The dispersion of 137Cs in a shallow Mediterranean embayment (Saronikos Gulf - Elefsis Bay), estimated inventories and residence times

► 137Cs levels were 2-3 times lower than those reported previously tending to background. ► Immobility was caused in summer and the strong surface evaporation increased 137Cs. ► The absence of seasonal trends denote the lack of the land impact. ► The initial deposition after Chernobyl was validated using the effective half-life (6.2 y). ► The area is expected to be depolluted in terms of Chernobyl-137Cs within 15 ± 4 y.