Ecological risk assessment of surficial sediment by heavy metals from a submerged archaeology harbor, South Mediterranean Sea,Egypt

A protected semi-enclosed embayment,the Eastern Harbor（EH）,is situated in the central sector of the Mediterranean coast of Alexandria,Egypt.It is a famous fishing dock and water-sport center and its importance arose after the discovery of the Ptolemaic royal quarter of ancient Alexandria.To protect this national treasure and improve its environmental health,the untreated anthropogenic effluents,which continued for decades into the EH since 1992,must be totally stopped.Accordingly,it is an important issue to continually monitor and asses the environmental status of the EH.The sediment texture,total organic carbon,and the accumulation,distribution,and ecological risks of Cd,Cr,Pb,As,Hg and A1 were determined with a total of 14 surficial sediments samples collected in the EH during 2010.Metal contents were compared to the literature data to assess the pollution status of sediments.Enrichment factors,Degree of contamination（mCd） and potential ecological risk were calculated as a criterion of possible contamination.Since mCd calculation produces an overall average value for a range of pollutants,in the present study the contamination factor that provides a measure of the degree of overall contamination in the surface layers in a particular sampling site may provide a better indication of the state of pollution in the EH sediments than other indicators.