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| Pichevin, Laetitia; Bard, Edouard; Martinez, Philippe; Billy, Isabelle. |
| Modern seawater profiles of oxygen, nitrate deficit, and nitrogen isotopes reveal the spatial decoupling of summer monsoon-related productivity and denitrification maxima in the Arabian Sea (AS) and raise the possibility that winter monsoon and/or ventilation play a crucial role in modulating denitrification in the northeastern AS, both today and through the past. A new high-resolution 50-ka record of delta(15) N from the Pakistan margin is compared to five other denitrification records distributed across the AS. This regional comparison unveils the persistence of east-west heterogeneities in denitrification intensity across millennial-scale climate shifts and throughout the Holocene. The oxygen minimum zone (OMZ) experienced east-west swings across... |
| Tipo: Text |
Palavras-chave: Marine N cycle; Abrupt climate changes; Arabian Sea. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00233/34461/32865.pdf |
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| Schmidt, Sabine; Gonzalez, Jean-louis; Lecroart, Pascal; Tronczynski, Jacek; Billy, Isabelle; Jouanneau, Jean-marie. |
| Quantifier les processus de remaniement sédimentaire procure une vision nouvelle du fonctionnement des écosystèmes benthiques de l'étang de Thau, lieu d'une importante production ostréicole. Afin d'évaluer les taux de bioturbation des sédiments de surface, des profils de deux traceurs radioactifs, le béryllium 7Be (T1/2 = 53 jours) et le thorium 234Th (T1/2 = 24.1 jours) ont été mesurés à partir de carottes sédimentaires prélevées entre décembre 2001 et décembre 2006. La sélection de plusieurs sites a permis de couvrir la diversité de l'étang de Thau : C4, T10, et T11 dans le bassin central, C5, T7 et T8 au niveau des secteurs ostréicoles, T2 et T4 à l'ouest du bassin, et T12 à l'est près de la zone industrielle. Le 234Th en excès (234Thxs ; i.e. apporté... |
| Tipo: Text |
Palavras-chave: Mediterranean Lagoon; Radionuclides; Biodeposition; Sedimentation. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2584.pdf |
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| Denis, Delphine; Crosta, Xavier; Schmidt, Sabine; Carson, Damien S.; Ganeshram, Raja S.; Renssen, Hans; Crespin, Julien; Ther, Olivier; Billy, Isabelle; Giraudeau, Jacques. |
| This study presents the first high-resolution multiproxy investigation of primary productivity ( PP) during the Holocene from the Antarctic continental margins. Micropaleontological and geochemical data from the sediment core MD03-2601, associated to sea ice model outputs, give unprecedented insights into the biological pump of the Antarctic coastal area off Adelie Land in response to climatic changes. Plurimillennial and millennial changes of PP are observed in the study area in response to changes in nutrient availability, stratification, and growing season duration, which are linked to sea ice, upwelling, wind, and glacier dynamics. The precessional cycle seems to be responsible in the PP long-term variations, while forcing factors involved at the... |
| Tipo: Text |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32930/31442.pdf |
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| Montero-serrano, Jean-carlos; Bout-roumazeilles, Viviane; Carlson, Anders E.; Tribovillard, Nicolas; Bory, Aloys; Meunier, Guillaume; Sionneau, Thomas; Flower, Benjamin P.; Martinez, Philippe; Billy, Isabelle; Riboulleau, Armelle. |
| The comparison of geochemical and mineralogical characteristics of terrigenous sediments deposited in the northern Gulf of Mexico (GoM) during the Holocene and Last Interglacial (LIG) is used to document the impact of slight differences in insolation and ice-sheet retreat rates on moisture transfer and precipitation patterns over central North America. The records indicate distinct sedimentological signatures over the two time periods, which likely reflect a modification of the main detrital provenance during the LIG compared to the Holocene. Here we postulate that the observed differences in the terrigenous supply during the LIG relative to the Holocene reflect a northeast migration of the main precipitation belt over the Mississippi River watershed... |
| Tipo: Text |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00227/33833/32460.pdf |
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| Caley, Thibaut; Extier, Thomas; Collins, James A.; Schefuss, Enno; Dupont, Lydie; Malaize, Bruno; Rossignol, Linda; Souron, Antoine; Mcclymont, Erin L.; Jimenez-espejo, Francisco J.; Garcia-comas, Carmen; Eynaud, Frederique; Martinez, Philippe; Roche, Didier M.; Jorry, Stephan; Charlier, Karine; Wary, Melanie; Gourves, Pierre-yves; Billy, Isabelle; Giraudeau, Jacques. |
| The past two million years of eastern African climate variability is currently poorly constrained, despite interest in understanding its assumed role in early human evolution1,2,3,4. Rare palaeoclimate records from northeastern Africa suggest progressively drier conditions2,5 or a stable hydroclimate6. By contrast, records from Lake Malawi in tropical southeastern Africa reveal a trend of a progressively wetter climate over the past 1.3 million years7,8. The climatic forcings that controlled these past hydrological changes are also a matter of debate. Some studies suggest a dominant local insolation forcing on hydrological changes9,10,11, whereas others infer a potential influence of sea surface temperature changes in the Indian Ocean8,12,13. Here we show... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00449/56059/57581.pdf |
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