Seasonal iron supply in the Southern Ocean is dominated by winter mixing

An international team of researchers analysed the available dissolved iron data taken from all previous studies of the Southern Ocean, together with satellite images taken of the area, to quantify the amount of iron supplied to the surface waters of the Southern Ocean. They found that in contrast to the processes that supply so-called macronutrients in the tropics, seasonal iron supply is dominated by winter mixing with little iron input afterwards. This is because the vertical profile of iron is distinct from other nutrients, with subsurface reserves located much deeper in the water column and therefore only accessible by the deeper mixing that occurs in winter. This means that after this input pulse, intense iron recycling by the ‘ferrous wheel’ is necessary to sustain biological activity. This unique aspect of iron cycling is yet to be explained but places important constraints on how climate models represent the iron distribution and how changes in ocean physics impact iron limitation.

14 Tagliabue2 l

Figure. This diagram represents the seasonal variability in Southern Ocean iron (Fe) cycling. Click here to view the figure larger.

References:

Tagliabue, A., Sallée, J.-B., Bowie, A. R., Lévy, M., Swart, S., & Boyd, P. W. (2014). Surface-water iron supplies in the Southern Ocean sustained by deep winter mixing. Nature Geoscience, 7(4), 314–320. doi:10.1038/ngeo2101 Click here to view the paper.

Latest highlights

Science Highlights

Decline of the anthropogenic lead imprint to the ocean confirmed by data from the South West Atlantic Ocean

This study reveals that the mean lead concentrations in the surface waters of the western South Atlantic Ocean decreased by 34 % between the 1990s and 2011.

29.03.2023

Science Highlights

Irradiance-normalized non-photochemical quenching (NPQ): a new proxy of iron stress for phytoplankton

Ryan-Keogh and his colleagues used NPQ to fingerprint the photo-physiological response of phytoplankton to their environment.

06.03.2023

Science Highlights

Exhaustive modelling study of the oceanic neodymium parameters

The conclusion of this study reinforces the important role of the solid particles in driving the neodymium oceanic cycle.

02.03.2023

Science Highlights

Dissolved manganese distribution in the Arabian Sea reveals many variable triggers

Analysis of dissolved manganese on samples collected on GEOTRACES cruises allowed Singh and colleagues to establish its basin-wide distribution in the Arabian Sea.

01.03.2023

Rechercher