Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Catherine Pradoux is active.

Publication


Featured researches published by Catherine Pradoux.


Geophysical Research Letters | 2008

Measurement of the isotopic composition of dissolved iron in the open ocean

Francois Lacan; Amandine Radic; Catherine Jeandel; Franck Poitrasson; Géraldine Sarthou; Catherine Pradoux; Rémi Freydier

This work demonstrates for the first time the feasibility of the measurement of the isotopic composition of dissolved iron in seawater for a typical open ocean Fe concentration range (0.1-1nM). It also presents the first data of this kind. Iron is preconcentrated using a Nitriloacetic Acid Superflow resin and purified using an AG1x4 anion exchange resin. The isotopic ratios are measured with a MC-ICPMS Neptune, coupled with a desolvator (Aridus II), using a 57Fe-58Fe double spike mass bias correction. Measurement precision (0.13‰, 2SD) allow resolving small iron isotopic composition variations within the water column, in the Atlantic sector of the Southern Ocean (from deltaFe=-0.19 to +0.32‰). Isotopically light iron found in the Upper Circumpolar Deep Water is hypothesized to result from organic matter remineralization. Shallow samples suggest that, if occurring, an iron isotopic fractionation during iron uptake by phytoplankton is characterized by a fractionation factor, such as: abs(deltaFe(plankton-seawater))< 0.48‰.


Global Biogeochemical Cycles | 2014

Iron sources and dissolved‐particulate interactions in the seawater of the Western Equatorial Pacific, iron isotope perspectives

Marie Labatut; Francois Lacan; Catherine Pradoux; Jérôme Chmeleff; Amandine Radic; James W. Murray; Franck Poitrasson; Anne M. Johansen; François Thil

This work presents iron isotope data in the western equatorial Pacific. Marine aerosols and top core margin sediments display a slightly heavy Fe isotopic composition (δ 56 Fe) of 0.33 ± 0.11‰ (2SD) and 0.14 ± 0.07‰, respectively. Samples reflecting the influence of Papua New Guinea runoff (Sepik River and Rabaul volcano water) are characterized by crustal values. In seawater, Fe is mainly supplied in the particulate form and is found with a δ 56 Fe between A0.49 and 0.34 ± 0.07‰. The particulate Fe seems to be brought mainly by runoff and transported across continental shelves and slopes. Aerosols are suspected to enrich the surface Vitiaz Strait waters, while hydrothermal activity likely enriched New Ireland waters. Dissolved Fe isotopic ratios are found between A0.03 and 0.53 ± 0.07‰. They are almost systematically heavier than the corresponding particulate Fe, and the difference between the signature of both phases is similar for most samples with Δ 56 Fe DFe – PFe = +0.27 ± 0.25‰ (2SD). This is interpreted as an equilibrium isotopic fractionation revealing exchange fluxes between both phases. The dissolved phase being heavier than the particles suggests that the exchanges result in a net nonreductive release of dissolved Fe. This process seems to be locally significantly more intense than Fe reductive dissolution documented along reducing margins. It may therefore constitute a very significant iron source to the ocean, thereby influencing the actual estimation of the iron residence time and sinks. The underlying processes could also apply to other elements.


Analytical Chemistry | 2010

High-precision determination of the isotopic composition of dissolved iron in iron depleted seawater by double spike multicollector-ICPMS.

Francois Lacan; Amandine Radic; Marie Labatut; Catherine Jeandel; Franck Poitrasson; Géraldine Sarthou; Catherine Pradoux; Jérôme Chmeleff; Rémi Freydier

This work demonstrates the feasibility of the measurement of the isotopic composition of dissolved iron in seawater for an iron concentration range, 0.05-1 nmol L(-1), allowing measurements in most oceanic waters, including Fe depleted waters of high nutrient low chlorophyll areas. It presents a detailed description of our previously published protocol, with significant improvements on detection limit and blank contribution. Iron is preconcentrated using a nitriloacetic acid superflow resin and purified using an AG 1-x4 anion exchange resin. The isotopic ratios are measured with a multicollector-inductively coupled plasma mass spectrometer (MC-ICPMS) Neptune, coupled with a desolvator (Aridus II or Apex-Q), using a (57)Fe-(58)Fe double spike mass bias correction. A Monte Carlo test shows that optimum precision is obtained for a double spike composed of approximately 50% (57)Fe and 50% (58)Fe and a sample to double spike quantity ratio of approximately 1. Total procedural yield is 91 +/- 25% (2SD, n = 55) for sample sizes from 20 to 2 L. The procedural blank ranges from 1.4 to 1.1 ng, for sample sizes ranging from 20 to 2 L, respectively, which, converted into Fe concentrations, corresponds to blank contributions of 0.001 and 0.010 nmol L(-1), respectively. Measurement precision determined from replicate measurements of seawater samples and standard solutions is 0.08 per thousand (delta(56)Fe, 2SD). The precision is sufficient to clearly detect and quantify isotopic variations in the oceans, which so far have been observed to span 2.5 per thousand and thus opens new perspectives to elucidate the oceanic iron cycle.


Proceedings of the National Academy of Sciences of the United States of America | 2017

Iron isotopes reveal distinct dissolved iron sources and pathways in the intermediate versus deep Southern Ocean

Cyril Abadie; Francois Lacan; Amandine Radic; Catherine Pradoux; Franck Poitrasson

Significance Iron is an essential micronutrient for life. However, its scarcity limits algae growth in about one-half of the ocean. Its cycle is therefore linked to the global carbon cycle and climate. We present an iron isotope section from the Southern Ocean. In contrast to the common but oversimplified view, according to which organic matter remineralization is the major pathway releasing dissolved iron below the surface layers, these data reveal other dominant processes at depth, likely abiotic desorption/dissolution from lithogenic particles. This suggests that the iron cycle, and therefore primary production and climate, may be more sensitive than previously thought to continental erosion, dissolved/particle interactions, and deep water upwelling. These processes likely impact other elements in the ocean. As an essential micronutrient, iron plays a key role in oceanic biogeochemistry. It is therefore linked to the global carbon cycle and climate. Here, we report a dissolved iron (DFe) isotope section in the South Atlantic and Southern Ocean. Throughout the section, a striking DFe isotope minimum (light iron) is observed at intermediate depths (200–1,300 m), contrasting with heavier isotopic composition in deep waters. This unambiguously demonstrates distinct DFe sources and processes dominating the iron cycle in the intermediate and deep layers, a feature impossible to see with only iron concentration data largely used thus far in chemical oceanography. At intermediate depths, the data suggest that the dominant DFe sources are linked to organic matter remineralization, either in the water column or at continental margins. In deeper layers, however, abiotic non-reductive release of Fe (desorption, dissolution) from particulate iron—notably lithogenic—likely dominates. These results go against the common but oversimplified view that remineralization of organic matter is the major pathway releasing DFe throughout the water column in the open ocean. They suggest that the oceanic iron cycle, and therefore oceanic primary production and climate, could be more sensitive than previously thought to continental erosion (providing lithogenic particles to the ocean), particle transport within the ocean, dissolved/particle interactions, and deep water upwelling. These processes could also impact the cycles of other elements, including nutrients.


Earth and Planetary Science Letters | 2013

The effect of particulate dissolution on the neodymium (Nd) isotope and Rare Earth Element (REE) composition of seawater

Christopher R. Pearce; Morgan T. Jones; Eric H. Oelkers; Catherine Pradoux; Catherine Jeandel


Limnology and Oceanography-methods | 2012

GEOTRACES intercalibration of neodymium isotopes and rare earth element concentrations in seawater and suspended particles. Part 1: reproducibility of results for the international intercomparison

Tina van de Flierdt; Katharina Pahnke; Hiroshi Amakawa; Per Andersson; Chandranath Basak; Barry J. Coles; Christophe Colin; Kirsty C. Crocket; Martin Frank; Norbert Frank; Steven L. Goldstein; Vineet Goswami; Brian A. Haley; Ed C. Hathorne; Sidney R. Hemming; Gideon M. Henderson; Catherine Jeandel; Kevin M. Jones; Katharina Kreissig; Francois Lacan; Myriam Lambelet; Ellen E. Martin; Derrick R Newkirk; Haijme Obata; Leopoldo D Peña; Alexander M. Piotrowski; Catherine Pradoux; Howie D. Scher; Hans Schöberg; Sunil K. Singh


Geochimica et Cosmochimica Acta | 2014

Rare earth elements and Nd isotopes tracing water mass mixing and particle-seawater interactions in the SE Atlantic

E. Garcia-Solsona; Catherine Jeandel; Marie Labatut; Francois Lacan; Derek Vance; V. Chavagnac; Catherine Pradoux


Geochemistry Geophysics Geosystems | 2013

Rare earth element concentrations and Nd isotopes in the Southeast Pacific Ocean

Catherine Jeandel; H. Delattre; Mélanie Grenier; Catherine Pradoux; Francois Lacan


Geochimica et Cosmochimica Acta | 2012

Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean

Torben Stichel; Martin Frank; Jörg Rickli; Ed C. Hathorne; Brian A. Haley; Catherine Jeandel; Catherine Pradoux


Geostandards and Geoanalytical Research | 2013

A Compilation of Silicon, Rare Earth Element and Twenty‐One other Trace Element Concentrations in the Natural River Water Reference Material SLRS‐5 (NRC‐CNRC)

Delphine Yeghicheyan; Cécile Bossy; Martine Bouhnik-Le Coz; Chantal Douchet; Guy Granier; Alexie Heimburger; Francois Lacan; Aurélie Lanzanova; Tristan C. C. Rousseau; Jean-Luc Seidel; Mickaël Tharaud; Frédéric Candaudap; Jérôme Chmeleff; Christophe Cloquet; Sophie Delpoux; Marie Labatut; Rémi Losno; Catherine Pradoux; Yann Sivry; Jeroen E. Sonke

Collaboration


Dive into the Catherine Pradoux's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Franck Poitrasson

Centre national de la recherche scientifique

View shared research outputs
Top Co-Authors

Avatar

Torben Stichel

University of Hawaii at Manoa

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge