Evaluation of Heavy Metal Phytoextraction Potential of Rhizophora Racemosa in Niger Delta Mangrove Forest, Rivers State, Nigeria

Abstract

The bio transfer and bio translocation factors of heavy metals in the tissues of Rhizophora racemose was evaluated in this study. Soil, roots and shoot samples of the study plant were randomly collected from Kono, Bomu, Ogu and Borokiri mangrove forests at wet and dry seasons, digested and analyzed for heavy metals using standard laboratory methods. The laboratory results of field samples were further subjected to bio transfer and bio translocation factors analysis. Findings on wet season bio transfer factor revealed the concentrations of Cr (0.36mg/kg), Ni (0.86 mg/kg), Cd (2.86 mg/kg), Pb (1.17 mg/kg) and Zn (1.85 mg/kg), while dry season showed Cr (0.36mg/kg), Ni (0.55 mg/kg), Cd (1.24 mg/kg), Pb (2.72 mg/kg) and Zn (1.99 mg/kg). The bio translocation factor results for wet season indicated the concentrations of Cr (0.51mg/kg), Ni (1.47 mg/kg), Cd (1.02 mg/kg), Pb (1.48 mg/kg) and Zn (0.88 mg/kg), while dry season result revealed Cr (0.41mg/kg), Ni (0.65 mg/kg), Cd (1.24 mg/kg), Pb (1.50 mg/kg) and Zn (0.81 mg/kg). This study therefore classifies Rhizophora racemose as a hyper accumulator of Pb and Cd in shoot tissues and non-hyper accumulator of Cr, Ni and Zn in root tissues. Beside other uses, the plant has shown high affinity for the accumulation of heavy metals and thus can be used for phytoremediation.