Artículo
Low source-inherited iron solubility limits fertilization potential of South American dust
Simonella, Lucio Esteban
; Cosentino, Nicolas Juan
; Montes, María Luciana
; Croot, Peter L.; Palomeque, Miriam Edid; Gaiero, Diego Marcelo
Fecha de publicación:
06/2022
Editorial:
Pergamon-Elsevier Science Ltd
Revista:
Geochimica et Cosmochimica Acta
ISSN:
0016-7037
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Where atmospheric processing is weak due to low anthropogenic emissions, fertilization of iron-limited oceans by non-volcanic mineral dust aerosols strongly depends on iron solubility at the sources. Southern South America (SSA) is a pristine environment and the main dust supplier to the southern oceans, the most sensitive to iron fertilization. Thus, the present-day lack of SSA dust fertilization of the southern oceans is hypothesized to reflect low source-inherited iron bioavailability. However, a dearth of geochemical studies on SSA dust prevents testing this hypothesis. To remedy this, we conducted the first systematic sampling of SSA dust sources. Iron leaching experiments showed fractional solubilities of close-to-source dust (bulk) and dust-emitting surface sediments (<63 µm) in pure water (0.05 ± 0.05%), seawater (0.03 ± 0.04%) and 1% nitric acid (5 ± 6%) that imply a low mass-normalized fertilization potential of SSA dust compared to dust from other regions. Based on grain size, size-resolved mineralogy, elemental chemistry and iron speciation determinations, we found that variability in labile iron is enhanced by high clay contents, small grain size and higher proportions of paramagnetic versus non-paramagnetic iron, irrespective of oxidation state. The independence of the most labile, water-soluble iron on grain size and its strong negative correlation to the Chemical Index of Alteration may imply that we currently underestimate the role of coarse glaciogenic dust as a supplier of bioavailable iron during drier-than-present ice ages when continental chemical weathering was reduced, and during which enhanced supply of dust-borne bioavailable iron to the southern oceans is observed.
Palabras clave:
DUST
,
IRON SOLUBILITY
,
OCEAN FERTILIZATION
,
SOUTH AMERICA
,
SOUTHERN OCEAN
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Identificadores
Colecciones
Articulos(CICTERRA)
Articulos de CENTRO DE INVEST.EN CS.DE LA TIERRA
Articulos de CENTRO DE INVEST.EN CS.DE LA TIERRA
Articulos(IFLP)
Articulos de INST.DE FISICA LA PLATA
Articulos de INST.DE FISICA LA PLATA
Citación
Simonella, Lucio Esteban; Cosentino, Nicolas Juan; Montes, María Luciana; Croot, Peter L.; Palomeque, Miriam Edid; et al.; Low source-inherited iron solubility limits fertilization potential of South American dust; Pergamon-Elsevier Science Ltd; Geochimica et Cosmochimica Acta; 335; 6-2022; 272-283
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