Marine Biogeochemistry of Iron

Simon J. Ussher; Eric P. Achterberg; Paul J. Worsfold

doi:10.1071/EN04053

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Marine Biogeochemistry of Iron

Simon J. Ussher ^A , Eric P. Achterberg ^A and Paul J. Worsfold ^A ^B

+ Author Affiliations

- Author Affiliations

^A School of Earth, Ocean and Environmental Sciences (SEOES) and Plymouth Environmental Research Centre (PERC), University of Plymouth, Plymouth PL4 8AA, UK.

^B Corresponding author. Email: pworsfold@plymouth.ac.uk

Simon Ussher is completing his Ph.D. thesis on iron(II) biogeochemistry in the Northeast Atlantic as part of the EU-funded IRONAGES project. This work has involved four cruises (CLIVAR Transect, Southern Ocean, R.V. Aurora Australis, Oct–Dec 2001; IRONAGES Cruise, European Continental Shelf, R.V. Pelagia, Mar–Apr 2002; IRONAGES Cruise, Canary Basin, R.V. Pelagia, Oct 2002; Sargasso Sea, R.V. Weatherbird, Jul–Aug 2003).

Eric Achterberg has been at the School of Environmental Sciences, University of Plymouth, since 1994. His interests are the aquatic biogeochemistry of trace metals (including speciation), nutrients, and their interaction with organisms. Current projects include iron uptake by marine phytoplankton, the application of in situ voltammetric trace metal monitors for biogeochemical studies, and the development and application of spectroscopy-based monitoring equipment. During the last six years, he has attracted about Â£1 million in research income.

Paul Worsfold has 25 years research experience. He has been Professor of Analytical Science at the UoP since 1990 and Director of the Plymouth Environmental Research Centre since 1995. He has authored over 200 research papers and supervised 36 Ph.D. completions. His major research interests are the design and deployment of instrumentation for monitoring of environmental processes, and the use of this high quality data to elucidate biogeochemical cycles, trends, and transient events. Recent projects include techniques for measuring trace metals in marine waters, advancements in global iron simulations, detection and characterization of iron complexes in seawater, and site characterization of the Southwest European marine sites. Paul Worsfold is a member of the Editorial Advisory Board of Environmental Chemistry.

Environmental Chemistry 1(2) 67-80 https://doi.org/10.1071/EN04053
Submitted: 30 June 2004 Accepted: 3 August 2004 Published: 21 October 2004

Environmental Context. Several trace elements are essential to the growth of microorganisms, iron being arguably the most important. Marine microorganisms, which affect the global carbon cycle and consequently indirectly influence the world’s climate, are therefore sensitive to the presence of iron. This link means iron-related oceanic processes are a significant ecological and political issue.

Abstract. The importance of the role of iron as a limiting micronutrient for primary production in the World Ocean has become increasingly clear following large-scale in situ iron fertilization experiments in high-nutrient, low-chlorophyll (HNLC) regions.^[¹^] This has led to intensive international research with the aim of understanding the marine biogeochemistry of iron and quantifying the spatial distribution and transport of the element in the oceans. Recent studies have benefited from improved trace metal handling protocols and sensitive analytical techniques, but uncertainties remain concerning fundamental processes such as redox transfer, solubility, adsorption, biological uptake, and remineralization.

This review summarizes our present knowledge of iron biogeochemistry. It begins with a discussion of the effects of the physicochemical speciation of iron in seawater from a thermodynamic perspective, including important topics such as inorganic and organic complexation and redox chemistry. This is followed by an overview of the fluxes of iron to the ocean interface and a description of iron cycling within the open ocean water column. Current uncertainties of iron biogeochemistry are highlighted and suggestions of future work provided.

Keywords. : aerosols — biogeochemistry — iron — marine chemistry — redox reactions

Acknowledgements

The authors would like to thank the Natural Environment Research Council for supporting this work through grant NER/A/S/2003/00489.

References

Marine Biogeochemistry of Iron

Acknowledgements

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