重金属随泥沙迁移过程的数学模型

A transport model for heavy metals in sediments

为更加准确地模拟重金属随泥沙迁移的过程,避免传统模型在描述重金属的吸附解吸时只能片面地考虑简单物理过程的不足,在水沙输移模拟的基础上,同时考虑了重金属随泥沙迁移的物理和化学过程,建立了完整的水动力-泥沙-重金属迁移数学模型。模型利用泥沙颗粒表面复杂形貌与电荷的关系来修正表面络合模型并以此分析了水体中的重金属与泥沙颗粒表面基团间的化学成键作用,同时根据化学反应的不同条件,并结合床面冲淤,将床面泥沙分为有氧层和无氧层分别考虑重金属的沉积与再释放。模型模拟了水槽试验中重金属Ni随泥沙迁移的情况,计算结果与实测数据的对比表明了建立的模型可以合理地反映重金属随泥沙的迁移过程。

In this study, we develop an integrated model of hydrodynamic-sediment-heavy metal transport, which ineludes physical and chemical dynamics during the process of heavy metal adsorption in sediments. For this model, the traditional surface eomplexation model is modified to include sediment surface discharge, and then applied to represent the chemical bonding activities between heavy metals and sediment surface groups. In addition, according to the con- ditions of chemical reactions, two layers （aerobic layer and anaerobic layer） are included to considering topography evolution. The model is finally calibrated by simulating the transport of Ni, a trace metal, in a flume experiment. A comparison between observed data and the simulated results indicates that the integrated model is rational and can properly describe the complex process of heavy metal transport in sediments.