Sediment characteristics and phase association and mobility of Fe, Mn, Zn, Cu, Pb and Cd in core sediments from lake edku

Abstract EN

The acid soluble and total concentrations of Fe, Mn, Cu, Zn, Pb and Cd were measured in sediment cores from Lake Edku; one of the Nile Delta coastal lagoons, southern Mediterranean sea.

The proportions of sand, silt and clay and the contents of CaC03 and organic carbon were also determined.

The results show that the average total concentrations ofFe.Mn, Zn, Cu, Pb and Cd are 57787 ± 19447,943 ± 395,81 ± 19,55 ±21,42 ± 10 and3.4 ± 0.7 jjLg g_I respectively.

The percentage of the acid leachable fraction of these metals in the given order are: 18, 64, 30, 52, 61 and 30.

The importance of the different binding substrates was inferred from the statistical relationships.

The results indicate two groups of metal associa-tions: Fe, Zn and Cu are preferentially associated with clay and to lesser ex-tent with silt; calcareous shells are the favorite sites for the second group comprising Mn, Pb and Cd.

The statistical relationships between the acid leachable metal phases and the different substrates maintain the same trend but with more specific and improved correlations.

The geochemical mobility of metals was inferred using a relative condi tional measure referred as Lability Index.

The studied metals showed a gen-era! mobility decrease with depth in cores.