Articles | Volume 7, issue 3
Biogeosciences, 7, 827–844, 2010

Special issue: Iron biogeochemistry across marine systems at changing times

Biogeosciences, 7, 827–844, 2010
03 Mar 2010
03 Mar 2010

The role of airborne volcanic ash for the surface ocean biogeochemical iron-cycle: a review

S. Duggen1,2, N. Olgun1,3, P. Croot3, L. Hoffmann4,5, H. Dietze3, P. Delmelle6, and C. Teschner1,7 S. Duggen et al.
  • 1IFM-GEOMAR, Leibniz-Institute of Marine Sciences, Division Dynamics of the Ocean Floor, Wischhofstrasse 1–3, 24148 Kiel, Germany
  • 2A. P. Møller Skolen, Upper Secondary School and Sixth Form College of the Danish National Minority in Germany, Fjordallee 1, 24837 Schleswig, Germany
  • 3IFM-GEOMAR, Leibniz-Institute of Marine Sciences, Division Marine Biogeochemistry, Düsternbrooker Weg 20, 24105 Kiel, Germany
  • 4Department of Plant and Environmental Sciences, Göteborg University, Carl Skottsberg Gata 22 B, 40530 Gothenburg, Sweden
  • 5Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
  • 6Environment Department, University of York, Heslington Y010 5DD, York, UK
  • 7IFM-GEOMAR, Leibniz-Institute of Marine Sciences, Division Ocean Circulation and Climate Dynamics, Wischhofstrasse 1–3, 24148 Kiel, Germany

Abstract. Iron is a key micronutrient for phytoplankton growth in the surface ocean. Yet the significance of volcanism for the marine biogeochemical iron-cycle is poorly constrained. Recent studies, however, suggest that offshore deposition of airborne ash from volcanic eruptions is a way to inject significant amounts of bio-available iron into the surface ocean. Volcanic ash may be transported up to several tens of kilometers high into the atmosphere during large-scale eruptions and fine ash may stay aloft for days to weeks, thereby reaching even the remotest and most iron-starved oceanic regions. Scientific ocean drilling demonstrates that volcanic ash layers and dispersed ash particles are frequently found in marine sediments and that therefore volcanic ash deposition and iron-injection into the oceans took place throughout much of the Earth's history. Natural evidence and the data now available from geochemical and biological experiments and satellite techniques suggest that volcanic ash is a so far underestimated source for iron in the surface ocean, possibly of similar importance as aeolian dust. Here we summarise the development of and the knowledge in this fairly young research field. The paper covers a wide range of chemical and biological issues and we make recommendations for future directions in these areas. The review paper may thus be helpful to improve our understanding of the role of volcanic ash for the marine biogeochemical iron-cycle, marine primary productivity and the ocean-atmosphere exchange of CO2 and other gases relevant for climate in the Earth's history.

Final-revised paper