Heavy metal uptake and phytoremediation potential of <i>Jatropha curcas</i> Linn in contaminated soils

Jatropha curcas is a great plant for restoring nutrients in the soil and exhibits the ability to recover and reclaim contaminated soils. This study aimed at evaluating the phytoremediation capacity of Jatropha curcas (IAR JAT 044) for selected heavy metals (Cu, Cd, Pb and Zn). The treatments included three dumpsites (Sabo, Ori-Apata, Kakuri) and a control site in Samaru, Kaduna state.  These were laid down in a Completely Randomized Design (CRD) repeated four times in a Screenhouse. The experiment was carried out for a period of three (3) months after transplanting. The selected heavy metals’ concentrations of the dumpsites and control soils were initially determined before the establishment of the experiment. Likewise, the concentrations of the heavy metals were determined from the plant shoots and residual soils after harvest. Results of the initial concentration of the heavy metals before establishment of the experiment ranged as follows; Cu (36.35- 325.50), Zn (411.25- 2440.25), Cd (8.75-32.00) and Pb (36.35-249.75) in mg/kg which were significantly higher than the concentration after planting, which ranged as follows; Cu (3.75- 44.69), Zn (37.36- 37.36), Cd (0.6- 3.9) and Pb (11.59- 43.19) in mg/kg respectively. The bioaccumulation factor for Cu (1.27-10.05), Zn (3.41-7.99), Cd (1.18-21.57) were higher in plants than soil indicating high uptake, while Pb (0.92-4.06) was lower in Jatropha curcas than soil of the control. Likewise, the translocation factor revealed ranges as follows; Cu 1.34-1.77, Zn 0.45-1.27, Cd 1.39-2.05 and Pb 1.48-2.39, which indicates the capability of plants to take up heavy metals in their roots and translocate them to above-ground parts in the study area. Hence, the study reveals Jatropha curcas (IAR JAT 044) as a potential heavy metal excluders and bioaccumulator that could be used for phytoremediation in the study area.