Heavy metal pollution in sediments of a typical mariculture zone in South China

► The sediments in Hailing Bay, a key maricultural zone, were polluted by heavy metals. ► The aquafarming zone was significantly more polluted than the non-aquafarming zone. ► Most metals in the sediments, except Cd, were mostly present in the residual fraction. ► The ecological risk of the polluted sediments stemmed mainly from Cd, As, Cu and Pb. ► Aquafarming activities were one of the major sources of heavy metals in Hailing Bay.