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SILVA, Paulo Ferreira da. "Fluxos de CO2, água e energia em pastagens e caatinga no semiárido pernambucano." Universidade Federal Rural de Pernambuco, 2015. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6574.
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The natural vegetation of Caatinga is relatively well adapted and tolerant to drought and to high temperatures. It is known that forest conversions to pasture and/or crop cultivation are human interventions, which affect energy exchanges, water and carbon between land surface and the atmosphere. However, up to the present moment, there is no study measuring these fluxes in the caatinga and pastures areas in the Brazilian semiarid lands. Thus, this paper aimed at determining the fluxes of energy, H2O and CO2 in areas of caatinga and pastures, as well as at analyzing the seasonal variability patterns of these fluxes. The land activities were carried out in two areas, one of them located on the Buenos Aires farm (7° 59’ 31’’ S and 38° 17’ 59’’ O), and the other located on the Lagoinha farm (07° 56’ 50,4’’ S and 38° 23’ 29’’ O), cultivated with pasture of grass chain (Urochloa mosambicensis), both properties located in the city of Serra Talhada, state of Pernambuco, Brazil. In order to determine the fluxes of energy, H2O and CO2, a methodology of correlation of swirls was adopted, by means of micrometeorological towers, installed in the center of each experimental area. Along with the index of foliar area, we have also measured the aboveground phytomass of both the pasture and the caatinga herbaceous vegetation, as well as water storage in the soil, by means of TDR sensors. On the basis of the results, it has been found that the maximum production of dry pasture mass was in the order of 2,208 kg ha-1 and annual average of 832 kg ha-1. On the other hand, the caatinga dry mass was in the order of 2,559 kg ha-1 and the annual average was 626 kg ha-1. Water storage in the soil (0-40 cm) of pasture was 29% greater than the one of the caatinga. This fact was possibly attributed to the interception of rain by the caatinga canopy. In relation the fluxes of energy, radiation balance (Rb) was used mainly as sensitive flow of heat (H), with 51% in the pasture and 47% in the caatinga. The fraction of Rb used as flow of latent heat (LE) was of 23% in the pasture and 32% in the caatinga. In relation to the evapotranspiration, the caatinga had total values (523 mm) and average values (1,4 mm d-1) greater than the pasture (389 mm and 1,1 mm d-1), possibly due to the greater depth of its radicular system. During the experimental period, the fluxes of daily average CO2 were ˗ 0,91 and ˗ 0,68 μmol m-2 s-1 for the caatinga and the pasture, respectively. Not only during the rainy season but also the dry season, the vegetation acted as atmospheric CO2 sink. The caatinga was more efficient than the pasture, sequestrating in average 14,6 kg of C ha-1 d-1, during the rainy season and 4,3 kg of C ha-1 d-1, in the dry season, while the pasture sequestrated 11,7 kg of C ha-1 d-1, in the rainy season and 2,5 kg of C ha-1 d-1, in the dry season. The caatinga has proved more efficient than the pasture in using soil water (greater ET) and in sequestrating atmospheric CO2.
A vegetação natural da Caatinga é relativamente bem adaptada e tolerante à seca e a altas temperaturas. Sabe-se que a conversão de florestas em pastagens e/ou cultivo de lavouras são intervenções humanas que afetam as trocas de energia, água e carbono entre a superfície da terra e a atmosfera. No entanto, até o momento não se tem nenhum estudo medindo esses fluxos em áreas de caatinga e de pastagens no semiárido brasileiro. Desse modo, este trabalho teve como objetivo determinar os fluxos de energia, H2O e CO2 em áreas de caatinga e de pastagens, além de analisar os padrões de variabilidade sazonal desses fluxos. A s atividades de campo foram realizadas em duas áreas, sendo uma localizada na Fazenda Buenos Aires (7º 59’ 31” S e 38º 17’ 59” O) e a outra localizada na Fazenda Lagoinha (07° 56’ 50,4”S e 38° 23’ 29” O), cultivada com a pastagem capim corrente (Urochloa mosambicensis), ambas propriedades localizadas no Município de Serra Talhada PE. Para a determinação dos fluxos de energia, H2O e CO2 foi usada a metodologia da correlação dos turbilhões, por meio de torres micrometeorológicas instaladas no centro de cada área experimental. Foram medidos o índice de área foliar e a biomassa áerea da pastagem e da vegetação herbácea da caatinga e o armazenamento de água no solo, por meio de sensores TDR. Dos resultados, verificou-se que a produção máxima de massa seca da pastagem foi de 2.208 kg ha-1 e média anual de 832 kg ha-1, já a massa seca máxima da caatinga foi de 2.559 kg ha-1 e a média anual de 626 kg ha-1. O armazenamento de água no solo (0-40 cm) da pastagem foi 29% maior que da caatinga, possivelmente devido a interceptação da chuva pelo dossel da caatinga. Com relação aos fluxos de energia, o saldo de radiação (Rn) foi utilizado principalmente como fluxo de calor sensível (H), com 51% na pastagem e 47% na caatinga. A fração do Rn usada como fluxo de calor latente (LE) foi de 23% na pastagem e 32% na caatinga. Com relação a evapotranspiração, a caatinga teve valores totais (523 mm) e médios (1,4 mm d-1) maiores que a pastagem (389 mm e 1,1 mm d-1), possivelmente, devido a maior profundidade de seu sistema radicular. Durante o período experimental os fluxos de CO2 médios diários foram de -0,91 e -0,68 mol m-2 s-1 para a caatinga e a pastagem, respectivamente. Tanto na estação chuvosa quanto na estação seca, ambas as vegetações atuaram como sumidouro de CO2 atmosférico. A caatinga foi mais eficiente que a pastagem, sequestrando em média 14,6 kg de C ha-1 d-1, na estação chuvosa e 4,3 kg de C ha-1 d-1, na estação seca; enquanto a pastagem sequestrou 11,7 kg de C ha-1 d-1, na estação chuvosa e 2,5 kg de C ha-1 d-1, na estação seca. A caatinga demonstrou ser mais eficiente em usar a água do solo (maior ET) e sequestrar CO2 atmosférico que a pastagem.
RIBEIRO, Apolo Alves. "Fluxos de CO2 e de vapor d’água em feijão cultivado no agreste meridional pernambucano." Universidade Federal Rural de Pernambuco, 2014. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6645.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Many important processes occurring in ecosystems, such as photosynthesis and productivity of vegetation, are associated with the exchange of CO2, water and energy. Accurate measurement of these fluxes are therefore fundamental to a broad understanding of the carbon cycle in terrestrial ecosystems. However, no such study was conducted under the conditions of the Agreste of Pernambuco, with the bean crop. Given the above, this study aimed to quantify the water, energy and CO2 fluxes in soil cultivated with bean under rainfed conditions. The study was conducted in a bean producing area of the city of São João, where were installed sensors to measure these fluxes, using the energy balance method - eddy covariance (energy and CO2 fluxes) and soil water balance method (water fluxes) in the period from 31/05/2013 to 08/20/2013. In addition to these measurements were also measured height, leaf area index (LAI) and the bean yield. Regarding the components of the water balance was found that the flow of water at a depth of 35 cm (deep drainage and/or capillarity rise) had very low values. It was also observed that the periods of high rainfall resulted in higher water storage in soil and increased evapotranspiration (ET). The ET obtained by water balance method had a total and average values of 146.0 mm and 1.78 mm d-1, respectively. The bean presented its highest water consumption during the reproductive period (29/06/2013 to 29/07/2013), with an average value of 2.55 mm d-1. Regarding the energy fluxes, it was found that the latent heat flux (LE) consumed on average 78.46% of the radiation (Rn). The ET, measured by the eddy covariance method, was total value of 179.3 mm, with a mean value of 2.2 mm d-1. Bean yield was 2,050 kg ha-1, with water use efficiency of 1.16 kg m-3. Regarding the CO2 fluxes, it was observed that the same varied from -11.21 to -0.75 mol m-2 s-1, indicating the occurrence of carbon sequestration by the crop. On average, bean sequestered 54 kg C ha-1 per day, the equivalent to 3.3 t C ha-1 during the trial period.
Muitos processos importantes que ocorrem nos ecossistemas, tais como, a fotossíntese e a produtividade da vegetação, estão associados com as trocas de CO2, água e energia. Medições precisas desses fluxos são, portanto, fundamentais para uma ampla compreensão do ciclo do carbono em ecossistemas terrestres. No entanto, nenhum estudo desse tipo foi realizado nas condições do agreste meridional de Pernambuco, com a cultura do feijão. Diante do exposto, o presente trabalho objetivou quantificar os fluxos de água, de energia e de CO2 em solo cultivado com feijão sob condições de sequeiro. O trabalho foi realizado em uma área produtora de feijão do município de São João, onde se instalou sensores para medir esses fluxos, usando as metodologias do balanço de energia - correlação dos turbilhões (fluxos de energia e de CO2) e do balanço hídrico no solo (fluxos de água) no período de 31/05/2013 a 20/08/2013. Também foram determinadas a altura, o índice de área foliar (IAF) e a produtividade do feijão. Em relação aos componentes do balanço hídrico verificou-se que o fluxo de água (drenagem profunda e/ou ascensão capilar) na profundidade de 35 cm teve valores muito baixos, como também que os períodos de elevada pluviosidade resultaram em maior armazenamento de água no solo e maior evapotranspiração (ET). A ET do feijão pelo método do balanço hídrico teve valor total e médio de 146,0 mm e 1,78 mm d-1, respectivamente. A cultura apresentou seu maior consumo de água no período reprodutivo (29/06/2013 a 29/07/2013), com valor médio de 2,55 mm d-1. Quanto aos fluxos de energia, verificou-se que o fluxo de calor latente (LE) consumiu em média 78,46% do saldo de radiação (Rn). A ET medida pela metodologia da correlação dos turbilhões obteve valor total durante o período experimental de 179,3 mm, com média de 2,2 mm d-1. A produtividade do feijão foi de 2.050 kg ha-1, com eficiência do uso de água de 1,16 kg m-3. Em relação aos fluxos de CO2, observou-se que os mesmos variaram de -0,75 a -11,21 mol m-2 s-1, indicando a ocorrência de sequestro de carbono pelo feijão. Em média, o feijão sequestrou 54 kg de C ha-1 por dia, o equivalente a 3,3 t de C ha-1 durante o período experimental.
Bianchi, Alejandro. "Sea-air CO2 fluxes in the Patagonia sea." Paris 6, 2010. http://www.theses.fr/2010PA066613.
Full textVandeburie, Emile. "CO2-emissions from rivers and streams : Seasonal variation of pCO2-levels and CO2-fluxes." Thesis, Mittuniversitetet, Institutionen för ekoteknik- och hållbart byggande, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-40804.
Full text2020-06-17
Molina, Carpio Luis. "Modélisation inverse des flux de CO2 en Amazonie." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV040/document.
Full textA better knowledge of the seasonal and inter-annual variations of the Amazon carbon cycle is critical to understand the influence of this terrestrial ecosystem on climate change. Atmospheric inverse modeling is a powerful tool to estimate these variations by extracting the information on the spatio-temporal patterns of surface CO2 fluxes contained in observations of atmospheric CO2. However, the confidence in the Amazon flux estimates obtained from global inversion frameworks is low, given the scarcity of observations in this region.In this context, I started by analyzing in detail the Amazon net ecosystem exchange (NEE) inferred with two global inversions over the period 2002 — 2010. Both inversions assimilated data from the global observation network outside Amazonia, and one of them also assimilated data from four stations in Amazonia that had not been used in previous inversion efforts. I demonstrated that in a global inversion the observations from sites distant from Amazonia, as well as local observations, controlled the NEE inferred through the inversion. The inferred fluxes revealed large-scale structures likely not consistent with the actual NEE in Amazonia. This analysis confirmed the lack of observation sites in Amazonia to provide reliable flux estimates, and exposed the limitations of global frameworks, using low-resolution models to quantify regional fluxes. This limitations justified developing a regional approach.Then I evaluated the benefit of the regional atmospheric model BRAMS, relative to the global forecast system ECMWF, when both models provided the meteorological fields to drive the atmospheric transport model CHIMERE to simulate CO2 transport in tropical South America at high resolution (~35 km). I simulated the CO2 distribution with both transport models―CHIMERE-BRAMS and CHIMERE-ECMWF. I evaluated the model simulations with aircraft measurements in vertical profiles, analyzing the concentrations associated to the individual measurements, but also with horizontal gradients along wind direction between pairs of sites at different altitudes, or vertically integrated. Both transport models simulated the CO2 observations with similar performance, but I found a strong impact of the uncertainty in the transport models. Both individual measurements and horizontal gradients were most sensitive to NEE, but also to biomass burning CO2 emissions (EFIRE) in the dry season. I found that horizontal gradients were more suitable for inversions than individual measurements, since the former were less sensitive fluxes outside South America and further decreased the impact of the transport model uncertainty in altitude.Finally, I developed two analytical regional inversion systems for tropical South America, driven with CHIMERE-BRAMS and CHIMERE-ECMWF, and made inversions with four observation vectors: individual concentration measurements and horizontal gradients at five vertical levels, close to the surface, or horizontal gradients vertically integrated. I found a strong dependency of the inverted regional and sub-regional NEE and EFIRE emissions budgets on both the transport model and the observation vector. Inversions with gradients yielded a better separation of NEE and EFIRE signals. However, the large uncertainties in the inverted fluxes, did not yield high confidence in the estimates. Therefore, even though my study did not improve the knowledge of seasonal and year-to-year variations of the NEE in Amazonia, it demonstrated need of further efforts to improve transport modeling in the region and the inverse modeling strategy, at least through a careful definition of the observation vector that accounts for the characteristics of the available data, and the limitations of the current transport models
Schneider, Julia [Verfasser]. "Dynamics of CO2 fluxes from boreal peatlands / Julia Schneider." Greifswald : Universitätsbibliothek Greifswald, 2011. http://d-nb.info/1016213255/34.
Full textGoret, Marine. "Etude des interactions entre le climat urbain et le CO2 : modélisation des flux de CO2 et application à l'échelle d'une ville." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0119.
Full textClimate and CO2 are closely tied. The link between them is so well established that the objectives for global warming mitigation are expressed in terms of the maximum amount of CO2 equivalent that can be emitted. The amount of CO2 present in the atmosphere at a given time is the result of complex exchanges and equilibriums between the atmosphere and the earth's surface. The latter is composed not only of oceans, vegetation and natural soils, but also cities. Exchanges between the atmosphere and urban surfaces come mainly from four contributors: building emissions, road traffic, human respiration and urban vegetation. Two of these contributors depend on climate: buildings and vegetation. Buildings emissions, at least at high and medium latitudes, are strongly related to space heating, and therefore fluctuate with the outside temperature. As for the vegetation, its growth and open-up speed depends on the weather and climate conditions and more particularly on temperature, precipitation and solar radiation. The CO2 emitted by the city is then transported through the atmosphere by the local atmospheric circulation which is the result of the synoptic situation modified by the city's influence. Therefore there are strong interactions between climate and CO2 at the city scale: the city's carbon footprint depends on the local climate, and the transport of CO2 through the atmosphere is influenced by the atmospheric circulation induced by the city. The aim of this thesis is to study these interactions. That's why, the modeling of CO2 exchanges between urban surfaces and the atmosphere has been added to the urban micro-climate model TEB. This allows to verify that the physical processes that link CO2 emissions/uptakes in the city and the urban climate are well identified and understood. The model is evaluated on two case studies each of which specifically assessed one of the contributors to city/atmosphere CO2 exchanges that is weather-sensitive: the buildings on the Toulouse site (France), and the vegetation on the Kumpula site (Finland). These two sites demonstrate the model's ability to reproduce CO2 exchanges between urban surfaces and the atmosphere as well as their daily and seasonal cycles. The Toulouse site underlines the importance of a detailed knowledge of the inhabitants' energy behaviour in order to simulate the CO2 emissions of buildings. Kumpula site demonstrates the ability of the ISBA model, designed to describe the interactions between non-urban vegetation and the atmosphere, to describe the CO2 exchanges between urban vegetation and the atmosphere. The model, thus validated, is used to carry our simulations of CO2 emissions from buildings on the scale of the entire urban agglomeration of Toulouse. These simulations once again highlighted the necessity of a good knowledge of the inhabitant's energy behaviors: on our case study (four days in winter), the 2°C reduction of the nigth-time space heating setpoint temperature reduces CO2 emissions by 33%. During these simulations, the transport of CO2 emitted by the city through the atmosphere is also monitored. This shows that, despite a calm wind situation, the CO2 plume created by the city dissipates rapidly (less than a day), limiting the increase in CO2 concentration over the city. Simulations on other cities are neeeded to determine if this result can be generalized. During this thesis, we studied climate/CO2 interactions at the city scale. In the future, it would be interesting to carry out simulations in future climate or in coupled mode with climate models in order to study the feedback between local and global climate/CO2 links
Fonseca, Fábio Luís Alves da. "Variação diurna do fluxo de CO2 na interface ar-mar do Oceano Atlântico Equatorial." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14133/tde-27062013-114814/.
Full textThe diurnal cycle of CO2 is estimated for the month of August on the Atlantic Ocean using a gas transfer algorithm. The algorithm is based on the Monin-Obukhov similarity theory for turbulent transfer at the air-sea interface and the physics of the CO2 transfer at the oceanic molecular layer.
Carvalho, Felipe Rust de. "Fluxo de CO2 e CH4 em uma lagoa tropical (Pantanal, Brasil) com gradiente de turbidez." Universidade Federal de Juiz de Fora, 2015. https://repositorio.ufjf.br/jspui/handle/ufjf/413.
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Ecossistemas de água doce (rios, lagos e reservatórios) desempenham um papel essencial na ciclagem de carbono nos continentes. Esses ambientes são fontes significantes de gases de efeito estufa (GEE) para a atmosfera, principalmente de gás carbônico (CO2) e metano (CH4). Apesar do aumento do número de estimativas, a dinâmica e o controle das emissões naturais de GEE em ambientes aquáticos ainda é pouco estudada, especialmente nos trópicos. O objetivo geral da dissertação foi estimar os fluxos de CO2 e CH4 em uma lagoa tropical rasa com gradiente de turbidez. O trabalho foi realizado na lagoa Sinhá Mariana (MT), uma lagoa pantaneira com a ocorrência de duas regiões hidrológicas distintas; a lagoa é ligada ao rio Mutum de águas claras, pobre em material em suspensão, e baixa turbidez e ao rio Cuiabá de águas túrbidas, que apresenta alta taxa de material em suspensão. Duas coletas foram realizadas no ambiente, caracterizando os períodos hidrológicos de águas altas e águas baixas. A variação temporal, espacial e o pulso de inundação mostraram serem fatores importantes no fluxo de CO2, que variou de -4,95 mmol m-2 d-1 a 282 mmol m-2 d-1 nos períodos amostrados e diferenças significativas foram observadas entre um período e outro, com maiores emissões no período de águas altas (142 ± 40 mmol m-2 d-1) e menores nas águas baixas (2,3 ± 11,5 mmol m-2 d-1). Além disso, os fluxos de CO2 foram significantemente m/aiores nas proximidades do rio Mutum e menores na região túrbida e intermediária da lagoa, em ambos os períodos. Diferentemente, o fluxo total de CH4, embora estimado apenas nas águas altas, registrou os maiores valores médios na região de maior turbidez da lagoa (10,9 ± 6,9 mmol m-2 d-1), seguido pela região intermediária (5,1 ± 3,9 mmol m-2 d-1) e pela região influenciada pela água clara (2,5 ± 1,4 mmol m-2 d-1). A ebulição foi o principal processo de emissão de CH4, responsável por 78% do fluxo total. O gradiente de turbidez registrado ao longo da lagoa pareceu ter sido um fator determinante na dinâmica do fluxo tanto de CO2 quanto do CH4. Os dados deste trabalho reforçam a necessidade da amostragem espacial dos fluxos de CH4 e CO2 em lagos tropical, além de reforçar que estes fluxos podem ser controlados principalmente pela turbidez e pelo pulso de inundação (CO2).
Freshwater ecosystems (lakes, rivers and reservoirs) play an essential role in carbon cycling in the continents. These environments are significant sources of greenhouse gases (GHG), especially carbon dioxide (CO2) and methane (CH4), to the atmosphere. Despite the increase in the number of estimates, the natural GHG emissions dynamics in aquatic environments is still poorly studied, especially in the tropics. The general aim of this work was to estimate the CO2 and CH4 fluxes in a shallow tropical lake with turbidity gradient. The work was conducted in the Sinhá Mariana lake (MT), a wetland lake with the occurrence of two distinct hydrological regions; the lake is connected to the Mutum river (clear water), poor in suspended material with low turbidity, and connected to the Cuiabá River (turbid waters), which features high rate of suspension material. Samples were taken for characterizing the hydrological periods of high and low water. The temporal, spatial variation and the flood pulse shoed to be important factors affecting the CO2 flux, which ranged from -4.95 mmol m-2 d-1 to 282 mmol m-2 d-1. Significant differences were observed from one period to another, with higher emissions during high waters (142 ± 40 mmol m-2 d-1) and lower in the low water (2.3 ± 11.5 mmol m-2 d-1). In addition, the CO2 flux was significantly higher near the Mutum river and lower in the turbid region, in both periods. The total CH4 flux, although estimated only in high waters, showed the highest mean rates in the higher turbidity region of the lake (10.9 ± 6.9 mmol m-2 d-1), followed by the intermediate region (5.1 ± 3.9 mmol m-2 d-1) and the area influenced by clear water (2.5 ± 1.4 mmol m-2 d-1). The ebullition flux was the main CH4 emission pathway, responsible for 78% of the total flux. The turbidity gradient observed along the lake appeared to have been a determining factor in the flux dynamics of both CO2 and CH4. This study data reinforce the need for spatial sampling of CH4 and CO2 fluxes in tropical lakes, in addition to reinforcing that these fluxes can be controlled by turbidity and by the flood pulse (CO2).
Boiron, Olivier. "Caractérisation aérothermique d'un laser CO2 de puissance à flux axial rapide." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX22093.
Full textNorman, Maria. "Air-Sea Fluxes of CO2 : Analysis Methods and Impact on Carbon Budget." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-194960.
Full textBeijer, Martin, and Madeleine Skoglund. "Summer CO2 fluxes : A field study from three large lakes in Sweden." Thesis, Linköpings universitet, Tema Miljöförändring, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157304.
Full textÖkande halter av CO2 i atmosfären är en bidragande faktor till klimatförändringar. För att få en bättre förståelse för de så behövs kunskap om naturliga flöden, inte enbart antropogena källor, som t.ex. förbränning av fossila bränslen som störst fokus kretsar kring. Den nuvarande kunskapsnivån om större nordiska sjöars CO2 utsläpp är begränsad, och det finns en tydlig brist i data från dessa typer av system. Målet med denna uppsats var att utforska CO2 flöden från Roxen, Glan och Vättern, tre stora sjöar i Sverige. Syftet med studien var också att jämföra olika sätt att samla in empiriskt material samt undersöka om det fanns skillnader mellan sjöarna samt de olika studerade perioderna. Flytande kammare användes för att samla in prover som mättes direkt genom en sensor, men de användes också för att ta manuella gasprover som sedan beräknade flödet av CO2 med hjälp av modeller i efterhand. Resultatet visade både på skillnader i tid och rum mellan perioderna och sjöarna. Resultatet visade även att det fanns en skillnad mellan de olika metoderna vi använde oss av, där sensor (direkta mätningar) var mellan -36 to 152 mmol m-2 d-1 och flödesberäkningarna från CC-modellen (Cole & Caraco 1998) var –29 to 58 mmol m-2 d-1.
Román, Cascón Carlos. "Variability of turbulent fluxes (momentum, heat andCO2) during Upwelling conditions. A case study." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303975.
Full textMätningar av flöden (impuls, värme, vattenånga och CO2) vid två olika höjder studerades med data från en mast på ön Östergarnsholm (i Östersjön) under en vecka, beräkningar av flödena gjordes med mätningar av atmosfäriska parametrar från samma mast samt data från två bojar på två olika platser. Man fann olika beteenden för de beräknade och uppmätta flödena. Direkt (sensibelt) värme visade högre korrelation mellan beräkningar och uppmätta sensibla värmeflöden . För CO2- flödet fann man inte detta samband. För alla flödena överensstämmer mätningarna bättre med beräknade flöden när de är gjorda under instabila förhållanden, vilket betyder att under dessa förhållanden representerar mätningarna i masten bättre området där bojarna är placerade. Den studerade perioden inkluderar en period med upvällning (upwelling) och en hög horisontell variabilitet i ytparametrar under den största delen av denna period. Detta visades genom jämförelser mellan de beräknade och de uppmätta flödena och även genom satellitmätningar. Det område uppvind masten där ytan påverkar flöden uppmätta i masten på en viss nivå kallas ”footprint area”, och denna footprint area förändras kontinuerligt på grund av det stora beroendet av skiktningen i atmosfären. Eftersom skiktningen under hela perioden förändrades från något stabilt till något instabilt, kan ytvariabiliteten även ses i variationen av uppmätta flöden på olika höjder. En viktig slutsats i studien är att beräkningar av flödena som görs med standardformler inte bör användas vid förhållanden med hög horisontell och vertikal variation av olika parameter (som havsytetemperatur och pCO2w), som till exempel under uppvällningssituationer och nära kusten, där phytoplankton markant kan påverka koncentrationen av CO2 vid ytan. Studien inkluderar meteorologiska, oceanografiska parametrar, flöden, samband med parametrar, överförings koefficienter, beroende av stabilitet och satellitbilder.
Flujos turbulentos (momento, calor sensible, calor latente y CO2) en 2 alturas diferentes fueron estudiadas usando medidas de una torre en la Isla de Östergarnsholm (Mar Báltico) durante una semana. Los flujos también fueron calculados usando formulaciones con medidas de la torre y de dos boyas ancladas en diferentes localizaciones. Diferentes características para los distintos flujos fueron encontradas. El flujo de calor latente muestra una relación más alta con los cálculos que el flujo de calor sensible. No se encontró esta relación para el flujo de CO2. También, todos los flujos medidos en la torre coinciden mejor con los flujos calculados cuando estos son hechos bajo condiciones de estratificación inestable, significando que la torre mide mejor el área donde son cogidas las medidas en las boyas (cerca de la torre). El periodo estudiado incluye un afloramiento costero y se encontró una alta heterogeneidad horizontal en la superficie del mar durante la mayoría de los periodos. Esto fue estudiado usando las comparaciones entre flujos calculados y medidos y también usando imágenes de satélite. El footprint area puede ser definido como el área a una distancia desde la torre hacia donde sopla el viento donde las condiciones de la superficie influyen las medidas del flujo de alguna cantidad en la torre, y este footprint area está continuamente cambiando debido a su alta dependencia con la estratificación. Durante todo el periodo la estratificación estuvo cambiando desde ligeramente estable a ligeramente inestable, y por ello la heterogeneidad de la superficie puede ser vista en la variabilidad de los flujos medidos a diferentes alturas. Una conclusión importante en este estudio es que los cálculos de los flujos usando formulaciones podrían no ser útiles cuando se espera una alta variabilidad de los diferentes parámetros (temperatura superficial del mar y pCO2w), como por ejemplo durante situaciones de afloramiento y también cerca de costa, donde el fitoplancton puede influenciar significativamente la concentración de CO2 en la superficie. Se presenta un amplio estudio, incluyendo parámetros meteorológicos y oceanográficos, comparaciones de flujos, relaciones con parámetros, coeficientes de transferencia, dependencias con la estratificación e imágenes de satélite.
Prytherch, John. "Measurement and parameterisation of the air-sea CO2 flux in high winds." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/209567/.
Full textSantos, André Luís Diniz dos. "Cálculo do fluxo de CO2 com modelo de interação superfície-vegetação-atmosfera ISBA." reponame:Repositório Institucional da UFPR, 2017. http://hdl.handle.net/1884/44982.
Full textDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Ambiental. Defesa: Curitiba, 26/07/2016
Inclui referências : f. 147-157
Resumo: Este trabalho implementa primeiramente um método para calcular o fluxo de gás carbônico em uma plantação de soja, utilizando uma versão modificada por Vissotto (2003) do modelo de transferência entre superfície-vegetação-atmosfera SVAT ISBA (Noilhan e Planton, 1989). O modelo ISBA consiste em seis equações diferenciais ordinárias prognósticas para temperatura na superfície, temperatura média na camada de raízes, umidade na camada superficial do solo, umidade média na camada de raízes, umidade média na camada de sub-raízes e umidade retida na vegetação, utilizando como forçantes a temperatura do ar, radiação solar incidente, umidade relativa do ar, velocidade do vento e precipitação. O modelo calcula fluxos de calor, temperaturas e umidades do solo. O cálculo da evapotranspiração utiliza parâmetros puramente físicos, pois havia apenas interesse na liberação de água para evapotranspiração. Adicionalmente foi acoplado o módulo A-gs proposto por Jacobs (1994) para descrever os processos fisiológicos na escala das folhas, levando em consideração a assimilação líquida de gás carbônico pela vegetação. Este novo modelo denominado de ISBA-A-gs, teve ainda nesta pesquisa módulos inseridos para o cálculo da respiração noturna da vegetação e estresse hídrico no solo. O modelo foi calibrado, utilizando-se duas séries de dados robustas de medições de campo no estado do Paraná e aplicado posteriormente com sucesso em uma região na Argentina onde existem dados do fluxo de CO2 medido sobre uma plantação de soja. Palavras-chave: fluxo CO2, modelo numérico, soja.
Abstract: In this dissertation we implement a model to calculate the carbon dioxide flux in a soybean culture, using a modified version of the surface-vegetation-atmosphere transfer model (SVAT) ISBA (Noilhan e Planton, 1989). The model consists of a six ordinary differential equations for the surface temperature, temperature of root soil layer, moisture of soil surface, moisture of root soil layer, moisture of the subroot soil layer. and moisture retained on the vegetation canopy, and it is forced by air temperature, solar radiation, air relative humidity, wind speed and precipitation. As in the original ISBA the model also predicts heat and moisture fluxes. While the original ISBA computes evapotranspiration with purely physical terms, the present model couples ISBA with the module A-gs proposed by Jacobs (1994) to describe the physiological processes in the leaves, taking into account the net assimilation of carbon dioxide by vegetation. This new model called ISBA-A-gs is similar to Calvet et al. (1998), with the inclusion of several improvements. The model was calibrated using two data series of measurements made in the state of Paraná and was successfully applied to a soybean field in Argentina where comparisons with the CO2 fluxes were made. Keywords: CO2 flux, numeric model, soy.
Sousa, Eliete dos Santos. "Fluxo evasivo de CO2 em ambientes fluviais no sudoeste da Amazônia, Acre, Brasil." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-04092013-142901/.
Full textIn the largest basin of the planet, the Amazon river carries large amounts of particulate and dissolved carbon to the oceans. This traditional view of rivers as carriers of carbon to the oceans has been reviewed in the last decades due to new results showing that CO2 emissions to the atmosphere from these systems can surpass C transport in discharge in one order of magnitude. Several studies have been conducted to evaluate the processes controlling these emissions. However they still remain a major source of uncertainty. The main objective of this study was to quantify CO2 evasive fluxes in rivers and streams of Southwestern Amazon (Purus river basin, Acre state), taking into account chemical and physical characteristics of each system, as well as seasonality in this region and, thus, contribute to improve estimates of carbon emissions throughout the Amazon basin. The results showed that during low water the rivers have relatively high bicarbonate concentrations, indicating that carbonate weathering is an important carbon source. Dissolved inorganic carbon isotopic composition corroborated these results. However, in streams the main carbon source is soil organic matter. Seasonality has a strong influence on pCO2 and consequently on CO2 fluxes, with the highest values occurring in the rainy season. However there was no seasonal variability in respiration rates, which shows that other factors than respiration are also influencing CO2 fluxes. During the dry period, increases in chlorophyll a indicate that photosynthetic processes also play an important role in the C balance of these systems.
Vendrame, Nadia. "Study of vegetation-atmosphere interactions over vineyards: CO2 fluxes and turbulent transport mechanics." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3425729.
Full textLo studio delle interazioni tra vegetazione e atmosfera è oggi un tema di grande interesse nell’ottica di migliorare la comprensione della risposta delle piante alle variabili ambientali e la modellizzazione del loro ruolo nel cambiamento climatico globale. Particolare attenzione è di solito rivolta ai flussi di anidride carbonica (CO2) e, in genere, gli ecosistemi naturali come le foreste hanno ricevuto una maggiore attenzione. In questa ricerca sono state studiate le interazioni vegetatione-atmosfera su una coltura agraria importante per il bacino mediterraneo, quale il vigneto, focalizzandosi sul monitoraggio del bilancio annuale di carbonio e approfondendo lo studio della meccanica del trasporto turbulento che è alla base degli scambi di energia e materia. Il vigneto è un sistema complesso con diverse sorgenti e sink di scalari (vapore d’acqua, anidride carbonica, calore), in cui le due principali componenti, vite e suolo, compongono il flusso totale della canopy in un rapporto che varia nel corso dell’anno. Nei vigneti del Nord Italia, l’interfila è solitamente non lavorata e inerbita, giocando un ruolo importante nel bilancio del carbonio del sistema. In questo contesto, risulta cruciale la ripartizione dello scambio netto di CO2 dell’ecosistema (Net Ecosystem Exchange, NEE) nelle componenti suolo e vite. Nel corso di questa indagine, la NEE di un vigneto è stata monitorata per tre anni utilizzando la tecnica micrometeorologica dell’ eddy covariance (EC), mentre la misura dei flussi di CO2 al suolo è stata effettuata con camere (a cupola trasparente e oscura). Nel 2015, il bilancio annuale di carbonio del vigneto è stato di circa ‒ 80 g C m‒ 2 a‒ 1, dimostrando quindi la capacità di agire da sink, ma la maggior parte dell’assimilazione è risultata legata al suolo inerbito (‒ 60 g C m‒2 a‒1). In ogni caso, il sistema ha dimostrato un’elevata variabilità interannuale del bilancio del carbonio stagionale, in cui ondate di calore e periodi di siccità estivi hanno giocato un ruolo primario. Nella stagione 2014, caratterizzata da un regime di precipitazione abbondante, la NEE ha raggiunto il valore massimo di circa ‒ 250 g C m‒2. L’organizzazione del vigneto in filari determina una particolare dinamica del trasporto turbolento dentro canopy. Inoltre, la struttura morfologica del vigneto è altamente variabile durante il corso dell’anno, passando da una canopy praticamente vuota nel periodo di dormienza della vite a una situazione dove il fogliame è denso e concentrato nelle file al culmine della stagione vegetativa. L’influenza dello sviluppo della densità fogliare sulle statistiche della turbolenza è stato studiato installando un profilo verticale di anemometri ad ultrasuoni. Il flusso turbolento è risultato fortemente influenzato dalla struttura della canopy. Senza foglie, il regime turbolento è caratteristico di un flusso di parete, mentre con lo sviluppo completo del fogliame assume le proprietà tipiche di un flusso con mixing‒layer, sebbene il flesso al limite superiore della canopy sia poco accentuato, a causa della bassa densità fogliare del vigneto. Infine, è stata condotta un’analisi specifica delle strutture coerenti coinvolte nel trasporto di quantità di moto e sulle loro scale temporali. L’importanza di eventi discendenti che trasportano aria più veloce del flusso medio (sweeps) è aumentata nel corso della stagione. La durata media delle strutture coerenti dominanti è stato nell’ordine di 6 ‒ 10 s e, in questo caso, non è stata riscontrata nessuna chiara correlazione con lo sviluppo della struttura della canopy. Lo studio ha messo in evidenza l’importanza del monitoraggio a lungo termine degli scambi tra vegetazione e atmosfera, ma anche la complessità dei fenomeni di trasporto turbolento che li caratterizzano. Tuttavia, solo la piena comprensione della meccanica di questi processi può portare alla corretta interpretazione del ruolo della vegetazione nei cicli biogeochimici più fondamentali.
Kleine, Barbara. "How do fluids move through rocks? : High fluxes of CO2 in the Earth's crust." Licentiate thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-84007.
Full textCorreard, Gilson Carlos de Castro. "Desenvolvimento de um laser de CO2 contínuo, de alta potência e de alto fluxo." Instituto Tecnológico de Aeronáutica, 2009. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=876.
Full textBrandão, Daysiane Barbosa. "Estimativa do fluxo de CO2 no oceano atlântico utilizando dados de navios e satélite." reponame:Repositório Institucional da UFC, 2017. http://www.repositorio.ufc.br/handle/riufc/27338.
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Atmospheric carbon dioxide (CO2) is responsible for more than half of the warming potential of the greenhouse effect by anthropogenic emissions, and its basis is the conversion of the balance between sources and sinks. The ocean is one of the main CO2 sinks, which can also act as a source of CO2 for an atmosphere, depending on its concentration in the ocean. An analysis of ocean temperature and salinity data and CO2 fugacity (fCO2) are essential for an estimation of the CO2 flow without an ocean-atmosphere system, which enables a better understanding of the role of the oceans without climate, as well as the Variability of atmospheric CO2. Studies have shown that the Tropical Atlantic Ocean (TAO) is an important source of CO2 for an atmosphere but little is known about seasonal and interannual variability of its flux at the ocean-atmosphere interface, as well as the impact of atmospheric CO2 flux, due, for example, to anthropogenic effects. In order to contribute to a better understanding of the CO2 flux at the ocean-atmosphere interface in the Tropical Atlantic Ocean, for the calculation of fCO2 data, sea surface temperature (SST), sea surface salinity (SSM), obtained by voluntary observation vessels, which crossed the tropical Atlantic Ocean (15º S to 20º N) during the years 2008 to 2014, and wind speed data during this period were obtained from ECMWF re-examinations (European Center for Medium-Time Forecasting). As analyzes indicated that the interannual variability of CO2 fugacity generally presents an increase in the sampled period when considered as a study area as a whole. However, a presence of the InterTropical Convergence Zone (ITCZ) caused a decrease in fCO2sw (CO2 fugacity in seawater). This decrease is related to the rainfall characteristic of the ITCZ, which causes a decrease in SSM. A correlation between fCO2sw and SSM was significant (r = 0.7 ~ 0.9), consequently, resulting in CO2 absorption causing this region of the OAT to act as a sink for atmospheric CO2. It was also verified that, in some periods, a CO2 fugacity showed no correlation with a SST and SSM, which suggests an influence of other biophysical variables in the estimation of fugacity. The region between 10 o N and 20o N presents seasonally related behavior, acting as a sink in the months in which the TSM (December to May), presents smaller values in magnitude when compared to the other periods. On the other hand, when a TSM is higher (June to October), it acts as a source of CO2 for the atmosphere. On average, the CO2 flow from the ocean to the atmosphere in the sampled period was 0.84 μmol.m-2.d-1, confirming its performance as a source of CO2 for the atmosphere. An elaboration of a single pre-launch model of fCO2sw for the entire study region proved to be infeasible because the study region was presented, for example, as being linked to the current system of currents in the region.
O dióxido de carbono (CO2) atmosférico é responsável por mais da metade do potencial de aquecimento do efeito estufa por emissões antropogênicas, sendo sua concentração resultante do balanço entre fontes e sumidouros. O oceano é um dos principais reservatórios sumidouros de CO2, o qual também pode atuar como fonte de CO2 para a atmosfera, dependendo de sua concentração no oceano. A análise de dados de temperatura e salinidade de águas oceânicas e fugacidade do CO2 (fCO2), são essenciais para a estimativa do fluxo de CO2 no sistema oceano-atmosfera, o que possibilita uma melhor compreensão do papel dos oceanos no clima, bem como da variabilidade do CO2 atmosférico. Estudos tem demostrado que o oceano Atlântico Tropical (OAT) é uma importante fonte de CO2 para a atmosfera, porém pouco se sabe sobre a variabilidade sazonal e interanual de seu fluxo na interface oceano-atmosfera, bem como o impacto nesse fluxo diante do aumento do CO2 atmosférico, devido, por exemplo, aos efeitos antropogênicos. Com finalidade de contribuir para um melhor entendimento do fluxo de CO2, na interface oceano-atmosfera, no OAT, utilizou-se, para o cálculo desse fluxo dados de fCO2, temperatura da superfície do mar (TSM), salinidade da superfície do mar (SSM), obtidos por navios de observação voluntária, que cruzaram o oceano Atlântico Tropical (20 ºN a 15 ºS), durante os anos de 2008 a 2014, sendo que os dados de velocidade do vento, nesse período, foram obtidos a partir das reanalises do ECMWF (European Centre for Medium-Range Weather Forecasts). As análises indicaram que a variabilidade interanual da fugacidade de CO2 apresentou, de modo geral, aumento no período amostrado, quando considerado a área de estudo como um todo. Porém, a presença da Zona de Convergência InterTropical (ZCIT) ocasionou diminuição na fCO2sw (fugacidade do CO2 na água do mar). Esta diminuição está relacionada ao regime pluviométrico característico da ZCIT, que causa diminuição da SSM. A correlação obtida entre o fCO2sw e a SSM foi significativa (r = 0,7 ~ 0,9), consequentemente, resultando em absorção de CO2 fazendo com que essa região do OAT atue como sumidouro do CO2 atmosférico. Verificou-se também que, em alguns períodos, a fCO2 não apresentou correlação com a TSM e a SSM, o que sugere a influência de outras variáveis biofísicas na estimativa da fugacidade. A região entre 10o N e 20o N, apresenta comportamento relacionado à sazonalidade, atuando como sumidouro nos meses em que a TSM (dezembro a maio), apresenta valores menores em magnitude se comparado aos demais períodos do ano. Por outro lado, quando a TSM está mais elevada (junho a outubro), ela atua como fonte de CO2 para atmosfera. Em média o fluxo de CO2 do oceano para a atmosfera, no período amostrado, foi 0,84 mmol.m-2.d-1, confirmando sua atuação como fonte de CO2 para a atmosfera. A elaboração de um único modelo preditivo de fCO2sw para toda a região de estudo mostrou-se inviável, devido a região do estudo apresentar diferentes características, por exemplo, como as ligadas ao sistema de correntes atuantes na região.
Alves, José Darlon Nascimento. "Partição do fluxo de CO2 e eficiência do uso de água em pastagem natural." Universidade Federal de Viçosa, 2017. http://www.locus.ufv.br/handle/123456789/10203.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico
As pastagens naturais são importantes para os ciclos de água e carbono no planeta, contribuindo para o armazenamento de matéria orgânica no solo, alimentação animal e para a diversificação da fauna e flora. Dessa forma, o objetivo do trabalho foi particionar o fluxo de carbono e quantificar a eficiência do uso de água em pastagem natural por meio da técnica de covariância de vórtices turbulentos. O sítio experimental está localizado em uma área de pastagem natural com aproximadamente 3.487 hectares, na Universidade do Estado do Kansas, em Manhattan, Kansas, Estados Unidos. Foram analisados dados de fluxos obtidos durante o período de maio a outubro de 2016. As medições dos fluxos de CO 2 e fluxo de calor latente foram realizadas por meio da técnica da covariância de vórtices turbulentos. As medidas de velocidade do vento, concentração de CO 2 , calor sensível e vapor d’água ocorreram a uma frequência de 20 Hz utilizando-se um sistema de aquisição de dados. Os dados brutos foram processados pelo software EddyPro 6.0. Foi realizada a estimativa da respiração durante o dia, a partir da relação não linear entre a troca líquida do ecossistema durante a noite e a temperatura e umidade do solo noturna, a cada dois meses (maio-junho, julho- agosto, setembro-outubro), em que foi obtida melhor relação apenas com a temperatura do solo. Em seguida, foi feita a separação do fluxo de CO 2 em fotossíntese (GPP) e respiração do ecossistema (Reco) e análise da eficiência do uso de água durante a estação de crescimento. Observou-se variação de NEE na pastagem entre -30 μmol CO 2 m -2 s -1 e 15 μmol CO 2 m -2 s -1 . Ao realizar a partição do fluxo de CO 2 do ecossistema, verificou-se maior intervalo de incerteza nos meses de julho e agosto, em decorrência do baixo R 2 encontrado, porém foram obtidas maiores taxas de fotossíntese em relação à respiração do ecossistema em todos os meses analisados. O valor médio de eficiência do uso de água do ano de 2016 foi de 3,1 gC/kg H 2 O. Durante o experimento, o ecossistema atuou como sumidouro de carbono, o que refletiu em aumento de biomassa. Além disso, as atividades metabólicas e balanço de água são afetados diretamente pela temperatura do ar.
Grasslands play an important role for water and carbon global cycles. Grasslands contribute to the storage of organic matter in the soil, animal feed and for biodiversity. The objective this study was to partition of the CO 2 net ecossystem exchange (NEE) and to quantify the use water use efficiency in grassland using the eddy covariance technique. The experimental site is located in a grassland ecossystem with and area of approximately 3,487 hectares at the Kansas State University in Manhattan, Kansas, United States. The flux data obtained were analyzed during the period from May to October 2016. The measurements of CO 2 and latent heat fluxes were measured using the eddy covariance technique. Measurements of wind velocity orthogonal components, CO 2 and water vapor concentration were taken at a frequency of 20 Hz using a datalogger. The raw files were processed using the EddyPro 6.0 software. Estimates of daytime respiration were performed using the nonlinear relationship between nighttime net ecosystem exchange and soil temperature for bi-monthly periods (May-June, July-August, September-October). Then, the net ecosystem exchange was separate in gross primary productivity (GPP) and ecosystem respiration (Reco). The water use efficiency was calculated for the growing season. The values of NEE in the grassland varied from -30 μmol CO 2 m -2 s - to 15 μmol CO 2 m -2 s -1 . The flux partitioning uncertainties were larger for the months of July and August, due to the low R 2 found. The average value of water use efficiency was 3,1 gC/kg H 2 O. Thus, that ecosystem acted as a carbon sink, which reflected an increase in biomass. In addition, metabolic activities and water balance are directly affected by air temperature.
Slonek, Jaroslav. "Využití spalin jako zdroje CO2 pro kultivaci řas v bioreaktorech." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442857.
Full textHu, Yukun. "CO2 capture from oxy-fuel combustion power plants." Licentiate thesis, KTH, Energiprocesser, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48666.
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Green, Vicki C. "CO2 Recovery by Scrubbing with Reclaimed Magnesium Hydroxide." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1378196688.
Full textMieres, Luciana da Silva. "Reanálise CFSR-NCEP aplicada ao modelo SiB2 na simulação de fluxos de CO2 sobre o cultivo de soja em Cruz Alta." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/62124.
Full textThe present work aimed to evaluate the behavior of CO2 fluxes, run by the Simple Biosphere Model (SiB2), by adopting CFSR-NCEP data reanalyzed as an atmospheric boundary condition. A statistical analysis was used in order to validate the results obtained using a coefficient for the adjusted model based on the simulation parameters when compared to the data observed in field, which was obtained by the micrometeorological tower located on the cultivation areas. The study was applied in a soybean experimental site located in Cruz Alta (-28,6036; -53,6736), in the state of Rio Grande do Sul, Southern Brazil between 2008 and 2009. Some of the parameters presented in the subroutines of the model had to be adjusted first. For such, a methodology in which the parameters were calibrated in sequential modules was applied according to the following order: aerodynamics, radiative transfer, hydraulic diffusion of the soil and photosynthesis and stomatal conductance. In the aerodynamics module, the calibration was made using the parameters for the canopy height, vegetation coverage and leaf-angle distribution. For the radiative transfer, the calibration used the parameters for the live leaf transmittance visible reflectance. The calibration for the hydraulic diffusion of the soil was accomplished in the soil porosity, depth of individual layers and humidity exponent. For the photosynthesis and stomatal conductance, the parameters tested were the leaf area index, minimum stomatal conductance and leaf respiration critical temperature. It could thus be possible to obtain a considerable improvement for the simulation of the CO2 fluxes in this model for a high-quality simulation. That stage was significantly important since it enabled the reanalysis data to be set in the best model for the studied area. Regarding the final stage of this study, data from the CFSR were used as the atmospheric boundary condition instead of originally applied meteorological variables from the INMET station. Variables concerning air temperature, air pressure at sea level, precipitation, incident short-wave radiation and wind speed were used in order to describe the physical condition of the atmosphere in new simulations with CO2 fluxes, and then compared to the data observed in the micrometeorological tower. From the results, using the CFSR-NCEP reanalysis data can be considered acceptable for studies on CO2 fluxes from the SiB2 model. Yet, calibrating this model for the studied area is a key factor for its suitability and for obtaining adequate results.
Chronopoulos, Theodore. "Microwave Swing Adsorption for post-combustion CO2 capture from flue gases using solid sorbents." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3199.
Full textChavrit, Déborah. "Cartographie globale des flux de CO2 à l'axe des dorsales océaniques : une approche pétrologique." Nantes, 2010. http://archive.bu.univ-nantes.fr/pollux/show.action?id=71f43d4d-5741-47b5-8add-0e8ca42daa12.
Full textVesicularity measurements in basalts are important because they are directly linked to magma degassing, the key parameter to understand gas transfer from the Earth interior to the hydrosphere and atmosphere. But such data are limited, preventing any global approach. In order to circumvent this problem, vesicularity characteristics have been precisely determined on 64 mid-ocean ridge basalts. Vesicle size distribution (VSD) shows that Pacific MORBs have vesicularities and mean diameter respectively 14 times and 5 times lower and bubble density 3 times greater than the ones from the Atlantic and Indian oceans. The comparisons of the vesicularities with a large range of geochemical and geophysical parameters suggest that 3 parameters control MORB vesicularity. We show that the main parameter is the spreading rate (50%), and to a lesser extent eruption depth and mantle compositional variations (25% each). The empirical equation defining the logarithm of vesicularity as a function of spreading rate, depth axis ridge and the K2O/TiO2 ratio, allows the calculation for the first time of the CO2 flux released at each ridge segment. CO2 total flux is 5. 8±1. 6. 1011 mol/yr and the mean CO2 content of the mantle is ppm, with higher values near hot spots. CO2 flux from the most important volcanic activity on Earth is only 0. 1% of the anthropogenic flux
Campbell, Elliott. "Optimal recovery of regional CO2 surface fluxes by data assimilation of anthropogenic and biogenic tracers." Diss., University of Iowa, 2007. http://ir.uiowa.edu/etd/182.
Full textDias, Jadson Dezincourt. "Fluxo do CO2 proveniente da respiração do solo em áreas de floresta nativa da Amazônia." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/91/91131/tde-04102006-163445/.
Full textCarbon dioxide is an important contributor to the greenhouse effect, and by extension, the global climate system as a whole; it is generated and consumed through the activities of terrestrial and aquatic microorganisms. Tropical forest CO2 fluxes at the soil-atmosphere interface depend on changes in the physical, chemical and biological characteristics of the soil surface. The objective of the present study is to investigate seasonal variability of CO2 fluxes from soil respiration in Amazonian native forest located in the municipalities of Sinop (MT), Caxiuanã (PA), Manaus (AM) e Santarém (PA) and to determine the effects of determining parameters such as temperature and soil moisture. The CO2 fluxes were measured using dynamic chambers during both dry and wet seasons at each site. As the concentration of the gas inside the chamber varies with time, samples were taken at given time intervals and fluxes then calculated using linear regression equations. The average values found for Sinop in the dry and wet seasons were 3.03 and 5.92 μmol.CO2 m-2s-1 respectively; for Caxiuanã, 5.07 μmol.CO2 m-2s-1 and 6.09 μmol.CO2 m-2s-1; for Manaus, 5.47 and 5.44 μmol.CO2 m-2s-1; and for Santarém, 5.64 μmol.CO2 m-2s-1 in the wet season and during the dry season and 6.09 μmol.CO2 m-2s-1. Our results showed that there was a seasonal variation of the CO2 flux. The results also showed that there was an influence of the seasonality in the dynamics of the soil CO2 flux, where the greater fluxes were obtained during the wet season, indicating that water availability and soil temperature were the main factors determining production. Litter samples had been collected and roots esteem the supply and influence it on the CO2 fluxs of in the soil, being these, ways of entrance of nutrients and mainly of carbon for the ground. For all the regions the biggest supplies had been found in the dry station.
Allard, Vincent. "Effects of elevated atmospheric CO2 concentrations on carbon and nitrogen fluxes in a grazed pasture." Vandoeuvre-les-Nancy, INPL, 2003. http://docnum.univ-lorraine.fr/public/INPL_T_2003_ALLARD_V.pdf.
Full textDufour, Carolina. "Rôle des tourbillons océaniques dans la variabilité récente des flux air-mer de CO2 dans l'océan Austral." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENU040/document.
Full textBy taking up large amounts of atmospheric CO2, the Southern Ocean helps to regulate the climate system. Southern Ocean carbon sink is poorly constrained, in part because data coverage is sparse and also because ocean models that have been used in such assessments fail to explicitly resolve key physical features such as mesoscale eddies. In recent decades, the growth of the Southern Ocean carbon sink may have been partly counteracted due to a loss of natural CO2 from the ocean driven by an intensification of westerlies, related to a positive trend in the Southern Annular Mode (SAM). This thesis focuses on documenting and understanding recent spatial and temporal variability of air-sea CO2 fluxes in the Southern Ocean. Sensitivity to positive phases of the SAM are tested by making simulations with a regional model of the Southern Ocean (south of 30°S) that couples biogeochemistry to the dynamics, is forced by atmosphere reanalysis data, and partially resolves the mesoscale. The resulting response of Southern Ocean CO2 fluxes to the SAM is dominated by a strong CO2 efflux to the atmosphere from the Antarctic Zone due to an increase in surface dissolved inorganic carbon (DIC). This increase is driven by the mixed-layer dynamics and is supplied by a meridional transport of DIC, a competition between the wind-driven circulation and the standing eddy-induced circulation. This work discusses the effect of increasing model resolution on simulated air-sea CO2 fluxes
Gemayel, Elissar. "Contribution à l'estimation des paramètres du système des carbonates en Mer Mediterranée." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0023/document.
Full textThe objective of the thesis is to contribute to the estimation of the carbonate system parameters in the Mediterranean Sea, in particular the partial pressure of CO2 in water (pCO2sw), total alkalinity (AT), total inorganic carbon (CT) and pH.The study was initiated by an adequate calculation of the water masses mixing coefficients in the Western and Eastern basins, using data from the Boum and MedSeA cruises in 2008 and 2013, respectively. The analysis of the mixing coefficients, allowed us to study the evolution of water masses in the Mediterranean Sea between the years 2008 and 2013.Subsequently, using data from the 2013 MedSeA cruise, we presented the results of recent measurements of pCO2sw on a wide longitudinal section from the Strait of Gibraltar to the Levantine sub-basin. The results indicated that the Western and Eastern basins were characterized by two different pCO2sw regimes. These regimes were mainly affected by the distinctive physico-chemical properties of each basin. From the direct measurements of pCO2sw we calculated along the track of the MedSeA cruise, the daily CO2 fluxes across the air-sea interface in May 2013. To achieve a more comprehensive analysis, we referred in a consecutive study to the data of the Thresholds and MedSeA cruises. From these data, we provided two equations to estimate in May 2007 and 2013; pCO2sw from satellite data of sea surface temperature, Chlorophyll_a and the chromophoric dissolved organic matter index. Furthermore, we calculated and mapped the air-sea CO2 fluxes in May 2013 across the whole Mediterranean Sea, with a spatial resolution of 4 km.Successively, we established from the MedSeA cruise data, linear regressions to estimate AT and CT from salinity, in each sub-basin of the Mediterranean Sea and for several depths. Later on, we focused on the physico-chemical data in surface waters, compiled from several oceanographic cruises between 1998 and 2013. The equations developed to estimate the AT and CT in surface waters, indicated that it is best to include in these polynomials both salinity and temperature. These polynomials were applied to the climatological fields of salinity and temperature of the World Ocean Atlas, in order to map the spatial and seasonal variability of AT and CT on a 7 years average.Moreover, we estimated from the MedSeA cruise data, the concentrations of anthropogenic carbon (CANT) and the variation of acidification (ΔpH) in the Mediterranean Sea. The results indicated that the Mediterranean Sea is heavily contaminated by CANT, with higher concentrations than those recorded in the Pacific or Indian Ocean. Also, the calculated ΔpH indicated that the Mediterranean Sea is already acidified from the surface to the deep waters. Finally, we presented a model to predict the ΔpH according to theoretical concentrations of CANT. Consequently, we showed that we already reached the tipping point of CANT, for which the acidification will strongly intensify in the Mediterranean Sea. Moreover, the deep waters of the Western and Eastern basins are very likely to become under saturated in calcite and aragonite by the end of the next century
Villela, Franco Nadal Junqueira. "Análise decadal do fluxo de CO2 entre o oceano e a atmostera na Passagem de Drake, Oceano Austral." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/90/90131/tde-24112011-125748/.
Full textVILLELA, FRANCO N. J. Decadal analysis of the CO2 sea-air flux in the Drake Passage, Southern Ocean 2011. 148 f. Dissertação (mestrado) Programa de Pós-Graduação em Ciência Ambiental (PROCAM), Universidade de São Paulo, São Paulo, 2011. For the area bounded by parallels 60°S and 62.5°S and meridians 60°W and 65°W, located in the southern Drake Passage in the Southern Ocean, near the Antarctic Peninsula, mean seasonal and annual distributions of CO2 flux at the ocean-atmosphere interface, from 2000 to 2009, have been computed, as well as their associated variables: the CO2 partial pressure at sea surface (PCO2sw), the CO2 partial pressure in atmosphere (PCO2ar), the CO2 pressure difference between ocean and atmosphere (PCO2), and the gas transfer rate (TR), which is the product of the CO2 solubility coefficient in sea water by the gas transfer velocity. The parameterization used to calculate fluxes was that of Takahashi et al. (2009) with TR depending on the squared wind speed multiplied by a scale factor 0.26. The study area has about 75,000 km2 and was divided into a grid of 0.5° x 0.5°, resulting in 50 area boxes. Over 46,000 PCO2sw measurements were used, which in the spatial mean varied from 362.7±11.2 to 371.9±17.5 µatm, in summer and spring, respectively. The PCO2 varied from 0.4 to 5.7 µatm in autumn and spring, respectively. TR varied from 0.065±0.04 to 0,088±0.002 gC.month-1.m-2.µatm-1, in summer and winter, respectively. The net flux, taking ice concentration as negligible, varied from 0.039±0.865 to 0.456±1.221 gC.month-1.m-2, in autumn and winter, respectively. The total annual carbon flux, estimated through the spatial mean per square, was 95 GgC.y-1. Thus, in the annual estimate the region acts as a source to the atmosphere, mainly due to the continental shelf having PCO2sw considerably greater than that of the atmosphere. Seasonally, it is suggested that in summer the greater availability of solar radiation, warmer sea surface temperature (SST), and weaker winds favor the production of phytoplanktonic mass, making the biological pump the dominating process in lowering the PCO2sw and the absorption of atmospheric CO2 by the sea surface. On the other hand, in winter winds intensify and, in association with the strong cooling of the SST, promote mixing with deep waters rich in dissolved inorganic carbon, leading the sea surface to a state of supersaturation in CO2 relative to the atmosphere. Stronger circumpolar west winds and displaced to the south have been pointed as the cause for the increase of PCO2sw at a rate equal to or greater than that occurring in the atmosphere. In the study area it has been detected a mean trend of wind intensity 0.23±0.03 m.s-1.decade-1 and an increase in the western zonal component of 1.47±1.3%.decade-1. It is suggested that these trends are related to the Southern Annular Mode (SAM). However, the decadal trend estimated for the PCO2sw was smaller than for the atmosphere, in spite of both indicating increasing tendencies. It is believed that the great variability and scatter distribution of the data have masked the magnitude of the PCO2SW trend estimate.
Khunsupat, Ratayakorn. "Poly(allylamine) and derivatives for co2 capture from flue gas or ultra dilute gas streams such as ambient air." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44909.
Full textCheung, Ocean. "Narrow-pore zeolites and zeolite-like adsorbents for CO2 separation." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-101629.
Full textAt the time of the doctoral defence the following papers were unpublished and had a status as follows: Papers 4-8: Manuscripts.
Andreo, Ana Paula. "Ensaios de respirometria : monitorização do CO2 utilizando um sistema FIA com detecção condutometrica." [s.n.], 1999. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258092.
Full textDissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Civil
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Resumo: A respirometria é uma técnica muito utilizada na determinação da biodegradação de resíduos misturados ao solo pela atuação de microrganismos presentes. O respirômetro normalmente utilizado é o de Bartha e Pramer, onde o CO2 produzido durante o processo é determinado via titulação ácido-base (convencional). O presente trabalho teve como objetivo a determinação do CO2 biodegradado, (CO2)b através de análise por injeção em fluxo (FIA) com detecção condutométrica, uma técnica cujas características são precisão, sensibilidade e curto tempo de resposta. Para tanto, fez-se necessário o estudo de parâmetros operacionais do sistema FIA utilizado. Realizou-se então ensaios de respirometria seguindo o Projeto de Norma 01:603.06-007/1993 da ABNT, com determinações do ((CO2)b por titulação e por sistema FIA. Os resultados obtidos foram bastante satisfatórios, verificando nas curvas obtidas o mesmo comportamento previsto pela teoria, permitindo assim, a identificação das fases do crescimento microbiano
Abstract: Respirometry is a technique frequently used for the determination of biodegradation of residues that are mixed to the soil, through the action of microorganisms present in it. The respirometer normally used is the Bartha and Pramer, in which the CO2 produced during the process is determined through acid-base volumetric analysis (conventional). The present work had as an objective the determination of the biodegraded CO2, (CO2)b, through the Flow Injection Analysis (FIA) with condutometric detection, a respected technique whose characteristics are precision, sensibility and shot response time. For this, the study of operation parameters of the FIA system used was made necessary, Assay of respirometry were done following the Project of Norm 01:603-06-007/1993 of ABNT, with the determination of (CO2 through volumetric analysis and FIA system. The results obtained are very satisfactory. It was possible to identify that the obtained curves present the same behavior as expected in theory, allowing the identification of the phase of microbiological growth
Mestrado
Saneamento e Ambiente
Mestre em Engenharia Civil
Andersson, Andreas. "Air-sea exchange of O2 and CO2 : Processes controlling the transfer efficiency." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-314166.
Full textJung, Kyung Sook. "CO2 separation and regeneration study from power plant flue gases with reclaimed Mg (OH)2." Cincinnati, Ohio : University of Cincinnati, 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1122333773.
Full textTitle from electronic thesis title page (viewed Apr. 3, 2006). Includes abstract. Keywords: CO2 removal, Power plant, Mg(OH)2, Absorption. Includes bibliographical references.
Okwananke, Anthony. "Flue gas injection for methane recovery from gas hydrate reservoirs and geological Storage of CO2." Thesis, Heriot-Watt University, 2017. http://hdl.handle.net/10399/3395.
Full textMongwe, Ndunisani Precious. "Understanding modelled sea-air CO2 flux biases in the Southern Ocean through the seasonal cycle." Doctoral thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29260.
Full textSmith, Pascalle. "Modélisation des cultures européennes au sein de la biosphère : phénologie, productivité et flux de CO2." Paris 6, 2008. http://www.theses.fr/2008PA066250.
Full textFerreira, Lilian Raquel Moretto. "Avaliação da corrosão por fluxo do aço AISI 1020 em solução de NaHCO3 saturada com CO2." reponame:Repositório Institucional da UFPR, 2012. http://hdl.handle.net/1884/37870.
Full textTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia e Ciência dos Materiais - PIPE. Defesa: Curitiba, 31/05/2012
Inclui referências
Área de concentração: Engenharia de materiais
Resumo: A corrosão por CO2 é a forma predominante de corrosão encontrada na produção de combustíveis fósseis e está presente tanto na composição das jazidas de petróleo e gás natural, quanto nos processos tecnológicos de extração e refino. Os aços carbono e de baixa liga são os mais utilizados na confecção de equipamentos e tubulações, principalmente por satisfazerem os requisitos mecânicos, estruturais e de fabricação, além de serem mais viáveis financeiramente. Entretanto, estes materiais possuem baixa performance em relação à corrosão generalizada e por CO2. Este trabalho tem como principal objetivo utilizar um eletrodo cilíndrico rotativo (ECR) nas técnicas eletroquímicas comumente empregadas para a avaliação da corrosão por fluxo do aço carbono em duas condições diferenciadas de acabamento superficial. Esta avaliação foi realizada, utilizando-se como meio corrosivo uma solução de NaHCO3 0,5 M saturada com CO2. Os eletrodos de trabalho tinham formato cilíndrico e foram confeccionados em aço carbono AISI 1020. Os resultados obtidos revelaram que a formação e a passivação da camada de carbonato de ferro, é influenciada pela presença do fluxo e da rugosidade superficial do aço. A taxa de corrosão do aço atingiu valores elevados e em seguida apresentou ligeira redução com o aumento da velocidade do fluxo para a superfície mais lisa. Para a superfície com rugosidade aumentada, o fluxo provocou um aumento na taxa de corrosão com tendência a um patamar, exibindo valores maiores do que os obtidos para a superfície mais lisa, somente a partir de uma velocidade de rotação em torno de 700 rpm. Como conclusão, observou-se que o eletrodo cilíndrico rotativo é uma importante ferramenta no estudo da corrosão em presença de fluxo e que o mecanismo de corrosão sob fluxo num meio contendo CO2 envolve basicamente a formação da camada de FeCO3 de acordo com a interação permitida pela estrutura da camada limite hidrodinâmica estabelecida. Palavras-chave: Corrosão por fluxo; CO2 ; Aço-carbono.
Abstract: The carbon dioxide corrosion (CO2) is the predominant form of corrosion found in the production of fossil fuels and is present both in the composition of petroleum and natural gas, as in technological processes of extraction and refining. Carbon steels and low alloy are the most used in equipment and pipes, mainly because they satisfy the requirements of mechanical, structural and manufacturing, in addition to being more financially viable. However, these materials have poor performance with respect to general corrosion and carbon dioxide corrosion. This work has as main objective to use a rotating cylinder electrode (ECR) in electrochemical techniques commonly used to assess the corrosion of carbon steel flow in two different conditions of surface finish. This evaluation was performed, using as solution with deionized water e 0.5 M NaHCO3 saturated with CO2. The working electrodes were cylindrical and were made of carbon steel AISI 1020. The results showed that formation and passivation layer of iron carbonate is influenced by the presence of flow and surface roughness of steel. The rate of corrosion of steel reached high values and then showed a slight decrease with increasing flow rate for the smoothest surface. For increased surface roughness, the flow caused an increase in rate of corrosion with a tendency to a threshold, displaying higher values than those obtained for the smoothest surface, only from a rotation rate about 700 rpm. In conclusion, it was observed that the rotating cylinder electrode is an important tool in the study of corrosion in the presence of flow and that the corrosion mechanism in a medium containing CO2 flow basically involves the formation of the layer FeCO3 according permitted by the interaction hydrodynamic boundary layer structure established. Keywords: Corrosion flow; carbon dioxide; carbon steel.
Fiedler, Björn [Verfasser]. "CO2 and O2 Dynamics and Ocean-Atmosphere Fluxes in the Eastern Tropical North Atlantic / Björn Fiedler." Kiel : Universitätsbibliothek Kiel, 2017. http://d-nb.info/1137509651/34.
Full textMacBean, N. L. "Using earth observation and ground-based data to improve modelled CO2 and CH4 fluxes from peatlands." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1333236/.
Full textCurtarelli, Marcelo Pedroso. "Variabilidade espacial e temporal do fluxo difusivo de CO2 no reservatório hidrelétrico de Tucuruí, Amazônia, Brasil." Instituto Nacional de Pesquisas Espaciais (INPE), 2016. http://urlib.net/sid.inpe.br/mtc-m21b/2016/02.13.02.35.
Full textThe hypothesis that motivated this research was that the current estimate of the total carbon emissions by Amazonian hydroelectric reservoirs is inaccurate, since the spatial and temporal variability of the diffusive CO$_{2}$ flux is not considered properly. Thus, this study aimed to study the spatial and temporal variability of the diffusive CO$_{2}$ flux in the Tucuruí reservoir, Pará, along the summer and winter seasons, and for current and future climate conditions. For this purpose we used an innovative approach which integrates data collected \emph{in situ}, data obtained by remote sensing and the use of three-dimensional numerical modeling to simulate the CO$_{2}$ diffusive flux. Experiments were carried out for present climate conditions (year 2013) and future climate conditions (2100), considering two different scenarios of climate and land use and land cover changes in the reservoir basin. The results obtained for the experiments conducted under present climate conditions showed that the diffusive CO$_{2}$ flux has a high spatial and temporal variability in Tucuruí. Temporally, the diffusive flux of CO$_{2}$ ranged, on average, between -86 and -24 mg C m$^{-2}$ hour$^{-1}$ throughout the day in the summer season and between -105 and -30 mg C m$^{-2}$ hour$^{-1}$ during the winter season. In seasons analyzed the highest emission rate was observed during the night and early morning, and the lowest rate during the afternoon. The mean daily value of the CO$_{2}$ diffusive flux obtained for the summer period was -1338 $\pm$ 1.335 mg C m$^{-2}$ day$^{-1}$ and -1395 $\pm$ 925 mg C m$^{-2}$ day$^{-1}$ for the winter period. From the spatial point of view, the diffusive flux of CO$_{2}$ showed a heterogeneous pattern during the summer, ranging between -6.950 (transition zone) and 32 mg C m$^{-2}$ day$^{-1}$ (absorption within the littoral zone). Moreover, during the winter season the diffusive flux of CO$_{2}$ showed a homogeneous pattern. The main environmental factors influencing the evasion of CO$_{2}$ in Tucuruí reservoir were the gas exchange piston velocity, temperature of the water column, partial pressure of CO$_{2}$ in the water and the components of energy balance in the mixed layer. Thus the occurrence of mesoscale convective systems over Tucuruí reservoir had the potential to increase the evasion of CO$_{2}$ by about 28\% on days in which they occurs, since these systems change the environmental conditions in the reservoir region. For the experiments under future climate conditions, the results showed that the diffusive CO$_{2}$ flux may be affected in different ways and the eutrophication of the reservoir, associated with the changes in land use and land cover in the reservoir basin, is one of the main factors that will influence the emissions of CO$_{2}$ in the future. The outcomes of this research allowed to accept the initial hypothesis, and demonstrated that the spatial and temporal variability of CO$_{2}$ diffusive flux are important aspects to be considered for the total carbon emission estimates in hydroelectric reservoir located at Amazon biome. Extrapolating the results obtained in this study for the entire Amazon biome, it is speculated that the total carbon emissions by hydroelectric reservoirs can be up to 22\% less than the latest estimate reported in the literature (9 Tg C yr$^{-1}$). This significant difference should not be neglected, since the carbon footprint is a key factor when comparing the environmental impacts of different sources of electricity generation and can influence the decision-making process for choosing the most appropriate source and the construction site of new hydroelectric projects.
Arnold, Karin von. "Forests and Greenhouse gases. Fluxes of CO2, CH4 and N2O from drained forests on organic soils." Doctoral thesis, Linköping : Dept. of Water and Environmental Studies, Univ, 2004. http://www.bibl.liu.se/liupubl/disp/disp2004/arts302s.pdf.
Full textLeal, Leila do Socorro Monteiro. "Variação sazonal do fluxo e da concentração de CO2 na região leste da Floresta Amazônica – PA." Universidade Federal de Viçosa, 2000. http://www.locus.ufv.br/handle/123456789/8131.
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Fundação de Amparo à Pesquisa do Estado de Minas Gerais
Na década de 70, a Floresta Amazônica era considerada o "pulmão" do mundo, em virtude de uma possível maior produção de O2 e consumo de CO2. Já na década de 80, o conceito de “clímax” foi estabelecido, acreditando-se estar a floresta em equilíbrio, isto é, internamente, tudo que era produzido era consumido. Hoje, ao contrário do que se acreditava, experimentos observacionais vêm evidenciando que a floresta está fixando CO2 atmosférico. Atualmente, os pesquisadores que estudam fluxos na Amazônia procuram entender a magnitude dos fluxos de CO 2 e suas variações inter e intra-anuais, assim como entre diferentes localidades da região. Este trabalho vem auxiliar neste assunto, tendo como objetivo analisar as variações diária e sazonal da concentração e dos fluxos de CO 2 acima e dentro do dossel da floresta, bem como a influência dos elementos do clima sobre essas variações na região leste da Amazônia. Os dados utilizados no presente trabalho são provenientes do Projeto ECOBIOMA, desenvolvido na região leste amazônica, e foram obtidos ao longo do ano de 1999. Coletaram-se dados meteorológicos e de fluxos de CO2 acima do dossel da floresta, sendo também coletados os dados da concentração de CO2 acima e dentro do dossel. O valor médio de fluxo de CO2 no período analisado foi sempre negativo, indicando que a floresta absorve mais CO2 do que produz. Em geral, observou-se maior fluxo de CO2 na época chuvosa em relação à seca, o que se explica pela maior disponibilidade de água nos solos. Em termos de médias, o acúmulo de carbono nessa localidade corresponde a 5,87 t C ha-1 ano-1. A variação da concentração de CO2 apresentou comportamento cíclico, observando-se aumento na concentração durante a noite e diminuição rápida após o nascer-do-sol. Desacoplamento entre os níveis inferiores e superiores do dossel também foi observado, apontando maior influência biótica na biossíntese dos níveis inferiores da floresta e maior contribuição atmosférica no nível da copa das árvores.
In the decade of 70, the Amazon forest was considered as the lung of the world, by virtue of a possible larger production of O2 and I consummate of CO 2. Already in the decade of 80, the climax " concept was established, being believed to be the forest in balance, that is to say, internally, everything that was produced was consumed. Today, unlike what it was believed, experiments observationals comes showing that the forest is fastening CO2 atmospheric. Actually, the studies on flows in Amazon try to understand the magnitude of the flows of CO2 and its variations interannual and intrannual, as well as among different places of the area. This work comes to aid in this sense, tends as objectives to analyze the daily and seasonal of the concentration variations and of the flows of CO2 above and inside of the canopy of the forest, as well as the influence of the elements of the climate about these variations in the area east of Amazon. The data used in the present work they are coming of the Project ECOBIOMA developed at the Amazon area east, and they were obtained along the year current. Meteorological data were collected and of flows of CO2 above the canopy of the forest. They were also collected above the data of the concentration of CO2 and inside of the canopy. The medium value of flow of CO 2, in the analyzed period, was always negative, indicating that the forest absorbs more CO2 than it produces. In general, larger flow of CO2 was observed at that time rainy, in relation to the drought, what is explained by the largest readiness of water of the soils. In medium terms, the accumulation of carbon in this place corresponds to 5,87 t C ha-1 ano -1. The variation of the concentration of CO2, showed a recurrent behavior, being observed an increase in the concentration during the night and a fast decrease after being born of the sun. A uncouplement among the inferior and superior levels of the canopy was also observed that indicate a larger influence biotic in the biosynthesis of the inferior levels of the forest and a larger atmospheric contribution for the levels of the cup of the trees.
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Tagliarolo, Morgana. "Adaptations métaboliques des organismes dans la zone de balancement des marées : implications sur la biodiversité locale dans un contexte de changement climatique." Phd thesis, Université de Bretagne occidentale - Brest, 2012. http://tel.archives-ouvertes.fr/tel-00816887.
Full textAntonio, Regina Vasconcellos. "Efeito de lasalocid-A sobre o fluxo de Ca2+ mitocondrial." [s.n.], 1989. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313903.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Em trabalho anterior,PEREIRA DA SILVA et alii (1984), apresentaram evidências de que lasalocid-A, em concentrações bastante abaixo da necessária para agir como ionóforo de Ca, inibe o efluxo do mesmo em mitocôndrias de fígado. No presente trabalho, estudamos o mecanismo desta inibição em mitocôndrias de fígado e de coração. Primeiramente, observamos que lasalocid-A, na faixa de concentração usada nestes experimentos (0-250 nM), promove a troca eletroneutra de K+ por H+ através da membrana interna mitocondrial e como conseqüência pode causar alterações importantes nos valores de 'delta¿ pH e à'delta¿U (os componentes químico e elétrico do potencial eletroquímico de prótons ('delta¿ 'mu¿ H+). O efeito indireto destas alterações na inibição da liberação de Ca2+ mitocondrial foi descartado pelos nossos experimentos nos quais são mostrados três padrões do efeito de lasalocid-A, dependendo do carregamento de Ca mitocondrial. Em baixo, carregamento de Ca (5-70 nmol de Ca /mg de proteína), sob condições experimentais nas quais a liberação de Ca é supostamente mediada por um antiporter Ca2+ /2H+, os dados cinéticos,indicam que lasalocid-Ainibe o efluxo do cátion por um mecanismo competitivo. A troca Ca /2Na , a via dominante para o efluxo de Ca2+ em mitocôndrias de coração, por lasalocid-A. Em carregamento intermediário de CA2+ . nmol de Ca /mg de proteína), lasalocid-A estimula levemente liberação de Ca2+. Este efeito parece estar relacionado a não foi afetada 2+ de Ca (70-110 a um aumento da permeabilidade da membrana causada pelo deslocamento de uma quantidade determinada de Mg estrutural ligado à membrana. Finalmente, em alto carregamento de Ca (110-140 2+ nmol de Ca rng de proteína ) , lasalocid-A aumentou a habilidade 60 de retenção de Ca2+ pela mitocôndria, mesmo na presença de agentes liberadores de Ca , tais como fosfato e agentes oxidantes de nucleotídeos de piridina mitocondriais. A manutenção de valores altos de potencial de membrana nestas condições, podem sugerir que lasalocid-A é um potente inibidor da abertura de "poros" induzidos na membrana pelo cátion.... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: A previous communication (PEREIRA DA SILVA et alii, 1984) presented evidence that lasalocid-A, at concentrations far below those required to act as Ca2+ ionophore, significantly inhibited Ca2+ efflux from liver mitochondria. In the present work we have studied the mechanism of this inhibition in liver and heart mitocondria. Firstly it was observed that lasalocid-A, in the range of concentration used in these experiments (0-250nM), promotes the electroneutral exchange of K+ for H+ across the inner mitochondrial membrane and as a consequence can cause important alterations in the values for 'delta¿PH and 'delta¿ U (chemical and electrical components, respectively, of the electrochemical membrane potential ('delta¿ UH+). The indirect effect of those alterations in the inhibition of mitochondrial Ca2+ release eas ruled out by our experiments which have shown three patters of lasalocid-A effect, depending on the size of the mitochondrial Ca2+ load. ... Note: The complete abstract is available with the full electronic digital thesis or dissertations
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Rangama, Yvan. "variabilite spatio-temporelle des flux air-mer de CO2 dans l'ocean sud : apport des mesures satellitaires." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2004. http://tel.archives-ouvertes.fr/tel-00007529.
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