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

Strong lithogenic imprints in the Indian Ocean waters

Ueki and co-authors reported the first sectional distributions of zirconium, hafnium and niobium along a north-source track in the Indian Ocean.

The development of the modern Antarctic Circumpolar Current occurred much later than previously thought!

This study is challenging the belief that the onset of the Antarctic Circumpolar Current was solely triggered by the opening and deepening of Southern Ocean Gateways.

A dynamic iron cycle in Peru

Gu and colleagues explore the temporal variation of iron over 11 cruises along the Peruvian shelf.

Trace metal fluxes of cadmium, copper, lead and zinc from the Congo River into the South Atlantic Ocean are supplemented by atmospheric inputs

Liu and colleagues show that rainfall augments some fluxes of trace metals from the Congo River.