Dissolved cobalt enrichments over the Kerguelen plateau confirm that most of the natural fertilization is due to partial dissolution of local basalts

Exceptionally high dissolved cobalt (Co) concentrations have been measured in the surface waters above the Kerguelen Plateau (KEOPS), and in intermediate and deep waters above its eastern slope. Lateral advection and dissolution of Co contained in basalt sediments around Heard Island were shown to imprint the process of surface enrichment over the plateau. Dissolved Co enrichment was strongest at the intercept of the eastern slope with intermediate and deep waters, probably due to more efficient mobilisation of the sediments in the slope current.

Estimate of the fertilization flux of iron inferred by using dissolved Co as a tracer of basalt sources is consistent with preceding ones (Zhang et al., DSR II, 55, 638-652, 2008; Chever et al., Biogeosciences, 7, 455-468, 2010), and the calculated iron supply matches with the phytoplankton demand (Sarthou et al., DSRII, 55, 734-751, 2008).



Bown, J., Boye, M., Laan, P., Bowie, A. R., Park, Y.-H., Jeandel, C., and Nelson, D. M.: Imprint of a dissolved cobalt basaltic source on the Kerguelen Plateau, Biogeosciences, 9, 5279-5290, doi:10.5194/bg-9-5279-2012, 2012. Paper.

Latest highlights

Science Highlights

Deep sea lithogenic weathering a source of iron colloids for the ocean

Homoky and co-workers determined the isotope composition of dissolved iron profiles in shallow surface sediments of the South Atlantic Uruguayan margin…


Science Highlights

Adding external sources allow a better simulation of the oceanic rare earth elements cycles

Oka and colleagues demonstrate that the global distribution of REE can be reproduced by considering the internal cycle associated with reversible scavenging and external REEs inputs around continental regions.


Science Highlights

First direct measurements of luxury iron uptake in natural phytoplankton communities: surprising results!

This study demonstrates the importance of biology and ecology to understanding iron biogeochemistry.


Science Highlights

Air-sea gas disequilibrium drove deoxygenation of the deep ice-age ocean

This study provides one of the first mechanistic explanations for Last Glacial Maximum deep ocean deoxygenation.