pH值对霞湾港沉积物重金属Zn、Cu释放的影响

Effect of pH on release of heavy metals Zn and Cu in sediment from Xiawan

以霞湾港(铜霞路段)的底泥沉积物为研究对象,采用重金属连续浸提法对重金属Zn、Cu在沉积物中的5种形态进行浸提,分析了其分布特征和在不同pH值与时间的条件下重金属的释放规律。研究结果表明,重金属Zn主要以铁锰氧化物结合态和碳酸盐结合态的形态存在,Cu主要以有机结合态和残渣态的形态存在,可交换离子态的重金属含量都很低。重金属Zn、Cu从沉积物中的释放,主要是在酸性条件下发生,在酸性区内释放量随pH的升高而迅速降低。释放能力和释放速率均为Zn>Cu,它们释放的过程基本相似,释放速率都比较小,向环境中的释放是个长期过程。

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.