Heavy Metal Concentrations in Cassava Leaves and Tubers Harvested from Some Communities in Gokana, Rivers State, Nigeria

The concentration of heavy metals in parts of edible plants and food crops is becoming a cause of concern to human beings. Samples of cassava leaves and tubers were collected from four communities in Gokana Local Government Area in Rivers State, Nigeria in the months of July and October 2019. The samples were analyzed for heavy metal concentrations after laboratory treatment. The results showed that the mean concentrations of the heavy metals in the leaves of cassava were; 0.127±0.110, 1.297±0.124, 2.410±0.736, 2.536±0.284, 98.566±9.767 and 2.306±0.480 mg/Kg for Cd, Pb, Cr, Cu, Fe and Ni in July, while the mean concentrations in the month of October were; 0.132±0.105, 1.287±0.210, 2.471±0.811, 2.571±0.291, 100.712±12.614 and 2.087±0.726 mg/Kg for Cd, Pb, Cr, Cu, Fe and Ni respectively. The mean concentrations of the examined heavy metals for July in the tubers were; 0.019±0.019, 0.377±0.341, 1.126±0.067, 1.567±0.304, 96.600±7.137 and 0.654±0.654 mg/Kg for Cd, Pb, Cr, Cu, Fe and Ni, while that of October were; 0.020±0.020, 0.364±0.300, 1.294±0.115, 1.872±0.119, 99.861±10.869 and 0.710±0.674for Cd, Pb, Cr, Cu, Fe and Ni respectively. All the Heavy metal concentrations showed higher values in the leaves than the tubers of cassava. The concentrations of heavy metals in the leaves were in the order; Fe > Cu > Cr > Ni >Pb> Cd and in the tubers, the order were, Fe > Cu > Cr > Ni >Pb> Cd. There is the need for adequate monitoring and implementing of necessary measures to reduce the levels of heavy metals in the cassava parts, so as to curb excessive intake by local consumers who consume the tuber as food and the leaves as medicine.