Efficiencies of Heavy Metal Hyper-accumulation Plants as Potential Land Remediators for Heavy Metal Polluted Soils

The purpose of this study was to determine which hyper accumulator plant is more efficient for phytoremediation of heavy metals in a heavy metal polluted soil. The plants used were Sunflower (Helianthus annuus), Asiatic dayflower (Commelina communis), Guinea grass (Panicum maximum), Bahama grass (Cynodon dactylon), and Vertiver grass (Chrysopogon zizanioides). Heavy metals such as Pb, Zn, Cu, Cd, Ag and Hg were impregnated in the soil samples and analyzed using atomic absorption spectrophotometer (AAS). The plants were planted in the heavy metal polluted soil and harvested after 75 days to determine the percentage concentration of the heavy metals in the root and shoot of the plants. The result showed that heavy metals were hyper-accumulated in the roots and shoots of the plants at the end of the investigation. The heavy metals with a percentage concentration above 50 % can be used as a phytoremediator of that particular metal in a polluted soil. It was discovered that the best hyperaccumulator plants for Pb is the Sunflower, for Zn and Cd is the Bahama grass, for Cu and Ag is the Vertiver grass whilst, for Hg is the Guinea grass.