节点文献
重金属迁移的实验及数值模拟
Experiment and Numerical Simulation of Heavy Metal Transport
【作者】 朱蕾；
【导师】 袁德奎；
【作者基本信息】 天津大学 ， 流体力学， 2010， 硕士
【摘要】 目前,众多水域环境都存在不同程度的重金属污染,部分区域比较严重。重金属经过富集会对整个生物链产生毒害。进入水体中的重金属会快速吸附在泥沙上,泥沙和水体成为重金属的共同载体。重金属会在泥沙与水体间不断地进行交换;沉入底床的部分重金属会储蓄在底泥中,一定条件下可重新进入水体,造成二次污染。与一些有机污染物相比,重金属的性质相对稳定,可以在一定程度上作为研究泥沙及其携带的污染物迁移扩散规律的指示剂。本文开展了扰动条件下的重金属垂向迁移扩散实验。首先测定了吸附动力学曲线和吸附等温线,由此确定出最佳吸附条件、一定条件下的饱和吸附量及吸附系数,同时分析了环境因素对吸附的影响;然后在以上基础上开展了重金属垂向迁移扩散实验,测定了不同动态扰动条件下重金属沿垂向的浓度分布情况,进而分析了重金属在垂向的分布规律。结果可供进一步改进重金属迁移转化数学模型参考。开展了重金属迁移扩散的数值模拟。首先对实验水槽中的底床冲淤进行了模拟,得到的底床表面高程结果与实测值符合良好,表明现有的泥沙模型可以适用于此类问题的研究。然后在此基础上模拟了重金属的迁移扩散,计算所得的重金属浓度分布与实测值差别较大。主要原因可能是在重金属迁移转化模型中对底部边界条件作了过于简单的处理,没有考虑重金属在底泥中的混合和垂向迁移扩散的影响。将本文的实验进一步系统地开展下去,获得对底泥重金属迁移扩散特性的深入理解,将有助于改进重金属迁移转化数学模型。
【Abstract】 At present, a number of water bodies are polluted with heavy metals to different extend, and in some of them the situations are quite serious. Due to the process of enrichment, heavy metals can affect the entire food chain. As heavy metals flowing into the water, it will be quickly absorbed to sediment, so sediment and water are the common carriers of heavy metals. Heavy metals exchange between sediment and water continuously. A part of the heavy metal settles down to the bed with the sediment particles. Under certain conditions the heavy metals in the bed sediment can be released to the water body, result in the second pollution. Compared with organic pollutants, heavy metals are more stable, they can be used as the indicators for studying the transport of sediment.The experiments were carried out to understand the transport of heavy metal in the bed sediment. Firstly, the adsorption kinetics and adsorption isotherms were tested and the optimal adsorption conditions, the maximum adsorption capacity and adsorption coefficient were determined. Secondly, based on the adsorption kinetics and adsorption isotherms, the experiments were carried out and the vertical distributions of heavy metal were measured under different disturbance conditions.The numerical model developed by our group was applied to simulate the transport of sediment and heavy metal in a flume, and the performance of the model was evaluated by comparing the numerical results against the measured data. The results show that the predicted bed forms are in good agreement with the measured data, while the predicted distributions of heavy metal are not very satisfied most possibly due to the over simplified bed boundary condition.