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| Fonseca-batista, Debany; Dehairs, Frank; Riou, Virginie; Fripiat, Francois; Elskens, Marc; Deman, Florian; Brion, Natacha; Queroue, Fabien; Bode, Maya; Auel, Holger. |
| Euphotic layer dinitrogen (N-2) fixation and primary production (PP) were measured in the eastern Atlantic Ocean (38 degrees N-21 degrees S) using N-15(2) and C-13 bicarbonate tracer incubations. This region is influenced by Saharan dust deposition and waters with low nitrogen to phosphorus (N/P) ratios originating from the Subantarctic and the Benguela upwelling system. Depth-integrated rates of N-2 fixation in the north (0 degrees N-38 degrees N) ranged from 59 to 370 mu mol N m(-2) d(-1), with the maximal value at 19 degrees N under the influence of the northwest African upwelling. Diazotrophic activity in the south (0 degrees S-21 degrees S), though slightly lower, was surprisingly close to observations in the north, with values ranging from 47 to 119... |
| Tipo: Text |
Palavras-chave: Nitrogen fixation; Atlantic Ocean; Primary production. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00379/49009/49451.pdf |
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| Fonseca-batista, Debany; Li, Xuefeng; Riou, Virginie; Michotey, Valérie; Deman, Forian; Fripiat, François; Guasco, Sophie; Brion, Natacha; Lemaitre, Nolwenn; Tonnard, Manon; Gallinari, Morgane; Planquette, Hélène; Planchon, Frédéric; Sarthou, Géraldine; Elskens, Marc; Laroche, Julie; Chou, Lei; Dehairs, Frank. |
| Diazotrophic activity and primary production (PP) were investigated along two transects (Belgica BG2014/14 and GEOVIDE cruises) off the western Iberian Margin and the Bay of Biscay (38.8–46.5°N; 8.0–19.7°W) in May 2014 close to the end of the spring bloom. We report substantial N2 fixation activities, reaching up to 65nmolNL−1d−1 and 1533µmolNm−2d−1 close to the Iberian Margin between 38.8°N and 40.7°N. Similar figures in the basin have only been reported in the temperate and tropical western North Atlantic waters with coastal, shelf or mesohaline characteristics, as opposed to the mostly open ocean conditions studied here. In agreement with previous studies, the qualitative assessment of nifH gene diversity (encoding the nitrogenase enzyme that fixes N2)... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00461/57266/59317.pdf |
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| Fripiat, Francois; Corvaisier, Rudolph; Navez, Jacques; Elskens, Marc; Schoemann, Veronique; Leblanc, Karine; Andre, Luc; Cardinal, Damien. |
| Regional and seasonal variability of the Si dissolution: production ratios in the surface ocean have not been well assessed. Here, we propose a new method for determining these rates, using the Si-30-isotopic dilution technique with a high-resolution sector field inductively coupled plasma mass spectrometer (HR-SF-ICP-MS). Relative analytical precision of the isotopic measurement is better than 1%, similar to that obtained by thermal ionization-quadrupole mass spectrometry (TIMS). Accuracy and reproducibility of the isotopic measurements have been checked on artificial and natural solutions by intercomparison between two HR-SF-ICP-MS instruments and one TIMS. Measurements of real Si production and dissolution rates are illustrated for two contrasted... |
| Tipo: Text |
Palavras-chave: Isotopic fractionation; Southern ocean; Acid uptake; Waters; Phytoplankton; Environments; Biosilica; Recovery; Balance; Tracer. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00205/31607/30033.pdf |
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