THE POTENTIAL OF COWPEA (VIGNA UNGUICULATA) AS BIOREMEDIATION TOOL OF HEAVY METALS CONTAMINATED SOIL

Abstract

An investigation of the potential of cowpea (Vigna unguiculata) as a bioremediator was performed to define how it can remove Cr, Zn, Mn, Pb, Cd and Fe in contaminated soil. 3kg of soil samples were separately contaminated with solutions of 2g of FeSO4, CdCO3 and 2g of Zn, Mn, Pb, and Cr metals dissolved in nitric acid, Cowpea seeds were planted into the contaminated soil in polythene bags which were perforated for aeration and watered frequently alongside the control sample. After 14, 28 and 42 days, the plant and soil samples were collected and analyzed by using atomic absorption spectrophotometer. The concentration of Fe in cowpea plant  was found to be the highest after 14 days and 28 days (7.570 ± 0.04 mgkg-1, 12.65 ±0.03 mgkg-1) while amount of  Cd  was the least (0.345±0.01 mgkg-1, 0.73±0.01 mgkg-1 and 0.928±0.02 mgkg-1). This investigation shows that Cowpea plant bioaccumulated Fe more and Cd was less bioaccumulated.