Experimental observation of signature changes in bulk soil electrical conductivity in response to engineered surface CO2 leakage

► CO2 leakage enhances the dependence of bulk soil electric conductivity on soil moisture. ► Bulk soil electric conductivity on soil temperature weakly, leaked CO2 enhances the dependence. ► After the CO2 leakage, soil bulk electric conductivity versus soil CO2 concentration experiences three distinct CO2 decay modes. ► Rainfall events are believed to be the driving forcing for these decay modes. ► Within each mode, increasing soil CO2 concentration results in higher bulk soil EC.