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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Diretrizes para projetos habitacionais sustentáveis baseadas na categoria 1 do processo AQUA / Guidelines for sustainable residential projects based on the first category of the AQUA Process

Esmeraldo, Lara Barrocas Soares 20 September 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / To achieve a green building, special attention is required to the project stage once it will give the guidelines for the implementation, operation and maintenance of the building. Designers play a key role in the sustainable principles of the buildings, and the project must be oriented, since its beginning, to reach this goal. This can provide some changes to the entire production chain of the built environment. In Brazil, there is an inertia to the development of sustainable projects. Although there are professionals engaged in environmental movements, sustainable actions are just beginning. Thus, the incorporation of environmental demands to the design process became urgent. Thereby, this research proposes to investigate about the design of sustainable residential projects. The purpose of this research is to perform a study about the difficulties faced in the project process of certificated sustainable residential buildings, specifically with regards to the first category of the Technical Reference of the AQUA certification, which is the object of this study. In this context, this work seeks to identify how designers apply sustainable concepts in the project stage of residential green buildings, in order to implement a simplified methodology to facilitate its inclusion into the first category of the AQUA Process. The end result of this work will be the development of guidelines for the design of sustainable residential projects, based on the criteria from AQUA\'s first category. This will collaborate for a better understanding of this technical reference component and may also assist companies and designers who have not yet completed or started the certification process. Difficulties could be minimized and consequently the certification process of residential sustainable buildings projects will become easier. / Para se obter uma construção sustentável é necessária atenção especial à fase de concepção de projetos, uma vez que esta dará as diretrizes para a execução, operação e manutenção da edificação. Os projetistas desempenham papel fundamental na concepção dos princípios de sustentabilidade dos edifícios e, o projeto deve ser orientado desde o início a esse objetivo, ajudando a modificar toda a cadeia produtiva do ambiente construído. No Brasil, em geral, há uma inércia para a elaboração de projetos sustentáveis, e apesar de existirem profissionais engajados em movimentos ambientalistas, é muito incipiente. Assim, torna-se urgente a incorporação das novas demandas ambientais ao processo de projeto. Dessa forma, nesta pesquisa se propõe investigar a respeito da concepção de projetos habitacionais sustentáveis. A temática central dessa proposta está voltada para a realização de um estudo sobre as dificuldades enfrentadas no processo de projeto de edifícios habitacionais certificados, especificamente com relação à Categoria 1 do Referencial Técnico da Certificação AQUA, objeto de estudo deste trabalho. Neste contexto, busca-se compreender a percepção dos profissionais quanto à aplicação dos requisitos de sustentabilidade no projeto de edifícios habitacionais, a fim de implementar uma metodologia simplificada para viabilizar o enquadramento destes dentro da categoria 1 Relação do edifício com o entorno - do Processo AQUA. O resultado final deste trabalho será a elaboração de diretrizes para a concepção de projetos habitacionais sustentáveis, tomando como base os requisitos propostos na Categoria Relação do edifícios com o seu entorno . O que colaborará para uma melhor compreensão deste componente do referencial técnico, podendo ainda, auxiliar empresas e projetistas que ainda não completaram ou não iniciaram o processo de certificação. Minimizando assim, as dificuldades e, facilitando a certificação de projetos de edifícios habitacionais ao Processo AQUA. / Mestre em Engenharia Civil
12

A adoção de sistemas de avaliação ambiental de edifícios (LEED e Processo AQUA) no Brasil: motivações, benefícios e dificuldades / The adoption of environmental assessment systems of buildings (LEED e Process AQUA) in Brazil: motivations, benefits e difficulties

Ana Dorys Muñoz Barros 22 August 2012 (has links)
Os sistemas de avaliação ambiental de edifícios são cada vez mais empregados no mercado de construção, servindo de suporte para a realização de diversos estudos acadêmicos sobre esta matéria. Muitos autores e sites ressaltam os benefícios das certificações LEED e do Processo AQUA, porém poucos discutem quantitativamente os efeitos, dificuldades e motivos de sua adoção, evidenciando, dessa forma, a necessidade e a importância de pesquisas como esta. Neste contexto, este trabalho tem como objetivo geral traçar um panorama da certificação ambiental de edifícios no Brasil, através da percepção dos principais intervenientes (stakeholder) no processo. Os objetivos principais deste trabalho consistem na identificação das motivações para a certificação de sistemas de avaliação ambiental de edifícios (LEED e Processo AQUA) e dos benefícios e dificuldades inerentes a sua implementação. Foi possível ainda efetuar várias recomendações destinadas a orientar e facilitar o processo de adoção destes sistemas, que inclui a proposta de ações a serem desenvolvidas pelas empresas, organismos de certificação e autoridades governamentais competentes. O método utilizado foi de pesquisa survey, junto a vários agentes envolvidos no processo de certificação ambiental. Para tal, foram concebidos diferentes questionários destinados a caracterizar a adoção dos sistemas de avaliação ambiental de edifícios que foram encaminhados aos empreendedores e consultores de empreendimentos certificados ou em processo de certificação. Obtiveram-se em total 21 questionários válidos que indicaram que as principais motivações para obter a certificação estão ligadas à melhoria da imagem e do empreendimento e que os principais benefícios estão relacionados com o marketing e a redução dos custos operacionais. Estes resultados também indicaram que existem dificuldades para essa adoção principalmente com a falta de integração no processo de projeto e a falta de fornecedores para materiais e tecnologias sustentáveis. / The building environmental assessment systems over the world are employing increasingly and we can find several studies concerning this subject. Many authors and websites emphasize the benefits of LEED and Process AQUA, but few discuss quantitatively the impacts, difficulties and reasons for its adoption, showing thus the need and importance of research like this. In this context, this paper aims to outline a general overview of the environmental certification of buildings in Brazil, through the key stakeholders perception (stakeholder) of the process. The main targets of this work were to identify the motivations for the environmental assessment systems for buildings and the corresponding benefits and difficulties concerning of implementation. It was also possible to make some recommendations to orientate and support the adoption of environmental assessment systems for buildings. These recomendations include the identification of actions to be implemented by companies, certification bodies and governmental authorities. In order to accomplish the defined targets, it were developed surveys which can lead to characterize the adoption of environmental assessment systems for buildings (LEED and AQUA Process). These survey was sent directly to entrepreneurs and consultants of a sample of brasilian companies with building certified or certification process (LEED and AQUA Process). It was received 21 answers that indicated that the main motivations for certification are linked to improving the image and building and that the main benefits are related to marketing and reducing operating costs. These results also indicated that there are difficulties in adopting this especially with the lack of integration in the design process and the lack of suppliers for materials and sustainable technologies.
13

Vliv aqua-činek na intenzitu zatížení při aqua-aerobiku v mělké vodě / Influence of buoyancy dumb-bells on load intensity during shallow water aerobic

Houdová, Veronika January 2011 (has links)
Title: Influence of buoyancy dumb-bells on load intensity during shallow water aerobic Objectives: The aim of this theses was to compare the heart rate to several variants during 14 minutes head-out aquatic exercise (with simultaneous legs and arms actions and with simultaneous legs and arms actions using buoyancy dumb-bells). 8 females, clinically healthy and with a regular level of physical activity in age between 25-60 years (age 42 ± 11,4 years) were studied. The other aim of this theses was to compare the heart rate during rest on land and rest in water during shallow water aerobic in an upright position with water level to shoulder depth. Methods: We monitored heart rate changes during 14 minutes head-out aquatic exercise by Sport Tester S610i. The results of the tests were analyzed and evaluated with Polar Precision Performance software. Chi-squared test was used to examine the average difference to heart rate during tests. Results: We found non-significant increases on load intensity during test with using buoyancy dumb-bells. Average heart rate during rest in water showed decreases by 13 beats per minute. Keywords: buoyancy dumb-bells, load intensity, heart rate, shallow water aerobic
14

Gestão de empreendimentos e soluções técnicas para a realização de edifícios sustentáveis certificados pelo processo AQUA. / Project management and technical solutions to carry out sustainable buildings

Rodrigo, Adriana Gouveia 12 September 2011 (has links)
A presente pesquisa contribui para a realização de edifícios com um maior desempenho socioambiental e em equilíbrio com as questões culturais e econômicas atuantes no contexto dos empreendimentos. Foram estudados três casos que utilizaram o referencial do Processo AQUA (método de avaliação de empreendimentos sustentáveis, de origem francesa). O escopo da pesquisa está limitado às etapas do empreendimento que vão da concepção do projeto ao término da construção. Os objetivos propostos são identificar e analisar como o processo de gestão de empreendimentos se altera para a realização de edifícios com um melhor desempenho socioambiental, e os impactos dos requisitos propostos pelo referencial do Processo AQUA na elaboração das soluções técnicas e de outras estratégias, presentes nos projetos dos edifícios estudados. Adota como método de pesquisa o estudo de caso, baseado em entrevistas e análise documental. Os resultados e conclusões apontam que deve haver a participação de todas as partes interessadas, dando especial atenção à necessidade da formação da equipe de projetos logo nas primeiras fases da realização do empreendimento; também indicam que novas competências passam a fazer parte do processo e devem ser integradas à equipe, em momentos adequados, e que as soluções técnicas se desenvolvem de forma contínua e mais acelerada nos empreendimentos de edifícios de alto desempenho socioambiental, pois estes apresentam novas proposições de projeto que demandam desenvolvimento tecnológico dos projetistas, dos fabricantes de materiais e das empresas construtoras. / This research contributes to carrying out buildings with a higher environmental performance and in harmony with economic and cultural issues that take place in the projects context. It studied three cases, which employed the reference guide of the AQUA Process (a sustainable buildings assessment method of French origin). The scope of the research is limited from the concept design phase to the end of the construction phase. The objectives are to identify and analyze how the process of project management changes in order to improve the environmental performance of the buildings, and the impacts of the AQUA Process requirements on the development of technical solutions and other strategies, in the buildings studied here. As a research methodology it makes use of the case study, based on interviews and documentary analysis. The findings and conclusions indicate the need for the participation of all stakeholders, giving special attention to the necessity of shaping the project\'s team in the very first stages of the activity; they also reveal that new skills become part of the process and should be integrated into the team, at appropriate times, and that technical solutions are developed continuously and faster in high-performance building projects due to the new proposals they present, which demand technology development of designers, material manufacturers and construction companies.
15

Conceito de densidade urbana aplicada no processo AQUA de certificação ambiental / Urban density concept applied to AQUA Process of environmental certification

Macedo, Elisa 22 April 2014 (has links)
Neste trabalho foi avaliado o conceito de densidade urbana adotado pelo processo de certificação AQUA (Alta Qualidade Ambiental) Bairros e Loteamentos emitido pela Fundação Vanzolini. Para analisar a aplicação prática dos critérios de desempenho exigidos foi realizado um estudo de caso do primeiro bairro brasileiro certificado pela fundação Vanzolini, o Jardim das Perdizes na cidade de São Paulo. Para análise crítica foram adotados conceitos de sustentabilidade urbana aplicada ao critério de densidade urbana como adensamento de cidade, compactação de edifícios e uso do solo. O estudo foi feito com base no \"Referencial Técnico de Certificação\" - Processo AQUA - (Bairros e Loteamentos/ Set 2011) Versão 0. Trata-se da primeira versão publicada pela Fundação Vanzolini. O referencial foi baseado numa adaptação da certificação original existente na França, o Démarche HQE(TM) Aménagement, da fundação francesa Certivéa. A escolha desse referencial deve-se ao fato do processo de certificação AQUA se propor a adequar-se a realidade brasileira, com base em normas do país e contexto local. A metodologia do trabalho consistiu em analisar os critérios apresentados pelo referencial de certificação servindo como indicador de metas a serem atingidas para obtenção de um planejamento urbano sustentável no que se refere ao tema de densidade urbana. A partir do conhecimento da ferramenta de certificação AQUA Bairros e loteamentos e com base em bibliografia referencial foram analisadas criticamente as metas propostas e sua compatibilidade com o meio urbano em estudo, o estudo de caso Jardim das Perdizes. / This study evaluated the concept of urban density adopted by AQUA (Alta Qualidade Ambiental - High Environmental Quality ) certification process Neighborhoods and Allotments issued by Vanzolini. To analyze the practice of applying performance criteria required has been analyzed a case study of Brazil\'s first certified neighborhood by foundation Vanzolini, the Jardim das Perdizes in Sao Paulo. For critical analysis of concepts of urban sustainability criteria applied to urban density and densification of the city, compaction of buildings and land use were adopted. The study was based on the technical reference AQUA Neighborhoods \"Referencial Técnico de Certificação\" - Processo AQUA ( Bairros e loteamentos / Sep 2011) Versão 0 . This is the first published version by Vanzolini. The framework was based on an original adaptation of existing certification in France , the HQE (TM) Démarche Aménagement , the French foundation Certivéa . The choice of this framework is due to the fact that AQUA certification process is proposed to adapt to the Brazilian reality, based on standards of the country and local context . The methodology of the study was to examine the criteria submitted by the benchmark certification serving as an indicator of targets to be met to achieve sustainable urban planning with regard to the topic of urban density. From the knowledge of the certification tool AQUA Neighborhoods and subdivisions and based on reference literature were critically analyzed the proposed goals and their compatibility with the urban environment under study, the case study of the Jardim das Perdizes.
16

Gestão de empreendimentos e soluções técnicas para a realização de edifícios sustentáveis certificados pelo processo AQUA. / Project management and technical solutions to carry out sustainable buildings

Adriana Gouveia Rodrigo 12 September 2011 (has links)
A presente pesquisa contribui para a realização de edifícios com um maior desempenho socioambiental e em equilíbrio com as questões culturais e econômicas atuantes no contexto dos empreendimentos. Foram estudados três casos que utilizaram o referencial do Processo AQUA (método de avaliação de empreendimentos sustentáveis, de origem francesa). O escopo da pesquisa está limitado às etapas do empreendimento que vão da concepção do projeto ao término da construção. Os objetivos propostos são identificar e analisar como o processo de gestão de empreendimentos se altera para a realização de edifícios com um melhor desempenho socioambiental, e os impactos dos requisitos propostos pelo referencial do Processo AQUA na elaboração das soluções técnicas e de outras estratégias, presentes nos projetos dos edifícios estudados. Adota como método de pesquisa o estudo de caso, baseado em entrevistas e análise documental. Os resultados e conclusões apontam que deve haver a participação de todas as partes interessadas, dando especial atenção à necessidade da formação da equipe de projetos logo nas primeiras fases da realização do empreendimento; também indicam que novas competências passam a fazer parte do processo e devem ser integradas à equipe, em momentos adequados, e que as soluções técnicas se desenvolvem de forma contínua e mais acelerada nos empreendimentos de edifícios de alto desempenho socioambiental, pois estes apresentam novas proposições de projeto que demandam desenvolvimento tecnológico dos projetistas, dos fabricantes de materiais e das empresas construtoras. / This research contributes to carrying out buildings with a higher environmental performance and in harmony with economic and cultural issues that take place in the projects context. It studied three cases, which employed the reference guide of the AQUA Process (a sustainable buildings assessment method of French origin). The scope of the research is limited from the concept design phase to the end of the construction phase. The objectives are to identify and analyze how the process of project management changes in order to improve the environmental performance of the buildings, and the impacts of the AQUA Process requirements on the development of technical solutions and other strategies, in the buildings studied here. As a research methodology it makes use of the case study, based on interviews and documentary analysis. The findings and conclusions indicate the need for the participation of all stakeholders, giving special attention to the necessity of shaping the project\'s team in the very first stages of the activity; they also reveal that new skills become part of the process and should be integrated into the team, at appropriate times, and that technical solutions are developed continuously and faster in high-performance building projects due to the new proposals they present, which demand technology development of designers, material manufacturers and construction companies.
17

Conceito de densidade urbana aplicada no processo AQUA de certificação ambiental / Urban density concept applied to AQUA Process of environmental certification

Elisa Macedo 22 April 2014 (has links)
Neste trabalho foi avaliado o conceito de densidade urbana adotado pelo processo de certificação AQUA (Alta Qualidade Ambiental) Bairros e Loteamentos emitido pela Fundação Vanzolini. Para analisar a aplicação prática dos critérios de desempenho exigidos foi realizado um estudo de caso do primeiro bairro brasileiro certificado pela fundação Vanzolini, o Jardim das Perdizes na cidade de São Paulo. Para análise crítica foram adotados conceitos de sustentabilidade urbana aplicada ao critério de densidade urbana como adensamento de cidade, compactação de edifícios e uso do solo. O estudo foi feito com base no \"Referencial Técnico de Certificação\" - Processo AQUA - (Bairros e Loteamentos/ Set 2011) Versão 0. Trata-se da primeira versão publicada pela Fundação Vanzolini. O referencial foi baseado numa adaptação da certificação original existente na França, o Démarche HQE(TM) Aménagement, da fundação francesa Certivéa. A escolha desse referencial deve-se ao fato do processo de certificação AQUA se propor a adequar-se a realidade brasileira, com base em normas do país e contexto local. A metodologia do trabalho consistiu em analisar os critérios apresentados pelo referencial de certificação servindo como indicador de metas a serem atingidas para obtenção de um planejamento urbano sustentável no que se refere ao tema de densidade urbana. A partir do conhecimento da ferramenta de certificação AQUA Bairros e loteamentos e com base em bibliografia referencial foram analisadas criticamente as metas propostas e sua compatibilidade com o meio urbano em estudo, o estudo de caso Jardim das Perdizes. / This study evaluated the concept of urban density adopted by AQUA (Alta Qualidade Ambiental - High Environmental Quality ) certification process Neighborhoods and Allotments issued by Vanzolini. To analyze the practice of applying performance criteria required has been analyzed a case study of Brazil\'s first certified neighborhood by foundation Vanzolini, the Jardim das Perdizes in Sao Paulo. For critical analysis of concepts of urban sustainability criteria applied to urban density and densification of the city, compaction of buildings and land use were adopted. The study was based on the technical reference AQUA Neighborhoods \"Referencial Técnico de Certificação\" - Processo AQUA ( Bairros e loteamentos / Sep 2011) Versão 0 . This is the first published version by Vanzolini. The framework was based on an original adaptation of existing certification in France , the HQE (TM) Démarche Aménagement , the French foundation Certivéa . The choice of this framework is due to the fact that AQUA certification process is proposed to adapt to the Brazilian reality, based on standards of the country and local context . The methodology of the study was to examine the criteria submitted by the benchmark certification serving as an indicator of targets to be met to achieve sustainable urban planning with regard to the topic of urban density. From the knowledge of the certification tool AQUA Neighborhoods and subdivisions and based on reference literature were critically analyzed the proposed goals and their compatibility with the urban environment under study, the case study of the Jardim das Perdizes.
18

Eco-services of mussel farms : An energy and cost comparison with traditional alternatives

Norell, Henrik January 2005 (has links)
Eutrophication of seas, particularly near the coasts, is a topic of high current concern. Itleads to increased primary production and a higher frequency of algal blooms. The enhancedprimary production also increases the turbidity of the water, making it harder for ecologicallyimportant benthic macro algae, e.g. seaweed, to colonize bottoms on deeper waters. EU directives, as well as national law, demand decreases in nutrients, e.g. nitrogen, reachingthe sea. Another approach to decreasing the amount of nutrients in the sea could be musselfarming. Mussel farming is an established, albeit small, industry on the Swedish west coast. The useof mussels to remove nitrogen, however, is a more recent application. Lysekil municipalityhas been granted exemption from improving the nitrogen removal in Långevik waste watertreatment plant. Instead, mussel farms are used to remove nitrogen, which was estimated to bea less costly solution. This thesis investigates the advantages in money and energy in using mussel farming. Theuse of a mussel farm to remove nitrogen from sea water is compared with removing nitrogenin a WWTP. In addition, the production of mussel fertilizer, through a composting process, iscompared with producing a corresponding amount of artificial fertilizers. The results show that mussel farms are neither more economic nor energy efficient inremoving nitrogen and producing fertilizer than the conventional alternatives examined Mussel fertilizer, however, is not the most lucrative product that the mussels from the farmcan give. Alternatives, such as fodder or human consumption, are discussed in the report. Furthermore, the mussel fertilizer qualifies as organic fertilizer. A comparison with otherorganic fertilizers could prove mussels more economic or energy efficient, but such acomparison is out of the scope for this thesis. Finally, some data, e.g. the energy demand for nitrogen removal in the WWTP, were roughestimations. More research and investigations are needed in order to achieve more accurateconclusions. / Eutrofiering i haven, speciellt kustnära vatten, är ett högaktuellt problem. Det leder till ökadprimärproduktion och frekvens av algblomningar. Den förhöjda primärproduktionen lederäven till ökad turbiditet, något som försvårar för ekologiskt viktiga bentiska arter, t.ex. sjögräs(ålgräs), att kolonisera bottnar på djupare vatten. Så väl EU-direktiv som nationell lagstiftning kräver en minskning i näringsämnen, bl.a.kväve, som når havet. Ett verktyg för att klara av dessa minskningar kan vara musselodlingar. Musselodling är en etablerad, men liten, industri på den svenska västkusten. Musslor som enkväveavskiljningsmetod är däremot en ny tillämpning. Lysekil kommun har fått undantag frånatt bygga ut kvävereningen i Långevik vattenreningsverk. I stället används musselodlingar föratt ta bort kväve, vilket ansågs vara en billigare metod. Detta examensarbete undersöker fördelarna i pengar och energi i att användamusselodlingar för att få bort kväve från havsvatten, jämfört med att avskilja kväve ivattenreningsverk. Dessutom jämförs produktionen av musselgödning, genom att komposteramusslor från musselodlingen, med att producera motsvarande mängder med konstgödsel. Resultaten visar att musselodlingar vare sig är billigare eller mer energieffektiva än dekonventionella alternativen för att ta bort kväve och producera gödsel. Musselgödning är däremot inte den mest lönsamma produkt som musslorna frånmusselodlingen kan ge. Alternativ som foder och mänsklig konsumption diskuteras i rapporten. Vidare kan musselgödning godkännas som KRAV-gödsel. I en jämförelse mot andraKRAV-gödsel kan musselgödning visa sig mer ekonomisk eller energieffektiv, men en sådan jämförelse ligger utanför detta arbetes tidsram. Slutligen var vissa data grova uppskattningar, t.ex. energiåtgången för kväveavskiljning i vattenreningsverk. Mer forskning och undersökningar behövs för att nå mer tillförlitligaslutsatser. / www.ima.kth.se
19

Correction des données satellitaires de fluorescence de la chlorophylle-a induite par le soleil pour les effets de bidirectionnalité

Roy, Pascale January 2016 (has links)
Les mesures satellitaires de réflectance de télédétection (Rrs) associée à la fluorescence de la chlorophylle-a induite par le soleil (FCIS), notées Rrs,f , sont largement utilisées dans le domaine de l’océanographie converties sous la forme de rendement quantique de la fluorescence (QYF). Le QYF permet de déterminer l’impact de l’environnement sur la croissance du phytoplancton. Tout comme les autres mesures qui reposent sur la luminance montante, le QYF, et donc la Rrs,f , sont influencés par les effets de bidirectionnalité. Ainsi, sachant que la variabilité naturelle du QYF est faible, les biais engendrés par une normalisation inadéquate de la Rrs,f peuvent avoir des impacts importants sur l’interprétation des mesures de QYF à l’échelle planétaire. La méthode actuelle utilisée pour corriger la dépendance angulaire du signal observé dans la bande de fluorescence par le spectroradiomètre imageur à résolution moyenne (MODIS), embarqué à bord du satellite Aqua, repose sur l’application d’une table de correspondance (LUT) développée par Morel et al. (2002). Toutefois, l’approche de Morel et al. (2002) ne tient pas compte du caractère isotrope de la FCIS ce qui induit des biais systématiques sur les mesures de Rrs,f selon la latitude, par exemple. Dans ce mémoire, une nouvelle méthode de calcul de la LUT ayant pour but de réduire ces biais est introduite. Tout d’abord, celle-ci intègre une mise à jour des propriétés optiques inhérentes (IOPs) dans le modèle de transfert radiatif sur la base de publications plus récentes. Ensuite, la gamme spectrale de son application est élargie à la bande de fluorescence contrairement à la méthode actuelle qui se limite à la longueur d’onde de 660 nm. Finalement, la LUT révisée tient compte des trois composantes principales de la réflectance de télédétection que sont (1) la rétrodiffusion élastique de la lumière par les molécules d’eau et par les particules en suspension, (2) la diffusion Raman (inélastique) par les molécules d’eau et (3) la FCIS. Les résultats de Rrs,f normalisées avec la nouvelle méthode présentent une différence de dispersion moyenne par rapport à celle obtenue par l’application de la méthode de Morel et al. (2002) de l’ordre de -15 %. Des différences significatives, de l’ordre de -22 %, sont observées à de grands angles d’observation et d’éclairement (> 55 %).
20

The Effects of Nutrient Ratios and Forms on the Growth Of Microcystis aeruginosa and Anabaena flos-aquae

Crawford, Kathryn A. 17 June 2008 (has links)
Cyanobacteria are ancient prokaryotic organisms capable of performing oxygenic photosynthesis. An increase in the temporal and spatial distribution of cyanobacteria blooms worldwide has drawn considerable research attention in recent decades because of the health risks cyanobacteria pose to humans and wildlife through the production of cyanotoxins, interference with recreation, and ecosystem changes. A variety of hypotheses have sought to explain the increasing frequency and severity of cyanobacteria blooms around the world, with the relationship between cyanobacteria abundance and eutrophication receiving considerable attention. While the impacts of phosphorus concentration on cyanobacteria success are relatively well-studied, less is known about how nutrient stoichiometry and nitrogen uptake kinetics of different species contribute to cyanobacteria dominance. The underlying mechanism for the impacts of nitrogen to phosphorus (N:P) ratio and nitrogen form on cyanobacteria involves internal cycling of nitrogen within lakes and aspects of cyanobacteria cell physiology. The primary objective of this study was to assess the impacts of N:P ratios and nitrogen form on the growth of Microcystis aeruginosa and Anabaena flos-aquae in both axenic cultures and natural phytoplankton assemblages from Missisquoi Bay, Lake Champlain. A second objective was to determine whether treatment condition affected the production of the cyanotoxin microcystin. A final objective was to document the presence of benthic ammonium in Missisquoi Bay and the vertical migration of cyanobacteria throughout the water column in the bay, to provide evidence in support of the underlying mechanisms that might provide advantages to cyanobacteria in the bay. In laboratory culture experiments with M. aeruginosa and A. flos-aquae alone and in a mixed community, N:P ratios were varied between 5, 15, 30 and 45:1, and nitrogen was supplied as both nitrate and ammonium at each ratio. Triplicate samples were preserved after one, three and six days for cell enumeration using the standard Ütermohl method. Differences in density between initial and later times were used as an estimate of growth. Microcystin concentration was measured with the ELISA method. Weekly field sampling was conducted in the summer of 2006 in Missisquoi Bay to measure benthic nitrogen concentrations. Nocturnal sampling at varied depths in the bay was used to explore the vertical migration of cyanobacteria throughout the water column. There were weak associations between ammonium-nitrogen and M. aeruginosa growth and nitrate-nitrogen and A. flos-aquae growth, while the effects of N:P ratio on growth was highly variable across time and treatment condition. Ammonium-nitrogen was documented in the benthic water of Missisquoi Bay throughout the growing season, and M. aeruginosa dominated the vertical migration of cyanobacteria throughout the water column. The lack of clear trends visible within the data from laboratory experiments can be in part attributed to high variability of cell density within treatment conditions and the limitations of the methodology used for cell enumeration. Taken together these data suggest that the distribution of nitrogen within an aquatic system and the ability of M. aeruginosa to vertically migrate may contribute to the M. aeruginosa dominance of the summer phytoplankton community.

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