Iron and other transition metals in Patagonian riverborne and windborne materials: Geochemical control and transport to the southern South Atlantic Ocean

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Gaiero, Diego M., Probst, Jean-Luc, Depetris, Pedro J., Bidart, Susana M., Leleyter, Lydia
• Other Authors: Facultad de Ciencias Exactas, Físicas y Naturales Córdoba, Universidad Nacional de Córdoba Argentina, Centre de géochimie de la surface (CGS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Mécanismes et Transfert en Géologie (LMTG), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: Iron; Patagonia riverborne; Atlantic Ocean; Aeolian; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Antarctic; Hudson; Patagonia; Antarc*; South Atlantic Ocean
• Online Access: https://hal.science/hal-04258897; https://doi.org/10.1016/S0016-7037(03)00211-4

International audience The bulk of particulate transition metals transported by Patagonian rivers shows an upper crustal composition. Riverine particulate 0.5 N HCl leachable trace metal concentrations are mainly controlled by Fe-oxides. Complexation of Fe by dissolved organic carbon (DOC) appears to be an important determinant of the phases transporting trace metals in Patagonian rivers. In contrast, aeolian trace elements have a combined crustal and anthropogenic origin. Aeolian materials have Fe, Mn, and Al contents similar to that found in regional topsoils. However, seasonal concentrations of some metals (e.g., Co, Pb, Cu, and Zn) are much higher than expected from normal crustal weathering and are likely pollutant derived.We estimate that Patagonian sediments are supplied to the South Atlantic shelf in approximately equivalentamounts from the atmosphere (30 106 T yr1) and coastal erosion (40 106 T yr1) with much lesscoming from the rivers (2.0 106 T yr1). Low trace metal riverine fluxes are linked to the low suspendedparticulate load of Patagonian rivers, inasmuch most of it is retained in pro-glacial lakes as well as indownstream reservoirs. Based on our estimation of aeolian dust fluxes at the Patagonian coastline, the highnutrient-low chlorophyll sub Antarctic South Atlantic could receive 1.0 to 4.0 mg m2 yr1 of leachable (0.5 N HCl) Fe. Past and present volcanic activity in the southern Andes—through the ejection of tephra—must be highlighted as another important source of Fe to the South Atlantic Ocean. Based on the 1991 Hudson volcano eruption, it appears that volcanic events can contribute several thousand-fold the mass of “leachable” Fe to the ocean as is introduced by annual Patagonian dust fallout.