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DFe patterns impacted by shallow hydrothermal sources along a transect through the Tonga-Kermadec arc
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  • Chloé Tilliette,
  • Vincent Taillandier,
  • Pascale Bouruet-Aubertot,
  • Nicolas Grima,
  • Christophe Maes,
  • Maryline Montanes,
  • Geraldine Sarthou,
  • Maria-Elena Vorrath,
  • Veronica Arnone,
  • Matthieu Bressac,
  • David González-Santana,
  • Frédéric GAZEAU,
  • Cécile Guieu
Chloé Tilliette
Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche

Corresponding Author:chloe.tilliette@imev-mer.fr

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Vincent Taillandier
Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche
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Pascale Bouruet-Aubertot
Pierre and Marie Curie University
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Nicolas Grima
French National Centre for Scientific Research (CNRS)
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Christophe Maes
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Maryline Montanes
Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche
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Geraldine Sarthou
Institut Universitaire Europeen de la mer
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Maria-Elena Vorrath
Univ Hamburg, Inst Geol, Bundesstr 55, D-20146 Hamburg, Germany
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Veronica Arnone
6Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria
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Matthieu Bressac
French National Centre for Scientific Research
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David González-Santana
Univ Brest, CNRS, IRD, Ifremer, LEMAR
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Frédéric GAZEAU
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Cécile Guieu
Laboratoire d'Oceanographie de Villefranche (LOV)
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In the Western Tropical South Pacific, a hotspot of N2-fixing organisms has recently been identified. The survival of these species depends on the availability of dissolved iron (dFe). dFe was measured along a transect from 175 °E to 166 °W near 19-21 °S. The distribution of dFe showed high spatial variability: low concentrations (~0.2 nmol kg-1) in the South Pacific gyre and high concentrations (up to 50 nmol kg-1) west of the Tonga arc, indicating that this arc is a clear boundary between iron-poor and iron-rich waters. An optimal multiparameter analysis was used to distinguish the relative importance of physical transport relative to non-conservative processes on the observed dFe distribution. This analysis demonstrated that distant sources of iron play a minor role in its distribution along the transect. The high concentrations observed were therefore attributed to shallow hydrothermal sources massively present along the Tonga-Kermadec arc. Nevertheless, in contrast to what has been observed for deep hydrothermal plumes, our results highlighted the rapid decrease in dFe concentrations near shallow hydrothermal sources. This is likely due to a shorter residence time of surface water masses combined with several biogeochemical processes at play (e.g., precipitation, photoreduction, scavenging, biological uptake). This study clearly highlights the role of shallow hydrothermal sources on the dFe cycle within the Tonga-Kermadec arc where a strong link to biological activity in surface waters can be assessed. It also emphasizes the need to consider the impact of these shallow hydrothermal sources for a better understanding of the global iron cycle.