Les glaces polaires, en plus d'améliorer notre compréhension du climat, donnent accès aux retombées de béryllium-10 (10Be), isotope d'origine cosmogénique formé par l'interaction du rayonnement cosmique et des hautes couches de l'atmosphère. Son taux de production dépend de l'intensité du rayonnement cosmique primaire, qui est modulé par l'activité solaire et le champ magnétique terrestre. Le 10Be contient donc des informations sur ces deux paramètres. Il a permis, entre autres, l'amélioration des chronologies des carottes de glace grâce à des marqueurs stratigraphiques absolus liés à des évènements remarquables du champ géomagnétique comme l'excursion de Laschamp ou l'inversion de Brunhes-Matuyama.EPICA Dome C (75° 06' S, 123° 21' E) est une carotte de glace de 3270 m de long forée en Antarctique Est. Elle offre un enregistrement climatique complet durant les 800 000 dernières années (kyr BP). Dans le cadre de cette thèse, 2200 échantillons de 10Be ont été mesurés entre 2384 m (269 kyr BP) et 2627 m (355 kyr BP) de profondeur. Cette séquence continue offre, d'une part, la possibilité d'étudier l'activité solaire durant la période interglaciaire du Stade Isotopique Marin (MIS) 9.3, où la résolution atteint ~20 ans. Nos résultats contrastent avec ceux durant l'Holocène, avec l'absence remarquée du cycle de de Vries (210 ans) dans notre profil de 10Be. D'autre part, cette séquence nous a permis de vérifier que l'estimation classique de l'accumulation de neige obtenue par les modèles de datation de carottes de glace est correcte à 20% près lors de la succession des cycles glaciaires – interglaciaires.Ces mesures ont été combinées avec celles précédemment effectuées sous la responsabilité de Grant Raisbeck (publication en préparation). Ceci permet de disposer d'un profil continu et détaillé (résolution de 20 à 250 ans) entre 200 et 800 kyr BP sur la carotte de glace EPICA Dome C. Les variations de flux de 10Be observées se comparent bien aux changements d'intensité du champ géomagnétique enregistrés dans les sédiments marins. À partir de cette observation, il est possible de proposer une synchronisation de ces profils afin de les placer sur une échelle d'âge commune. Les déphasages observés entre l'augmentation de température en Antarctique (augmentation du D à EDC) et la hausse du niveau marin global (baisse du 18O marin des archives sédimentaires) n'excèdent pas 3200 ans excepté à la Terminaison VII. La faible résolution des enregistrements de 18O dans les sédiments marins rend l'analyse des déphasages délicate. Les résultats obtenus encouragent à analyser des périodes plus récentes autour de la Terminaison II, incluant les excursions géomagnétiques de Blake et d'Iceland Basin. Ceci permettrait en effet de contraindre plus fortement la synchronisation entre le signal paléomagnétique dans les sédiments marins et le flux de 10Be à EDC. / The polar ice cores, in addition to improving our understanding of the climate, give access to beryllium-10 (10Be) fallout, an isotope of cosmogenic origin created by the interaction of Galactic Cosmic Rays with the upper atmosphere. Its production rate depends on the intensity of the primary cosmic rays, which are modulated by solar activity and the Earth's magnetic field. 10Be therefore provides information on these two parameters. It has allowed, among others, the improvement of ice cores chronologies thanks to absolute stratigraphic markers linked to remarkable events of the geomagnetic field as the Laschamp excursion or the Brunhes-Matuyama reversal.EPICA Dome C (75° 06' S, 123° 21' E) is a 3270~m ice core drilled in East Antarctica. It offers a complete climate record over the last 800 000 years (kyr BP). In the framework of the PhD, 2200 10Be samples were measured between 2384 m (269 kyr BP) and 2627 m (355 kyr BP) deep. This continuous sequence provides, on the one hand, the opportunity to study the solar activity during the interglacial period of the Marine Isotope Stage (MIS) 9.3, where the resolution reaches ~20 years. Our results contrast with those during the Holocene, with the noted absence of the de Vries cycle (210 years) in our 10Be profile. On the other hand, this sequence allowed us to verify that the classical estimate of snow accumulation obtained by the dating models of ice cores is correct to within 20% during the succession of glacial – interglacial cycles.These measurements were combined with those previously performed under the responsibility of Grant Raisbeck (publication in preparation). This allows to dispose of a continuous and detailed profile (resolution: 20 to 250 years) between 200 and 800 kyr BP on the EPICA Dome C ice core. The observed 10Be flux variations compare well with changes in the intensity of the geomagnetic field recorded in marine sediments. From this observation, it is possible to propose a synchronization of these profiles in order to place them on a common age scale. The observed phase shifts between the rise of temperature in Antarctica (increase of D at EDC) and the rise of global sea level (decrease of marine 18O from marine sediments) do not exceed 3200, except at the Termination VII. The low resolution of the 18O records from marine sediments makes it difficult to analyze the phase shifts. The obtained results encourage to analyze more recent periods around Termination II, including the Blake and Iceland Basin geomagnetic excursions. Indeed, this would allow to constrain more strongly the synchronization between the paleomagnetic signal in marine sediments and the 10Be flux at EDC.

Micro-organismos oriundos de ecossistemas restritivos e pouco explorados como o continente Antártico têm despertado grande interesse na comunidade científica, visto que pesquisas biotecnológicas podem resultar em produtos de alto valor agregado. Dentre estes produtos, enzimas de psicrófilos ou psicrotolerantes, que apresentam alta atividade catalítica aliada à flexibilidade, estimulam a busca de condições que favoreçam a sua produção. Assim, as proteases se destacam neste universo, visto que respondem por cerca de 60% do mercado mundial de enzimas. Neste contexto, o objetivo do presente trabalho foi o de selecionar, dentre os isolados de diferentes amostras do continente Antártico, leveduras produtoras destas enzimas, bem como de estabelecer condições de cultivo laboratorial para o favorecimento da atividade proteolítica. Foram utilizadas 99 leveduras previamente isoladas na Divisão de Recursos Microbianos da Coleção Brasileira de Micro-organismos de Ambiente e Indústria da UNICAMP, das quais 14,14% (n= 14) foram selecionadas como produtoras de proteases por meio de ensaios em placas contendo ágar Sabouraud com leite desnatado (10%). O perfil da atividade proteolítica extracelular, o crescimento e o consumo de açúcar das leveduras selecionadas foram avaliados a partir do cultivo das mesmas em caldo Sabouraud, pH 5,5, a 150rpm, a 25°C por 120h. Todos os isolados selecionados mostraram alguma atividade proteolítica em meio líquido. A levedura Rhodotorula mucilaginosa L07 foi então selecionada para a etapa seguinte, em função da máxima atividade proteolítica (33,36 U.mL-1) observada em meio líquido. Para avaliar o impacto da suplementação do meio de cultivo e da variação de parâmetros físico-químicos sobre a atividade proteolítica desta levedura, e ainda visando o favorecimento da produção de proteases, foi utilizado o planejamento fatorial fracionado 26-2, seguido de planejamento fatorial completo (DCCR 23). Os resultados obtidos permitiram estabelecer um modelo matemático que foi validado, elevando a atividade proteolítica inicial em 45,53%. A caracterização da protease produzida por R. mucilaginosa L07 revelou seu caráter ácido, cuja máxima atividade (71,14 U.ml-1) foi obtida em pH 5,0 a 50°C. Verificou-se ainda que 70% da atividade proteolítica foi conservada quando os ensaios foram realizados a 37°C e 80% em 45 e 60°C. Esta enzima mostrou-se altamente estável após incubação por 1h em temperaturas até 50°C, verificando-se a manutenção da atividade proteolítica. Estas características combinadas com a atividade proteolítica sugerem que esta protease exibe potencial para ser utilizada em processos biotecnológicos. / Microorganisms from restrictive and unexplored ecosystems as the Antarctic continent have been of great interest in the scientific community, because they can synthesize biotechnological products with high added value. Among these products, psychrotolerants or psychrophilic enzymes, which present high activity coupled with flexibility, stimulates the studies regarding to optimize conditions in order to favor their production. Proteases are highlighted in this universe, because that account for about 60 % of the enzymes world market. In this context, the aim of this work was to select among microorganisms strains isolated from Antarctica, specifically protease-producing yeast, as well as establishing its growth conditions at laboratory scale focusing on its proteolytic activity. Ninety-nine previously isolated yeasts (DRM CPQBA / UNICAMP), from different samples of the Antarctic continent were evaluated and 14,14% (n = 14) were selected as protease producers in Sabouraud Agar containing skim milk (10%). The profile of the extracellular proteolytic activity, growth conditions and sugar consumption by selected yeast strains was reported in Sabouraud broth at pH 5.5, agitation rate of 150 rpm, 25 ° C for 120h. The results showed that all selected strains presented proteolytic activity. The maximum activity values was observed with Rhodotorula mucilaginosa L07 (33,36 U.mL-1), which was selected to continue the experiments. In the next step it was studied the effect of nutrients supplementation of the culture medium and the variation of physicochemical parameters on the proteolytic activity of R. mucilaginosa L07 by using an experimental design consisting of 26-2 fractional factorial followed by a full factorial design (CCRD 23). The results obtained allowed to stablish a mathematical model, which was validated, allowing the increase of the initial proteolytic activity in 45.53%. Characterization of protease produced by R. mucilaginosa L07 showed an acid character, and a maximum activity of 71.14 U.ml-1 was obtained at pH 5.0 at 50°C. It was also found that 70% of the proteolytic activity was preserved when the assays were performed at 37°C and 80% at 45 and 60°C. This enzyme was highly stable after incubation at temperatures <= 50°C/ 1 h, maintaining the proteolytic activity. These characteristics combined with enzymatic activity, suggests that this protease exhibits potential use in biotechnological processes.

Micro-organismos oriundos de ecossistemas restritivos e pouco explorados como o continente Antártico têm despertado grande interesse na comunidade científica, visto que pesquisas biotecnológicas podem resultar em produtos de alto valor agregado. Dentre estes produtos, enzimas de psicrófilos ou psicrotolerantes, que apresentam alta atividade catalítica aliada à flexibilidade, estimulam a busca de condições que favoreçam a sua produção. Assim, as proteases se destacam neste universo, visto que respondem por cerca de 60% do mercado mundial de enzimas. Neste contexto, o objetivo do presente trabalho foi o de selecionar, dentre os isolados de diferentes amostras do continente Antártico, leveduras produtoras destas enzimas, bem como de estabelecer condições de cultivo laboratorial para o favorecimento da atividade proteolítica. Foram utilizadas 99 leveduras previamente isoladas na Divisão de Recursos Microbianos da Coleção Brasileira de Micro-organismos de Ambiente e Indústria da UNICAMP, das quais 14,14% (n= 14) foram selecionadas como produtoras de proteases por meio de ensaios em placas contendo ágar Sabouraud com leite desnatado (10%). O perfil da atividade proteolítica extracelular, o crescimento e o consumo de açúcar das leveduras selecionadas foram avaliados a partir do cultivo das mesmas em caldo Sabouraud, pH 5,5, a 150rpm, a 25°C por 120h. Todos os isolados selecionados mostraram alguma atividade proteolítica em meio líquido. A levedura Rhodotorula mucilaginosa L07 foi então selecionada para a etapa seguinte, em função da máxima atividade proteolítica (33,36 U.mL-1) observada em meio líquido. Para avaliar o impacto da suplementação do meio de cultivo e da variação de parâmetros físico-químicos sobre a atividade proteolítica desta levedura, e ainda visando o favorecimento da produção de proteases, foi utilizado o planejamento fatorial fracionado 26-2, seguido de planejamento fatorial completo (DCCR 23). Os resultados obtidos permitiram estabelecer um modelo matemático que foi validado, elevando a atividade proteolítica inicial em 45,53%. A caracterização da protease produzida por R. mucilaginosa L07 revelou seu caráter ácido, cuja máxima atividade (71,14 U.ml-1) foi obtida em pH 5,0 a 50°C. Verificou-se ainda que 70% da atividade proteolítica foi conservada quando os ensaios foram realizados a 37°C e 80% em 45 e 60°C. Esta enzima mostrou-se altamente estável após incubação por 1h em temperaturas até 50°C, verificando-se a manutenção da atividade proteolítica. Estas características combinadas com a atividade proteolítica sugerem que esta protease exibe potencial para ser utilizada em processos biotecnológicos. / Microorganisms from restrictive and unexplored ecosystems as the Antarctic continent have been of great interest in the scientific community, because they can synthesize biotechnological products with high added value. Among these products, psychrotolerants or psychrophilic enzymes, which present high activity coupled with flexibility, stimulates the studies regarding to optimize conditions in order to favor their production. Proteases are highlighted in this universe, because that account for about 60 % of the enzymes world market. In this context, the aim of this work was to select among microorganisms strains isolated from Antarctica, specifically protease-producing yeast, as well as establishing its growth conditions at laboratory scale focusing on its proteolytic activity. Ninety-nine previously isolated yeasts (DRM CPQBA / UNICAMP), from different samples of the Antarctic continent were evaluated and 14,14% (n = 14) were selected as protease producers in Sabouraud Agar containing skim milk (10%). The profile of the extracellular proteolytic activity, growth conditions and sugar consumption by selected yeast strains was reported in Sabouraud broth at pH 5.5, agitation rate of 150 rpm, 25 ° C for 120h. The results showed that all selected strains presented proteolytic activity. The maximum activity values was observed with Rhodotorula mucilaginosa L07 (33,36 U.mL-1), which was selected to continue the experiments. In the next step it was studied the effect of nutrients supplementation of the culture medium and the variation of physicochemical parameters on the proteolytic activity of R. mucilaginosa L07 by using an experimental design consisting of 26-2 fractional factorial followed by a full factorial design (CCRD 23). The results obtained allowed to stablish a mathematical model, which was validated, allowing the increase of the initial proteolytic activity in 45.53%. Characterization of protease produced by R. mucilaginosa L07 showed an acid character, and a maximum activity of 71.14 U.ml-1 was obtained at pH 5.0 at 50°C. It was also found that 70% of the proteolytic activity was preserved when the assays were performed at 37°C and 80% at 45 and 60°C. This enzyme was highly stable after incubation at temperatures <= 50°C/ 1 h, maintaining the proteolytic activity. These characteristics combined with enzymatic activity, suggests that this protease exhibits potential use in biotechnological processes.

Vulcões ativos na Antártica contrastam com a paisagem predominantemente gelada do continente. Eles fornecem condições únicas capazes de selecionar uma grande variedade de adaptações microbianas. A Ilha Deception localiza-se na região da Península Antártica e difere de outros vulcões antárticos especialmente pela influência marinha e temperaturas mais elevadas. Foram coletadas amostras de sedimentos associados a fumarolas e geleiras em dois sítios geotermais de Deception, com temperaturas variando entre 0°C a 98°C. Diferentes técnicas independentes de cultivo foram empregadas com o intuito de entender como as comunidades microbianas respondem as variações ambientais extremas produzidas pela atividade vulcânica. Os resultados indicaram que a co-ocorrência de arqueias hipertermófilas e suas adaptações com micro-organismos metabolicamente diversos adaptados a regiões geladas representa uma estrutura de comunidades única para ecossistemas antárticos. Este trabalho forneceu dados ineditos sobre questoes centrais de diversidade e adaptacao microbiana a ambientes geotermais polares. / Active volcanoes in Antarctica contrast with the predominately icy landscape. They harbor unique conditions capable to select an extreme range of microbial adaptations. Deception Island is located in the Antarctic Peninsula region and differs from other Antarctic volcanoes specially by its higher temperatures and marine influence. We collected sediment samples associated to active fumaroles and glaciers on two geothermal sites of Deception Island, with temperatures ranging from 0°C to 98°C. Different cultivation-indepedent techniques were used to understand how microbial communities respond to extreme environmental variations produced by volcanic activity. The results indicate that co-occurrence of hyperthermophiles and their specific adaptations with metabolically diverse cold-adapted micro-organisms represents a unique community structure for antarctic ecosystems. This study provided primordial data on central questions about microbial diversity and adaptation to polar geothermal environments.

O Vírus da influenza, apesar de todas as epidemias e pandemias referirem-se a infecções em seres humanos, não está restrita a espécie humana e é capaz de causar debilidade ou mortalidade em várias outras espécies, incluindo cavalos, suínos, mamíferos marinhos e aves, entre outros. Estudos ecológicos das viroses de influenza conduziram a hipótese que todas as que acometem mamíferos derivam de reservatórios destes vírus em aves. Mesmo com programas de monitoramento contínuo de aves silvestres em alguns países do mundo que possuem casos originados pelos vírus aviário H5N1, pouco foi feito na Antártica e por isso, o presente trabalho foi realizado nas estações de verão antártico de 2006, 2007 e 2008 em duas localidades no território Antártico, a Península Keller, localizada na Ilha Rei George e na ilha Elefante 61°08S, 55°07W, a primeira onde está situada a Estação Antártica Comandante Ferraz-EACF e a segunda onde está localizada uma base de apoio a estudos avançados. Para este estudo foi realizada a coleta de 283 amostras de quatro diferentes espécies de pinguins: Pygoscelis adeliae; P. papua; P. antarctica; Aptenodytes patagonicus. Para o diagnóstico das amostras colhidas, foi aplicada a detecção direta dos produtos amplificados pelo método de RT-PCR em gel de agarose confirmados pelo método de Real-Time PCR (Applied Biosystems) e pelo RT-PCR-GeneScan no laboratório de Virologia Clínica e Molecular, do Departamento de Microbiologia, da Universidade de São Paulo. Os resultados obtidos em nosso estudo foram 8 amostras positivas em pinguins para o vírus Influenza A. As amostras positivas por RT-PCR foram encaminhadas para o laboratório de Influenza do Department of Infectious Diseases, St. Jude Children\'s Research Hospital, Memphis, TN, USA, para isolamento em ovos embrionados, não havendo crescimento de vírus da influenza A. Quatro destas amostras positivas puderam ser sequenciadas e comparadas com sequências de Influenza A depositadas no Genbank apresentando uma identidade de 96,8 % a 100 % entre elas e o controle tendo este último uma identidade de 100% com as do banco de dados, confirmando a presença do vírus nestas aves. / Epidemics and pandemics of influenza usually refer to infections in human beings. The influenza virus is not, however, restricted to humans and can cause infirmity and death in other species including horses, swine, marine mammals, birds, and others. Ecological studies of viral infections have led to the hypothesis that the influenza viruses that attack mammals have their origin in the accumulation of these viruses in birds (avian flu). In some countries with influenza cases caused by the avian H5N1 virus, there was monitoring of wild birds but little had been done in Antarctica. The present work was therefore carried out during the Antarctic summer seasons of 2006, 2007, and 2008 in two Antarctic locations: The Commander Ferraz Antarctic Station, on the Keller Peninsula of King George Island, and at the Base of Advanced Studies located on Elephant Island (61°08S, 55°07W). Two hundred eighty-three (283) samples from four different penguin species Pygoscelis adeliae, Pygoscelis papua, Pygoscelis antarctica; and Aptenodytes patagonicus were collected for this study. Diagnoses of the samples were performed not only by application of direct detection and amplification according to the RT-PCR method in agar-gel, but also by Real-Time PCR (Applied Biosystems), and by RT-PCR gene scan at the Laboratory of Clinical and Molecular Virology of the Department of Microbiology of the University of Sao Paulo. Eight of the penguin samples tested positive for the Influenza-A virus. The positive samples, as determined by RT-PCR, were sent to the Influenza Laboratory of the Department of Infectious Diseases of the St. Jude Research Hospital in Memphis, Tennessee, USA, to be isolated in egg embryos where no further growth of the Influenza-A virus took place. Four of these positive samples could be sequenced and compared with those of Influenza-A on deposit at the Gene Bank and ranged from 96.85 to 100% when compared with the control samples (100% positive), thus confirming the presence of the virus in the tested birds.

Submitted by Ana Damasceno (ana.damasceno@unipampa.edu.br) on 2016-10-31T16:19:59Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Sequenciamento por Ion Torrent revela padrões de interação e distribuição de comunidades microbianas em um perfil de solo ornitogênico da Ilha Seymour, Península Antártica.pdf: 907768 bytes, checksum: 05c430f88f8f32e041e763c1d453d54a (MD5) / Made available in DSpace on 2016-10-31T16:19:59Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Sequenciamento por Ion Torrent revela padrões de interação e distribuição de comunidades microbianas em um perfil de solo ornitogênico da Ilha Seymour, Península Antártica.pdf: 907768 bytes, checksum: 05c430f88f8f32e041e763c1d453d54a (MD5) Previous issue date: 2014 / Neste estudo, foram analisadas e comparadas comunidades bacterianas do solo de uma pinguineira da Ilha Seymour (Península Antártica) em termos de abundância, estrutura, diversidade e rede de interações, a fim de se identificar padrões de interação entre os vários grupos de bactérias presentes em solos ornitogênicos em diferentes profundidades (camadas). A análise das sequências revelou a presença de oito filos distribuídos em diferentes proporções entre as Camadas 1 (0-8 cm), 2 (20-25 cm) e 3 (35-40 cm). De acordo com os índices de diversidade, a Camada 3 apresentou os maiores valores de riqueza, diversidade e uniformidade quando comparado com as Camadas 1 e 2. Em termos de estrutura da comunidade microbiana, a análise UniFrac mostrou que as comunidades microbianas das três camadas foram muito diferentes umas das outras. A análise de redes revelou a existência de um padrão único de interações no qual a rede microbiana formou uma topologia de agrupamento, mas não estruturado em módulos, como de costume em comunidades biológicas. Da mesma forma, através da utilização de análise de redes, foi possível identificar táxons específicos como sendo potencialmente importantes para a estruturação e funcionamento da comunidade microbiana. Além disso, as análises de simulação indicaram que a perda de grupos importantes de microorganismos pode alterar significativamente os padrões de interação dentro da comunidade microbiana. Estes resultados fornecem novos insights sobre as interações bacterianas e ecologia microbiana desse importante, mas ameaçado ambiente. / In this study, we analyzed and compared the soil bacterial communities from a penguin rookery site at Seymour Island (Antarctic Peninsula) in terms of abundance, structure, diversity and interaction network in order to identify interaction patterns among the various groups of bacteria presented in an ornithogenic site at three depths (layers). The analysis of the sequences revealed the presence of 8 phyla distributed in different proportions among the Layers 1 (0-8 cm), 2 (20-25 cm) and 3 (35-40 cm). According to the diversity indexes, Layer 3 presented the highest values of richness, diversity and evenness when compared to Layers 1 and 2. In terms of bacterial community structure, the unweighted and weighted UniFrac analysis showed that the soil bacterial communities from the three layers were quite different from each other. Network analysis revealed the existence of a unique pattern of interactions in which the soil microbial network formed a clustered topology, but not structured in modules, as usual in biological communities. In addition, through the use of network analysis, it was possible to identify specific taxa as potentially important for the structuring and functioning of the microbial community. Furthermore, simulation analyzes indicated that the loss of potential keystone groups of microorganisms may significantly alter the patterns of interactions within the microbial communityThese findings provide new insights into the bacterial interactions and microbial ecology of this important, but threatened environment.

How long has the extant flora been present in the Antarctic? Glaciological reconstructions propose that most areas in Antarctica were covered by thick ice sheets throughout the Last Glacial Maximum (LGM; ~22-18 kya) as well as previous glaciations, suggesting terrestrial life must have been extremely limited during these periods. In contrast, recent biogeographic and genetic studies support most extant groups of Antarctic terrestrial fauna having survived past glaciations in situ. However, studies on the origin and age of the Antarctic flora remain sparse. Applying population genetic, phylogeographic and divergence time analyses I assessed the global biogeography, origin and age of several abundant Antarctic moss species, including: four Polytrichaceae mosses, characterised by having bipolar distributions, the most common (~45% of species) distribution pattern amongst Antarctic mosses; the globally widespread moss Ceratodon purpureus; the bank-forming moss Chorisodontium aciphyllum, also known for its old sub-fossils in Antarctica and long-term viability from revival experiments; and, lastly, the genus Schistidium, the most species-rich moss genus in Antarctica, including many endemic species. Genetic analyses revealed evidence of long-term (multi-million year) survival of plants in Antarctica (several species of Schistidium, Ceratodon purpureus, and possibly Polytrichum juniperinum). However, evidence for a likely more recent (< 100 ky) arrival of Chorisodontium aciphyllum was also found. Some species revealed multiple separate dispersal events to the Antarctic, suggesting the region may be less isolated for spore-dispersed organisms than previously thought. Evidence for increased genetic diversity in the northern maritime Antarctic compared to other regions point at it including potential refugial areas. Furthermore, genetic patterns revealed geographic features that enable and limit the connectivity of bryophytes globally as well as in Antarctica. This study suggests that, despite the harsh polar climate during glaciation periods, many bryophytes have had a much longer presence in Antarctica than previously thought.

A região antártica é foco de constante observação por ser uma região de importante monitoramento climático global. Ao sedimento de fundo marinho está associada uma biota que responde aos processos de alterações ambientais e dentre seus representantes os foraminíferos são considerados bons indicadores marinhos. O objetivo do presente estudo é avaliar a fauna de foraminíferos recentes na Baía do Almirantado durante três verões austral consecutivos (2002/2003, 2003/2004 e 2004/2005) e, através da determinação de algumas variáveis ambientais, compreender melhor a ecologia e a distribuição desses organismos na região. Foram coletadas 56 amostras de sedimento de fundo marinho ao longo da Baía do Almirantado para análise e identificação da fauna de foraminíferos e de variáveis abióticas amostradas na água de fundo e no sedimento. Foram encontradas 66 espécies de foraminíferos bentônicos, sendo 36 espécies aglutinantes e 30 espécies calcárias. As espécies mais freqüentes foram as calcárias Bolivina pseudopunctata, Cassidulinoides parkerianus e Globocassidulina biora, e as aglutinantes Portatrochammina antarctica, Pseudobolivina antarctica e Spiroplectammina biformis. As espécies Portatrochammina antarctica e Pseudobolivina antarctica foram as mais abundantes na porção central e em algumas estações das três enseadas da baía. As regiões mais internas das enseadas apresentaram predominância de espécies hialinas principalmente do gênero Globocassidulina e Cassidulinoides. A predominância de espécies hialinas também foi observada nas estações próximas a desembocadura da Baía do Almirantado com as espécies Bolivina pseudopunctata e Fursenkoina fusiformis. / The Antarctic region is focus of constant scientific surveys because of its importance as global climate changing area. The marine bottom sediment has an associated biota that indicates some environmental changes and among them Foraminifera could be considered as one of the best marine biomarkers. The aim of the present study is describe the recent benthic foraminifera fauna from Admiralty Bay collected during three consecutive austral summers (2002/2003, 2003/2004 and 2004/2005) and better understand its ecology and distribution patterns throughout the bay and its relations with some environmental factors. Fifty-six bottom sediment samples were collected along the Admiralty Bay for analysis and identification of the forams fauna and abiotic factors from sediment and bottom water. We found 66 species of benthic foraminifera, 36 agglutinated and 30 calcareous. The most frequent species were the calcareous Bolivina pseudopunctata, Cassidulinoides parkerianus and Globocassidulina biora, and the agglutinated Portatrochammina antarctica, Pseudobolivina antarctica and Spiroplectammina biformis. The species Portatrochammina antarctica and Pseudobolivina antarctica were the most abundant in the central portion of the bay and in some samples of the three inlets of the bay. The inner parts of the inlets there was a predominance of calcareous such as Globocassidulina spp. and Cassidulinoides spp.. The predominance of calcareous species, such as Bolivina pseudopunctata and Fursenkoina fusiformis was also observed at samples near the connection between the Admiralty Bay and the Bransfield Strait.

Documenter la variabilité climatique récente est nécessaire à la compréhension des mécanismes en jeu, associés au rôle du bilan de masse de l’Antarctique pour l’élévation du niveau des mers globale. Les enregistrements issus des carottes peu profondes d’Antarctique sont des données précieuses, complémentaires aux observations instrumentales et satellitaires, pour couvrir en continu l’ensemble du continent. Mesurés le long de ces carottes de glace, les isotopes stables de l’eau sont traditionnellement utilisés pour quantifier les changements passés de la température locale.Cette thèse doctorale a été initiée dans le cadre du programme de l’Agence Nationale de la Recherche ASUMA (“Improving the Accurancy of SUrface Mass balance of Antarctica”), ayant pour objectif de reconstruire et identifier les processus contrôlant la variabilité spatio-temporelle du bilan de masse de surface (BMS) de la Terre Adélie. J’ai utilisé des données d’isotopes stables de l’eau enregistrées dans des carottes de névé, des simulations atmosphériques produites par le modèle atmosphérique de circulation générale de haute résolution ECHAM5-wiso équipé des isotopes stables de l’eau, des réanalyses atmosphériques, des rétro-trajectoires, ainsi que des observations instrumentales satellitaires et de surface.Dans une première partie, j’ai évalué les capacités du modèle ECHAM5-wiso à simuler les températures de l’Antarctique, le BMS, le δ18O et le d-excess (ci-après, d-excess), comme prérequis à l’exploitation du modèle pour interpréter les compositions isotopiques. J’ai développé des diagnostics pour les relations δ18O-température et d-excess- δ18O sur l’ensemble du continent de l’Antarctique, en montrant que les différences issues des pentes des relations δ18O-température spatiales, inter-annuelles et saisonnières. Au sein du groupe de travail international de PAGES (Past Global Changes) Antarctica2k, j’ai utilisé des calibrations établies issues du modèle ECHAM5-wiso pour reconstruire la température de 7 régions d’Antarctique à partir d’une synthèse d’enregistrements de δ18O issus de carottes de glace couvrant les 2 000 dernières années.Dans une seconde partie, de nouveaux enregistrements issus de deux carottes de névé extraites en Terre Adélie, la S1C1 et la TA192A, ont été exploités, couvrant respectivement les périodes 1947-2007 et 1998-2014. Les BMS reconstruits décrivent une grande variabilité spatiale (74,11 ± 14,1 cm w.e. y-1 et 21,8 ± 6,9 cm w.e. y-1 pour la TA192A et la S1C1 respectivement), cohérente avec les données de balise disponibles. En utilisant une base de données mise à jour des isotopes stables de l’eau de l’Antarctique, j’ai montré que les valeurs moyennes isotopiques de Terre Adélie appartiennent à l’intervalle des valeurs côtières de l’Antarctique. Des analyses statistiques montrent une absence de relation entre nos enregistrements avec la température de surface locale à l’échelle inter-annuelle, mais des relations significatives avec des rétro-trajectoires atmosphériques et des simulations isotopiques suggérant que les isotopes de l’eau de la Terre Adélie fournissent des indications de la variabilité de la dynamique atmosphérique et du transport d’humidité, aux échelles saisonnière et inter-annuelle.Les analyses de cette thèse ont été limitées par la quantité d’enregistrements isotopiques disponibles pour la Terre Adélie, ainsi que par le manque de compréhension des effets de dépôt et de post-dépôt. Il est donc nécessaire d’exploiter les nouvelles carottes de névé extraites au cours du programme ASUMA, et d’effectuer en continu des mesures de la composition isotopique des précipitations, de la vapeur d’eau et de la neige de surface de Terre Adélie, en combinaison avec des outils de simulations atmosphériques, tels que des rétro-trajectoires associées à un diagnostic des sources d’humidité, et des modèles atmosphériques de circulation générale et régionaux équipés des isotopes stables de l’eau. / Documenting recent Antarctic climate variability is needed in order to understand the mechanisms at play, associated with the role of Antarctic mass balance for global sea level rise. Proxy records from Antarctic shallow firn cores are precious data, which complement instrumental and remote sensing observations to continuously cover the whole continent. Within these ice cores, water stable isotopes are commonly used to quantify past changes in local temperature.This PhD thesis was initiated within the French Agence Nationale de la Recherche “Improving the Accurancy of SUrface Mass balance of Antarctica” (ASUMA) project, which aims to reconstruct and to identify the processes controlling the spatio-temporal variability of the surface mass balance (SMB) in Adélie Land. I used water stable isotopes records from recently drilled shallow firn cores, as well as atmospheric simulations performed with the high resolution atmospheric general circulation model ECHAM5-wiso model, equipped with water stable isotopes, atmospheric reanalyses and back-trajectories, instrumental and remote sensing climate observations.In a first part, I assessed the skills of the ECHAM5-wiso with respect to Antarctic temperature, SMB, δ18O and deuterium excess (hereafter d-excess), as a prerequisite for the exploitation of the model to interpret isotope compositions. I developed Antarctic-wide diagnostics of the δ18O-temperature and d-excess- δ18O relationships, showing differences in the spatial, seasonal and interannual δ18O-temperature slopes. Within the international working group of PAGES (Past Global Changes) Antarctica 2k, I used the calibrations inferred from ECHAM5-wiso to reconstruct temperatures over 7 Antarctic regions from a synthesis of ice core δ18O records spanning the past 2,000 years.In a second part, new water stable isotope records from two firn core drilled in Adélie Land, the S1C1 and the TA192A, were investigated, covering the periods 1947-2007 and 1998-2014 respectively. The reconstructed SMB display a high spatial variability (74.1 ± 14.1 cm w.e. y-1 and 21.8 ± 6.9 cm w.e. y-1 for the TA192A and S1C1 respectively), consistent with Adélie Land stake data. Using an updated database of Antarctic water stable isotope datasets, I showed that the mean isotopic values (δ18O and d-excess) in Adélie Land are in line with the range of Antarctic coastal values. Statistical analyses show no relationship between our records and local surface air temperature, at the inter-annual scale, but significant relationships with atmospheric back-trajectories and isotopic simulations, suggesting that water stable isotopes in Adélie Land provide fingerprints of the variability of atmospheric dynamics and moisture transport, at the seasonal and inter-annual scales.The analyses performed during this PhD thesis have been limited by the few available Adélie Land water stable isotope records, and by the lack of understanding of deposition and post-deposition processes. Further work is thus needed to exploit the new firn cores drilled within the ASUMA project, and to monitor continuously Adélie Land water stable isotopes in precipitation, surface water vapour and surface snow, in combination with tools of atmospheric simulations such as back-trajectory simulations provided with moisture sources diagnostics, as well as water stable isotopes-enabled atmospheric general and regional circulation models.

Esta pesquisa enfoca o uso do processo eletrolítico, como alternativa para tratamento de efluentes líquidos na Estação Antártica Comandante Ferraz (EACF), considerando as limitações ambientais locais e aspectos de consumo de energia. Este processo, classificado como não convencional, vem sendo estudado pela comunidade científica nacional e internacional para tratamento de diversos efluentes, inclusive esgotos domésticos, apresentando várias vantagens que estimularam a verificação de sua aplicabilidade para as condições peculiares da EACF. Foram realizados ensaios, em escala de laboratório, com esgotos domésticos coletados em um condomínio no Rio de Janeiro, usando reatores eletrolíticos com capacidade de 4 L, com eletrodos de desgaste de alumínio (Al) e de ferro (Fe), distância entre as placas de 0,9 cm e 1,8 cm, temperaturas na faixa de 7C a 22C, e ensaios para verificação da sua eficiência, por meio de parâmetros como DQO, DBO5, SST, turbidez e volume de lodo gerado. Sob temperatura de 15C e condições de condutividade da ordem de 900 S/cm, estimada para os esgotos da EACF, aplicando densidade de corrente de 22,9 A/m2, 4,5 V, tempo de retenção de 25 min, os resultados apresentaram valores de DQO no efluente tratado de 65 mg/L(redução de 89%), DBO de 56 mg/L (redução de 64 %), SST de 8 mg/L, com turbidez de 11,3 uT e, após filtração, turbidez de 3,2 uT, consumo de energia de 0,8 Wh/L. O aspecto é límpido e a qualidade final obtida é compatível para ser submetida a tratamento de desinfecção. A partir dos dados obtidos, foram avaliadas por meio de pré-projeto: a viabilidade de sua implantação em container, a estimativa de consumo de energia e de lodo gerado, requisitos de manutenção, operação, além da sugestão de monitoramentos e de medidas de mitigação de impactos ambientais associados à respectiva instalação. / This research focuses on the use of the electrolytical process as alternative for treatment of wastewater in Ferraz Station, considering the local environmental limitations, and aspects of consumption of energy. This process, classified as unconventional, has been studied by the national and international scientific community to treat several effluents, besides domestic sewage, presenting several advantages which stimulated the verification of its applicability in the peculiar conditions of Ferraz Station. Laboratory experiments, with domestic sewage collected in a condominium in Rio de Janeiro were accomplished using electrolytical reactors of 4 L, with electrodes of aluminum (Al) and of iron (Fe), distance between the plates of 0,9 cm and 1,8 cm, temperatures, in the strip from 7C to 22C, and analyses laboratories for verification of its efficiency through COD, BOD5, Suspended Solids, turbidity and generated sludge. Under temperature of 15C and conditions of conductivity of 900 S/cm, estimated for the station sewage, applying density of current of 22,9 A/m2, 4,5 V, time of retention of 25 min, the results presented values of COD in the treated effluent of 65 mg/L (reduction of 89%), BOD of 56 mg/L (reduction of 64%), Suspended Solids of 8 mg/L, with turbidity of 11,3 Tu and after filtration 3,2 Tu, consumption of energy of 0,8 Wh/L. Its appearance is very clean and the final result is compatible to be submitted to disinfection treatment. Based on the obtained data, the viability of its implantation in container, the estimate of consumption of energy and generated sludge and maintenance requirements, operation, besides the monitoring suggestion, and mitigating measures of environmental impacts were evaluated in a preliminary project.