Bentonite addition to a PCB-contaminated sandy soil improved the growth and phytoremediation efficiency of Zea mays L. and Alternanthera sessilis L.

posted on 19.08.2019 by Maryam Salimizadeh, Mehran Shirvani, Hossein Shariatmadari, Mohammad Seddiq Mortazavi

In this study, the removal of 17 selected PCBi congeners was assessed in a transformer oil-contaminated soil amended with bentonite clay powder applied at the three levels of 0, 2, and 4% and cultivated by Zea mays L. or Alternanthera sessilis L. in a pot experiment. Results showed that Z. mays and A. sessilis were able to reduce the residual concentrations of the PCBi congeners in the contaminated soil significantly (p < 0.05). The average reductions in the ƩPCBi due to Z. mays or A. sessilis cultivations were 34.3 and 21.4%, respectively, depending on initial soil ƩPCBi loading and plant growth period. Moreover, addition of bentonite led to significant (p < 0.05) enhancements in plant growth and dissipation of residual soil PCBi congeners under Z. mays and A. sessilis cultivations. Addition of 4% bentonite to the soil was found to have the greatest positive impact on PCBi removal so that average PCBi dissipations in the soil were 56.1 and 51.8% after growing Z. mays and A. sessilis, respectively. It might be concluded that the combined phytoremediation and bentonite addition is an effective technique for removing PCBi and remediating transformer oil-contaminated coarse-textured soils.