Publication Date:
2013-02-28
Description:
[1] Iron deposition influences primary production and the oceanic sequestration of atmospheric carbon dioxide. Iron has two oxidation states, Fe(II) and Fe(III), where Fe(II) is more soluble and available for oceanic phytoplankton uptake. The past proportions of soluble iron in aerosol dust have remained unknown. Here, we present iron speciation (Fe 2+ and Fe 3+ ) in the Antarctic Talos Dome ice core over millennial timescales. We demonstrate that iron speciation over the last 55 ky is linked to increasing quantities of fine dust (0.7 – 5 µm) and intensified long-range dust transport. We propose that Fe(II) and Fe 2+ production is principally enhanced in fine dust by photo-reduction, although pH and organic complexation may also contribute to speciation dynamics. During the Last Glacial Maximum, Fe 2+ concentrations in dust increased by up to 7 times more than interglacial levels while Fe 3+ only doubled. Cold and dusty climatic periods may increase the percentage of biologically-available Fe(II) and Fe 2+ deposited in the nutrient-limited Southern Ocean, allowing greater phytoplankton uptake and perhaps increased carbon dioxide drawdown.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
Permalink
