Effect of pH on release of heavy metals Zn and Cu in sediment from Xiawan
pH值对霞湾港沉积物重金属Zn、Cu释放的影响

The distribution characteristics of zinc & copper in sediment of Xiawan (tong xia section) and their release law with different pH values and times were studied. Five forms of the two heavy metals in the sediment were extracted using sequential extraction procedure. The results show that the main existence forms of Zn in the sediment were metals bound to Fe-Mn oxides and bound to carbonates, and the main existence forms of Cu were metals bound to organic matter and sulfides and residual. The amount of exchangeable metals in the sediment was less than that of other forms. Heavy metals Zn, Cu release from the sediment mainly occurred in the acidic conditions, and with the pH increasing the release amount decrease rapidly in the acidic pH region. The releasing capability and the releasing rate follow the order: Zn> Cu .The release process of Zn was similar to Cu. The release rates were relatively small, and the release to the environment was a long term process.