Γεωχημικές κατανομές μετάλλων σε διαγενετικώς ενεργά, πλούσια σε σιδηροπυρίτη ιζήματα λιμνοθάλασσας

The fractionation of Fe, Mn, Cu and Zn was determined in selected core sediment samples obtained from a coastal lagoon located at Corfu Island, by means of sequential extraction schemes. Post depositional diagenetic processes, resulting in the formation of framboidal pyrite (revealed by powder-XRD and SEM-EDS) were found to significantly change metal –solid phase associations with depth. In most cases, the oxidizable fraction displayed a downcore increasing trend at the expense of the reducible fraction, implying that metals were released from Fe/Mn oxyhydroxides and transferred to the sulfide phase. Similarly, the Degrees Of Pyritization of Fe (DOP) and trace metals (DTMP) were higher at deeper strata of sediments than at the near-surface ones. High values of DOP (86%), moderate DTMP values for Cu (60%) and Mn (42%), and low DTMP values for Zn (15%) in the deep sediment sample indicate that even when pyritization is favourable, the presence of competing binding phases for Mn, Cu, and Zn may inhibit their incorporation to pyrite.