Consulta: creatorFacets:"Helias-nunige, Sandra"
Registros recuperados: 3
Data/hora: 08/06/2024 09:39:21

Sensitive Determination of the Dissolved Phosphate Pool for an Improved Resolution of Its Vertical Variability in the Surface Layer: New Views in the P-Depleted Mediterranean Sea
Provedor de dados: 5
Autores: Djaoudi, Kahina; Van Wambeke, France; Coppola, Laurent; D'Ortenzio, Fabrizio; Helias-nunige, Sandra; Raimbault, Patrick; Taillandier, Vincent; Testor, Pierre; Wagener, Thibaut; Pulido-villena, Elvira.
An accurate understanding of the biogeochemistry of dissolved phosphate pool in the upper waters of P-depleted oceanic regions is constrained by the low sensitivity of routine phosphate measurements. In this study, by using the sensitive Liquid Waveguide Capillary Cell method, we report the first extensive cross-basin survey of nanomolar dissolved inorganic phosphate (DIP) and dissolved organic phosphate (DOP) concentration in P-depleted surface waters of the Mediterranean Sea during the stratification period. In the north western Mediterranean Sea (NWMS), DIP above the mixed layer depth (MLD) ranged between 4.9 and 26.5 nM. Along an E-W transect crossing Ionian and Tyrrhenian Seas (E-W transect), DIP above the MLD was lower, ranging between 0.9 and 11.4...
Tipo: Text
Palavras-chave: The Mediterranean Sea; Dissolved inorganic phosphate; Dissolved organic phosphate; N:P ratios; Liquid waveguide capillary cell.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00450/56184/57731.pdf

N2 fixation as a dominant new N source in the western tropical South Pacific Ocean (OUTPACE cruise)
Provedor de dados: 5
Autores: Caffin, Mathieu; Moutin, Thierry; Foster, Rachel Ann; Bouruet-aubertot, Pascale; Doglioli, Andrea Michelangelo; Berthelot, Hugo; Guieu, Cecile; Grosso, Olivier; Helias-nunige, Sandra; Leblond, Nathalie; Gimenez, Audrey; Petrenko, Anne Alexandra; De Verneil, Alain; Bonnet, Sophie.
We performed nitrogen (N) budgets in the photic layer of three contrasting stations representing different trophic conditions in the western tropical South Pacific (WTSP) Ocean during austral summer conditions (February–March 2015). Using a Lagrangian strategy, we sampled the same water mass for the entire duration of each long-duration (5 days) station, allowing us to consider only vertical exchanges for the budgets. We quantified all major vertical N fluxes both entering (N2 fixation, nitrate turbulent diffusion, atmospheric deposition) and leaving the photic layer (particulate N export). The three stations were characterized by a strong nitracline and contrasted deep chlorophyll maximum depths, which were lower in the oligotrophic Melanesian archipelago...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00439/55074/56503.pdf

In-depth characterization of diazotroph activity across the western tropical South Pacific hotspot of N2 fixation (OUTPACE cruise)
Provedor de dados: 5
Autores: Bonnet, Sophie; Caffin, Mathieu; Berthelot, Hugo; Grosso, Olivier; Benavides, Mar; Helias-nunige, Sandra; Guieu, Cecile; Stenegren, Marcus; Foster, Rachel Ann.
Here we report N2 fixation rates from a  ∼ 4000km transect in the western and central tropical South Pacific, a particularly undersampled region in the world ocean. Water samples were collected in the euphotic layer along a west to east transect from 160°E to 160°W that covered contrasting trophic regimes, from oligotrophy in the Melanesian archipelago (MA) waters to ultra-oligotrophy in the South Pacific Gyre (GY) waters. N2 fixation was detected at all 17 sampled stations with an average depth-integrated rate of 631±286µmol N m−2 d−1 (range 196–1153µmol N m−2 d−1) in MA waters and of 85±79µmol N m−2 d−1 (range 18–172µmol N m−2 d−1) in GY waters. Two cyanobacteria, the larger colonial filamentous Trichodesmium and the smaller UCYN-B, dominated the...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00419/53049/53987.pdf