多孔介质中轻非水相液体挥发过程的电阻率成像法监测

Monitoring the volatilization process of light non-aqueous phase liquids in porous media using electrical resistivity tomography

在含有细砂透镜体的三维非均质砂槽中进行了轻非水相液体(LNAPLs)的挥发实验,并应用电阻率成像法进行同步动态监测,尝试通过电阻率图像的变化反映砂槽中LNAPLs的挥发过程。结果表明,砂槽注油后电阻率明显上升,LNAPLs污染中心区域的电阻率大于边缘区域,由上往下电阻率减小,其图像近似半球形。注油结束后,污染物逐渐挥发,污染区域LNAPLs浓度不断减小,表现为电阻率逐渐降低。监测过程表明,应用电阻率成像法监测LNAPLs挥发过程是有效的。

In this paper, volatilization experiment of light non-aqueous phase liquids （LNAPLs） was conducted in a three dimensional heterogeneous sand tank containing fine sand lens. Electrical resistivity tomography was used for synchronous and dynamic monitoring. The volatilization process was demonstrated by means of variation of electrical resistivity distribution. Results showed that after the LNAPLs were injected into the sand tank,the electrical resistivity increased obviously. The electrical resistivity was higher in the central area than in the edge,and higher in the top area than in the bottom area. The distribution of electrical resistivity appeared as a semi-sphere. With the LNAPLs volatilizing gradually, the electrical resistivity decreased along time,indicating that the concentration of LNAPLs in the pollution area decreased. In conclusion,it is effective to apply the electrical resistivity tomography to monitor the volatilization process of LNAPLs.