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

Gaiero, Diego M. and Probst, Jean-Luc and Depetris, Pedro J. and Bidart, Susana M. and Leleyter, Lydia Iron and other transition metals in Patagonian riverborne and windborne materials: Geochemical control and transport to the southern South Atlantic Ocean. (2003) Geochimica et Cosmochimica Acta, vol. 6 (n° 19). pp. 3603-3623. ISSN 0016-7037

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Official URL: http://dx.doi.org/10.1016/S0016-7037(03)00211-4

Abstract

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 equivalent amounts from the atmosphere (30 106 T yr1) and coastal erosion (40 106 T yr1) with much less coming from the rivers (2.0 106 T yr1). Low trace metal riverine fluxes are linked to the low suspended particulate load of Patagonian rivers, inasmuch most of it is retained in pro-glacial lakes as well as in downstream reservoirs. Based on our estimation of aeolian dust fluxes at the Patagonian coastline, the high nutrient-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.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Geochimica et Cosmochimica Acta website : http://www.sciencedirect.com/science/journal/00167037
Audience (journal):International peer-reviewed journal
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Institution:Other partners > Universidad Nacional de Cordoba - UNC (ARGENTINA)
French research institutions > Institut de Recherche pour le Développement - IRD
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Other partners > Université de Caen Basse-Normandie (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS
Other partners > Université Louis Pasteur-Strasbourg I - ULP (FRANCE)
Other partners > Universidad Nacional del Sur - UNS (ARGENTINA)
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Deposited By:Florence Amor

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