A study of light nonaqueous phase liquid transport in low-permeability clays based on high density electrical resistivity tomography
In order to grasp the transportation law of light non-aqueous phase liquid(LNAPL)in clay after leakage,a modeling test was conducted.The soil layer was divided into two parts,with the upper clay having a uniform water content and the lower soil containing capillary water.The resistivity changes of the soil were monitored by electrical resistivity tomography,and the transportation law of LNAPL was obtained during the filling process as well as at the end of the filling process.The results showed that LNAPL infiltration into clay can improve the resistivity of the clay,and the resistivity of a clay with 10％water content can be increased by 50 Ω·m.With the increase of water content,its effect on improving clay resistivity gradually decreased.During the filling phase of LNAPL from 0 to 9 h,the peak value of the horizontal diffusion velocity of LNAPL was nearly 90 cm2·h-1 in the soil layer with 10％water content.When LNAPL transported to the unsaturated capillary zone,the peak value of its horizontal diffusion velocity gradually decreased with the increase of soil water content.The location of the contamination zone of high concentration of LNAPL in the clay gradually shifted downward after cessation of spiking.In regional area,the pollution plume front retracted with a speed of up to 0.15 cm2·h-1.This study can provide a reference for exploring the migration and distribution characteristics of LNAPL in the low-permeability clay polluted areas along the coast and river.
claylight non-aqueous liquidelectrical resistivity tomography(ERT)law of transport
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