A Praia do Cassino, localizada no sul do Brasil, é freqüentemente coberta por extensivos depósitos de lama, ocasionando importantes efeitos de curta e longa duração. Alterações no volume das precipitações interferem diretamente no escoamento fluvial e, conseqüentemente, no volume de sedimentos que aportam na Lagoa dos Patos. Dados do regime de precipitação ao longo de 15 estações pluviométricas no período de 1968 a 2008 foram analisados estatisticamente e correlacionadas com eventos de El Niño e La Niña e com a ocorrência de lama na praia do Cassino. Períodos de El Niño e La Niña estão associados com precipitações acima e abaixo da normal, respectivamente, principalmente durante a primavera. Além disso, as anomalias climáticas apresentam influência potencial nos depósitos lamíticos do Cassino. Durante os eventos de El Niño são registradas precipitações mais intensas e, com um tempo de resposta mais rápido a partir do início da anomalia no Oceano Pacífico, além de um intervalo de tempo menor entre os eventos de deposição. As precipitações nas bacias da região sul, nas adjacências da Lagoa dos Patos, apresentam uma forte relação com esta anomalia. Em eventos de La Niña são observadas precipitação mais moderadas além de um período de tempo maior entre o início da anomalia negativa na TSM no Oceano Pacífico e os depósitos de lama. A bacia hidrográfica localizada ao norte da Lagoa dos Patos apresenta uma influência predominante sobre a precipitação durante esse evento. Foi analisada a provável fonte mineralógica das argilas presentes na praia do Cassino e adjacências a Lagoa dos Patos, por meio de difratometria de raio-X. A esmectita é o argilomineral predominante na plataforma continental e praia do Cassino enquanto que na Lagoa dos Patos o argilomineral mais abundante é a ilita. A aplicação da análise estatística paramétrica e multivariadas, juntamente com pesquisas bibliográficas permitiram definir as principais fontes de dispersão da lama na região costeira. / Cassino Beach, placed in the south of Brazil, is frequently covered by extensive deposition of mud which causes important short and long term effects on the beach environment, as well as on the tour activities of the region. Oscillations on the volume of rainfall interferes directly on the basins fluvial outflow and consequently on the volume of sediments that flow into Patos Lagoons System. Data record of the rainfall regime of fifteen rain gauge stations in the period between 1968 and 2008 were analyzed statistically and correlated with the events of El Niño and La Niña and with the occurrence of mud in Cassino beach. The periods are associated with rainfall that is above and below average both El Niño and La Niña occur, especially during spring. Frequently climate anomalies have potential influenced on the mud deposition in Cassino Beach. Duriing El Niño’s events, more intense rainfall is registered and its response is faster considering the time of the beginning of the anomaly in the Pacific Ocean. Besides that the interval between the events of deposition have become shorter. Rainfall in the south basin region adjacent to the Patos Lagoons Systems, have a strong relation with this anomaly. During La Niña’s events more moderate rainfalls are observed, as well as a longer interval between the beginning of the negative anomaly in the sea surface temperature in the Pacific Ocean and the deposition of mud. The basin drainage located on the north of Patos Lagoons Beach has a predominant influence over rainfall during this event. Eventually, the presumable mineral source of the clay found in Cassino Beach and adjacent to Patos Lagoons Systems was analyzed through x-ray diffraction. Smectite are the predominant clay minerals on the continental platform and on Cassino Beach while the sediment found in Patos Lagoons Systems presents higher concentration of iIlite. The sources and dispersal mud in the coastline region was defined with used the parametric and multivariate statistical analysis and bibliographical review.

Made available in DSpace on 2014-06-11T19:29:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-07-30Bitstream added on 2014-06-13T20:48:14Z : No. of bitstreams: 1 santos_fl_me_ilha.pdf: 5580224 bytes, checksum: 7664797be424662e0d0d1021e9ee4dc5 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Em função da concentração de material sólido, misturas resultantes de argila e água conferem, via de regra, propriedades não-Newtonianas. Essa concentração passa a variar com a granulometria e a composição do mineral do sedimento, bem como com a qualidade da água. Algumas tentativas foram feitas na busca de melhor explicar a reologia e a dinâmica global dessas misturas nessa última década, notadamente no contexto de lavas torrenciais e misturas hiperconcentradas. Essa dissertação de mestrado tem por objetivo desenvolver uma caracterização reológica de misturas sólido-líquido (água+argila caulinítica e água+areia fina+argila caulinítica) com diferentes concentrações em volume (Cv) para as quais são determinadas, a partir de ensaios de reometria de precisão, as propriedades tais como a viscosidade aparente, tensão crítica de cisalhamento e curva de tensão de cisalhamento x taxa de deformação. Verificou-se, em condições controladas, a influência da temperatura, pH e concentração em volume (Cv) sobre a curva reológica dessas misturas, além de eventuais fenômenos de tixotropia e modo de preparo. O modelo reológico melhor ajustado para as argilas foi o de Herschel-Bulkley ( ( )n τ =τ c + k γ& ), onde: τ é a tensão de cisalhamento; τc é a tensão crítica (ou rigidez inicial); k é um termo de consistência (viscosidade aparente); n é o índice de escoamento; e dy γ& = du é a taxa de deformação. Obtém-se também, a partir de uma análise quantitativa global, leis de evolução dos diversos parâmetros reológicos em função da concentração em volume. Após a etapa de caracterização física e reológica das misturas, realizaram-se, sob condições controladas, ensaios dinâmicos através de escoamentos de lamas em canal inclinado. Nesses ensaios foram medidos os parâmetros lâmina normal, vazões... ; n is flow index; and dy γ& = du is shear rate. It is also obtained, from a global quantitative analysis, evolution laws of the several rheologics parameters in function of the solid volume concentration. After the stage of rheological and physical characterization of mixing samples, dynamics experiments were made, under controlled conditions, than the flow of mud was observed in the open channel. These analyses were made in order to examine the behavior of parameters such as: normal depth, discharge and velocities. In fact, the experience showed that is possible to deduce wall friction laws from the rheological proprieties based on high mud concentrated suspensions and the dynamic of these muds.

A Praia do Cassino, localizada no sul do Brasil, é freqüentemente coberta por extensivos depósitos de lama, ocasionando importantes efeitos de curta e longa duração. Alterações no volume das precipitações interferem diretamente no escoamento fluvial e, conseqüentemente, no volume de sedimentos que aportam na Lagoa dos Patos. Dados do regime de precipitação ao longo de 15 estações pluviométricas no período de 1968 a 2008 foram analisados estatisticamente e correlacionadas com eventos de El Niño e La Niña e com a ocorrência de lama na praia do Cassino. Períodos de El Niño e La Niña estão associados com precipitações acima e abaixo da normal, respectivamente, principalmente durante a primavera. Além disso, as anomalias climáticas apresentam influência potencial nos depósitos lamíticos do Cassino. Durante os eventos de El Niño são registradas precipitações mais intensas e, com um tempo de resposta mais rápido a partir do início da anomalia no Oceano Pacífico, além de um intervalo de tempo menor entre os eventos de deposição. As precipitações nas bacias da região sul, nas adjacências da Lagoa dos Patos, apresentam uma forte relação com esta anomalia. Em eventos de La Niña são observadas precipitação mais moderadas além de um período de tempo maior entre o início da anomalia negativa na TSM no Oceano Pacífico e os depósitos de lama. A bacia hidrográfica localizada ao norte da Lagoa dos Patos apresenta uma influência predominante sobre a precipitação durante esse evento. Foi analisada a provável fonte mineralógica das argilas presentes na praia do Cassino e adjacências a Lagoa dos Patos, por meio de difratometria de raio-X. A esmectita é o argilomineral predominante na plataforma continental e praia do Cassino enquanto que na Lagoa dos Patos o argilomineral mais abundante é a ilita. A aplicação da análise estatística paramétrica e multivariadas, juntamente com pesquisas bibliográficas permitiram definir as principais fontes de dispersão da lama na região costeira. / Cassino Beach, placed in the south of Brazil, is frequently covered by extensive deposition of mud which causes important short and long term effects on the beach environment, as well as on the tour activities of the region. Oscillations on the volume of rainfall interferes directly on the basins fluvial outflow and consequently on the volume of sediments that flow into Patos Lagoons System. Data record of the rainfall regime of fifteen rain gauge stations in the period between 1968 and 2008 were analyzed statistically and correlated with the events of El Niño and La Niña and with the occurrence of mud in Cassino beach. The periods are associated with rainfall that is above and below average both El Niño and La Niña occur, especially during spring. Frequently climate anomalies have potential influenced on the mud deposition in Cassino Beach. Duriing El Niño’s events, more intense rainfall is registered and its response is faster considering the time of the beginning of the anomaly in the Pacific Ocean. Besides that the interval between the events of deposition have become shorter. Rainfall in the south basin region adjacent to the Patos Lagoons Systems, have a strong relation with this anomaly. During La Niña’s events more moderate rainfalls are observed, as well as a longer interval between the beginning of the negative anomaly in the sea surface temperature in the Pacific Ocean and the deposition of mud. The basin drainage located on the north of Patos Lagoons Beach has a predominant influence over rainfall during this event. Eventually, the presumable mineral source of the clay found in Cassino Beach and adjacent to Patos Lagoons Systems was analyzed through x-ray diffraction. Smectite are the predominant clay minerals on the continental platform and on Cassino Beach while the sediment found in Patos Lagoons Systems presents higher concentration of iIlite. The sources and dispersal mud in the coastline region was defined with used the parametric and multivariate statistical analysis and bibliographical review.

A baía de Guajará é um sistema fluvial altamente influenciado por maré inserido no contexto e na área de influência da foz do rio Amazonas. Na sua margem direita, localiza-se a cidade de Belém (população da região metropolitana: 2,12 milhões de habitantes). A margem esquerda corresponde a um conjunto insular de 39 ilhas. Levantaram-se dados batimétricos e sedimentológicos, visando caracterizar a dinâmica e a textura do substrato e a sua respectiva aplicação na gestão ambienta] da baía. Os potenciais impactos e riscos de acidentes ambientais foram avaliados com base nesses dados e nas características do uso e ocupação das margens. Na área de estudo, observam-se zonas de baixa profundidade (~1O m) e canais bem definidos com profundidade considerável (~25 m). O canal da ilha das Onças, na margem esquerda, corresponde à maior província geomorfológica, além de ser o canal de vazante. Já os canais do Meio e Oriental correspondem aos canais de enchente e localizam-se na margem direita. Há depósitos sedimentares arenosos e areno-Iamosos nas zonas norte e sul, respectivamente. Enquanto a margem esquerda é marcada por processos erosivos, a direita apresenta extensas planícies de maré lamosa e considerável taxa de sedimentação. São constantes as dragagens para manter navegáveis os canais de acesso ao Porto de Belém e ao Terminal Petroquímico de Miramar. Quanto à sedimentologia, as classificações texturais predominantes foram: si/te (Phi médio); si/te arenoso (Shepard); e Lamas Siliciclásticas - LLl (Larsonneur). A aplicação do Diagrama de Pejrup mostrou que 95% das amostras correspondem a ambientes de hidrodinâmica alta ou muito alta. Na porção sul da baía, os depósitos lamosos resultam da quebra de energia de correntes e decréscimo da competência dos rios Guamá e Acará. Na zona norte, contudo, existem sedimentos arenosos devido a maior influência das correntes de maré oriundas da baía de Marajó. A orla do município de Belém encontra-se totalmente ocupada, enquanto a ocupação é incipiente na região insular. Os habitantes das ilhas possuem grande dependência dos recursos naturais. Habitações precárias (construí das, em geral, em madeira) são observadas em ambas as margens. Resultam da relação custo/benefício, sendo a adequação necessária às inundações semi-diurnais, pois se localizam sobre a planície de maré lamosa. Na capital, a aglomeração dessas habitações forma favelas. Nas ilhas, constituem moradias de famílias simples que tiram o sustento do extrativismo vegetal (açaí) e animal (pesca, caça e comércio de animais silvestres). Na Orla Oeste de Belém, as atividades de risco estão ligadas às indústrias de médio/grande porte, enquanto a Orla Sul apresenta problemáticas relacionadas à prostituição, ao comércio ilegal de animais silvestres, ao trabalho informal e ao grande número de portos e terminais fluviais, construídos em madeira e sobre a planície de maré lamosa. A Orla Central, densamente urbanizada, é menos suscetível. Com sucesso, pôde-se aplicar dados sedimentológicos e batimétricos na gestão ambiental da baía de Guajará. Assim, conclui-se que dados abióticos e socioeconomicos, analisados à luz dos processos ecológicos de média/larga escala, podem gerar diagnósticos específicos e contribuir na geração de planos de mitigação e controle de danos ambientais. / The Guajará Bay (to southeast of Marajó lsland) is a fluvial system with high tidai influence, inserted in the context and influence area of the estuarine complex of Amazonas River Mouth. ln the right margin, is located the Belém city (metropolitan population: 2.12 million peoples). The left margin is an islander set composed by 39 islands. Bathymetrical and sedimentological data were collected, aiming to characterize the dynamic and textural of botiom and the application of these data in the environmental management of the Guajará Bay. The risks of environmental accidents were available with aid of the characteristics of use and occupation of flood marginal areas. In the Guajará Bay, is observed zones with low depth and well defined channels (depth reaches of 25 m). The Onças Island Channel, in the left margin, is the major geomorphologic province and is the ebb channel. The Oriental and do Meio Channel are the flood channel, and is located in the right margin. Have sedimentary sandy and sand-muddy deposits in the north and south zones, respectively. While in the left margin is observed erosion processes, the right margin IS an extensive and continuous tidal mudflat, with considerable sedimentation rate (needing constant dredging to maintain navigable the access channel of Belém city Port and Miramar Petrochemical Terminal). In relation to sedimentology, the textural classifications were: silt (mean gram-slze method); sandy si/t (Shepard method); and Siliciclastic Mud - LU (Larsonneur method). The application of Pejrup diagram shows that 95% of samples come from to environmental with high or so high hydrodynamic. In the south portion, the muddy deposits are result of the break energy and consequently decrease of Guamá and Acará fluvial competence. Therefore, in the north portion were observed sandy deposits because the major influence oftidal currents from the Marajó Bay. The border of Belém city show high occupation, in contrast to starter occupation of the insular region. The habitants of the islands of Guajará Bay have considerable dependence of the natural resources. Precarious houses made in general with wood are observed in both margins. This is result of the relation price / usefulness and they are the necessary adaptation for the semi-diurnal flood. Therefore, in Belém city the agglomeration of these houses form shanty-town on the mudflat. In the islands, are houses of simple families, whose sustenance is the vegetal (açaí) and animal extrativism - fishing, chasing and business of wild animaIs. The borders West and South of Belém city were the most susceptible to environmental damage. The Central border, with high urbanization, was low susceptible. While in the West border the hazard activities have relation with the industries, in the South border the activities have relation with the prostitution, the illegal business of wild animais, the informal work and the large concentration of fluvial ports and terminais, made with wood and on the tidal mudflat. With success can be applied the application of sedimentological and bathymetrical data in the environmental management of the Guajará Bay. ln such way, the conc\usion is that abiotics and socioeconomics data, analyzed together to the ecological process of large scale, can to make specify diagnoses and to aid in the generation of plane of diminution and control of environmental damages.

Tese(doutorado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2012. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-11-19T12:24:44Z No. of bitstreams: 1 fernanda.pdf: 1386021 bytes, checksum: e67fec86c13546d730d06a2d26086f69 (MD5) / Approved for entry into archive by Angelica Miranda (angelicacdm@gmail.com) on 2013-11-20T21:40:54Z (GMT) No. of bitstreams: 1 fernanda.pdf: 1386021 bytes, checksum: e67fec86c13546d730d06a2d26086f69 (MD5) / Made available in DSpace on 2013-11-20T21:40:54Z (GMT). No. of bitstreams: 1 fernanda.pdf: 1386021 bytes, checksum: e67fec86c13546d730d06a2d26086f69 (MD5) Previous issue date: 2012 / Na zona de arrebentação de praias arenosas e expostas ocorrem acumulações de diatomáceas, as quais são importantes produtores primários. Visando entender se existe uma variação espacial e temporal do fitoplâncton na zona de arrebentação da Praia do Cassino, foram analisadas semanalmente cinco estações no período de deposição lama (maio a julho de 2009), e posteriormente (agosto de 2009 a abril 2010) três estações quinzenalmente ao longo de 21 km. As relações entre variáveis ambientais e a composição e biomassa do fitoplâncton foram comparadas, verificando-se que a deposição de lama influenciou a transparência da água, mas não foi detectada diferença significativa entre os valores médios de nutrientes e de clorofila a nas estações ao longo do ano. As diatomáceas foram dominantes, destacando-se a contribuição de cêntricas unicelulares do microplâncton e Skeletonema spp., e das penadas Asterionellopsis glacialis e Pseudo-nitzschia sp. Porém, a densidade de A. glacialis encontrada neste ano foi menor do que em anos anteriores, enquanto os gêneros planctônicos Skeletonema e Pseudo-nitzschia apareceram em alta densidade. Em laboratório foram realizados experimentos curtos com enriquecimento de nutrientes inorgânicos dissolvidos testando-se ao todo sete proporções de silicato, nitrato e fosfato, com objetivo de determinar sua influência sobre as microalgas da Praia do Cassino. Como resultado, a biomassa fitoplanctônica exibiu um aumento significativo nos tratamentos com adição de nitrato, independentemente da proporção adicionada, indicando que o nitrato é o nutriente mais importante no controle da biomassa e do crescimento das diatomáceas da Praia do Cassino. / In the surf zone of exposed sandy beaches significant accumulations of diatoms occur, which are important primary producers. In order to determine the spatial and temporal variability of phytoplankton in the surf zone, five and three stations were studied in the period with mud deposition (weekly sampling, May to July 2009) and without (every two weeks, August 2009 to April 2010), respectively, along 21 km of Cassino Beach. The relationships among environmental variables and phytoplankton composition and concentration were compared. The influence of mud was evident on the water transparency, but not on the mean values of nutrients and chlorophyll a. The diatoms were dominant, emphasizing the contribution of the unicellular centric microplankton and Skeletonema spp., and the pennates Asterionellopsis glacialis and Pseudo-nitzschia spp. However, the density of A. glacialis found in this study was lower than in previous years. Moreover, the planktonic species Skeletonema and Pseudo-nitzschia appeared in high density. In laboratory, short experiments were performed with dissolved inorganic nutrient enrichment by testing seven proportions of silicate, nitrate and phosphate, in order to determine their influence on the microalgae from Cassino Beach. In both experiments, density showed a significant increase (mainly diatoms) in the treatments with nitrate addition, regardless of the proportion added, showing that nitrate is the most important nutrient controlling diatoms density and growth at the sandy Cassino Beach.

Le littoral guyanais accueille chaque année les pontes de tortues marines. En Guyane, les tortues doivent faire face à l’instabilité côtière liée au passage d’imposants bancs de vase le long du littoral. Dans ce contexte, les plages de ponte peuvent devenir non attractives si elles présentent une érosion trop marquée ou si elles sont envasées. L’instabilité de ce littoral peut également induire la création de nouveaux sites sableux (cheniers), sites de ponte potentiels.Ce travail de thèse s’attache à étudier la dynamique morphosédimentaire des plages sableuses servant d’habitat de ponte aux tortues et les répercussions de la migration des bancs sur ces plages. La principale zone d’étude, la plage d’Awala-Yalimapo, a été instrumentée entre 2011 et 2013, et a permis de comprendre le fonctionnement hydro-sédimentaire d’une des principales plages de ponte guyanaises à une échelle mensuelle à pluriannuelle. Parallèlement à ce travail, l’activité de ponte des tortues marines a été recensée permettant de mettre en évidence l’utilisation de certains paramètres environnementaux dans la sélection finale du site de ponte. Les principaux déterminants sont la configuration de l’avant-plage, la hauteur d’eau, les courants de marée et la dynamique morphosédimentaire de la plage d’accueil. / French Guiana coast host, each year, marines turtles nesting. In French Guiana, marine turtles managed with the extreme coastal variability due to the migration of huge mud bank. In this context, nesting beaches could be unattractive if erosion is too intense or if there are silted-up. The instability of this coast could induce the creation of new sandy coastline (cheniers) and so on potential nesting site.The aim of this PhD work was to study the morphodynamics of sandy beaches which are also nesting site for marine turtles and the consequence of mud bank migration on these beaches. In-situ measurements were carried-out on the principal study area, Awala-Yalimapo beach, and permitted to increase our knowledge on the hydro-sedimentary evolution of one of the primary nesting site from daily to multiannual time scale. In the same time, the nesting activity of marine turtles was listed to highlight the use of environmental parameters in the finale selection of the nesting site. Principal environmental clues were the beach configuration, the water level, tidal current and the morphodynamics of the nesting habitat.

La mangrove de Guyane est caractérisée par un dynamisme spatial exceptionnel. Ce caractère découle de processus hydro-sédimentaires côtiers très intenses. Les objectifs de la thèse ont été de : (1) quantifier la dynamique spatiale de l'écosystème mangrove à l'échelle régionale et multi-décennale par l'analyse de données d'archives issues de la télédétection ; (2) tester l'hypothèse selon laquelle le climat océanique serait à l'origine de cette dynamique en évaluant les corrélations avec des séries temporelles de données atmosphériques et d'états de surface de l'océan ; (3) quantifier les conséquences de cette dynamique spatiale sur le stockage du carbone en mangrove. Les résultats ont montré qu'environ 15 000 ha de mangrove fluctuent à l'échelle multi-décennale en opposition avec les phases de l'Oscillation Nord Atlantique (NAO), principal mode de variabilité atmosphérique en Atlantique Nord. Le lien est opéré par l'intermédiaire des vagues océaniques dont l'énergie est modulée par les phases de la NAO. L'étude suggère que la diminution des surfaces de mangrove est la conséquence de périodes où les vagues sont puissantes (phase NAO+), ce qui favorise l'érosion côtière, la remise en suspension des sédiments et leur transport le long de la côte. Au contraire, les périodes où les vagues sont faibles (phase NAO-) favorisent le dépôt des sédiments, ce qui est à l'origine de l'expansion des surfaces de mangrove. Les résultats montrent que l'alternance entre des périodes d'expansion et de retrait génère une mosaïque d'âges de mangrove qui détermine la capacité de stockage du carbone par l'écosystème. A partir de ce dernier résultat, l'étude suggère qu'au cours du temps la mangrove puisse alternativement passer d'une fonction de puis à celle de source de carbone pour l'océan côtier et l'atmosphère. / Mangroves in French Guiana are characterized by their spatial dynamism. This specificity is the result of intense coastal sedimentary processes. The goals of this study are to: (1) quantify mangrove spatial dynamics on a regional level and a multi-decadal timescale using archives of remote sensing images; (2) test the hypothesis of the role played by the atmosphere using correlations with time series of atmospheric and ocean surface reanalysis datasets; (3) quantify consequence of this spatial dynamism on coastal carbon storage. Results showed that approximatively 15 000 ha of mangroves fluctuate on a multi-decadal timescale in opposition to the North Atlantic Oscillation (NAO) phases, the main mode of atmospheric multi-decadal variability in the North Atlantic. This relation is operated by ocean waves whose energy is modulated by NAO phases. The study suggests that, on the one hand, decrease of mangrove surface areas is due to periods of high wave energy (NAO+) which favour coastal erosion and mangrove retreat, sediment resuspension and transport. On the other hand, the study suggests that periods of low wave energy (NAO-) favour sediment deposition on the coast and is at the origin of mangrove surface area expansion. Results also showed that alternation between phases of retreat and expansion generates the demographic structure of mangrove ages, which determines the mangrove carbon storage capacity. The study finally suggests that through time mangrove can switch from a source to a sink of carbon, and vice and versa, for the ocean and the atmosphere.

Les processus de bioturbation constituent un exemple classique d’ingénierie de l’écosystème. Ils sont le fait d’espèces bioturbatrices qui contribuent à la structuration physique et biogéochimique des environnements sédimentaires. Dans les environnements marins meubles, les thalassinidés comptent parmi les bioturbateurs les plus influents. Ainsi, la crevette de vase Upogebia cf. pusilla est à l’origine d’un important remaniement sédimentaire et d’une large bioirrigation des sédiments dans le bassin d’Arcachon. Ces activités de bioturbation modulent les processus de minéralisation de la matière organique et les flux biogéochimiques à l’interface eau-sédiment. L’intensité de la bioturbation de U. cf. pusilla dépend de son état physiologique, celui-ci pouvant être altéré par divers facteurs de stress. Une approche couplant études de terrain et expérimentations en laboratoire a permis d’évaluer l’influence du parasitisme et de la contamination métallique sur les activités de U. cf. pusilla. Ce travail avait pour objectifs de (1) caractériser la pression parasitaire chez U. cf. pusilla à l’échelle locale, (2) déterminer les niveaux de base des éléments métalliques chez cet organisme dans le bassin d’Arcachon et d’évaluer le potentiel rôle des parasites dans les processus d’accumulation des métaux et (3) estimer l’impact du parasitisme et de la contamination métallique, seuls et en interaction, sur U. cf. pusilla et ce à deux échelles d’organisation, moléculaire et comportementale. In situ, un suivi spatial et un suivi temporel ont permis de caractériser la dynamique spatio-temporelle de deux parasites chez U. cf. pusilla¸ un bopyre infestant la cavité branchiale (Gyge branchialis), et un trématode (Maritrema sp.), infectant l’ensemble des organes de l’animal. Au sein de leur hôte, ces deux parasites sont négativement associés, le bopyre limitant probablement les processus d’infection par le trématode. Par ailleurs, un suivi saisonnier d’un an a permis de noter de faibles concentrations en métaux chez U. cf. pusilla, dans le bassin d’Arcachon. Ces concentrations ont été mises en parallèle avec le statut parasitaire des spécimens échantillonnés. Aucune corrélation n’a été notée entre la présence des trématodes et les quantités de métaux accumulées. A l’inverse, les observations de terrain ont permis d’envisager que le parasite bopyre puisse interférer avec les processus d’accumulation des métaux chez cet organisme. Cette dernière hypothèse a été testée en laboratoire au cours d’expérimentations visant à évaluer l’influence d’une contamination métallique (en utilisant le cadmium comme contaminant modèle) et du parasite bopyre, seuls et en interaction, sur U. cf. pusilla. A l’échelle moléculaire, le bopyre n’a été associé à aucune modification de l’expression d’une dizaine de gènes cibles. Par ailleurs, à l’échelle comportementale, ce parasite réduit peu le remaniement sédimentaire de son hôte, à l’inverse de ce qui avait été montré au cours d’une étude antérieure. En ce qui concerne l’influence du cadmium, ce métal module amplement l’expression de gènes codant notamment des protéines impliquées dans la réponse au stress oxydant et dans les mécanismes de détoxication. Ces observations suggèrent que U. cf. pusilla est capable de mettre en place des mécanismes de lutte contre le stress métallique. Au niveau comportemental, le cadmium semble stimuler le remaniement sédimentaire des organismes. Finalement, les expériences « doubles stress » ont montré un effet antagoniste du bopyre et du cadmium à la fois à l’échelle génique et à l’échelle comportementale. Ainsi, cette étude souligne la complexité des interactions entre facteurs de stress multiples et la nécessité d’effectuer de telles expérimentations. [...] / Bioturbation is a typical example of ecosystem engineering. Bioturbating species are mainly epi- or endobenthic organisms, which profoundly affect the physical structure and biogeochemical properties of sediments. In marine soft-bottom environments, thalassinidean mud shrimp are considered as one of the most prominent bioturbating organisms. Among these species is the mud shrimp Upogebia cf. pusilla, which is recognized as an important sediment reworker, also significantly contributing to the bioirrigation of sediments. In fine, this species greatly modulates organic matter mineralization and biogeochemical fluxes at the sediment-water interface. The influence of U. cf. pusilla in ecosystem functioning depends on the intensity of its bioturbation and thus on its fitness. Several factors can affect the physiological status of organisms, potentially resulting in behavioural changes and causing modifications of their activities. Amongst potential stressors, we evaluated the influence of parasitism and trace metal contamination on the mud shrimp U. cf. pusilla in Arcachon Bay, France. Field surveys and laboratory experiments were undertaken in order to evaluate (1) the parasite infestation levels in the mud shrimp at the local scale, (2) the metal contamination background and potential relationship between the metal accumulation and the parasitic status of organisms in the field and (3) estimate the distinct and interactive impacts of parasitism and metal contamination on two scales of organisation, by targeting a molecular (gene expression) and a behavioural (sediment reworking) endpoint.A large spatial and temporal survey conducted in Arcachon Bay showed that at least two parasites species occur in mud shrimp: a bopyrid isopod (Gyge branchialis), living in one of the gill chambers of its host, and a trematode parasite (Maritrema sp.), infecting the whole body of mud shrimp. These two parasite species are negatively associated within their host, in which the bopyrid likely interferes with trematodes establishment. Additionally, a one year seasonal sampling demonstrated that mud shrimp displayed very low levels of metals in Arcachon Bay. The bopyrid parasite could interfere with the process of metal accumulation in mud shrimp, while such correlation was not found for the trematode parasite. Finally, complementary laboratory experiments highlighted that, at the molecular level, the bopyrid parasite did not affect the expression of the genes targeted in this study in mud shrimp. Similarly, at the behavioural level, and conversely to a previous study, the effects of the bopyrid parasite were minor, i.e. only associated to small modifications of the bioturbation activity of its host. Indeed, the intensity of the sediment reworking of mud shrimp was slightly reduced when organisms were infested with this parasite. Regarding trace metal contamination, we noticed that mud shrimp largely accumulated cadmium. This accumulation was associated to an important modulation of gene expression, especially of genes encoding proteins involved in detoxification processes, highlighting, at this organisation level, the capability of mud shrimp to deal with the deleterious effect of cadmium. At the behavioural scale, cadmium contamination positively affected the sediment reworking activity of mud shrimp. Finally, double-stress experiments evidenced an antagonistic effect of both stressors on the two targeted endpoints. This study highlights the complexity of the interactions between multiple stressors and that the response of organisms cannot be predicted from “single-stress” experiments. [...]

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Red mud is the waste from alumina production, contain high amount of residual alkaline, aluminate and some metals oxide such as iron oxide, silicon oxide, titanium oxide...; in which aluminum and silica proportions could be used for zeolite synthesis. The zeolite was synthesized by the hydrothermal method for obtaining RM-ZeO-Si which was signed for Si added and RM-ZeO- Si- Al for both Si and Al added. The obtained zeolites were then characterized by the XRD, EDX, SEM, BET and FT-IR methods. The results indicate that the synthesized zeolite is likely the new kind one with one surfur atom in the crystaline unit and has general formula of Na8(Al6Si6O24)S.4H2O. We tested the ability of ammonium and nitrite adsorption of the synthesized zeolites and found that the synthesized zeolites had very high adsorption capacity of both cation ammonium and anion nitrite; but the adsorption mechanism of each was different. Adsorption mechanism of ammonium was suggested as predominant ion exchange between ammonium cation in solution and sodium cation in zeolite crystals; while nitrite adsorbed on surface material by electrostatic attractive force between nitrite anion and electropositive surface of iron oxide particles. / Bùn đỏ là chất thải từ quá trình sản xuất nhôm, chứa lượng lớn kiểm, oxit nhôm và một số oxit khác như sắt oxit, silic oxit, titan oxit…trong đó tỷ lệ nhôm và silic có thể sử dụng để tổng hợp zeolit. Vật liệu zeolit được tổng hợp bằng phương pháp thủy nhiệt, thêm Si được ký hiệu là RMZeO- Si; vật liệu thêm đồng thời Si, Al được ký hiệu là RM- ZeO-Si/Al. Vật liệu zeolit tổng hợp được phân tích đặc trưng cấu trúc bằng các phương pháp XRD, EDX, SEM, BET và FT-IR. Các kết quả phân tích cho thấy vật liệu zeolit tổng hợp có điểm mới khác biệt so với các zeolit thông thường bởi trong cấu trúc phân tử có chứa nguyên tử S, công thức phân tử của zeolit là Na8(Al6Si6O24)S.4H2O. Kết quả khảo sát hấp phụ ban đầu cho thấy vật liệu có khả năng hấp phụ với cả ion amoni và nitrit, cơ chế hấp phụ khác nhau. Quá trình hấp phụ cation amoni là do quá trình trao đổi ion giữa cation amoni với cation natri trong tinh thể zeolit, còn quá trình hấp phụ nitrit trên bề mặt vật liệu do tương tác tĩnh điện giữa nitrit với các cấu tử oxit sắt.