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Dissolved iron distributions and Fe-limitation
C. Guieu S. Bonnet Laboratoire
docéanographie de Villefranche S.
Blain Laboratoire docéanographie et de
biogéochimie (Marseille)
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Objective 1
- To gather the first Fe data set in the South
Pacific gyre including deep waters.
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Objective 2
- Does natural Fe enrichment of surface waters
exist in the wake of Marquesas islands? Does it
explain chlorophyll plume?
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What s about water circulation around Marquesas
islands?
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Objective 3
- To investigate role of iron on biological
activity in the oligotrophic area.
First priority In situ observations To
compare the depth of the Fecline and the depths
of other nutriclines, max of chloro
Second priority Incubation experiments (long
station gyre 2) ?? - Effect of dust addition
on biological activity - Others???
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 Material and methods
Concentrations of dissolved iron

• Ultra-clean sampling technique
• goflo kevlar line 0-400m (nutrient analysis
  required to validate sampling)
• or clean pump (10-50m)
• or zodiac for surface waters (0-10 m)
• rosette for deep profiles (0-4000m) (?)
• Clean container. On the deck!!!
• On board measurement of Fe by chemiluminescence
  for different fractions
• dissolvable unfiltered and acidified
• dissolved - lt0.2 µm
• soluble (dissolved colloidal) lt 0.02 µm
• other analysis
• Fe-ligand type porhyrine (analysis at LOB)

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 Material and methods Incubation experiments ??
- Only possible at long stations (priority gyre
2) To be decided soon because it requires a
specific logistic. Incubators, incubation and
sub sampling bottles...
- But clean seawater can be provided at short
stations if requested for specific experiments.