Vetiver (Vetiveria Zizanioides) As Phytoremediator on Chromium and Nickel Uptake inLowland Rice Soils Affected by Mining Activities

The use of vetiver (Vetiveria zizanioides) is one of a few plant species meeting all the criteria required for phytoremediation. However, very limited studies have been done to use this plant as a phytoremediator in lowland rice soils. The study was conducted to determine the effect of phytoremediation using different time durations of vetiver grown for 3 and 8 months in the field and to evaluate the accumulation and translocation of Cr and Ni at various growth stages of the crop after planted with 3 months of vetiver. The field experimental set-up was conducted for two cropping seasons. Results revealed that vetiver had a Bio-accumulation factor of 0.97 for Cr and 1.07 for Ni after 3 months of growth and 1.48 for Cr and 1.38 for Ni after 8 months, indicating a higher concentration of Cr and Ni in the plant than in the soil. The translocation factors at both 3 and 8 months were below 0.2 mg kg -1 suggesting that vetiver accumulates Cr and Ni in the roots and very small amount is translocated to the shoots, making the plant safe for forage purposes. The Cr and Ni content in rice grains after planting the area with 3 months vetiver, were efficiently reduced to below detection limits.