中文摘要：

分析了挥发性污染物在土壤中迁移转化机制以及耕作层土壤的特点，在考虑耕作层土壤大孔隙流的特点基础上，以质量守恒原理为基础，建立了挥发性污染物在土壤中迁移转化的两区数学模型，并给出了模型的数值解法。以典型的挥发性污染物为例，对其在土壤中的迁移转化的动力学行为进行分析，认为农药的挥发性以及不动水区含水率是农药在土壤中浓度分布的主要影响因素，验证了土壤中农药挥发性数学模型的应用更符合其发生机制以及所建立的两区模型的正确性。这对于预测挥发性污染物释放对环境污染的变化趋势和控制挥发性污染物对环境的污染具有重要意义，并为土壤中挥发性污染物的安全评价提供了手段。

英文摘要：

Based on analyzing the characteristics of flow through large soil pores and the transport and transformation mechanisms of volatile contamination, a two-region model for volatile contamination transport and transformation in soil is established; and a numerical solution of this model is qiven; and the behaviors of volatile contamination suck as volatility and absorption etc. in soil are described quantitatively. Taking heptachlor for example and simulating its dynamic transport and transformation behavior in soil, it is concluded that the volatility of pesticide and the water content of immobile region are key factors affecting the concentration distribution of pesticide; and that the volatile mathematical model of pesticide used in the two-region numerical model in soil can more reasonably manifest its behavior mechanism. The study is of significance for predicting and restricting pesticide pollution.