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| Registros recuperados: 42 | |
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| Bayon, Germain; Burton, K. W.; Soulet, Guillaume; Vigier, N.; Dennielou, Bernard; Etoubleau, Joel; Ponzevera, Emmanuel; German, C. R.; Nesbitt, R. W.. |
| The combined use of Lu-Hf and Sm-Nd isotope systems potentially offers a unique perspective for investigating continental erosion, but little is known about whether, and to what extent, the Hf-Nd isotope composition of sediments is related to silicate weathering intensity. In this study, Hf and Nd elemental and isotope data are reported for marine muds, leached Fe-oxide fractions and zircon-rich turbidite sands collected off the Congo River mouth, and from other parts of the SE Atlantic Ocean. All studied samples from the Congo fan (muds, Fe-hydroxides, sands) exhibit indistinguishable Nd isotopic composition (epsilon(Nd)similar to - 16), indicating that Fe-hydroxides leached from these sediments correspond to continental oxides precipitated within the... |
| Tipo: Text |
Palavras-chave: Congo fan; Seawater array; Continental erosion; Silicate weathering; Hafnium isotopes; Neodymium isotopes. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6451.pdf |
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| Gueguen, Bleuenn; Rouxel, Olivier; Ponzevera, Emmanuel; Bekker, Andrey; Fouquet, Yves. |
| Although initial studies have demonstrated the applicability of Ni isotopes for cosmochemistry and as a potential biosignature, the Ni isotope composition of terrestrial igneous and sedimentary rocks, and ore deposits remains poorly known. Our contribution is fourfold: (a) to detail an analytical procedure for Ni isotope determination, (b) to determine the Ni isotope composition of various geological reference materials, (c) to assess the isotope composition of the Bulk Silicate Earth relative to the Ni isotope reference material NIST SRM 986 and (d) to report the range of mass-dependent Ni isotope fractionations in magmatic rocks and ore deposits. After purification through a two-stage chromatography procedure, Ni isotope ratios were measured by MC-ICP-MS... |
| Tipo: Text |
Palavras-chave: Nickel; Stable isotopes; MC-ICP-MS; Geological reference materials; Bulk Silicate Earth; Abiotic fractionation. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00159/27069/25332.pdf |
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| Ratie, G.; Quantin, C.; Maia De Freitas, A.; Echevarria, G.; Ponzevera, Emmanuel; Garnier, J.. |
| Ultramafic derived soils are characterized by low nutrient soils, a low Ca:Mg ratio, and high metal contents such as Ni, Co and Cr. The vegetation growing on these soils is highly adapted and includes both Ni hyperaccumulator and accumulator species. Today, approximately 530 Ni hyperaccumulator species are listed worldwide and the Ni concentration can be extremely high, e.g. up to 25% in latex from Pycnandra acuminata (Sapotaceae), a tree found in New Caledonia. The aim of this study is to identify the potential role of Ni hyperaccumulator plants in the Ni biogeochemical cycle at the soil surface by using Ni isotopes. A set of Ni hyperaccumulator and Ni accumulator plants as well as topsoils were sampled on the Barro Alto and Niquelândia ultramafic... |
| Tipo: Text |
Palavras-chave: Nickel; Isotope; Ni hyperaccumulator species; Ultramafic environment. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00464/57565/59740.pdf |
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| Chever, Fanny; Rouxel, Olivier; Croot, Peter L.; Ponzevera, Emmanuel; Wuttig, Kathrin; Auro, Maureen. |
| Vertical distributions of iron (Fe) concentrations and isotopes were determined in the total dissolvable and dissolved pools in the water column at three coastal stations located along the Peruvian margin, in the core of the Oxygen Minimum Zone (OMZ). The shallowest station 121 (161 m total water depth) was characterized by lithogenic input from the continental plateau, yielding concentrations as high as 456 nM in the total dissolvable pool. At the 2 other stations (stations 122 and 123), Fe concentrations of dissolved and total dissolvable pools exhibited maxima in both surface and deep layers. Fe isotopic composition (δ56Fe) showed a fractionation toward lighter values for both physical pools throughout the water column for all stations with minimum... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00266/37715/35733.pdf |
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| Bayon, Germain; Toucanne, Samuel; Skonieczny, Charlotte; Andre, L.; Bermell, Sylvain; Cheron, Sandrine; Dennielou, Bernard; Etoubleau, Joel; Freslon, Nicolas; Gauchery, T.; Germain, Yoan; Jorry, Stephan; Menot, G.; Monin, L.; Ponzevera, Emmanuel; Rouget, M. -l.; Tachikawa, K.; Barrat, Jean-alix. |
| Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world’s major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes. Our results... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00276/38733/37249.pdf |
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| Quetel, Christophe R.; Ponzevera, Emmanuel; Rodushkin, Ilia; Gerdes, Axel; Williams, Ross; Woodhead, Jon. |
| A blind comparison on Pb-isotope delta-scale measurements by MC-ICPMS of 0.01 parts per thousand to 0.1 parts per thousand level was organised, involving five laboratories. Test samples were obtained from the series of candidate ERM-3810 delta-isotopic Certified Reference Materials (delta-iCRMs), and comprise four pairs of a material with similar to natural Pb-isotopic composition ('delta zero' or 'delta-0') and the same natural Pb progressively enriched in Pb-207 (with delta Pb-207 values certified to similar to 0.1% relative uncertainty, k = 2). Participants were free to apply the measurement strategy of their choice. A result was considered 'acceptable' only when, simultaneously, there was agreement within stated uncertainties with the corresponding... |
| Tipo: Text |
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| Ano: 2009 |
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| Ferreira Araujo, Daniel; Ponzevera, Emmanuel; Briant, Nicolas; Knoery, Joel; Bruzac, Sandrine; Sireau, Teddy; Brach-papa, Christophe. |
| Toulon bay is severely impacted by metal contamination induced by past and recent naval activities. In this work, Cu, Zn and Pb isotope compositions and elemental concentrations of fifty-five surface sediments were determined in order to map the spatial distribution of anthropogenic and natural sources along this land-sea continuum. Two sub-systems of Toulon Bay, the Small and Large bays, showed well-marked patterns on metal contamination levels and isotope signatures for Cu and Pb. The Small bay had the highest metal concentrations, and displayed average Pb and Cu isotope compositions of 1.1664 ± 0.0043 (1s, expressed as 206Pb/207Pb ratios) and −0.17 ± 0.19‰ (1s, expressed as δ65CuNIST values), respectively. It contrasted with the Large bay, with moderate... |
| Tipo: Text |
Palavras-chave: Metal isotopes; Isotope tracers; Geochemical isotopes; Environmental pollution; Coastal pollution; Toulon bay. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00566/67784/67226.pdf |
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| Fujii, Toshiyuki; Moynier, Frederic; Agranier, Arnaud; Ponzevera, Emmanuel; Abe, Minori; Uehara, Akihiro; Yamana, Hajimu. |
| Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand exchange reactions of them. In order to deepen the knowledge of Tl chemistry, we investigated fractionation of Tl stable isotopes (Tl-203 and Tl-205) in a chemical exchange system. Tl isotopes were fractionated in a liquid-liquid extraction system, in which aqueous and organic phases are hydrochloric acid solution and dichloroethane including a crown ether, respectively. After purification by ion-exchange chemistry, the isotope ratio of Tl-205/Tl-203 in equilibrated aqueous phase was measured precisely by multiple-collector-inductively-coupled-plasma-mass-spectrometry. A large isotope fractionation > 1 aEuro degrees was found. Electronic structures of... |
| Tipo: Text |
Palavras-chave: Thallium; Isotope fractionation; Redox; Ligand exchange; Nuclear field shift; Ab initio calculation. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00135/24624/22691.pdf |
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| 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 |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00152/26358/24440.pdf |
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| Bouchoucha, Marc; Tomasino, Corinne; Amouroux, Isabelle; Andral, Bruno; Brach-papa, Christophe; Briand, Marine; Buchet, Remi; Delmas, Lucile; Galgani, François; Gonzalez, Jean-louis; Grouhel-pellouin, Anne; Mauffret, Aourell; Mille, Tiphaine; Munaron, Dominique; Ponzevera, Emmanuel; Wessel, Nathalie; Boissery, Pierre. |
| Ce rapport fait le bilan de la surveillance de la contamination chimique opérée par l’Ifremer, en partenariat avec l’agence de l’eau Rhône Méditerranée Corse, entre 1998 et 2018. Il présente sur la forme de graphiques et de cartes les principaux résultats obtenus durant cette période ainsi que l’évolution des méthodes et des stratégies de surveillance des eaux côtières de Méditerranée. |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00673/78554/80744.pdf |
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| Gueguen, Bleuenn; Rouxel, Olivier; Rouget, Marie-laure; Bollinger, Claire; Ponzevera, Emmanuel; Germain, Yoan; Fouquet, Yves. |
| Ferromanganese (Fe-Mn) crusts are potential archive of the Ni isotope composition of seawater through time. In this study we aim at (1) understanding Ni isotope fractionation mechanisms and metal enrichment processes in Fe-Mn deposits, (2) addressing global vs. local control of Ni isotope composition of these deposits. Two Fe-Mn crusts from the North Pacific Ocean (Apuupuu Seamount, Hawaii) and two Fe-Mn crusts from the South Pacific Ocean (near Rurutu Island, Austral archipelago of French Polynesia) were characterized for their elemental geochemistry and Ni isotope composition. Geochemical analyses were performed at millimeter intervals in order to provide time-resolved record of Ni isotopes. Chronology and growth rates were determined using cosmogenic... |
| Tipo: Text |
Palavras-chave: Ferromanganese crusts; Nickel isotopes; Paleoceanography; Pacific Ocean; Biogeochemical cycling. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00341/45255/44696.pdf |
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| Ruffine, Livio; Germain, Yoan; Polonia, Alina; De Prunele, Alexis; Croguennec, Claire; Donval, Jean-pierre; Pitel-roudaut, Mathilde; Ponzevera, Emmanuel; Caprais, Jean-claude; Brandily, Christophe; Grall, Celine; Bollinger, Claire; Geli, Louis; Gasperini, Luca. |
| Within the Sea of Marmara, the highly active North Anatolian Fault (NAF) is responsible for major earthquakes (Mw>=7), and acts as a pathway for fluid migration from deep sources to the seafloor. This work reports on pore water geochemistry from three sediment cores collected in the Gulfs of Izmit and Gemlik, along the Northern and the Middle strands of the NAF, respectively. The resulting data set shows that anaerobic oxidation of methane (AOM) is the major process responsible for sulfate depletion in the shallow sediment. In the Gulf of Gemlik, depth concentration profiles of both sulfate and alkalinity exhibit a kink-type profile. The Sulfate Methane Transition Zone (SMTZ) is located at moderate depth in the area. In the Gulf of Izmit, the low... |
| Tipo: Text |
Palavras-chave: Anaerobic oxidation of methane; North Anatolian Fault; Pore water geochemistry; Sea of Marmara; Seismic activity. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00272/38339/36570.pdf |
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| Bayon, Germain; Delvigne, C.; Ponzevera, Emmanuel; Borges, A. V.; Darchambeau, F.; De Deckker, P.; Lambert, T.; Monin, L.; Toucanne, Samuel; Andre, L.. |
| The δ30Si stable isotopic composition of silicon in soils and fine-grained sediments can provide insights into weathering processes on continents, with important implications on the Si budget of modern and past oceans. To further constrain the factors controlling the distribution of Si isotopes in sediments, we have analysed a large number (n=50) of separate size-fractions of sediments and suspended particulate materials collected near the mouth of rivers worldwide. This includes some of the world’s largest rivers (e.g. Amazon, Congo, Mackenzie, Mississippi, Murray-Darling, Nile, Yangtze) and rivers from the case study areas of the Congo River Basin and Northern Ireland. Silt-size fractions exhibit a mean Si isotopic composition (δ30Si = -0.21 ± 0.19‰; 2... |
| Tipo: Text |
Palavras-chave: World rivers; Congo basin; Northern Ireland; Si isotopes; Clay minerals; Weathering; Temperature; Precipitation. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00434/54609/55991.pdf |
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| Bayon, Germain; Dennielou, Bernard; Etoubleau, Joel; Ponzevera, Emmanuel; Toucanne, Samuel; Bermell, Sylvain. |
| About 3000 years ago, a major vegetation change occurred in Central Africa, when rainforest trees were abruptly replaced by savannas. The consensus is that the forest disturbance was caused by climate change. We show here that chemical weathering in Central Africa, reconstructed from geochemical analyses of a marine sediment core, intensified abruptly at the same period, departing significantly from the long-term weathering fluctuations related to the Late Quaternary climate. Evidence that this weathering event was also contemporaneous with the migration of Bantu-speaking farmers across Central Africa suggests that human land-use intensification at that time already had a significant impact on the rainforest. |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00069/18031/15574.pdf |
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| Ruffine, Livio; Fandino Torres, Olivia; Etoubleau, Joel; Cheron, Sandrine; Donval, Jean-pierre; Germain, Yoan; Ponzevera, Emmanuel; Guyader, Vivien; Dennielou, Bernard; Etiope, Giuseppe; Gasperini, Luca; Bortoluzzi, Giovanni; Henry, Pierre; Grall, Celine; Cagatay, M. Namik; Charlou, Jean-luc; Geli, Louis. |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00139/24982/23065.pdf |
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| Registros recuperados: 42 | |
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