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Mechanisms driving the dispersal of hydrothermal iron from the northern Mid Atlantic Ridge
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  • Alessandro Tagliabue,
  • Alistair Lough,
  • Vic Clément,
  • Vassil Roussenov,
  • Jonathan Gula,
  • Maeve C Lohan,
  • Resing Joseph,
  • Williams Richard Guy
Alessandro Tagliabue
University of Liverpool

Corresponding Author:[email protected]

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Alistair Lough
University of Leeds
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Vic Clément
Ifremer
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Vassil Roussenov
University of Liverpool
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Jonathan Gula
Université de Bretagne Occidentale
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Maeve C Lohan
University of Southampton
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Resing Joseph
U. of Washington and NOAA-PMEL
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Williams Richard Guy
University of Liverpool
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Abstract

The dispersal of dissolved iron (DFe) from hydrothermal vents is poorly constrained. Combining field observations and a hierarchy of models, we show that the dispersal of DFe from the Trans-Atlantic-Geotraverse vent site occurs predominantly in the colloidal phase and is controlled by multiple physical processes. Enhanced mixing near the seafloor and transport through fracture zones at fine-scales interacts with the wider ocean circulation to drive predominant westward DFe dispersal away from the Mid-Atlantic ridge at the 100km scale. In contrast, diapycnal mixing predominantly drives northward DFe transport within the ridge axial valley. The observed DFe dispersal is not reproduced by the coarse resolution ocean models typically used to assess ocean iron cycling due to their omission of local topography and mixing. Unless biogeochemical models include high-resolution nested grids, they will inaccurately represent DFe dispersal from axial valley ridge systems, which make up half of the global ocean ridge crest.