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| Format: | Artículo científico |
| Language: | en |
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Universidad Autónoma de Baja California
2003
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| Online Access: | https://www.redalyc.org/articulo.oa?id=48029407 |
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Table of Contents:
- Trace metal distribution in muddy-patch sediments from the northern Portuguese Shelf Maria João Madureira Nuno Fonseca Carlos Vale Ciencias de la Tierra sulphides trace metals early diagenesis northern Portuguese Shelf Three sediment cores were collected in the muddy patches of the northern Portuguese Shelf located offshore the Douro andMinho rivers. Bivalves and worms were found in the upper and sub-surface layers of two cores. Vertical distributions of dissolvedmanganese and iron, iron oxides and acid volatile sulphide (AVS) in the bioturbated cores differ dramatically from those in thecore where macrofauna was not observed. Also, Fe, Zn, Cu, Pb and Cd simultaneously extracted with AVS (1 M HCl) showedpronounced increases in concentrations deeper in the sediments. Where bioturbation was not visible the profiles of extractableCu, Pb and Cd are consistent with the precipitation of downward diffusing dissolved metals. However, this redistribution did notaffect the metal-total vertical profiles. Reactive metals exhibited multiple peaks in the irrigated sub-surface layers where AVS anddissolved Fe showed successive maxima and minima with the depth. We interpreted these profiles as the net result of dissolvedoxygen being pumped into the sediment and the formation of several oxic/anoxic interfaces. At these depths trace metals aremobilized in the oxidized layers, diffused a few millimetres towards the layers where sulphide is present, and precipitated. Theconsequence of this internal redistribution was the broad maxima of total metal concentrations in irrigated sediment depths. 2003 artículo científico 0185-3880 https://www.redalyc.org/articulo.oa?id=48029407 en http://www.redalyc.org/revista.oa?id=480 Ciencias Marinas application/pdf Universidad Autónoma de Baja California Ciencias Marinas (México) Num.4 Vol.29