Sediments from Lake Mariut, Egypt, after its rehabilitation, and its anoxic diverted polluted drains were subjected to five sequential steps to define different geochemical fractions of eight studied metals. Results cleared out that 30-50% of its total Cd and total Co contents are easily bioavailable with a high-risk assessment code (RAC) to enter the food chain in the lake basin. Whereas Cu and Fe are safe and the remaining studied metals, i.e., Mn, Zn, Pb, and Cr are of medium risk for the environment. Individual contamination factor (ICF) is high (> 6) for all the studied metals except for Fe and Cu which are tightly held in sediments confirming their safeness to biota. Cadmium accounted for > 94% of the total risk in the study area. Metal pollution loading (MPL) from the sediments was found in the order: Fe > Mn > Zn > Pb > Cu > Cr > Co > Cd.
Keywords: Bioavailability; Ecological risk assessment; Lake Mariut; Metals; Sediment; Toxicity.