Review Article | Published:

The biogeochemical cycle of iron in the ocean

Nature Geoscience volume 3, pages 675682 (2010) | Download Citation

Abstract

Advances in iron biogeochemistry have transformed our understanding of the oceanic iron cycle over the past three decades: multiple sources of iron to the ocean were discovered, including dust, coastal and shallow sediments, sea ice and hydrothermal fluids. This new iron is rapidly recycled in the upper ocean by a range of organisms; up to 50% of the total soluble iron pool is turned over weekly in this way in some ocean regions. For example, bacteria dissolve particulate iron and at the same time release compounds — iron-binding ligands — that complex with iron and therefore help to keep it in solution. Sinking particles, on the other hand, also scavenge iron from solution. The balance between these supply and removal processes determines the concentration of dissolved iron in the ocean. Whether this balance, and many other facets of the biogeochemical cycle, will change as the climate warms remains to be seen.

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Acknowledgements

We thank A. Bowie (Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania) for providing unpublished dissolved iron data from the Southern Ocean (Fig. 1a), and L. Bucke (Department of Chemistry, University of Otago) for help with the graphics. We thank S. Solokov and S. Rintoul (CSIRO, Hobart, Tasmania) and G. Jackson (Texas A&M) for providing personal communications regarding bottom pressure torque and vertical changes in particle surface area, respectively.

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  1. National Institute of Water and Atmosphere Centre of Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin, New Zealand

    • P. W. Boyd
  2. Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia.

    • M. J. Ellwood

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Correspondence to P. W. Boyd.

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