcane processing are ethanol and electricity. With the increased mechanized harvesting, a considerable amount of biomass becomes available in the field, and some mills have already started to recover and use that biomass as supplementary fuel to bagasse, extending the period of power generation beyond the sugarcane season. Additionally, there are ongoing research efforts aimed at the better utilization of the sugarcane lignocellulosic material (bagasse and straw), enabling the production of higher value-added products through the integration of new conversion technologies. In face of these alternatives, debates arise about which would be the most efficient, cost effective and environmental friendly conversion alternative. The Life Cycle Assessment (LCA) is a technique that can be used to analyze the efficiency and sustainability of alternatives when compared to conventional technologies. In this work, six technology scenarios for sugarcane biomass conversion were compared in terms of GHG emissions mitigation and costs: steam cycle and BIG-GT systems, for electricity generation; production of ethanol via biochemical and thermochemical conversion; slow pyrolysis for the production of biochar (to be used as soil conditioner); and production of pellets (to be exported to Europe). Such scenarios were compared with the most common configuration of an ethanol distillery in the new expansion of the Brazilian industry. Uncertainty and sensitivity analyses were also performed. The results show that the biomass pelletizing is the most interesting option due to the good mitigation potential (23 tCO2eq/ha.a) and low required carbon price (-7 R$/t CO2eq). Slow pyrolysis, despite the high uncertainties, features the second largest mitigation potential (21 t CO2eq/ha.a) through the carbon sequestration promoted by biochar, although it is the most expensive option (260 R$/t CO2eq). In general, among the alternatives investigated in this study, those featuring the lowest mitigation costs are also those with the lowest mitigation potential / Mestrado / Planejamento de Sistemas Energeticos / Mestra em Planejamento de Sistemas Energéticos
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Mobilisation et transformations du mercure et du carbone dans les réservoirs hydroélectriques de la rivière Romainede Bonville, Jérémy 08 1900 (has links)
Les réservoirs hydroélectriques contribuent à la remise en suspension du mercure (Hg) inorganique terrestre et de la matière organique suite à l’inondation des terres lors de la construction d’un barrage. Le développement de zones anoxiques dû à l’augmentation de la colonne d’eau et à la dégradation de matière organique inondée est une condition propice pour la méthylation du Hg par les communautés bactériennes aquatiques, le rendant neurotoxique et bioamplifiable. Les résultats de cette étude, conduite dans le complexe de réservoirs hydroélectriques de la rivière Romaine, démontrent que le pourcentage du mercure total (THg) étant du méthylmercure (MeHg) retrouvé dans les zones inondées est en moyenne 10 fois plus élevé que dans les systèmes naturels avoisinants et dans la portion de la rivière en amont de la série de barrages. Les concentrations en MeHg demeurent toutefois relativement faibles comparativement à d’autres réservoirs au Québec et ailleurs dans le monde. Des patrons de l’amont vers l’aval ont pu être observés, où le MeHg augmente de façon concomitante au dioxyde de carbone (CO2) à travers les réservoirs, les deux ayant des valeurs plus élevées au printemps, suite à la fonte des glaces, qu’en été, suggérant qu’une production sous la glace est probable due à une anoxie partielle avant que le retrait des glaces ne revienne oxygéner la colonne d’eau. De plus, les concentrations de mercure total ainsi que les patrons des composantes de matière organique dissoute et du carbone organique dissous demeurent très peu variables entre les sites inondés et naturels. Cela suggère que les réservoirs hydroélectriques agissent plutôt comme réacteurs de transformation du mercure inorganique terrestre en méthylmercure que comme mobilisateurs de mercure nouvellement importé dans le système, et que les processus opérant des centaines de kilomètres en amont et des mois auparavant sont importants pour les dynamiques de carbone et de mercure observées dans ce système hautement connecté. / Following the flooding of soil during the construction of hydroelectric reservoirs, terrestrial inorganic mercury (Hg) and organic matter typically increase in concentrations in the aquatic environment. The anoxia developed due to the deepening of the water column and the degradation of organic matter due to aquatic microbial communities create new conditions in the system that are prone to the methylation of mercury into its neurotoxic and bioaccumulative form : methylmercury (MeHg). Results from this study, led in the hydroelectric complex of reservoirs of the Romaine River, showed that the percentage of total mercury which is methylmercury in the flooded area is on average 10 times higher than in surrounding natural systems from the watershed and in the upstream section of the river. MeHg concentrations in the Romaine River, however, remain relatively low when compared to other reservoirs in Quebec and worldwide. Upstream to downstream patterns have been observed, where MeHg increases along with carbon dioxide (CO2) throughout the series of reservoirs and where both showed higher values in June than in August, following the snowmelt and the melting of the ice cover. Concentrations were lower in the summer campaign, suggesting there was under-ice production due to the development of partial anoxia before the water column is mixed and oxygenated in spring. Moreover, the distribution of total mercury concentrations, dissolved organic carbon and dissolved organic matter components remained stable between flooded and natural sites. This suggests that hydroelectric reservoirs act as reactors for the transformation of terrestrial inorganic Hg in MeHg rather than as mobilizers of newly imported Hg and that processes occurring several kilometers upstream and months prior to sampling affect the carbon and Hg dynamics of this inter-connected system.
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Indicadores de qualidade física e química de solo em sistemas de pecuária extensiva no Cerrado Brasileiro /Tavanti, Renan Francisco Rimoldi January 2020 (has links)
Orientador: Rafael Montanari / Resumo: A qualidade do solo não é algo que se pode medir diretamente, no entanto, pode ser avaliada pelos atributos que caracterizam seu estado físico, químico e biológico. A escolha de atributos mais relevantes e a interpretação das medidas obtidas não é algo simples, devido aos efeitos da mudança de uso da terra e as interações entre eles e as condições climáticas e serviços ecossistêmicos de cada região. O objetivo desse estudo foi fornecer uma visão geral de alguns indicadores de qualidade física e química do solo no contexto de restauração de pastagens do Cerrado Brasileiro. A tese é disposta em capítulos, compondo além das considerações gerais apresentadas no Capítulo 1, os Capítulos 2 e 3, que são estudos científicos de avaliação da qualidade física e química do solo. Os experimentos foram desenvolvidos no município de Selvíria – MS em duas áreas destinadas à pecuária extensiva de corte, subsidiadas pela planta forrageira Urochloa brizantha cv. Marandu. Malhas experimentais de 2,7 e 1,4 hectares, com 70 e 65 pontos, respectivamente, foram instaladas nas áreas e amostras de solo de estrutura deformada e indeformada foram tomadas para avaliação dos atributos físicos e químicos. Também se avaliou os estoques de carbono orgânico total, suas frações granulométricas e a emissão de CO2 nas áreas, visando enxergar os efeitos da reforma sob o aporte de carbono e as emissões de gases de efeito estufa. Em uma das áreas avaliou-se a curva de retenção de água do solo e índice S em todos os... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Soil quality is not something that can be directly measured; however, it can be assessed by the attributes that characterize its physical, chemical and biological state. The choice of more relevant attributes and the interpretation of the measures obtained is not a simple matter, due to the effects of land use change and the interactions between them, the climatic conditions and ecosystem services of each region. The aim of this study was to provide an overview of some indicators of physical and chemical quality of the soil in the context of pasture restoration in the Brazilian Cerrado. The thesis is laid out in chapters, composing in addition to the general considerations presented in Chapter 1, Chapters 2 and 3, which are scientific studies to assess the physical and chemical quality of the soil. The experiments were carried out in the municipality of Selvíria – MS in two areas for extensive beef cattle, subsidized by the forage plant Urochloa brizantha cv. Marandu. Experimental meshes of 2.7 and 1.4 hectares, with 70 and 65 points, respectively, were installed in the areas and soil samples of deformed and undeformed structure were taken to assess the physical and chemical attributes. The total organic carbon stocks, their particle size fractions and the CO2 emission in the areas were also evaluated, aiming to see the effects of the reform under the carbon input and the greenhouse gas emissions. In one of the areas, the soil water retention curve and S index were evaluated ... (Complete abstract click electronic access below) / Doutor
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Variability in Tropospheric Oxidation from Polluted to Remote RegionsBaublitz, Colleen Beverly January 2021 (has links)
Tropospheric oxidation modulates pollution chemistry and greenhouse gas lifetimes. The hydroxyl radical (OH) is the primary oxidant and the main sink for methane, the second-most influential anthropogenic contributor to climate change. OH is produced following the photolysis of ozone, an oxidant, respiratory irritant and greenhouse gas. Trends in methane or ozone are frequently attributed to their sources, but sink-driven variability is less often considered. I investigate the influence of fluctuations in turbulent loss to the Earth’s surface, also known as deposition, on tropospheric ozone concentrations and chemistry over the relatively polluted eastern United States. I use idealized sensitivity simulations with the global chemistry-climate model AM3 to demonstrate that coherent shifts in deposition, on the order recently observed at a long-term measurement site, affect surface ozone concentrations as much as decreases in its precursor emissions have over the past decade. I conclude that a sub-regional deposition measurement network is needed to confidently attribute trends in tropospheric ozone.
Next, I turn to the remote marine troposphere to evaluate two theoretical proxies for variability in the methane sink, OH, with observations from the NASA Atmospheric Tomography (ATom) aircraft campaign. The low concentration and short lifetime of OH preclude the development of a representative measurement network to track its fluctuations in space and time. This dearth of constraints has led to discrepancies in the methane lifetime across models that project atmospheric composition and climate. Observational and modeling studies suggest that few processes control OH fluctuations in relatively clean air masses, and the short OH lifetime implies that it is at steady-state (total production is equal to loss). I leverage this chemistry by evaluating a convolution of OH drivers, OH production scaled by the lifetime of OH against its sink with carbon monoxide, as a potential “steady-state” proxy. I also assess the predictive skill of formaldehyde (HCHO), an intermediate product of the methane and OH reaction.
I find that both proxies broadly reflect OH on sub-hemispheric scales (2 km altitude by 20° zonal bins) relative to existing, well-mixed proxies that capture, at best, hemispheric OH variability. HCHO is produced following methane loss by reaction with OH and reflects the insolation influence on OH, while the steady-state proxy demonstrates a stronger relationship with OH and offers insight into its sensitivity to a wider array of drivers. Few components—water vapor, nitric oxide, and the photolysis rate of ozone to singlet-d atomic oxygen—dominate steady-state proxy variance in most regions of the remote troposphere, with water vapor controlling the largest spatial extent. Current satellite instruments measure water vapor directly, and other retrievals like nitrogen dioxide columns or aerosol optical depth or could be used to infer nitric acid or the rate of ozone photolysis. Thus satellite observations may be used to derive a steady-state proxy product to infer OH variability and sensitivity in the near-term. HCHO is also retrieved from satellite instruments, and an OH product using satellite-observed HCHO columns is already in development. The relatively high fluctuation frequency of HCHO or the steady-state proxy advances our insight into the connection between OH and its drivers. The observed steady-state proxy demonstrates a widespread sensitivity to water vapor along the ATom flight tracks, and I conclude that an improved and consistent representation of the water vapor distribution is a necessary step in constraining the methane lifetime across global chemistry-climate models.
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Měření koncentrací skleníkových plynů / Measurement of greenhouse gas concentrationsDohnal, Jan January 2017 (has links)
This master thesis deals with the greenhouse effect, various gases and methods of measurement. On the greenhouse effect is viewed from its historical dating, despite changes in atmospheric composition. It contains a theoretical analysis of the individual gases. It focuses on the most harmful greenhouse gases such as water vapor, carbon dioxide, nitrous oxide, methane, ozone, chlorofluorocarbons and halons. Analysis methods for detection of gaseous substances. Part of this work is focus on the detection of nitrogen dioxide, chloro-fluorocarbon and methane. The data is processed using a ATmega’s microcontroller and then sent to an Internet server thingspeak.com. If the device proves successful, will be used as a laboratory exercise in the course Ecology in electronics.
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Effects of Hydrochar, Digestate, Synthetic Fertilizer on Soil Greenhouse Gas Fluxes in Miscanthus x giganteus Grown as Advanced Biofuel FeedstockAdjuik, Toby A. 18 September 2019 (has links)
No description available.
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Měření koncentrací skleníkových plynů / Measurement of greenhouse gas concentrationsDohnal, Jan January 2016 (has links)
This semester thesis deals with the greenhouse effect, various gases and methods of measurement. On the greenhouse effect is viewed from its historical dating, despite changes in atmospheric composition and reactions of individual institutions. It contains a theoretical analysis of the individual gases. It focuses on the most harmful greenhouse gases such as water vapor, carbon dioxide, nitrous oxide, methane, ozone, chlorofluorocarbons and halons. Analysis methods for detection of gaseous substances. Part of this work is focus on the detection of nitrogen dioxide and chloro-fluorocarbon. The data is processed using a microcontroller and then sent to an Internet server thingspeak.com. If the device proves successful, will be used as a laboratory exercise in the course Ecology in electronics.
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Freonförbudet – Varför lyckades detta globalt och är detta tillämpbart idag på en liknande gas? / The Freon Bans-A success story, can it be replicated?Ringlander, Evelina January 2021 (has links)
Freoner är ett stort problem för människors hälsa och andra levande organismer på grund av freons nedbrytande effekt på ozonlagret. Forskare upptäckte problemen med freon och varningar från forskningssamhället uppmärksammades av huvudproducenter av freoner samt av allmänheten då påverkan på ozonlagret ökar risken för bland annat hudcancer. Montrealprotokollet blev starten på de internationella konventioner som senare implementerades. Dock finns det ett flertal växthusgaser idag som också är ozonnedbrytande som inte ingår under någon konvention. Den globala uppvärmningen är en effekt av ökad mängd växthusgaser i atmosfären och detta kräver ett internationellt samarbete för att kunna lösas. I Montrealprotokollet ingår ODS (Ozonnedbrytande substanser) där freon innefattas. Syftet för denna studie var att belysa vad som gjorde freonförbudet lyckat, och om det är möjligt att tillämpa dessa nyckelaspekter på en av dagens växthusgaser som liknar freon. NO2 valdes för att begränsa urvalet. Denna litteraturstudie använde sig av databaser för att finna relevanta källor genom nyckelord, därefter valdes källor utefter relevansen till frågeställningen samt att de skulle vara opartiska. Resultatet av denna studie pekar på svårigheterna med att implementera det arbetssätt som ledde till freonförbudet, på gasen NO2, som hade liknande egenskaper som freon. Detta på grund av att dagens växthusgaser är svåra att reglera utsläppet på. Växthusgaser finns globalt och det finns inte en tydlig utsläppskälla som går att reglera samt hitta ett substitut för. Korrelationen till den mänskliga hälsan och miljön, är också en nyckelaspekt till varför förbudet mot freoner var lyckat. / Freons became a large problem for society when scientists proved the ozone depletion effect, which proved to have a negative effect on human health and other living organisms. The ozone layer which was known for its protective qualities against UV-radiation lead to a new field of study, ODS (ozone depleting substances). The warnings from the scientist society and the public were eminent. The research pointed out, among other things, the increasing risk of skin cancer. This forced fast new research and several international conventions to save the ozone layer. But there are several greenhouse gases, which also have the degrading effect on the ozone layer, that are in use today. This require an international cooperation for the environment to be able to solve. The aim of this report was to illustrate why the freon ban was a success and why it would be hard to implement these key concepts on a similar present greenhouse gas. In this literature study, several databases were used to find relevant sources for the main questions and unbiased for the topic. The key aspects in this study is presented in the result section. The result pointed at the difficulties with implementing the same way of work as at the freon ban to the greenhouse gas ban. Different aspects play an important role in this, but one of the greater difficulties for implementing this is to pinpoint it to a specific source for gas emissions and finding a sustainable solution for it. The correlation between human health and environmental issues was a key factor in the freon ban.
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Greenhouse gases investigations in ice from periglacial environmentsBoereboom, Thierry 11 July 2012 (has links)
L’environnement périglaciaire en général et les régions de permafrost en particulier, connus pour être très sensibles au changement climatique actuel, sont le sujet de beaucoup d’études sur les émissions de gaz à effet de serre. En effet, le dégel de ces milieux engendre la mobilisation d’une quantité importante de matière organique, précédemment piégée par le froid, favorisant les émissions de dioxyde de carbone et/ou de méthane. L’objectif premier, du présent travail, est de contribuer à l’étude des gaz enfermés dans certains types de glace de ces régions afin de mieux quantifier leur impact potentiel sur le climat.<p>Dans un premier temps, une analyse multiparamétrique a été menée sur deux coins de glace du nord de la Sibérie dans la cadre d’une collaboration avec l’Alfred Wegener Institut (Allemagne). Cette première approche a révélé que l’analyse conjointe de la cristallographie, de l’orientation des axes optiques, du contenu en gaz total et de la composition en gaz des coins de glace est un outil puissant, complémentaire aux analyses des isotopes stables, pour comprendre les conditions paléo-climatiques qui ont régi la construction des coins de glace. Cette étude soutient également l’hypothèse de variations spatiales importantes de l’origine des masses d’air durant les variations climatiques du Pléistocène.<p>Dans un deuxième temps, une analyse des caractéristiques de la glace annuelle de 4 lacs du nord de la Suède a été réalisée afin d’étudier le rôle de la couverture de glace sur les émissions de gaz à effet de serre. En effet, les lacs de ces régions contribuent fortement aux émissions de méthane durant la période d’eau libre et très peu d’études ont analysé la quantité de méthane emprisonnée dans la glace hivernale et relâchée au printemps. Ce projet nous a amené à établir une nouvelle classification des bulles dans la glace de lac basée sur leur contenu en méthane, leur origine, leur forme et leur densité. Il nous a également permis de montrer que plusieurs facteurs interviennent sur le contenu en gaz dans la couverture de glace :le système hydrologique, la variation de la pression atmosphérique, la variabilité des émissions et potentiellement la proximité des sédiments sont autant de facteurs qui déterminent le contenu en gaz. L’analyse de la composition des gaz a révélé que la composition observée dans la glace est sensiblement différente de celle observée durant les périodes d’eau libre. Nous avons également, pour la première fois, établit un budget des émissions de méthane relâchées par la fonte de la couverture de glace au niveau mondial.<p>Cette étude a été complétée par l’analyse des isotopes 13C des gaz des différents types de bulles de notre classification en collaboration avec l’Université d’Utrecht. Nous avons alors mis en évidence que la couverture de glace influence l’équilibre biogéochimique dans l’eau en favorisant l’oxydation du méthane en dioxyde de carbone.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
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