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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 10, issue 10 | Copyright
Biogeosciences, 10, 6617-6628, 2013
https://doi.org/10.5194/bg-10-6617-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 22 Oct 2013

Research article | 22 Oct 2013

Solubility of iron and other trace elements in rainwater collected on the Kerguelen Islands (South Indian Ocean)

A. Heimburger, R. Losno, and S. Triquet A. Heimburger et al.
  • Laboratoire Interuniversitaire des Systèmes Atmosphériques, CNRS UMR7583, Université Paris Diderot, Université Paris Est-Créteil, 94010 Créteil Cedex, France

Abstract. The soluble fraction of aerosols that is deposited on the open ocean is vital for phytoplankton growth. It is believed that a large proportion of this dissolved fraction is bioavailable for marine biota and thus plays an important role in primary production, especially in HNLC oceanic areas where this production is limited by micronutrient supply. There is still much uncertainty surrounding the solubility of atmospheric particles in global biogeochemical cycles and it is not well understood. In this study, we present the solubilities of seven elements (Al, Ce, Fe, La, Mn, Nd, Ti) in rainwater on the Kerguelen Islands, in the middle of the Southern Indian Ocean. The solubilities of elements exhibit high values, generally greater than 70%, and Ti remains the least soluble element. Because the Southern Indian Ocean is remote from its dust sources, only a fraction of smaller aerosols reaches the Kerguelen Islands after undergoing several cloud and chemical processes during their transport, resulting in a drastic increase in solubility. Finally, we deduced an average soluble iron deposition flux of 27 ± 6 μg m−2 d−1 (~0.5 μmol m−2 d−1) for the studied oceanic area, taking into account a median iron solubility of 82% ± 18%.

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