Potential of butterfly pea (Clitoria ternatea) and yam bean (Pachyrhizus erosus) plants for phytoremediation of anthracene- and pyrene-contaminated soil

Abstract

The ability of butterfly pea (Clitoria ternatea) and yam bean (Pachyrhizus erosus) to stimulate the removal of anthracene and pyrene from contaminated soil was investigated. Of the two plants, only butterfly pea enhanced the removal of anthracene and pyrene from soil on day 30. The initial concentrations in soil of anthracene and pyrene were 86.3 and 74.1 mg/kg, respectively, while their remaining concentrations were 20.1 and 27.1 mg/kg on day 30. In comparison, the respective concentrations in unplanted soil on day 30 were 67.6 and 68.2 mg/kg. Anthracene and pyrene were completely removed from soil planted with butterfly pea and yam bean on day 75. In comparison, 17.8 and 18.2 mg/kg of anthracene and pyrene, respectively, remained in unplanted soil on day 75. Neither anthracene nor pyrene accumulated in any of the plant tissues examined during the study, so the mechanism for enhanced anthracene and pyrene removal was the stimulation by these plants of competent indigenous microorganisms to degrade the PAH compounds.

Keywords

• anthracene
• butterfly pea
• phytoremediation
• phytostimulation
• pyrene
• yam bean