Risk assessment of heavy metals in coastal sediments of the Red Sea in Egypt

The Red Sea's near-shore zones are considered nurseries and grazing grounds for the various economic fish species. To illustrate the relation between human health and seafloor sediments, the geological and geochemical properties of seafloor sediments were investigated in near-shore zones at Marsa Alam and Hurghada cities along the Red Sea. The obtained data illustrated that the sediment nature at Hurghada is primarily of biogenic origin, as indicated by the high carbonate contents; however, the sediment nature at Marsa Alam is attributed mainly to the terrigenous origin. Accordingly, the studied heavy metals at both localities showed different feeding sources; Marsa Alam sites showed high levels of Fe, Mn, Zn, Ni, and Cu attributed to terrigenous inputs; however, the high averages of Cd and Pb at Hurghada indicating influence from land-based and anthropogenic activities. The calculated risk assessment parameters and carcinogenic risk (ILCR) do not indicate any significant risk. Geochemically and as indicated by the statistical parameters: correlation coefficient, PCA, and Geo-accumulation (Igeo); Mn, Zn, Cu, and Ni were found to be mainly associated with Fe in the same source of accumulation and similar geochemical forms. However, the adsorption over sediment particles and/or assimilation inside the carbonate lattices are possible occurrences of Cd, Pb, and partially Ni. The calculated risk assessment parameters and carcinogenic risk (ILCR) do not indicate any significant risk to marine organisms and human consumption.