Bioremediation of polychlorinated biphenyls (PCBs)-contaminated soil by phytoremediation with Chromolaena odorata(L) R.M. King and Robinson

Abstract

The ability of Chromolaena odorata propagated by stem cuttings and grown for six weeks in the greenhouse to thrive in soil containing different concentrations of PCB congeners found in Aroclor and transformer oil, and to possibly remediate such soil was studied under greenhouse conditions. Chromolaena odorata plants were transplanted into soil containing 100, 200, and 500 ppm of Aroclor and transformer oil (T/O) in 1L pots. The experiments were watered daily at 70% moisture field capacity. Parameters such as mature leaves per plant, shoot length, leaf colour as well as the root length at harvest were measured. C. odorata growth was negatively affected by T/O in terms of shoot length and leaf numbers, but no growth inhibition was shown by Aroclor. At the end of six weeks of growth, Plants size was increased by 1.4 and 0.46%, but decreased at -1.0% in T/O, while increases of 45.9, 39.4 and 40.0% were observed in Aroclor treatments. Mean total PCB recoveries were 6.40, 11.7, and 55.8μg in plants tissues at Aroclor treated samples resulting in a percentage reduction of PCB from the soil to 2.10, 1.50, and 1.10 at 100, 200, and 500mg/kg Aroclor treatments respectively. There was no PCB recovery from plants in transformer oil treatments as a result of its inhibition to growth. Root uptake was found to be the probable means of remediation of PCB-contaminated soil by C. odorata, this was perhaps aided by microbes. This study has provided evidence on the ability of C. odorata to remediate PCB contaminated soil. However, the use of C. odorata for phytoremediation of PCB contaminated soil under field condition is therefore advised.