The master?s thesis is part of the project GA ČR č. P504/11/1151- Role of plants in the greenhouse gas budget of a sedge fen. This thesis deals with the decomposition of aboveground vegetation in a herbaceous wetland. The decomposition rate was established on the flooded part of the Wet Meadows near Třeboň. The rate of the decomposition processes was evaluated using the litter-bag method. Mesh bags filled with dry plant matter were located in the vicinity of the automatic meteorological station at four randomly selected sites. Values of the decomposition rate were assessed in two experiments. In the first experiment the litter bags were fixed in April 2009. The litter bags were fixed in the vertical position and they had one size. Values of the decomposition rate were assessed for 6 sampling dates and the total exposure time was 2,5 years. The decrease of the total dry mass was 18,37 % in the first year and 13,05 % in the second year. The value of LDR was 0,7227 in the first year and 0,4740 in the second year. In the 2nd experiment the litter bags were fixed in November 2010. The litter bags were fixed in the vertical and horizontal position, respectively, and they were of two sizes (small, big). Values of the decomposition rate were assessed for 2 sampling dates and the total exposure time was one year. The total annual value of LDR was 0,5212 for the vertical bags and 1,0676 for horizontal bags.

The global carbon cycle is a central part of the climate system which forms a direct link between human activity and climate change. This thesis presents my contribution to the field of research into the global carbon cycle with complex numerical models and its use to inform climate mitigation policy. Firstly, I present work I led to build, configure and apply the Hadley Centre Earth System Model, HadGEM2-ES, that successfully delivered the CMIP5 simulations. Then I present work that led to the design of the next generation of coupled carbon cycle intercomparison experiments. The aim of these experiments is to understand and quantify future centuryscale changes in land and ocean carbon storage and fluxes and their impact on climate projections. A set of ESM simulations was devised, with a common protocol, which all participating modelling centres should follow. A theoretical framework is commonly used to quantify carbon cycle feedbacks. I played an active role in its recommended use and definitions of terms. A feedback analysis I performed of future carbon cycle projections formed a central component of the IPCC’s Fifth Assessment Report. This is the first time that that the IPCC carbon cycle chapter had a section devoted to the feedbacks and future projections from coupled carbon cycle ESMs. Finally, I present three specific applications of my research and their relevance to climate mitigation policy. 1) I was the first to define the concept of committed ecosystem changes and demonstrate that ecosystems may continue to respond for many years or decades after climate is stabilised, leading to the recommendation that such committed change should be included in definitions of dangerous climate change. 2) I performed the first Earth System model analysis of the carbon emissions reductions required to follow the RCP pathways leading to the IPCC AR5 statement that, “For RCP2.6, an average 50% emission reduction is required by 2050 relative to 1990 levels”. 3) My research on carbon cycle feedbacks, especially the response of the carbon cycle to low CO2 pathways, found that models predict significant weakening, or even potential reversal, of natural carbon sinks in response to removal of CO2, which potentially hinders the effectiveness of the negative emissions. My research presented in this thesis has been influential in setting international research priorities in this field. It continues to inform global negotiations on climate mitigation policy.

Increased nutrient input into wet-meadow ecosystems can affect activity of decomposers and carbon cycle in soil. This thesis observed the effect of fertilization on carbon sequestration and mineralization in soils of wet meadows, which differed in quantity and quality of soil organic matter. Studied locations are situated in the protected area Třeboňsko.

abstract: Growth of the Phoenix metropolitan area led to exposures of the internal bedrock structure of surrounding semi-arid mountain ranges as housing platforms or road cuts. Such exposures in the Sonoran and Mojave deserts reveal the presence of sedimentary calcium carbonate infilling the pre-existing fracture matrix of the bedrock. Field surveys of bedrock fractures filled with carbonate (BFFC) reveal an average of 0.079 +/- 0.024 mT C/m2 stored in the upper 2 m of analyzed bedrock exposures. Back-scattered electron microscopy images indicate the presence of carbonate at the micron scale, not included in this estimation. Analysis of the spatial extent of bedrock landforms in arid and semi-arid regions worldwide suggests that ~1485 GtC could potentially be stored in the upper 2 m horizon of BFFCs. Radiocarbon dating obtained at one of the sites indicates it is likely that some of the carbonate was flushed into the bedrock system during glacial wet pulses, and is stored on Pleistocene timescales or longer. Strontium isotope analysis at the same site suggest the potential for a substantial cation contribution from weathering of the local bedrock, indicating the potential exists for sequestration of atmospheric carbon in BFFCs. Rates of carbon release from BFFCs are tied to rates of erosion of bedrock ranges in desert climates. / Dissertation/Thesis / M.A. Geography 2013

Orientador: Lúcia Helena Innocentini Mei / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T00:20:01Z (GMT). No. of bitstreams: 1 Allganer_Katlen_M.pdf: 1913407 bytes, checksum: 0db427a1d4ddf8feb850924e6810f020 (MD5) Previous issue date: 2010 / Resumo: As sociedades hoje têm de enfrentar os problemas resultantes dos padrões de consumo, como a geração de resíduos e sua destinação em áreas inadequadas, com conseqüentes impactos ambientais que dependem da composição dos resíduos e do tipo de disposição. Gerenciar a geração de resíduos significa administrar o processo produtivo e o consumo de bens, viabilizando o retorno dos materiais ao meio ambiente sem causar danos. Assim, é importante avaliar todo o ciclo de um processo, para promover a melhoria do desempenho ambiental de um produto e o uso de tecnologias sustentáveis. Diante desta realidade, o objetivo deste estudo foi avaliar as emissões de gases de efeito estufa durante etapas específicas do ciclo de vida do amido de milho plastificado com glicerol (plantio de milho e compostagem), fundamentando conhecimentos sobre os conceitos da Avaliação de Ciclo de Vida; e contribuindo com possíveis novos direcionamentos no uso de embalagens plásticas destinadas à compostagem, com conseqüente redução no uso de recursos não renováveis. Deste modo, este trabalho visa marcar o início de uma linha investigatória ainda incipiente na Unicamp, por tratar-se de um assunto pouco estudado e com muitas restrições na coleta de dados; e alertar a comunidade nacional sobre a importância deste tipo de estudo para o desenvolvimento sustentável tão apregoado no mundo todo. Os valores de emissões de CO2 obtidos neste estudo assemelham-se aos resultados divulgados na literatura internacional, considerando as restrições e a abrangência estabelecidas no escopo dos estudos comparados. Utiliza-se a metodologia de gestão ambiental, a Avaliação do Ciclo de Vida, descrito pelas Normas NBR 14040 e 14044, para orientações de divulgação dos resultados obtidos. A base de dados utilizada literatura e parte experimental, em que a amostra de amido de milho plastificado com glicerol é produzida em misturador de alto cisalhamento e submetida ao teste de biodegradação sob a Norma ASTM D5988-03 / Abstract: Today society has to face problems that result from consumerism, like waste production and its inadequate disposal, with consequent environmental impacts that are linked to waste composition and kind of disposal. Managing waste production means to control the productive processes and the consuming of goods, in a way that waste materials return to the environment without causing much impact. It is then important to evaluate all the full cycle of a process in order to enhance the environmental performance of a product and the use of sustainable technologies. Under these concepts, the objective of this study was to assess greenhouse gases emissions during specific stages of the plasticized corn starch life cycle (corn growing and composting), underlying the knowledge of Life Cycle Assessment concepts; and contributing with possible new directions to the use of plastic packages for composting, with consequent reduction of non-renewable sources. Furthermore, this work aims to start an investigative line still incipient at Unicamp, for not being a very well known subject and with a lot of restrictions in data collection; and warn the national community about this kind of study for the sustainable development so publicized in the world. The results of CO2 emissions obtained in this study are similar to the results found in international works, considering the restrictions and the established range in the scope of the compared studies. It is used the environmental management tool, Life Cycle Assessment, described by Brazilian standards NBR 14040 and 14044 as orientation for results publication. As database, it is made a literature review and an experimental part, in which a corn starch sample is plasticized with glycerol in a high shear mixer and gone under biodegradation test using ASTM D5988-03 standard / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Made available in DSpace on 2014-10-09T12:51:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:30Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:04/04148-3

Estudos recentes têm demonstrado resultados surpreendentes acerca do ciclo do carbono nos ambientes aquáticos da Amazônia, com fluxos evasivos de CO2 a partir dos mesmos superando àqueles que ocorrem na descarga para o oceano. Porém, os processos que controlam estes fluxos permanecem como uma grande fonte de incerteza nas medidas dos mesmos e, conseqüentemente, nos balanços regionais de carbono. Desta forma, os objetivos deste estudo foram avaliar a variabilidade espacial e temporal (sazonal e circadiana) do fluxo de CO2 em diferentes sistemas aquáticos da Amazônia e os principais parâmetros físicos envolvidos no controle do coeficiente de troca gasosa (k600). Para isto utilizamos os dados, disponibilizados pela Rede Beija-Rio, de fluxo de CO2 (medido com câmara flutuante) e demais parâmetros, medidos em sete rios da bacia Amazônica, ao longo dos anos de 2007 a 2009. Fizemos também campanhas intensivas de medidas de fluxo e, em duas destas campanhas, realizamos medidas de fluxo utilizando simultaneamente as técnicas de câmara e de covariância dos vórtices turbulentos (eddy correlation). Os resultados mostraram que o ciclo sazonal de fluxo de CO2, com os maiores valores sendo observados no período de cheia, está diretamente relacionado ao ciclo sazonal da pCO2 que, por sua vez, é paralela à hidrógrafa. A variabilidade circadiana está relacionada às mudanças na velocidade do vento em ambientes lóticos e, em ambientes lênticos estratificados, além da velocidade de vento a mistura convectiva desempenha também um papel importante neste controle. Rios de águas pretas apresentaram os maiores fluxos, enquanto que, rios de águas claras como o Araguaia e Teles Pires, apresentaram fluxos negativos no período de seca. A produção primária em lagos e rios de águas claras desempenha um papel importante na variabilidade circadiana e sazonal da pCO2 e, consequentemente, no fluxo de CO2. As análises do k600 mostraram diferentes condições de turbulência na calha principal do rio Javaés e nas áreas mais extensas e rasas ao longo do Rio Negro, gerando modelos para a estimativa de k600 com a velocidade do vento no rio Javaés, e com a velocidade do vento e a relação entre velocidade da corrente e profundidade do canal [(w/z)0,5] no Rio Negro / Recent studies have shown surprising results on the carbon cycle in aquatic environments of the Amazon, with evasive fluxes of CO2 larger than the carbon exported by discharge into the 2ocean. However, the processes that control these fluxes remain a major source of uncertainty in upscaling and, consequently, on regional carbon balances. Thus, the objective of this study was to evaluate the spatial and temporal variability (seasonal and circadian) of CO2 flux in different aquatic systems in the Amazon basin and the main physical parameters involved in controlling the gas exchange coefficient (K600). For this we used the CO2 flux data from Rede Beija-Rio (measured with floating chamber) and other parameters measured in seven rivers of the Amazon basin, over the years 2007 to 2009. Additionally, we also conducted intensive flux measurements campaigns, in two of which we compared chamber and eddy covariance (eddy correlation) approaches. The results showed that the seasonal cycle of CO2 flux, which is higher during the high water period, is directly related to the seasonal cycle of pCO2 which, in turn, parallels the hydrograph. Circadian variations are related to changes in wind speed in lotic environments. At stratified lentic environments both wind speed the convective mixing play important roles in this control. Black-water rivers showed the highest fluxes, while clear water rivers Araguaia and Teles Pires showed negative fluxes during the dry period. Primary production in lakes and clear water rivers plays a more important role than previously observed in circadian and seasonal variability of pCO2 and hence in CO2 fluxes. Analyses of K600 showed different turbulent conditions in the main channel of the Javaés river and in longer and shallower areas along the Rio Negro, with significant models for estimation of K600 based on wind velocity in the Javaés river and on wind speed and the relationship between water current and depth [(w / z) 0.5 ] in the Negro river

O principal papel dos rios no ciclo global biogeoquímico do carbono tem sido considerado como o de exportador fluvial de carbono orgânico total (COT) e carbono inorgânico dissolvido (CID) para os oceanos. Entretanto, estudos recentes mostraram a importância dos fluxos evasivos de CO2 a partir de rios da Amazônia, sugerindo que uma parte significativa do carbono fixado pela floresta retornaria para a atmosfera por esta via. A troca gasosa entre a atmosfera e as águas supersaturadas dos rios é função do gradiente de concentração do gás através da interface ar-água. A pCO2 da água é fortemente determinada pela concentração de carbono inorgânico dissolvido e pH, que, por sua vez, são função de processos físicos, químicos e biológicos. O foco principal deste estudo foi estabelecer a importância dos fluxos evasivos de CO2 nos balanços de C, uma vez que os sistemas aquáticos são uma fonte significativa de C para a atmosfera nos ambientes tropicais úmidos. Ao mesmo tempo, avaliou-se a influência das concentrações de CID e pH na evasão de CO2. A área de estudo foi a bacia do rio Ji-Paraná, Rondônia. Vários rios desta bacia foram amostrados entre maio/99 e maio/03. Concentrações de CID, temperatura e pH foram utilizadas para calcular a pCO2 da água, baseado nas equações de equilíbrio termodinâmico. Para estimar o fluxo evasivo de CO2 utilizou-se o modelo teórico de fluxo difusivo. Os resultados mostraram que rios que drenam áreas de solos mais férteis apresentam as maiores concentrações de CID e um maior potencial de evasão. Apesar da variabilidade sazonal da pCO2, as concentrações de CO2 dissolvido indicam que as trocas de CO2 com a atmosfera são unilaterais (evasão para a atmosfera) ao longo do ano. Durante o período de cheia, mesmo com concentrações de CID menores, a diminuição do pH observado neste período foi suficiente para promover potenciais de evasão maiores; neste período a evasão é cerca de 4 vezes maior que no período de seca. Baseado no modelo de fluxo difusivo, a evasão de CO2 para a atmosfera a partir das águas superficiais dos rios da bacia do Ji-Paraná foi estimada em 128 a 318 Gg C ano-1. A descarga fluvial exporta anualmente cerca de 370 Gg C ano-1. Portanto, a evasão é da mesma ordem de magnitude da descarga fluvial, demonstrando a importância desta via no ciclo do carbono nos sistemas aquáticos da Amazônia. / The major biogeochemical role of river systems in the global carbon cycle is considered to be the fluvial export of total organic carbon (TOC) and dissolved inorganic carbon (DIC) to the ocean. However, recent studies have shown the importance of CO2 outgassing from rivers of the Amazon, suggesting that a significant part of the carbon fixed by forests returns to the atmosphere through this pathway. Gas exchange between the atmosphere and river waters supersaturated in CO2 is a function of gaseous gradients across the air-water interface. Water pCO2 is strongly influenced by concentrations of dissolved inorganic carbon (DIC) and pH, which are, in turn, a function of physical, chemical and biological processes. This study focus on the importance of CO2 outgassing in the carbon cycle of drainage basins, assuming that river systems are significant sources of atmospheric C in tropical environments, and also on the influence of DIC concentrations and the pH on CO2 evasion. The study area was the Ji-Paraná river basin, Rondônia. Several rivers of the basin were sampled between May/99 and May/03. Temperature, pH and DIC concentrations were used do calculate pCO2, based on thermodynamic equilibrium equations. A theoretical diffusive flux model was used to estimate CO2 evasion. The results show that rivers draining areas with more fertile soils present larger concentrations of DIC and of potential CO2 evasion. In spite of the pCO2 seasonality, the concentrations of dissolved CO2 suggest that this CO2 exchange with the atmosphere is unilateral (evasion to the atmosphere) throughtout the year. During high waters, even with lower DIC concentrations, decreases in pH are of a magnitude enough to promote higher potential evasions; in this period evasion is around four times higher than in the falling water. Based on a diffusion model, CO2 evasion to the atmosphere from rivers of Ji-Paraná basin was estimated to be from 128 to 318 Gg C yr-1. Since the annual export in fluvial discharge is 370 Gg C yr-1, this means that evasion is on the same order of magnitude, demonstrating the importance of this pathway in the carbon cycle of riverine systems in the Amazon.

Peatlands are a globally important, terrestrial store of carbon and the UK is recognised as an internationally significant holder of peatlands. Of all the kinds of peatland found in the UK, blanket bogs are dominant, representing 87% of the UK’s peatland area. The UK’s peatlands, in contrast to many other areas of boreal/temperate peat, are relatively accessible and as such have been subject to land-management pressures for many thousands of years. These management pressures have led to the deterioration of many peatlands in the UK, with only 1% of England’s peatlands being considered ‘pristine’ in a Natural England report (Natural England, 2010). Climate change and increasing land-use pressures are predicted to affect all UK peatlands in coming years. As such, studies of the drivers of carbon cycling on UK peatlands are being undertaken in order to help in the construction of models to predict the dynamics of peatland carbon balance. These models will subsequently enable land-managers and policy makers to take informed decisions regarding peatland management and carbon storage. One such model of peatland carbon balance is the Durham Carbon Model, which uses a mass balance between fluxes of carbon in and out of a peatland in order to estimate its net carbon budget. While the Durham Carbon Model is able to deal with the effects of some aspects of land-management on peatland carbon balance, there remain a number of important drivers as yet unaccounted for in the model. As such, the remit of this thesis was to conduct in-situ, experiments in order to provide additional data on peatland carbon cycling with a view to incorporating these drivers into the model. Specifically, this research examines three areas as yet unaccounted for in the Durham Carbon Model: altitude, vegetation and diurnal processes. These factors are considered relative to CO2 flux and, in some cases, soil pore water dissolved organic carbon concentration. Additional experiments were also performed to determine whether empirical models of CO2 flux can be physically interpretable. Results obtained for this thesis suggest that the most important factor in predicting CO2 flux on blanket peat soils is vegetation type and vegetation mediated processes, i.e. photosynthetic controls on respiration. Moreover, the relationship between respiration and photosynthesis was found across a range of other factors and temporal scales. In addition to vegetation, altitude was found to significantly affect CO2 for some vegetation types. Therefore, both of these factors are to be incorporated into the Durham Carbon Model. Experiments suggested that empirical models of CO2 flux can be physically interpretable. The results of the diurnal experiment gave evidence to support the hypothesis that some component of the relationship between photosynthesis and respiration is temporally lagged, perhaps by 3 hours. However, the results were not unequivocal and thus further work is needed to fully examine some of the results presented herein.

The overarching goal of this thesis is to develop a diagnostic and predictive model to quantify the estuarine CO2 dynamics across scales – from catchment to the globe – using an approach that explicitly resolves the strong physical and biogeochemical gradients typically observed in these systems.Chapter 1 provides fundamental definitions and descriptions of estuaries, as well as an assessment of their role in the global carbon cycle. It also raises the specific objectives and research questions tackled in the present study. Chapter 2 presents the rationale behind the novel modelling approach (C-GEM, Carbon-Generic Estuary Model) developed in the framework of this thesis. First, the dominant processes that control the estuarine biogeochemistry in estuaries are discussed in detail. Then, the power of reactive-transport models (RTMs) in understanding and quantifying the estuarine biogeochemical functioning is illustrated on the basis of local modelling studies. Finally, trends in estuarine biogeochemical dynamics across different geometries and environmental scenarios are briefly explored with C-GEM and results are discussed in the context of improving the modelling of estuarine carbon dynamics at regional and global scales. In Chapter 3, a detailed description of C-GEM, both in terms of structure and set-up, is provided and model’s performance is successfully evaluated through comprehensive model-data and model-model comparisons in the macro-tidal Scheldt estuary (BE/NL). In Chapter 4, C-GEM is combined with a generic set of forcing conditions and parameter values to quantify the carbon dynamics (net ecosystem metabolism, CO2 exchange at the air-water interface, carbon filtering capacity) in three idealized estuaries subject to temperate climatic conditions. Their hydro-geometrical characteristics span the wide diversity of estuarine morphological characteristics. Model results are used to upscale the estuarine CO2 dynamics under present-day conditions and to quantify the response of the estuarine filter to future atmospheric CO2, land use and climate change scenarios. In Chapter 5, C-GEM is applied to derive estimations of carbon export and CO2 outgassing from all tidal estuaries discharging in the North Sea. Overall, our results suggest that the estuarine carbon filtering capacity and the contribution of these land-ocean transition systems to the atmospheric CO2 budget might not be as high as previously thought. Finally, a conclusive chapter (Chapter 6) provides a synthesis of the key findings and arguments projected by the present research work. Moreover, recommendations are given in the light of further applications of the modelling approach developed during this thesis. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished