Oxygen-mediated dielectric barrier discharge plasma for enhanced degradation of chlorinated aromatic compounds

•DBD plasma coupled with oxygen accelerated the degradation of chlorinated aromatic compounds (CACs) in water.•O3, ·OH, ·O2– and 1O2 were the dominant reactive oxygen species.•High mineralization efficiency of CACs was achieved in DBD/O2 process.•The intermediates of CACs degradation were consistent with the theoretical calculation.•Completed degradation was also achieved in the CACs contaminated soils.