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.

Keywords

• Heavy metals
• Phytoremediation
• Bioaccumulation
• Vigna unguiculata

References

1. Anyalogbu, E. A. A., Anadi, C. C., Nweje-Anyalowu, P. C. & Nnoli, M. C. (2017). Use of waterleaf (Talinum triangulare) in remediation of soil exposed to heavy metals: A green technology approach. World Journal of Pharmaceutical and Life Sciences, 3(9), 48-53.
2. Berti, W. R. & Cunningham, S. D. (2000). Phytostabilization of metals. Phytoremediation of toxic metals: Using plants to clean up the environment. Wiley, New York, 71-88.
3. Cachada, A., Rocha-Santos, T. & Duarte, A. C. (2018). Soil and pollution: An introduction to the main issues. In Soil pollution. Academic Press, 1-28.
4. Cristaldi, A., Conti, G. O., Jho, E. H., Zuccarello, P., Grasso, A., & Copat, C. (2017). Phytoremediation of contaminated soils by heavy metals and PAHs. A brief review. Environ. Technol. Innov. 8, 309–326.
5. Gerhardt, K. E., Gerwing, P. D. & Greenberg, B. M. (2017). Opinion: Taking phytoremediation from proven technology to accepted practice. Plant Science, 256, 170-185.
6. Herniter, I. A., Jia, Z. & Kusi, F. (2019). Market preferences for cowpea (Vigna unguiculata [L.] Walp) dry grain in Ghana. African J. Ag. Res, 14(22), 928-934.
7. Jacob, J. M., Karthik, C., Saratale, R. G., Kumar, S. S., Prabakar, D., Kadirvelu, K. & Pugazhendhi, A. (2018). Biological approaches to tackle heavy metal pollution: A survey of literature. Journal of Environmental Management, 217, 56-70.