RELEASE OF HEAVY METALS FROM HARBOUR'S SEDIMENT TO SEAWATER: A LABORATORY STUDY

The release and removal behaviour of Cd, Cu, Co, Ni, Pb and Zn from the sediment of Xiamen Harbour to sea water have been studied under ultra-clean laboratory condition within 168 b. Initial rapid increases in dissolved Cu, Pb, Zn and Co were observed in the first six hours and twelve hours respectively after addition of various amounts of sediment. Then Pb and Co decreased to background values, while Zn decreased to less than the background value and Cu remained unchanged. Cd and Ni did not increase during the experiment. The results indicated that the weakly bound heavy metals were released from the sediment through desorption or exchange. Simultaneously, they might form complexes or be adsorbed in colloids or particles. The two processes existed simultaneously, changing with time and conditions.