Atmospheric iron fluxes over the last deglaciation: Climatic implications

Vania Gaspari (1) , Carlo Barbante (1, 2) , Giulio Cozzi (1) , Paolo Cescon (1, 2) , Claude F. Boutron (3, 4) , Paolo Gabrielli (1, 3) , Gabriele Capodaglio (1, 2) , Christophe P. Ferrari (3, 5) , Jean Robert Petit (3) , Barbara Delmonte (6)

1 Environmental Sciences Department
2 Institute for the Dynamics of Environmental Processes-CNR
3 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
4 Unité de Formation et de Recherche de Physique
5 Polytech Grenoble
6 DISAT - Dipartimento di Scienze dell'Ambiente e del Territorio

A decrease in the micronutrient iron supply to the Southern Ocean is widely believed to be involved in the atmospheric CO2 increase during the last deglaciation. Here we report the first record of atmospheric iron fluxes as determined in 166 samples of the Dome C ice core and covering the last glacial-interglacial transition (22–9 kyr B.P.). It reveals a decrease in fallout flux from 24 × 10−2 mg Fe m−2 yr−1 during the Last Glacial Maximum to 0.7 × 10−2 mg Fe m−2 yr−1 at the onset of the Holocene. The acid leachable fraction of iron determined in our samples was the 60% of the total iron mass in glacial samples, about twice the value found for Holocene samples. This emerging difference in iron solubility over different climatic stages provides a new insight for evaluating the iron hypothesis over glacial/interglacial periods.

Mots clés: Greenhouse gases; Ice cores

Domaines: Glaciologie; Climatologie

Vania Gaspari, Carlo Barbante, Giulio Cozzi, Paolo Cescon, Claude F. Boutron, et al.. Atmospheric iron fluxes over the last deglaciation: Climatic implications. Geophysical Research Letters, 2006, 336 (L03704), 1 à 4 p. ⟨10.1029/2005GL024352⟩. ⟨insu-00375478⟩