Metal-sulphides formation in the sediment of the Venice canals (Italy). (Abstract/Poster in atti di convegno)

Type
Label
  • Metal-sulphides formation in the sediment of the Venice canals (Italy). (Abstract/Poster in atti di convegno) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Alternative label
  • L. Zaggia (1), J. Rosso (1), P. Frizzo (2), R. Zonta (1) (2006)
    Metal-sulphides formation in the sediment of the Venice canals (Italy).
    in ECSA 41ST International Conference "Measuring and managing changes in estuaries and lagoons", Venezia, 15-20 October 2006
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • L. Zaggia (1), J. Rosso (1), P. Frizzo (2), R. Zonta (1) (literal)
Pagina inizio
  • 104 (literal)
Pagina fine
  • 105 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#titoloVolume
  • Measuring and Managing Changes in Estuaries and Lagoons. Book of Abstracts (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#note
  • Proceedings, p. 104 (literal)
Note
  • Abstract (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • 1) CNR - National Research Council - Institute of Marine Sciences (CNR-ISMAR), San Polo 1364, 30125 Venezia, Italy 2) University of Padua - Department of Mineralogy and Petrology, COrso Garibaldi 37, 35100 Padova, Italy (literal)
Titolo
  • Metal-sulphides formation in the sediment of the Venice canals (Italy). (literal)
Abstract
  • The fate of anthropogenic heavy metal in the contaminated anoxic sediments of the Venice canals is mainly conditioned by sulphidic transformations occurring during the early diagenesis. Bacterial sulphate reduction is the key process in the metabolism of organic matter supplied to the system by the untreated effluents directly discharged in the network. Based on our recent measurements of sulphate reduction rates in representative sites, an average of more than 500 kg d-1 of sulphate-S is converted into S 2- in the warm period (May-October). Part of the so formed S2- can diffuse across the sediment water-interface, being eventually released to the water column and readily oxidised. However, a considerable proportion of S2- combines with reactive iron in pore waters forming insoluble sulphides, mainly FeS, which accumulate in the sediment ultimately leading to the formation of FeS2. Anthropogenic heavy metal are generally adsorbed to or coprecipitated in these newly formed phases. However, if metals enter the system as coarse particles, as easily occurs in the Venice canals, a variety of bulk metal-sulphides can form as the result of direct sulphurisation of the original metallic compounds. The partitioning of sulphur compounds in sediments from 5 selected sites of the network was investigated by collecting 35 cm-long cores. Pore water concentration of heavy metals, SO42- and S2- as well as the distribution of solid-phase sulphur (S0, AVS, CRS) and AVS-metals concentrations were considered revealing interesting implications, particularly for As and S2-. The gravity-separation of dried sediment aliquots permitted a detailed investigation on sulphide particles by reflected light optical microscopy, and the study of their microchemistry by scanning electron microscopy combined to energy dispersive x-ray fluorescence. The results show as Cu and Zn sulphides are commonly found in replacement of original compounds and can coexist in intimate association with FeS and FeS2, sometimes forming reaction rims. (literal)
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