A Baía de Sepetiba, localizada entre a Baía de Guanabara e a Baía de Ilha Grande, Estado do Rio de Janeiro, está inserida em um cenário estratégico para o desenvolvimento econômico do Estado. Isto ocorre devido ao aumento da concentração populacional, que está diretamente relacionado com o turismo, com a presença de portos e de áreas industriais. Sendo assim, se faz necessário estudar sua estrutura geológica e dinâmica sedimentar para entender sua evolução ao longo do tempo e para uma utilização mais racional desta área. Utilizando-se da sísmica rasa de alta resolução e da sonografia de varredura lateral juntamente com dados pretéritos de amostragem superficial de sedimentos, o presente trabalho tem como objetivo principal analisar sua geologia holocênica. A investigação, em subsuperfície, da geologia estrutural e sedimentar dessa baía, através da interpretação de 09 perfis sísmicos, baseada na determinação de diferentes tipos de ecotexturas, revelou a presença de diferentes pacotes sedimentares depositados ao longo do Holoceno. Ao todo, foram encontrados 15 tipos de ecotexturas perfazendo 14 camadas sedimentares, que estão relacionados em 4 Grupos de acordo com sua distribuição. Já a investigação em superfície através dos registros sonográficos, baseada nos diferentes graus de reflexão acústica (backscattering) e parametrizada pelos dados de amostragem direta pretérita, identificou 6 padrões sonográficos distintos. Com isso foi confeccionado um novo mapa de distribuição textural dos sedimentos superficiais da Baía de Sepetiba. Com a correlação dos dados de sísmica rasa com os dados sonográficos, foi possível ainda sugerir a provável existência de neotectonismo na área de estudo. / The Sepetiba Bay, located between the Guanabara Bay and the Ilha Grande Bay, Rio de Janeiro State, is part of a strategic scenario for the economic development of the State. This is due to increased population density, which is directly related to tourism, with the presence of ports and industrial areas. Therefore, it is necessary to study its geological structure and sediment dynamics to understand its evolution over time and to a more rational use of this area. By using high resolution seismics and side scan sonar data, this study aims to investigate the holocenic geology. The subsurface investigation of its structural and sedimentary geology, by interpretation of seismic profiles, were based in the determination of the seismic facies, along the Holocene. It was found 15 seismic facies premaking 14 sedimentaries layers that were separated in 4 Groups according to their distribution. The research with the side scan sonar, was based on the different degrees of acoustic backscattering and was parameterized by data from direct sampling. It was identified six distinct sonar patterns . Thus a new textural map of the distribution of surface sediments was made. With the correlation of seismic profiles and side scan sonar data it is possible to map a shallow fault that suggests the existence of a possible neotectonism in the study area.

Orientador: Rogério Caetano da Costa / Banca: Fernando José Zara / Banca: Valter José Cobo / Resumo: As análises deste trabalho envolveram a estrutura da assembleia (riqueza e diversidade de espécies, equidade, similaridade) e distribuição ecológica dos camarões marinhos frente aos fatores ambientais, com o intuito de averiguar se estes diferem entre duas regiões localizadas acima e abaixo do fenômeno da ressurgência de Cabo-Frio (RJ), sendo elas Macaé (RJ) e Ubatuba (SP). O paradigma do efeito latitudinal no padrão da abundância e distribuição espaço-temporal foi verificado com o intuito de testar se o mesmo pode ser proposto para este grupo. As coletas foram efetuadas mensalmente com dois barcos camaroneiros em três transectos em áreas com profundidades dos 5 aos 20 metros. Cada transecto foi percorrido por 60 minutos em cada região. Foi estimada a diversidade (H‟) aplicando o índice de Shannon-Wiener. A equidade (J‟) e a similaridade das espécies entre as estações do ano e regiões também foram calculadas. A análise de correlação canônica (CANONICA) foi empregada com o intuito de observar a relação entre a abundância das espécies e os fatores ambientais analisados. Foram capturados 148.266 indivíduos (102.832 em Macaé e 45.434 em Ubatuba), pertencentes a 15 espécies, 13 gêneros e 6 famílias (Penaeidae, Solenoceridae, Sicyoniidae, Palaeomonidae, Alpheidae e Hippolytidae). Quase todas as espécies foram coletadas nas duas regiões amostradas, excetuando-se Sicyonia laevigata, Periclimenes paivai e Lysmata sp., que foram capturadas apenas na região de Macaé, e Leander paulensis, capturada apenas na região de Ubatuba. Uma espécie do gênero Lysmata foi encontrada na região de Macaé e, provavelmente, representa um novo registro para o estado do Rio de Janeiro ou ainda uma nova espécie. Já o camarão P. paivai teve sua distribuição geográfica ampliada para o estado do Rio de Janeiro. Foram verificados maiores valores de riqueza, equitabilidade e diversidade na região de Macaé. As variáveis ... / Abstract: Not available / Mestre

Orientador: Adilson Fransozo / Banca: Katia Aparecida Nunes Hiroki / Banca: Aridiane Cristine Almeida / Banca: Rogério Caetano da Costa / Banca: Antonio Leão Castilho / Resumo: Não disponivel / Abstract: Not avaliable / Doutor

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Volumes considerÃveis de esgoto domÃstico e efluentes industriais, sem tratamento, sÃo lanÃados nos oceanos causando a contaminaÃÃo dos ecossistemas aquÃticos e colocando em risco a saÃde pÃblica e ambiental. O presente estudo teve por objetivo investigar a presenÃa de metais-traÃo, fosfato, coliformes termotolerantes e Escherichia coli em Ãgua e sedimento de galerias pluviais de Fortaleza que, freqÃentemente, encontram-se contaminadas por esgoto domÃstico, buscando representatividade das medidas de balneabilidade nas praias de Fortaleza. As anÃlises de Cu e Pb foram realizadas por espectrofotometria de absorÃÃo atÃmica pelas tÃcnicas de forno de grafite e chama para as medidas em Ãgua e sedimento, respectivamente. Para a detecÃÃo do Hg em Ãgua foi usada a espectrofotometria de fluorescÃncia com tÃcnica de geraÃÃo de vapor frio e em sedimento a espectrofotometria de absorÃÃo atÃmica utilizando a tÃcnica de vapor frio. O fosfato foi medido por espectrofotometria de absorÃÃo molecular na regiÃo do visÃvel. Nas anÃlises microbiolÃgicas empregou-se a tÃcnica dos tubos mÃltiplos. Os resultados obtidos para coliformes termotolerantes variaram na Ãgua de 1,3 x103 a 1,6 x 108 NMP/100mL e no sedimento de 0,3 x 10 a 1,0 x 106 NMP/g. Os valores de E. coli em Ãgua variaram de 0,3 x 10 a 9,2 x 107 NMP/100mL e no sedimento de 0,3 x 10 a 4,6 x 104 NMP/g. As concentraÃÃes de metais-traÃo na Ãgua variaram de 0,36 a 16,34 &#956;g.L-1 para Cu, 0,08 a 3,71 &#956;g.L-1 para Pb e 1,1 a 150,4 ng.L-1 para Hg. Nas anÃlises de sedimento as variaÃÃes foram de 0,23 a 9,64 &#956;g.g-1 para Cu, 1,41 a 21,73 &#956;g.g-1 para Pb e 0,7 a 21,4 ng.g -1 para Hg. Os teores de fosfato na Ãgua variaram de <0,01 a 1,32 mg.L-1 e no sedimento de 1,12 a 13,39 &#956;g.g-1. Os resultados mostraram que a contaminaÃÃo das Ãguas pluviais drenadas para orla de Fortaleza à constante e elevada para coliformes termotolerantes, E. coli e fosfato, com correlaÃÃes estatÃsticas significativas (p=0,05) entre esses parÃmetros. No entanto, os dados obtidos de metais-traÃo se mostraram pouco eficientes para determinaÃÃo da balneabilidade. / Considerable volumes of domestic and industrial effluent sewage, without treatment, are released in the oceans having caused the contamination of aquatic ecosystems and placing at risk the public and ambient health. The aim of this study was to investigate the presence of trace metals, phosphate, thermotolerant coliforms and Escherichia coli in water and sediment of storm sewers of Fortaleza, frequently, contaminated by domestic sewage, thus decreasing the environmental quality and balneability in Fortalezaâs beaches. The analyses of Cu and Pb in the water and sediment were perfomed by atomic absorption espectrophotometry, graphite furnace and flame techniques, respectively. To evaluate the concentration of Hg in water, cold vapor fluorescence espectrophotometry were used and cold vapor atomic absorption espectrophotometry was used for sediment. In the microbiological analyses a multiple tubes assay was used. Phosphate was measured by molecular absorption espectrophotometry. The results for thermotolerant coliforms varied in water from 1.3 x103 to 1.6 x 108 NMP/100mL and in sediment from 0.3 x 10 to 1.0 x 106 NMP/g. The values of E. coli in water varied between 0.3 x 10 to 9.2 x 107 NMP/100mL and in sediment from 0.3 x 10 to 4.6 x 104 NMP/g. Trace metal concentrations in water varied between 0.36 to 16.34 &#956;g.L-1 for Cu, 0.08 to 3.71 &#956;g.L-1 for Pb and 1.1 to 150.4 ng.L-1 for Hg. In sediment they varied between 0.23 to 9.64 &#956;g.g-1 for Cu, 1.41 to 21.73 &#956;g.g-1 for Pb and 0.7 a 21.4 ng.g-1 for Hg. Phosphate concentrations in the water varied between 0,01 to 1.32 mg.L-1 and in sediment from 1.12 to 13.39 &#956;g.g-1. The results had shown a constant and high contamination of drained pluvial waters of Fortalezaâs coast by thermotolerant coliforms, E. coli and phosphate, with correlate statistical signification (p=0.05). However, the results of trace metal had showed poor efficiency as balneability parameters.

Submitted by Daniella Santos (daniella.santos@ufma.br) on 2017-08-25T12:08:40Z No. of bitstreams: 1 ClarissaCosta.pdf: 1231835 bytes, checksum: 3655b948694a345a3265c60479119d68 (MD5) / Made available in DSpace on 2017-08-25T12:08:40Z (GMT). No. of bitstreams: 1 ClarissaCosta.pdf: 1231835 bytes, checksum: 3655b948694a345a3265c60479119d68 (MD5) Previous issue date: 2017-03-22 / CAPES / Macrozoobenthos of different grain size intertidal habitats were sampled during wet and dry seasons on Raposa Channel, Maranhão State, Brazil. The sampling was made with a PVC corer. The benthic organisms was sieved using 1 and 0,5 mm sieves and identified under a stereoscopic microscope. There were a few dominant species despite of many rare ones. Paraonis agilis, Notomastus aberans, Capitella capitata and Odontosyllis heterofalchaeta had high densities on Raposa Channel habitats. The macrozoobenthos had higher densities during wet season, specially the deposit and suspension feeders. The deposit feeders were dominant at higher silt/clay content habitats, while the suspension feeders dominated higher sand content ones. These habitats were the most diverse. Ceratia rustica, Vitrinella filifera, Paraonis agilis, Scaphopoda indet. and Caecum sp had high contribution on dissimilarity between habitats, most expressive during dry season. Sediment humidity, organic mater content, sand, silt and clay percentages and grain selection showed that habitats were significantly differents. / Macrozoobentos de habitats entremarés de diferentes classificações granulométricas foram amostrados nos períodos chuvoso e de estiagem no Canal da Raposa, Ilha de São Luís, Maranhão, Brasil. A amostragem utilizou um cilindro de PVC e os organismos bentônicos foram submetidos à triagem em peneiras geológicas (1 e 0,5 mm de malha) e sob microscópio estereoscópico. Foram representados por poucas espécies amplamente dominantes a despeito de numerosas espécies raras. Paraonis agilis, Notomastus aberans, Capitella capitata e Odontosyllis heterofalchaeta foram as espécies de Polychaeta mais abundantes nos habitats estudados no Canal da Raposa. O macrozoobentos atingiu maiores densidades no período chuvoso, especialmente detritívoros e filtradores. Os detritívoros foram dominantes nos habitats com maiores porcentagens de silte e argila, enquanto filtradores foram dominantes nos habitats com maiores porcentagens de areia, nos quais houve maior diversidade. Ceratia rustica, Vitrinella filifera, Paraonis agilis, Scaphopoda indet. e Caecum sp foram as espécies que mais contribuíram para a dissimilaridade entre os habitats estudados, que foi maior no período de estiagem. Umidade, teor de matéria orgânica, porcentagens de areia, silte e argila e desvio padrão dos grãos mostraram diferenças significativas entre os habitats estudados no Canal da Raposa.

Os oceanos são usados pelo homem há centenas de anos, no entanto, seu estudo é acontecimento relativamente recente, sendo a maior parte exercida no ensino superior. Este trabalho pretendeu desenvolver metodologia utilizando a Oceanografia como ferramenta para desenvolvimento interdisciplinar dos conteúdos científicos no Ensino Fundamental II. Em escola localizada na Zona Oeste de São Paulo, estudantes de duas turmas do 5° ano de escolarização participaram de trabalho de estudo do meio, experimento em laboratório utilizando Artemia salina (Crustacea: Branchiopoda), debate e questionários abertos (aplicados como pré e pós-teste) sobre problemas ambientais e conflito de interesses numa cidade hipotética. As respostas a três das questões que enfocavam alterações físicas, influência dessas alterações na biota e propostas para resolução do problema foram analisadas qualitativamente e enquadradas em modelos organizadores do pensamento. A metodologia utilizada mostrou-se adequada a este nível de ensino. Observou-se que para responder às questões do pós-teste os alunos utilizaram habilidades e conhecimentos prévios, adquiridos em viagem de estudo do meio, em laboratório e no debate. Notou-se também aperfeiçoamento da linguagem científica e busca de caminho consensual ou democrático para resolver o problema proposto. Por fim, sugeriram-se temas para debate relacionados a diversos experimentos clássicos no Ensino Fundamental. / The oceans have served mankind over hundreds of years for different purposes, however, its study is relatively recent, and the vast majority of it is developed in higher education institutions. This work aimed to develop a methodology using oceanography as a tool for interdisciplinary development of scientific content in the Elementary School. This study was developed in a school located in the city of São Paulo, where students from two classes of the 5th grade , participated in a field study, a laboratory experiment using Artemia salina (Crustacea: Branchiopoda), debates and responded to open-ended questionnaires (applied as pre- and post-tests) dealing with environmental problems and conflict of interests in a hypothetical city. The answers to three questions that focused on physical changes, its influences in biota and proposals for solving the problem, were qualitatively analyzed and grouped into organizing models of thought. The methodology proved to be adequate at this level of education. It was observed that in order to answer the post-test questions the students applied prior skills and knowledge, those acquired in the field study, in the laboratory and in the debate. Improvement in scientific language and seeking of consensual or democratic ways to solve the conflict proposed was also noted. Finally, topics for classroom discussion related to several classical experiments conducted in Elementary School are suggested.

The objectives of the thesis were, on the one hand, to test the possibilities of a well-known experimental configuration (oscillating grid mixing box), used to study stratified fluids in turbulent flows with zero-mean, on the study of sediment transport, and to find out what aspects involved in this phenomena could be explored from this new perspective. On the other hand, compare a well-established criterion, such as Shields parameter, with the local turbulent energy ( ), as well as to compare the differences between zero-mean and sheared induced lift-off.Verification and adjustments to the parameterizations given in the bibliography for the r.m.s. turbulent velocity, , generated by an oscillating grid were done as well as the calibration of the different mixing boxes and grids to be used through a series of experiments. This gave a clear view of the behaviour of the flow in all the mixing boxes used. A special experimental configuration was designed and performed for the first time, and measurements were taken to get to know the flow properties in the region between the grid and the bottom (solid boundary). Experiments were performed with actual sediment with different characteristics, for instance, different sediment sizes (from clay to medium sands) including samples made of single sediment size and samples extracted from the seabed. An experiment to compare the sediment behaviour under a sheared flow (recirculation tank) and under a no-sheared flow (oscillating grid mixing box) was designed and performed. The present work concluded that the experimental configuration used could be employed in further works to investigate aspects of sediment transport under a turbulent flow with great accuracy. This experimental configuration, in combination with techniques of image analysis, greatly improves the capabilities of the grid stirred experimental configurations, mainly on the study of sediment behaviour. The flow behaviour, between the grid and the free surface, and between the grid and the bottom, is, in general terms, the same. Other important contributions of the present work are the measurements taken near the boundary. Vortices do not distort before impingement. After vortex impingement, no constant mean flow is distinguished. The former enhanced the idea that these experimental configurations are suitable for studying the behaviour of a sediment bed under the influence of a turbulent flow. A smaller magnitude of than of was required to start sediment motion, through comparing the theoretical critical friction velocity, (Critical Shields Parameter), needed to start sediment motion with the measured critical for different sediment sizes. The results obtained show the importance that the time span between extraction and analysis has on the measured value of , and that cohesiveness of sediment play a more important role than sediment size hampering the erosion processes that cause sediment lift off from the sediment bed. Under the same circumstances, a turbulent flow is more efficient than eroding the sediment bed, since it does not depend on the roughness of the sediment bed. It was possible to measure sediment velocities during lift-off and settling, using grid stirred experimental configurations in conjunction with image analysis techniques. It is even possible to determine the sediment size (size mode), even in the range of clays and silts, with an error as small as 6 or 8 percent. It was possible to quantify the sediment flux at a given turbulence intensity. Velocity fluctuations are about the same in the three directions and in a random way above the sediment bed, meaning no preferential direction of stresses. The former hampers the process of particle imbrication making it easier to dislocate the particles from the bed.

Amb aquest treball es preté comprovar la universalitat de la relació estequiomètrica de Redfield i recercar patrons consistents de les desviacions d'aquesta raó promig en ambients oligotrofics. Per tal de dur a terme aquest propòsit s'han desenvolupat relacions estequiomètriques en el compartiment particulat i dissolt orgànic i inorgànic per el C, N, P i Si.La estequiometria dels nutrients a l'oceà s'ha examinat al Mar Mediterrani i a l'Oceà Atlàntic subtropical, mentre que la zona costenera del Mar Mediterrani ha servit per estudiar aquestes relacions sota l'influència d'aports terrestres. En el segon capítol de la tesi es descriuen patrons meridionals del fluxe de nitrogen i fósfor vers la capa biogènica de l'Oceà Atlàntic Central. La raó promig entre el fluxe difusiu del nitrogen inorgànic dissolt (DIN) i del fósfor (DIP) es mostra similar a la raó de Redfield al llarg de l'Oceà Atlàntic Central, però tendeix a valors per sota dels establerts per Redfield a la part sud del trajecte i superiors a la raó de Redfield al centre del gir sudtropical. La raó N:P del fluxe difusiu i la raó N:P dels nutrients dissolts inorgànics en la capa biogènica es troben fortament correlacionats, mentre que no existeix cap correlació amb els valors de la raó N:P de les aigües intermitges. Els resultats trobats en aquest capítol de la tesi indiquen que la recirculació vertical de nutrients a la capa biogènica de l'oceà Atlàntic Central és capaç d'operar amb raons estequimètriques que difereixen de Redfield i per tant els components biogènics i biolítics s'adapten a les variacions locals de la raó de Redfield. La hipòtesis que existeixen raons estequiomètriques previsibles en la reserva oceànica de material dissolt orgànic que es troben en equilibri amb la reserva del material particulat orgànic i dissolt inorgànic, es corrobora en el tercer capítol d'aquesta tesi. La majoria del carboni orgànic present en aigües oligotrofiques del Mediterrani estratificat es troba en forma d'orgànic dissolt, mentre que el POC (carboni orgànic particulat) representa un percentatge menor. El nitrogen i fósfor orgànic dissolt que comprenen el 50-80% del "pool" total de P i N a la capa biogènica, decreix en percentarge a la capa biolítica. S'ha comprovat una distribució uniforme del nitrogen disolt total (TDN). L'increment en el percentatge de N inorgànic disolt i el decreixement en percentatge de N orgànic dissolt amb la fondària, és un indicador clar de l'equilibri dinàmic que existeix entre les reaccions bioquímiques entre les reserves oceàniques. Mitjançant un sistema de balanços, s'estableix un intercanvi de nutrients (exportació-importació) entre els pools dissolt orgànic i dissolt inorgànic en el sistema. S'ha comprovat que el fluxe de nitrogen orgànic dissolt (DON) excedeix al fluxe difusiu de nitrogen inorgànic i per tant els aports atmosfèrics i terrestres són importants en aquesta regió.En el quart capítol de la tesi es descriu el lligam existent entre el component pelàgic i els component del bentos d'una àrea litoral del Mar Mediterrani, és a dir un compartiment anabolic que produeix matèria orgànica i un de catabolic que actúa com agent oxidant de la reserva de matèria orgànica del sistema. El compartiment pelàgic es mostra heterotrofic. Al mateix temps, existeix una contribució important de material terrestre als sediments. Per contra, el compartiment bentònic és autotrofic on el dèficit en la producció grossa es compensa amb l'excés de producció neta del sistema. Mitjançant la quantificació simultànea dels fluxes anuals de sedimentació per al C, N, P i Si així com dels fluxes sediment-aigua de les espècies orgàniques i inorgàniques dissoltes, s'ha establert un sistema de balanços de matèria del sistema. El compartiment bentonic es configura com a sumider o exportador de matèria orgànica, degut als aports terrestres de carboni en el sistema.Els patrons de distribució de nutrients derivats dels resultats dels capítols anteriors es comproven mitjançant un experiment d'addició de nutrients. En el capítol cinquè d'aquesta tesi s'estudien els canvis en la distribució de nutrients en les diferents reserves nutricionals d'un sistema quan es troba sotmès a aports controlats de nutrients. S'ha comprovat que, mentre el tamany relatiu de la reserva de nutrients inorgànics dissolts no varia amb l'increment de nutrients en el medi. Hi ha una tendència a l'increment del tamany relatiu de la reserva del material particulat, paral.lela a un decreixement simultani de la reserva de material dissolt orgànic. Aquest experiment contribueix a verificar el paper del DOM (matèria dissolta orgànica) com a principal reserva nutricional en sistemes oliogotròfics. / The stoichiometric ratios are powerful tools to model basic biogeochemical patterns of the sea when the fluxes of a single element are known. It is, therefore essential to understand the full implications of variable stoichiometries to predict the effect of the living components of the ocean on biogeochemical processes. Here, the stoichiometry between C, N, P and Si in different chemical pools (particulate and dissolved organic and dissolved inorganic matter) were examined in contrasting oceanic and littoral ecosystems, and the changes in nutrient partitioning in response to nutrient inputs was tested through experimental research. In the Central Atlantic Ocean, the average ratio between dissolved inorganic nitrogen and phosphorus in the estimated vertical diffusive fluxes was similar to the Redfield ratio, but tended to be above the Redfield ratio at the center of the South subtropical gyre. The N:P supply ratio and the N:P ratio of dissolved inorganic nutrients in the biogenic layer were strongly correlated, but were not positively correlated to that in the intermediate waters. The vertical nutrient conveyor belt of nutrients in the upper waters operates relatively independently of the underlying waters in the Central Atlantic, so that both the biogenic and the biolythic components should be able to adapt to local variation about the Redfield ratio.In the stratified NW Mediterranean Sea, the stoichiometry between dissolved inorganic, organic and particulate organic matter pools indicated an excess nitrogen relative to phosphorus, particularly in the biolythic layer, as well as a general silicate deficiency relative to both N and P. Most (> 80 %) of the organic carbon was present as dissolved organic carbon, with POC representing a minor percent of total organic C throughout the water column. The increasing C/N ratio of DOM with depth indicates that N is recycled faster than C in the DOM. There exists a dynamic equilibrium between the biological transformations between these pools with depth, with a dominance of DON production in surface waters and remineralization in the underlying layers, from which dissolved inorganic nitrogen is re-supplied to the biogenic layer. Alocthonous N inputs must be important in the region since the downward DON flux exceeded the diffusive DIN supply. The coupling between anabolic and catabolic compartments of a littoral area in the NW Mediterranean Sea are characterized. The pelagic compartment was heterotrophic, supported by significant allochthonous inputs of land material, whereas the benthic compartment was autotrophic, with the excess net benthic community production balancing the deficit in pelagic community production, leading to a system in metabolic equilibrium. Sedimentary inputs of phosphorus and silicon were compensated by sediment release of phosphate and silicate, whereas nitrogen was lost or accumulated in the sediment compartment. Carbon inputs to the benthic compartment also exceeded requirements, due to the allocthonous subsidies to the system, so that the benthic compartment stored or exported organic carbon.Experimental nutrient additions lead to a parabolic change in C/N and C/P ratios in the dissolved organic matter with increasing nutrient inputs. The relative size of the dissolved inorganic nutrient pools did not vary, but there was a tendency towards an increase in the relative size of the particulate pool at the expense of a decrease in the relative importance of DOM as a reservoir of N, P and C, with increasing nutrient inputs.The relative importance of different nitrogen pools was examined in relation to the total nutrient stoichiometry of the oligotrophic system. The ratio of dissolved inorganic nutrients reported in the research presented is indicative of a general deficiency in nitrogen compared to the global ratios reported in literature. The dissolved organic matter was highly depleted in P relative to N and C at all locations investigated and the resulting POC:PON ratio (11.7) of this study in the particulate pool deviates greatly from the literature values which approximates Redfield value (5.5-6). The shift of the dominance of DON towards PON at TOC/TN values higher than 20 on the oligothrophic areas of the study, gives evidence of increasing carbon export fluxes in a system dominated by particulate pool and points to the effect of the biota on the gradient-driven export to sinking carbon fluxes in the ocean.

Es tracta d'una tesi fonamentalment interdisciplinària que aborda l'anàlisi de la dinàmica fitoplanctònica, en condicions de mar obert i en termes de fixació de carboni, en funció de pressos estrictament físics com són la difusió turbulenta, la sedimentació, etc.En primer terme, el fitoplàncton està constituït per organismes vegetals microscòpics, que com a tals necessiten llum i sals minerals (anomenats generalment "nutrients"). La llum és en qualsevol cas sempre més abundant a nivell de la superfície del mar, mentre que els nutrients són més abundants en profunditat. La majoria d'organismes fitoplanctònics presenten una capacitat natatòria molt reduïda, o simplement nul·la. Per tant, aquests organismes depenen en gran mesura de l'aport de nutrients que per transport turbulent els arriba des de les capes més profundes fins la capa superior il·luminada (o capa eufòtica).Primerament es dugué a terme una anàlisi d'escales en base als temps característics dels processos biològics clau, susceptibles de poder presentar un major grau de sensibilitat envers l'efecte de la trubulència, tals com l'absorció de nutrients i la fixació de carboni (fotosíntesi).Les principals característiques d'aquest nou model són la capacitat de poder resoldre els processos biològics amb una resolució temporal de l'ordre de segons minuts o segons, coincidint, per tant, amb l'escala temporal de la turbulència. I segon, el seguiment simultani del transport vertical de carboni i nitrogen.La turbulència de petita escala s'introdueix en el model numèric a través de les parametritzacions proposades per Osborn, i per Gaspar i col·laboradors, metodologia àmpliament utilitzada en l'actualitat, i contrastada experimentalment. Finalment s'analitza la relació entre la difusió turbulenta de petita escala i la producció primària fitoplanctònica en termes de fluxes verticals de carboni i nitrogen.Són destacables els resultats obtinguts en l'estudi del transport de matèria a través de la capa límit present al voltant dels organismes fitoplanctònics (les anomenades Diffusive Boundary Layers), identificant-se limitacions estrictament físiques al co-transport de carboni, nitrogen i fósfor. / This Ph.D. thesis introduces an interdisciplinary approach to the modeling of phytoplankton carbon fixation and nutrient uptake (nitrogen) according to the influence of small-scale turbulence in the open ocean. The modeling exercise presents a new strictly biological model with five state-variables, and a vertical 1-D coupled physical-biological model of the uppermost 100 meters of the marine water column. The two shared state-variables of the 1-D model are phytoplankton biomass (in terms of carbon), and an external limiting nutrient (in terms of nitrate).The biological model accounts for carbon and nitrogen biomass state-variables, following explicitly the track of both fluxes. As a relevant achievement the model successfully couples the different timescales of the carbon fixation (hours to days) and nitrogen uptake rates (seconds to minutes) by means of two intermediate carbon and nitrogen highly dynamical internal pools.Simulation runs are presented for the biological model alone, and in for the coupled physical-biological 1-D model.The thesis also provides a significative insight into the transport of mass through the diffusive boundary layers around phytoplanktonic organisms, and presents a potential strictly physical limitation to Redfield requirements.

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