中小河流水体重金属Zn、Pb、As沿程迁移扩散过程模拟——以沘江为例

Simulation of migration and diffusion processes of heavy metals Zn,Pb and As in medium and small rivers:Taking Bijiang River as an example

为揭示中小河流水体中重金属Zn、Pb、As的沿程迁移变化特征,以沘江为例,重点考虑金顶铅锌矿的影响.以矿区上、下游15个沘江水样的样品分析数据为基础,根据水体中重金属迁移转化的水动力学特性建立沘江水体重金属迁移转化的一维数学模型,并运用试错法率定了模型中Zn、Pb、As的综合衰减系数K,进而采用MATLAB建立了适合沘江水体Zn、Pb、As迁移转化的模拟模型.结果显示:(1)枯水期沘江流域金顶矿区下游重金属Zn、Pb、As的综合衰减系数K分别为Zn全程0.015 s^(-1),果朗村上游Pb为0.006 s^(-1),As为0.018 s^(-1),下游Pb为0.004 s^(-1),As为0.002 s^(-1);(2)金顶矿区下游水体重金属Zn、Pb、As含量变化的模拟值与实测值的拟合效果较好,模拟方程具有一定的实用性;(3)模拟沘江丰水期水体重金属Zn、Pb、As质量浓度的沿程变化,还可通过重新率定综合衰减系数K或补充个别样点采样数据进行验证,以进一步优化模拟效果.研究结论可为沘江流域环境污染防治及生态恢复等提供科学依据.

Taking the Bijiang River as an example,in order to reveal the characteristics of the migration and change of the heavy metals Zn,Pb and As in the water bodies of small and medium rivers,the impact of the Jinding Lead-Zinc Mine is mainly considered.Based on the analytical data of 15 water samples from the upstream to downstream areas of the mine,combined with the hydrodynamic characteristics of the migration and transformation of heavy metals in the water body,the comprehensive attenuation coefficients K of Zn,Pb and As in the water were determined by the method of trial and error.A simulation model suitable for the migration and transformation of Zn,Pb and As in the Bijiang River was established by using MATLAB.The results showed that:(1)The comprehensive attenuation coefficients K of the heavy metals Zn,Pb,and As in the lower reaches of the Jinding Mining area in the Bijiang River Basin during the dry season are respectively,0.015 per second for the whole process of Zn,0.006 per second for Pb and 0.018 per second for As in the upstream of Golang Village,0.004 per second for Pb and 0.002 per second for As in the downstream.(2)The simulated values of Zn,Pb and As contents in the downstream water body of the mining area fit well with the measured values,and the simulation equation has certain practicability.(3)Simulating the changes in the mass concentration of heavy metals Zn,Pb,and As in the water during the high water period of the Bijiang River can also be verified by re-calibrating the comprehensive attenuation coefficient K or supplementing the sampling data of individual samples to further optimize the simulation effect.The research conclusions can provide a scientific basis for environmental pollution control and ecological restoration in the Bijiang River Basin.