非饱和土壤中重金属污染物迁移机理分析

The theory analysis for the transport of heavy metal pollutant in unsaturated soil

视土壤为非饱和多孔介质,将描述非饱和多孔介质中多种迁移场量耦合的热质传递模型,结合土壤中溶质迁移的对流-弥散规律,并考虑土壤固体骨架对重金属污染物的吸附特性,建立非饱和土壤中重金属污染物迁移的数学模型.数值分析了非饱和土壤不同深度处和土壤含湿量不同时,污染物在土壤中的迁移状况.随着土壤深度的增加,污染物在土壤中的迁移呈现滞后性;湿含量较高的土壤,在迁移状况趋于稳定时,污染物沿土壤深度的增加其浓度梯度相对较小,数值分析所得污染物在土壤中的迁移规律与文献已有试验结果相一致.因此,所建立的数学模型和数值分析结果,可为分析重金属污染物在土壤中的迁移状况和修复重金属污染的土壤提供一定的理论指导.

In the paper, the mathematical model on the heat and mass transfer in unsaturated soil was integrated with the convective - dispersion equation of the solute in soil and the adsorption effects of the soil on the solute to describe the transport characteristics of heavy metal pollutant in unsaturated soil. The numerical analysis of heavy metal pollutant transport at the various depths in the soil was conducted. With an increase in the depth, the transport of the pollutant delayed in the soil; the rise of the water content in the soil decreased the concentration gradient of the pollutant along the longitudinal direction of the soil. The comparisons between the numerical simulation and the experiment which was conducted in reference were also given. All the results could be utilized for the soil of heavy metal pollution remedy.