Assessment of the Phytoremediation Potential of Heavy Metal Contaminated Soil Using Vigna Unguiculata L. (Walp)

Abstract

Phytoremediation is a plant-based approach involving use of plants to extract and remove elemental pollutants or lower their bioavailability in soil. Thus, this study aimed at assessing the phytoremediation potential of Vigna unguiculata grown in heavy metal contaminated soil. Mature seeds of V. unguiculata were obtained from local farmers in Ojo-Lagos, Nigeria; heavy metal contaminated, and control soils were obtained from Iba and LASU Botanical Garden, Ojo-Lagos respectively. Physiochemical analyses of soil samples were done before and after transplanting. Nurseries were made and one seedling was transplanted into 5 buckets each for control and contaminated soils respectively. Growth parameters-stem height, stem girth, leaf length, and so on were measured. Heavy metal analysis was done using standard analytical procedures. Metal transfer factors and bioaccumulation potential were also studied. Data collected were analyzed using mean-standard deviation. Soil physiochemical parameters and heavy metals analyzed showed reduction in most of the metals studied before and after soil analyses. Results showed the transfer factors for Zn (0.07 mg/kg), Fe (6.72mg/kg), Mn (1.33 mg/kg), As (1.00mg/kg), Pb (0.19mg/kg), Cd (0.007mg/kg) while the bioaccumulation potential of Zn (0.08 mg/kg), Fe (3.86mg/kg), Mn (1.09mg/kg) As (1.00mg/kg), Pb (0.20mg/kg), Cd (0.001mg/kg). Also, the result revealed the metal uptake rate of Fe (21.75%), Cd (0.94%), Zn (1.40%), Pb (84.80%) and Mn (0.11%). It could be concluded that V. unguiculata reduces heavy metals in soil, had high transfer factors, bioaccumulation, and uptake rates. This study recommends that V. unguiculata could be used for phytoremediation of heavy metal environmental contaminated soils.