Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 62
Primeira ... 1234 ... Última
Imagem não selecionada

Imprime registro no formato completo
A microbiological and biogeochemical investigation of the cold seep tubeworm Escarpia southwardae (Annelida: Siboglinidae): Symbiosis and trace element composition of the tube ArchiMer
Duperron, Sebastien; Gaudron, Sylvie M.; Lemaitre, Nolwenn; Bayon, Germain.
Tubeworms within the annelid family Siboglinidae rely on sulfur-oxidizing autotrophic bacterial symbionts for their nutrition, and are among the dominant metazoans occurring at deep-sea hydrocarbon seeps. Contrary to their relatives from hydrothermal vents, sulfide uptake for symbionts occurs within the anoxic subsurface sediment, in the posterior ‘root’ region of the animal. This study reports on an integrated microbiological and geochemical investigation of the cold seep tubeworm Escarpia southwardae collected at the Regab pockmark (Gulf of Guinea). Our aim was to further constrain the links between the animal and its symbiotic bacteria, and their environment. We show that E. southwardae harbors abundant sulfur-oxidizing bacterial symbionts in its...
Tipo: Text Palavras-chave: Sulfur-oxidizing bacteria; RTCA; Trace elements; RubisCO; Symbiosis.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00191/30251/28683.pdf
Imagem não selecionada

Imprime registro no formato completo
Abrupt drainage cycles of the Fennoscandian Ice Sheet ArchiMer
Soulet, Guillaume; Menot, Guillemette; Bayon, Germain; Rostek, Frauke; Ponzevera, Emmanuel; Toucanne, Samuel; Lericolais, Gilles; Bard, Edouard.
Continental ice sheets are a key component of the Earth’s climate system, but their internal dynamics need to be further studied. Since the last deglaciation, the northern Eurasian Fennoscandian Ice Sheet (FIS) has been connected to the Black Sea (BS) watershed, making this basin a suitable location to investigate former ice-sheet dynamics. Here, from a core retrieved in the BS, we combine the use of neodymium isotopes, high-resolution elemental analysis, and biomarkers to trace changes in sediment provenance and river runoff. We reveal cyclic releases of meltwater originating from Lake Disna, a proglacial lake linked to the FIS during Heinrich Stadial 1. Regional interactions within the climate–lake–FIS system, linked to changes in the availability of...
Tipo: Text Palavras-chave: Ice dynamics; Meltwater routing; European hydrographic network.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00134/24489/22516.pdf
Imagem não selecionada

Imprime registro no formato completo
Abrupt response of chemical weathering to Late Quaternary hydroclimate changes in northeast Africa ArchiMer
Bastian, Luc; Revel, Marie; Bayon, Germain; Dufour, Aurelie; Vigier, Nathalie.
Chemical weathering of silicate rocks on continents acts as a major sink for atmospheric carbon dioxide and has played an important role in the evolution of the Earth’s climate. However, the magnitude and the nature of the links between weathering and climate are still under debate. In particular, the timescale over which chemical weathering may respond to climate change is yet to be constrained at the continental scale. Here we reconstruct the relationships between rainfall and chemical weathering in northeast Africa for the last 32,000 years. Using lithium isotopes and other geochemical proxies in the clay-size fraction of a marine sediment core from the Eastern Mediterranean Sea, we show that chemical weathering in the Nile Basin fluctuated in parallel...
Tipo: Text
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00376/48697/49030.pdf
Imagem não selecionada

Imprime registro no formato completo
African humid periods triggered the reactivation of a large river system in Western Sahara ArchiMer
Skonieczny, Charlotte; Paillou, P.; Bory, A.; Bayon, Germain; Biscara, L.; Crosta, X.; Eynaud, F.; Malaize, B.; Revel, M.; Aleman, N.; Barusseau, J-p.; Vernet, R.; Lopez, S.; Grousset, F..
The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, however, no major river exists in this area; therefore, the origin of these sediments remains unclear. Here, using orbital radar satellite imagery, we present geomorphological data that reveal the existence of a large buried paleodrainage network on the Mauritanian coast. On the basis of evidence from the literature, we propose that reactivation of this major paleoriver...
Tipo: Text
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00303/41381/40559.pdf
Imagem não selecionada

Imprime registro no formato completo
Are deep-sea ecosystems surrounding Madagascar threatened by land-use or climate change? ArchiMer
Fontanier, Christophe; Mamo, Briony; Toucanne, Samuel; Bayon, Germain; Schmidt, Sabine; Deflandre, Bruno; Dennielou, Bernard; Jouet, Gwenael; Garnier, Eline; Sakai, Saburo; Lamas, Ruth Martinez; Duros, Pauline; Toyofuku, Takashi; Sale, Aurelien; Belleney, Deborah; Bichon, Sabrina; Boissier, Audrey; Cheron, Sandrine; Pitel, Mathilde; Roubi, Angelique; Rovere, Mickael; Gremare, Antoine; Dupre, Stephanie; Jorry, Stephan.
In this short communication, we present a multidisciplinaty study of sedimentary records collected from a deep-sea interfluve proximal to the mouths of major northwestern Madagascan rivers. For the last 60 years, the seafloor has been repeatedly disturbed by the deposition of organic rich, tropical, terrestrial sediments causing marked reductions in benthic biodiversity. Increased soil erosion due to local land-use, deforestation and intensifying tropical cyclones are potential causes for this sedimentary budget and biodiversity shift. Our marine sedimentary records indicate that until now, these conditions have not occurred within the region for at least 20,000 years.
Tipo: Text Palavras-chave: Multidisciplinary study; Benthic foraminifera; Land-use; Tropical cyclones.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00413/52488/53276.pdf
Imagem não selecionada

Imprime registro no formato completo
Authigenic carbonates related to active seepage of methane-rich hot brines at the Cheops mud volcano, Menes caldera (Nile deep-sea fan, eastern Mediterranean Sea) ArchiMer
Pierre, Catherine; Bayon, Germain; Blanc-valleron, Marie-madeleine; Mascle, Jean; Dupre, Stephanie.
On the passive margin of the Nile deep-sea fan, the active Cheops mud volcano (MV; ca. 1,500 m diameter, ~20–30 m above seafloor, 3,010–3,020 m water depth) comprises a crater lake with hot (up to ca. 42 °C) methane-rich muddy brines in places overflowing down the MV flanks. During the Medeco2 cruise in fall 2007, ROV dives enabled detailed sampling of the brine fluid, bottom lake sediments at ca. 450 m lake depth, sub-surface sediments from the MV flanks, and carbonate crusts at the MV foot. Based on mineralogical, elemental and stable isotope analyses, this study aims at exploring the origin of the brine fluid and the key biogeochemical processes controlling the formation of these deep-sea authigenic carbonates. In addition to their patchy occurrence in...
Tipo: Text
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00186/29735/28189.pdf
Imagem não selecionada

Imprime registro no formato completo
Behaviour of rare earth and trace elements during fluid venting at cold seeps ArchiMer
Birot, Dominique; Bayon, Germain; Ruffine, Livio; Caprais, Jean-claude; Bollinger, C.; Ponzevera, Emmanuel; Rongemaille, Emmanuelle; Voisset, Michel.
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00023/13414/10493.pdf
Imagem não selecionada

Imprime registro no formato completo
Constraints on the dynamic of gas hydrates in Niger Delta sediments from U/Th dating of cold-seep carbonates ArchiMer
Henderson, Gm; Bayon, Germain; Pierre, C; Caprais, Jean-claude; Voisset, Michel.
Tipo: Text
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3587.pdf
Imagem não selecionada

Imprime registro no formato completo
delta(44/42) Ca in gas hydrates, porewaters and authigenic carbonates from Niger Delta sediments ArchiMer
Henderson, Gm; Chu, Nc; Bayon, Germain; Benoit, M.
Tipo: Text
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3588.pdf
Imagem não selecionada

Imprime registro no formato completo
Description of a contourite depositional system on the Demerara Plateau: Results from geophysical data and sediment cores ArchiMer
Tallobre, Cedric; Loncke, Lies; Bassetti, Maria-angela; Giresse, Pierre; Bayon, Germain; Buscail, Roselyne; De Madron, Xavier Durrieu; Bourrin, Francois; Vanhaesebroucke, Marc; Sotin, Christine.
The Demerara Plateau, belonging to the passive transform margin of French Guiana, was investigated during the IGUANES cruise in 2013. The objectives of the cruise were to explore the poorly-known surficial sedimentary column overlying thick mass transport deposits as well as to understand the factors controlling recent sedimentation. The presence of numerous bedforms at the seafloor was observed thanks to newly acquired IGUANES bathymetric, high resolution seismic and chirp data, while sediment cores allowed the characterization of the deposits covering the mass transport deposits. Modern oceanographic conditions were determined in situ, using mooring monitoring over a 10-month period. Our data indicate the presence of a Contourite Depositional System...
Tipo: Text Palavras-chave: Marginal plateau; Contourite; Comet tail; Demerara Plateau.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00308/41957/41220.pdf
Imagem não selecionada

Imprime registro no formato completo
Determination of rare earth elements and other trace elements (Y, Mn, Co, Cr) in seawater using Tm addition and Mg(OH)(2) co-precipitation ArchiMer
Freslon, Nicolas; Bayon, Germain; Birot, Dominique; Bollinger, Claire; Barrat, Jean-alix.
This paper reports on a novel procedure for determining trace element abundances (REE and Y, Cr, Mn, Co) in seawater by inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The procedure uses a combination of pre-concentration using co-precipitation onto magnesium hydroxides and addition of thulium spike. The validity of the method was assessed onto 25 ml volumes of certified reference materials (NASS- and CASS-4) and in house seawater standard. Procedural blanks were determined by applying the same procedure to aliquots of seawater previously depleted in trace elements by successive Mg(OH)(2) co-precipitations, yielding estimated contributions to the studied samples better than 1.1% for all elements, with the exception of Cr (<3.3%)...
Tipo: Text Palavras-chave: Trace elements; Rare earth elements (REE); Seawater; Mg(OH)(2) co-precipitation; ICP-MS; Thulium.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00041/15220/15855.pdf
Imagem não selecionada

Imprime registro no formato completo
Determination of Rare Earth Elements, Sc, Y, Zr, Ba, Hf and Th in Geological Samples by ICP-MS after Tm Addition and Alkaline Fusion ArchiMer
Bayon, Germain; Barrat, Jean Alix; Etoubleau, Joel; Benoit, Mathieu; Bollinger, Claire; Revillon, Sidonie.
We present a revised method for the determination of concentrations of rare earth (REE) and other trace elements (Y, Sc, Zr, Ba, Hf, Th) in geological samples. Our analytical procedure involves sample digestion using alkaline fusion (NaOH-Na2O2) after addition of a Tm spike, co-precipitation on iron hydroxides, and measurement by sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS). The procedure was tested successfully for various rock types (i.e., basalt, ultramafic rock, sediment, soil, granite), including rocks with low trace element abundances (sub ng g(-1)). Results obtained for a series of nine geological reference materials (BIR-1, BCR-2, UB-N, JP-1, AC-E, MA-N, MAG-1, GSMS-2, GSS-4) are in reasonable agreement with published...
Tipo: Text Palavras-chave: Digestion des Echantillons; Spike de Tm; ICP MS; MatEriaux de rEfErence; Echantillons gEologiques; ElEments du groupe des Terres Rares; Sample digestion; Tm spike; ICP MS; Reference materials; Geological samples; Rare earth elements.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6449.pdf
Imagem não selecionada

Imprime registro no formato completo
Determination of trace elements in seawater by ICP-SFMS after Tm addition and co-precipitation ArchiMer
Freslon, Nicolas; Bayon, Germain; Birot, Dominique; Bollinger, C.; Barrat, J. A..
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00023/13411/10486.pdf
Imagem não selecionada

Imprime registro no formato completo
Determination of ultra-low U-236/U-238 isotope ratios by tandem quadrupole ICP-MS/MS ArchiMer
Tanimizu, Masaharu; Sugiyama, Naoki; Ponzevera, Emmanuel; Bayon, Germain.
Isotope ratios of U-236/U-238 were measured at levels below 10(-7) by single collector ICPMS with a tandem quadrupole mass separation mechanism. Peak tailing of the prominent U-238(+) ion beam on the U-236(+) peak was reduced to the level of similar to 10(-10) by use of two quadrupole mass filters. The (UH+)-U-235 interference on U-236(+) was efficiently reduced to a UH+/U+ ratio of 1 x 10(-8) by an ion-molecule reaction between UH+ and O-2 in a collision/reaction cell placed between the two quadrupoles. The resultant detection limit for U-236/U-238 measurement was better than those reported by any other ICPMS study. The U-236/U-238 ratios, measured as (UO+)-U-236-O-16/(UO+)-U-238-O-16, were determined in the range 10(-9) to 10(-7) without correction for...
Tipo: Text
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00152/26358/24440.pdf
Imagem não selecionada

Imprime registro no formato completo
Dinocyst assemblage constraints on oceanographic and atmospheric processes in the eastern equatorial Atlantic over the last 44 kyr ArchiMer
Hardy, William; Penaud, Aurelie; Marret, Fabienne; Bayon, Germain; Marsset, Tania; Droz, Laurence.
A new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts (dinocysts) is presented from a marine sediment core collected on the Congolese margin with the aim of reconstructing past hydrological changes in the equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. Our high-resolution dinocyst record indicates that significant temperature and moisture variations occurred across the glacial period, the last deglaciation and the Holocene. The use of specific dinocyst taxa, indicative of fluvial, upwelling and Benguela Current past environments for instance, provides insights into the main forcing mechanisms controlling palaeohydrological changes on orbital timescales. In particular, we are able, for the last 44 kyr, to...
Tipo: Text
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00349/46006/45675.pdf
Imagem não selecionada

Imprime registro no formato completo
Environmental Hf–Nd isotopic decoupling in World river clays ArchiMer
Bayon, Germain; Skonieczny, Charlotte; Delvigne, Camille; Toucanne, Samuel; Bermell, Sylvain; Ponzevera, Emmanuel; Andre, Luc.
The hafnium and neodymium radiogenic isotope systems behave differently during Earth surface processes, causing a wide dispersion of Hf and Nd isotopic compositions in sediments and other sedimentary rocks. The decoupling between Hf and Nd isotopes in sediments is generally attributed to a combination of preferential sorting of zircon during sediment transport and incongruent weathering processes on continents. In this study, we analysed size-fractions of sediment samples collected near the mouth of 53 rivers worldwide to better understand the factors controlling the distribution of Hf and Nd isotopes in sediments. Our results for rivers draining old cratonic areas and volcanic provinces demonstrate that both granite and basalt weathering can lead to...
Tipo: Text Palavras-chave: Hafnium isotopes; Neodymium; Rivers; Clays; Weathering; Climate.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00310/42094/41479.pdf
Imagem não selecionada

Imprime registro no formato completo
Evidence and age estimation of mass wasting at the distal lobe of the Congo deep-sea fan ArchiMer
Croguennec, Claire; Ruffine, Livio; Dennielou, Bernard; Baudin, Francois; Caprais, Jean-claude; Guyader, Vivien; Bayon, Germain; Brandily, Christophe; Le Bruchec, Julie; Bollinger, Claire; Germain, Yoan; Droz, Laurence; Babonneau, Nathalie; Rabouille, Christophe.
On continental margins, sulfate reduction occurs within the sedimentary column. It is coupled with the degradation of organic matter and the anaerobic oxidation of methane. These processes may be significantly disturbed by sedimentary events, leading to transient state profiles for the involved chemical species. Yet, little is known about the impact of turbidity currents and mass wasting on the migration of chemical species and the redox reactions in which they are involved. Due to its connection to the River, the Congo deep-sea fan continuously receives huge amount of organic matter-rich sediments primarily transported by turbidity currents, which impact on the development of the associated ecosystems (Rabouille et al., 2016). Thus, it is well suited to...
Tipo: Text
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00363/47410/47403.pdf
Imagem não selecionada

Imprime registro no formato completo
Evidence for intense REE scavenging at cold seeps from the Niger Delta margin ArchiMer
Bayon, Germain; Birot, Dominique; Ruffine, Livio; Caprais, Jean-claude; Ponzevera, Emmanuel; Bollinger, C.; Donval, Jean-pierre; Charlou, Jean-luc; Voisset, Michel; Grimaud, S..
For many trace elements, continental margins are the location of intense exchange processes between sediment and seawater, which control their distribution in the water column, but have yet to be fully understood. In this study, we have investigated the impact of fluid seepage at cold seeps on the marine cycle of neodymium. We determined dissolved and total dissolvable (TD) concentrations for REE and well-established tracers of fluid seepage (CH4, TDFe, TDMn), and Nd isotopic compositions in seawater samples collected above cold seeps and a reference site (i.e. away from any fluid venting area) from the Niger Delta margin. We also analyzed cold seep authigenic phases and various core-top sediment fractions (pore water, detrital component, easily leachable...
Tipo: Text Palavras-chave: Rare earth elements; Neodymium isotopes; Seawater; Cold seeps; Fe-Mn oxyhydroxides; Benthic fluxes.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00066/17754/15571.pdf
Imagem não selecionada

Imprime registro no formato completo
Evolution of neodymium isotopic signature of seawater during the Late Cretaceous: Implications for intermediate and deep circulation ArchiMer
Moiroud, Mathieu; Puceat, Emmanuelle; Donnadieu, Yannick; Bayon, Germain; Guiraud, Michel; Voigt, Silke; Deconinck, Jean-francois; Monna, Fabrice.
Neodymium isotopic compositions (εNd) have been largely used for the last fifty years as a tracer of past ocean circulation, and more intensively during the last decade to investigate ocean circulation during the Cretaceous period. Despite a growing set of data, circulation patterns still remain unclear during this period. In particular, the identification of the deep-water masses and their spatial extension within the different oceanic basins are poorly constrained. In this study we present new deep-water εNd data inferred from the Nd isotope composition of fish remains and Fe-Mn oxyhydroxide coatings on foraminifera tests, along with new εNd data of residual (partly detrital) fraction recovered from DSDP sites 152 (Nicaraguan Rise), 258 (Naturaliste...
Tipo: Text Palavras-chave: Cretaceous; Neodymium isotopes; Ocean circulation; Southern Ocean.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00278/38962/37502.pdf
Imagem não selecionada

Imprime registro no formato completo
Extensive wet episodes in Late Glacial Australia resulting from high-latitude forcings ArchiMer
Bayon, Germain; De Deckker, Patrick; Magee, John W.; Germain, Yoan; Bermell, Sylvain; Tachikawa, Kazuyo; Norman, Marc D..
Millennial-scale cooling events termed Heinrich Stadials punctuated Northern Hemisphere climate during the last glacial period. Latitudinal shifts of the intertropical convergence zone (ITCZ) are thought to have rapidly propagated these abrupt climatic signals southward, influencing the evolution of Southern Hemisphere climates and contributing to major reorganisation of the global ocean-atmosphere system. Here, we use neodymium isotopes from a marine sediment core to reconstruct the hydroclimatic evolution of subtropical Australia between 90 to 20 thousand years ago. We find a strong correlation between our sediment provenance proxy data and records for western Pacific tropical precipitations and Australian palaeolakes, which indicates that Northern...
Tipo: Text
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00375/48585/48906.pdf
Registros recuperados: 62
Primeira ... 1234 ... Última
 

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Embrapa
Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco

Valid HTML 4.01 Transitional