铅从污染疏浚物的释放作用

THE RELEASE OF Pb FROM POLLUTED DREDGED MATERIALS

模拟研究厦门港员当湖重污染疏浚物中Pb向海水的释放作用。Pb的释放过程非常缓慢,平衡时间约15—20d,平衡释放率在2％左右,溶出平衡浓度为1μg/L。提供两种动力学模式,分别测定溶出速率常数、表观活化能和平衡分配系数。研究表明,在一般疏浚物的海上倾倒过程中,颗粒Pb的释放对海水水质不致产出明显影响。

The release kinetics of Pb from severely polluted dredged materials of Yuandang Lake in Xiamen to seawater has been simulated. The particulate Pb very slowly releases in seawater with an equilibrium time of 2-3 weeks, equilibrium efficiency of 2%, equilibrium release concentration of lμg/L.and equilibrium distribution coefficient of about 9×l04 (ml/g).The release of particulate Pb follows the exchange equilibrium kinetic model. The calculated equilibrium release capacity xd (eg) is close to measured capacity, that can provide the release limit under certain conditions.The increase rate of dissolved Pb principally follows the first order kinetic equation, and the release rate constant k2 and apparent activation energy E2 can be determined. E2 of about 54KJ.mol-1 suggests a chemical combination of Pb to the surface lof particles, which inhibits its release from particles to seawater.