Resistivity imaging of soil during electrokinetic transport

摘要

Electrical resistance imaging of soil specimensduring electrokinetic treatment is reported. Column experimentswere carried out on Speswhite kanlinite contaminated with leadnitrate to levels both above and below its cation exchangecapacity (CEC). Post test chemical analyses of the speciments andtheir pore fluids show that resistivity variations correlate withchanges in pore fluid chemistry but do not show the extent of decontamination.Regions of high resistivity correspond with precipitation zoneswith in the specimens whereas regions of low resistivitycorrespond with regions of high pore fluid ionic strength. Wherethe contamination level is below the CEC, decontamination isslow as lead ions are mostly sorbed to the clay so most thecurrent is carried by electrolysis products and clay dissolutionproducts. A broad resistive zone forms over the cathode haltwhere hydroxyl and HCO3- ions formed in the cathode reservoirprecipitate clay with dissolution products and other ions. Wherethe contamination level is above the CEC, lead ions are initiallymajor charge carriers and decontamination over the bulk of thespecimen is rapid. However, lead still precipitates immediatelyadjacent to the cathode reservoir to form a narrow resistive region.