资源环境科技发展态势分析平台

Atmospheric pressure fluctuations can induce subsurface airflow, affecting Volatile Organic Compound (VOC) contaminant migration in the vadose zone. When modelling this process, traditional vapor intrusion models have relied on the assumption of local equilibrium conditions and neglected kinetic mass transfer processes among different phases. In this study, a nonequilibrium multiphase flow and transport model was developed to investigate the impact of atmospheric pressure fluctuations on VOC release from groundwater to the atmosphere. Kinetic mass transfer processes between vapor & liquid phases, and between liquid & solid phases were taken into consideration. A series of soil column experiments with downward/upward pumped gas flow were conducted to validate the model. The experimental results imply the necessity to use nonequilibrium models for quantifying the impact of atmospheric pressure fluctuation. The validated model was used to investigate the role of atmospheric pressure fluctuations for various practical hydrogeologic settings under daily pressure fluctuations. It was found that when the soil organic carbon content is relatively large, the nonequilibrium model more accurately represents VOC migration than a traditional equilibrium model. Therefore, this study suggests the need to apply nonequilibrium vapor intrusion models at sites with high soil organic matter content.

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