Uptake and release of chromium and nickel by Vetiver grass (Chrysopogon zizanioides (L.) Roberty)

The effectiveness of using Vetiver grass (Chrysopogon zizanioides) in phytoremediation of wastewater has been proven. In this study, the phytoremediation potential of C. zizanioides planted in Cr- and Ni-contaminated soil was evaluated through investigating the behaviors on uptake and release of metals. Three treatments: control, Cr, and Ni, with three concentrations (50, 150, and 300 ppm), were applied. The potential of C. zizanioides is assessed by the determination of metal uptake rate, metal release rate, bioconcentration factor (BCF), biological absorption coefficient (BAC), and translocation factor (TF). The experiment showed that Cr uptake was higher than release rate and on the other hand low in uptake and release of Ni. Accumulation of Cr and Ni was 167.8 mg kg−1 and 66.3 mg kg−1, respectively. Excess of Cr in the soil was absorbed in high uptake rate making vetiver grass suitable for Cr phytoremediation. During 28-day uptake and 28-day release periods, it was found that BCF, BAC, and TF values in some treatments showed greater than 1 (one) and Ni-treated plants were able to translocate Ni to aerial plant parts supported by its high TF value. Low acidity of soil causes low solubility and low mobility of metals, resulting in low metal absorption. C. zizanioides has shown the potential as a heavy metal-tolerant species and could be potentially used as phytoremediation alternative species at least in lightly polluted areas.