Le fer à l'interface océan-atmosphère : Flux et processus de dissolution dans l'eau de mer.

Abstract : Studying the fluxes and the fate of atmospheric iron in seawater is crucial to estimate its contribution to ocean iron stock and biogeochemical cycles. For large oceanic areas in the southern hemisphere so far unexplored regarding aerosols, this work shows that iron atmospheric inputs are associated to extremely low concentrations of lithogenic particles which have been transported over very long distances. Atmospheric inputs of iron to these oceanic regions, determined in this work, are well below (up to two orders of magnitude) recent estimations from global dust models which are commonly used in biogeochemical models. Regarding the fate of atmospheric iron in seawater, this work suggests that iron dissolution results from the combination of a fast process (i.e. instantaneous) and a slow process (scale of several days). The “instantaneous” process is controlled by physicochemical parameters depending both on the nature (source) and on the history (atmospheric transport) of aerosols at the atmosphere-ocean interface. The “slow” process depends on the amount of free ligands in seawater and it is proportional to dissolved organic matter concentration. The dissolution of atmospheric iron is thus related not only to the source and transport of the particles but also to the characteristics of the seawater where they are deposited, illustrating the unfeasibility of considering a unique value of atmospheric iron dissolution at the global scale. A parametrization integrating all these controlling factors is proposed. This work, by estimating both the fluxes and the dissolution of atmospheric iron, shows that, for certain oceanic regions, the incertitude on iron fluxes is as much critical as the incertitude on dissolution.
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https://tel.archives-ouvertes.fr/tel-00270558
Contributor : Thibaut Wagener <>
Submitted on : Sunday, April 6, 2008 - 9:03:34 AM
Last modification on : Saturday, May 25, 2019 - 1:42:37 AM
Long-term archiving on : Friday, September 28, 2012 - 12:21:17 PM

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  • HAL Id : tel-00270558, version 1

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Thibaut Wagener. Le fer à l'interface océan-atmosphère : Flux et processus de dissolution dans l'eau de mer.. Océan, Atmosphère. Université de la Méditerranée - Aix-Marseille II, 2008. Français. ⟨tel-00270558⟩

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