The signature of river- and wind-borne materials exported from Patagonia to the southern latitudes: a view from REEs and implications for paleoclimatic interpretations

Riverine and wind-borne materials transferred from Patagonia to the SW Atlantic exhibit a homogeneous rare earth element (REE) signature. They match well with the REE composition of Recent tephra from the Hudson volcano,and hence this implies a dominance of material supplied by this source and other similar Andean volcanoes. Due to the trapping effect of proglacial and reservoir lakes,the larger Patagonian rivers deliver to the ocean a suspended load with a slightly modified Andean signature,that shows a REE composition depleted in heavy REEs. In this paper we redefine Patagonia as a source of sediments,which is in contrast with other sources located in southern South America. Quaternary sediments deposited in the northern and,to a lesser extent, in the southern Scotia Sea, and most of the dust in ice cores of east Antarctica have REE compositions very similar to the loess from Buenos Aires Province and to Patagonian eolian dust. However,we rule out Buenos Aires province as a Holocene major source of sediments. Similarly to Buenos Aires loess (a proximal facies),it is likely that the REE compositions of most sediment cores of the Scotia Sea and Antarctica reflect a distal transport of dust with an admixed composition from two main sources: a major contribution from Patagonia,and a minor proportion from source areas containing sediments with a clear upper crustal signature (e.g.,western Argentina) or from Bolivia’s Altiplano. Evidence indicates that only during the Last Glacial Maximum,Patagonian materials were the predominant sediment source to the southern latitudes

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

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

Fate of aluminium released by sacrificial anodes – Contamination of marine sediments by environmentally available compounds

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Sols et sédiments pollués : Teneurs élémentaires totales et biodisponibles ISBN: 978-3-330-87630-9

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Sols et sédiments pollués : Teneurs élémentaires totales et biodisponibles

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Prediction of phytoavailability of trace metals to plants: Comparison between chemical extractions and soil-grown radish

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Selectivity and efficiency of the acido-soluble extraction in sequential extraction procedure

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Sustanaible re-use of marine dredged sediments: roads and bricks as two examples

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Évaluation de la mobilité des métaux dans les sédiments fluviaux du bassin de la Vire (Normandie, France) par extractions simples ou séquentielles

International audienceReçu le 1 er mars 2004 ; accepté après révision le 21 décembre 2004 Disponible sur Internet le 8 mars 2005 Présenté par Georges Pédro Résumé Ce travail compare la quantité de métaux présents dans des sédiments fluviaux de la Vire (Normandie), mobilisés par dif-férentes extractions chimiques, simples (Mg(NO 3) 2 , HCl et EDTA) ou séquentielle. Le lessivage par Mg(NO 3) 2 sous-évalue la mobilité, tandis que l'extraction séquentielle est la plus agressive des méthodes utilisées (sauf pour le calcium et le plomb), sans qu'il soit possible de déterminer de façon satisfaisante et univoque à quelle(s) fraction(s) du sédiment correspondent les quantités mobilisées par les lessivages simples, de grandes variabilités apparaissant suivant l'élément considéré. Enfin, on note un enrichissement en polluants métalliques (Cd, Pb et Zn) des sédiments étudiés. Pour citer cet article : L. Leleyter, F. Baraud, C. R. Geoscience 337 (2005). 2005 Académie des sciences. Publié par Elsevier SAS. Tous droits réservés. Abstract Evaluation of metals mobility in sediments of the Vire basin (Normandy, France) by single or sequential extractions. This work compares the quantities of labile metals removed from the Vire River (Normandy) sediments by a sequential extraction procedure to those liberated by single leaches (Mg(NO 3) 2 , HCl and EDTA). Compared to the other extractions, Mg(NO 3) 2 underestimated the mobility results. The sequential procedure was the most aggressive, except for Ca and Pb. The hypothetic correlation between quantities of an element removed by single leaches and its fractionation in the sediment according to the sequential procedure was not satisfying. Finally, it should be underlined that enrichments of Cd, Pb and Zn were noticed in the Vire sediments. To cite this article: L. Leleyter, F. Baraud, C. R. Geoscience 337 (2005). 2005 Académie des sciences. Publié par Elsevier SAS. Tous droits réservés