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| Fumenia, Alain; Petrenko, Anne; Loisel, Hubert; Djaoudi, Kahina; De Verneil, Alain; Moutin, Thierry. |
| Using biogeochemical-Argo float measurements, we propose, for the first time, an optical proxy for particulate organic nitrogen concentration (PON) in the Western Tropical South Pacific, an area influenced by dinitrogen (N2) fixation. Our results show a significant relationship between the backscattering coefficient at 700 nm (bbp) and PON, especially when the latter is measured using the wet oxidation method (R2=0.87). bbp may be used to estimate PON concentrations (PONopt) between 0.02 and 0.95 ìM, allowing for unprecedented monitoring using autonomous profiling floats. The bbp vs PON relationship can be used to study phytoplanktonic biomass dynamics at relevant seasonal temporal scales, with clear evidence of PONopt as a proxy of phytoplanktonic... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00640/75226/75367.pdf |
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| Moutin, Thierry; Wagener, Thibaut; Caffin, Mathieu; Fumenia, Alain; Gimenez, Audrey; Baklouti, Melika; Bouruet-aubertot, Pascale; Pujo-pay, Mireille; Leblanc, Karine; Lefevre, Dominique; Nunige, Sandra Helias; Leblond, Nathalie; Grosso, Olivier; De Verneil, Alain. |
| Surface waters (0–200 m) of the western tropical South Pacific (WTSP) were sampled along a longitudinal 4000 km transect (OUTPACE cruise, 18 Feb., 3 Apr. 2015) during the stratified period between the Melanesian Archipelago (MA) and the western part of the SP gyre (WGY). Two distinct areas were considered for the MA, the western MA (WMA) and the eastern MA (EMA). The main carbon (C), nitrogen (N), phosphorus (P) pools and fluxes allow for characterization of the expected trend from oligotrophy to ultra-oligotrophy, and to build first-order budgets at the daily and seasonal scales (using climatology). Sea surface chlorophyll a reflected well the expected oligotrophic gradient with higher values obtained at WMA, lower values at WGY and intermediate values at... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00420/53113/54067.pdf |
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| Fumenia, Alain; Moutin, Thierry; Bonnet, Sophie; Benavides, Mar; Petrenko, Anne; Helias Nunige, Sandra; Maes, Christophe. |
| As part of the Oligotrophy to UlTra-oligotrophy PACific Experiment cruise, which took place in the Western Tropical South Pacific during the austral summer (March–April 2015), we present data on nitrate, phosphate and on particulate and dissolved organic matter. The stoichiometric nitrogen-to-phosphorus ratios of the inorganic and organic material and the tracer N* are described. N* allows to trace changes in the proportion of fixed nitrogen due to diazotrophy and/or denitrification. Our results showed that the Melanesian archipelago waters between 160° E and 170° W are characterized by a deficit of nitrate and phosphate in the productive layer, significant dinitrogen fixation rates and an excess of particulate organic nitrogen compared to the canonical... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00422/53383/54232.pdf |
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