Phytoremediation of Heavy Metals Using Some Selected Leguminous Crops

Abstract

The phytoremediation of heavy metals (cadmium, chromium, copper and lead) using Phaseolus vulgaris and Arachis hypogaea were investigated using standard techniques. Heavy metal polluted soil samples were collected from Crush Rock Industries Ishiagu, Ebonyi State and heavy metal free soil samples (used as control) were obtained from Ebonyi State Ministry of Agriculture, Ishiagu Station. The seeds of the two plants were collected from the Enugu State Ministry of Agriculture. The experimental setup consists of 4 contaminated potted soils each of P. vulgaris and A. hypogaea. Another 4 potted soils not contaminated with heavy metals served as control. Soil analysis was carried out prior to planting. The polluted soil sample had slightly acidic pH (pH was 6.34±0.29), higher Cation Exchange Capacity (21.80±0.33), higher Cd (25.18±0.34), Cr (10.20±0.21), Cu (28.54±0.49) and Pb (9.92±0.36) levels but lesser soil organic carbon (0.87±0.10). After the duration of 62 days the plants were harvested, their leaves and roots were digested and subjected to further experimental tests [determination of Metal concentration, transfer factor and bioaccumulation factor (BAF)]. A. hypogaea showed highest Cd translocation factor 1.63±0.08, TF<1 was observed in all the plants examined for Cr. A. hypogaea showed the highest BAF for Cd, (1.16±0.08). BAF<1 was observed for Cr and Cu in the two plants examined. The BAF of A. hypogaea was higher than that of P. vulgaris. Plants from the control showed zero to very minute concentration of heavy metals in their tissues. Although the study plants are food crops, they can also play a role in the phytoremediation of some heavy metals.