Assessment of heavy metals contamination and ecological risks in coastal sediments of the Mediterranean seashore

Seawater pollution from sewage is associated with many environmental risks, which pose threat to marine organisms and human life. Nine heavy metals were determined at 22 georeferenced stations along the Mediterranean seashore, Egypt, including four major cities (Ras El-Bar, New Damietta, Gamasa, and New Mansoura), that are characterized by high anthropogenic activities. The results demonstrated high heavy metals levels in Gammasa, followed by Ras El-Bar and New Damietta cities. The heavy metals' abundance was found in sequence of Fe > Mn > Cr > Zn > Co > Pb > Cu > Ni > Cd. Zinc concentrations showed lower levels than threshold effect level (TEL), while Pb, Ni, Cu, Cr and showed lower values. Also, Zn concentration was lower than LEL, while Pb, Ni, Cu, Cr, and Cd showed lower values. The concentrations of Pb and Zn were lower than effects range low (ERL), while Ni, Cu, Cr, and Cd showed values. Regarding Cd, 18.18% of samples were higher than effects range median (ERM) that reflect adverse effects on organisms at these sites. The order of EF was Cd > Co > Pb > Cr > Zn > Cu > Mn > Ni. The geo-accumulation index (Igeo) was Cr > Ni > Pb > Zn > Mn > Cu suggesting that sediments are not polluted by these metals, while Igeo of Cd is-0.84 reflecting moderate contamination with Cd. According to contamination factor (Cf) and degree of contamination (Dc) data, Gamasa city was the most contaminated, followed by Ras El-Bar, New Damietta, and New Mansoura cities. This can be attributed to various anthropogenic activities and industrial effluents that are discharged into different drains before pouring into seawater. Policymakers must take into account strict laws and regulations to limit unmanaged industrial activities, especially those causing pollution from sewage and industrial wastewater.& COPY; 2023 Elsevier B.V. All rights reserved.