Iron dissolution from Patagonian dust in the Southern Ocean: under present and future conditions - Institut de Physique du Globe de Paris Accéder directement au contenu
Article Dans Une Revue (Article De Synthèse) Frontiers in Marine Science Année : 2024

Iron dissolution from Patagonian dust in the Southern Ocean: under present and future conditions

Barry Lai
  • Fonction : Auteur
Pierre Burckel
  • Fonction : Auteur
Yan Feng
  • Fonction : Auteur
Rémi Losno
  • Fonction : Auteur
Stephan Borensztajn
  • Fonction : Auteur
Pascale Besson
  • Fonction : Auteur

Résumé

Although the input of desert dust as a key source of trace metals in the Southern Ocean (SO) has been previously studied, the dissolution process of metals in surface waters, particularly iron (Fe), remain poorly understood. Given the crucial role of Fe in primary production and the biological carbon pump in the SO, we focused on experimental estimations of Fe dissolution from Patagonian dust, the primary natural dust source in the SO. Our study considered both current and projected future conditions, encompassing sea-surface warming, acidification, increased photosynthetically active radiation, and doubled dust inputs. Through controlled laboratory experiments using filtered SO seawater, conducted over 7 days, we assessed changes in particulate Fe (pFe) concentrations, Fe redox speciation (Fe(II)/Fe(III)), and in the mineralogy of Fe-bearing dust in abiotic condition. The predominant minerals in the dust included quartz and aluminosilicates, with silicon (Si), aluminum (Al), and Fe as the major elements. No significant alterations in the mineralogy and the elemental composition of the dust were recorded during the dissolution experiments, neither under present nor under projected future conditions. The particulate Fe(II)/Fe(III) ratio remained consistently at 0.25 during the experiments, unaffected by changed conditions. Consequently, changes in environmental conditions in the SO would therefore not significantly alter the mineralogy and redox speciation of pFe in the Patagonian dust. On the contrary, pFe exhibited a dissolution rate of 3.8% and 1.6% per day under present and future conditions, respectively. The environmental changes anticipated for 2100 in the SO will likely to result in a decrease in the dissolution rate of pFe. Thus, even though a doubling of dust input by 2100 is anticipated, it will unlikely provide significantly more dissolved Fe (dFe) in seawater in the SO. Consequently, the future intensification of Patagonian dust inputs may not alleviate the Fe limitation in the SO.
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hal-04574680 , version 1 (16-05-2024)

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Clément Demasy, Marie Boye, Barry Lai, Pierre Burckel, Yan Feng, et al.. Iron dissolution from Patagonian dust in the Southern Ocean: under present and future conditions. Frontiers in Marine Science, 2024, 11, ⟨10.3389/fmars.2024.1363088⟩. ⟨hal-04574680⟩
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