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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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| Frings, Patrick J.; Clymans, Wim; Fontorbe, Guillaume; De La Rocha, Christina L.; Conley, Daniel J.. |
| The silicon isotope composition of biogenic silica (delta Si-30(BSi)) in the ocean is a function of the delta Si-30 of the available dissolved Si (DSi; H2SiO4), the degree of utilisation of the available DSi, and, for some organisms, the concentration of DSi. This makes delta Si-30(BSi) in sediment archives a promising proxy for past DSi concentrations and utilisation. At steady-state, mean delta Si-30(BSi) must equal a weighted average of the inputs, the majority of which are of continental origin. Variation in the functioning of the continental Si cycle on timescales similar to the residence time of DSi in the ocean (similar to 10 ka) may therefore contribute to downcore variability in delta Si-30(BSi) on millennial or longer time-scales. The direction... |
| Tipo: Text |
Palavras-chave: Global silicon cycle; Biogenic silica; Silicon isotopes; LGM; Palaeoceanography; Biogeochemical cycling. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53252/54714.pdf |
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| Dickow,Kauana Melissa Cunha; Marques,Renato; Pinto,Carolina Benghi. |
| The aim of this work was to analyze the concentration of N, P, K, Ca and Mg in mature and litter leaves and nutrient mobilization in leaves of different tree species from secondary forests of the Atlantic Forest. At the study site, located in Floresta do Palmito (Paranaguá, PR), three different forest typologies namely Initial, Intermediary and Advanced were selected. The predominant sequence of nutrients in litter leaves was: N > Ca > Mg > K > P. This sequence was very similar to that found for mature leaves, the difference being only the change in order between Mg and K. Nutrients mobilized in leaves were higher in the typology Advanced compared to the typology Initial, mainly N, P and K. The majority of the species studied did not mobilize... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Atlantic forest; Biogeochemical cycling; Forest nutrition; Brazil. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132009000500006 |
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