A geochemical-physical coupled approach to study phytoplankton plume dynamics off the Crozet Islands (Southern Ocean)

Interaction of the currents with the sediments deposited on the margins of the Crozet Islands (Southern Ocean) contributes to the supply of iron and other micronutrients to marine waters. This natural fertilization feeds a phytoplankton bloom that was object of study of the KEOPS 2 GEOTRACES process study.

Sanial and co-authors (2014, see reference below) combined three independent methods – including geochemical and physical methods. This allowed them to assess the origin of the natural iron fertilization and the rates and times scale of the offshore transport in the phytoplankton bloom of Crozet. Shelf-water contact ages were determined using radium isotopes and were compared to in situ drifter data and modeling data based on altimetry.

This work highlights the key role played by the horizontal transport in the natural iron fertilization and provides constraints on the transit time of surface waters between the shelf and offshore waters.

14 Sanial lowFigure: Ages of surface waters derived from a Lagrangian model based on altimetry data. The drifter launched offshore Crozet Islands followed the numerical plume deduced from the model. White circles show the location of radium samples. Please click here to view the figure larger.

 

Reference:

Sanial, V., van Beek, P., Lansard, B., D’Ovidio, F., Kestenare, E., Souhaut, M., Zhou, M., Blain, S. (2014). Study of the phytoplankton plume dynamics off the Crozet Islands (Southern Ocean): A geochemical-physical coupled approach. Journal of Geophysical Research: Oceans, 119(4), 2227–2237. doi:10.1002/2013JC009305. Click here to access the paper.

Latest highlights

Iron and zinc isotopes disentangle the anthropogenic, natural and wildfire sources of aerosols over the North and Equatorial Pacific Ocean

Bunnell and co-authors analysed aerosol iron and zinc isotopic compositions along the North Pacific GEOTRACES GP15 section (Alaska-Tahiti).

Contribution of sandy beaches to the oceanic silica cycle

This paper calls into question the commonly accepted idea of an oceanic silicon cycle in equilibrium.

North – South contrasting behavior of dissolved cobalt in the Indian Ocean

Malla and Singh have studied the complex biogeochemical processes of total dissolved cobalt in the Indian Ocean.

The Amazonian mangrove systems accumulate and release dissolved neodymium and hafnium to the oceans

Xu and colleagues investigated the concentrations of rare earth elements in the Amazonian mangrove.

Rechercher