Assessment of Heavy Metals (Zn, Cu, Pb, Cr, Cd and Ni) Concentration in the Leaves, Stems and Tubers of Manihot esculenta (Cassava) Harvested from the Egi Community, Rivers State

Heavy metals are usually associated with oil and gas exploration and exploitation activities. This study determined the levels of Zn, Cu, Pb, Cr, Cd and Ni in cassava (leaves, stems and tubers) grown in Egi. Samples of cassava collected from four locations, Control (Ohali-Elu) Location 1 (New Elf Road), Location 2 (Ugada) and Location 3 (Egita Land) were analysed using the AA500 model Atomic Absorption Spectrophotometer. Results of heavy metals concentration (mg/kg) in cassava leaf, stem and tuber from the study showed that all the metals were present in the plant tissues in both wet and dry season. Furthermore, their values were below the permissible limit in food crops by WHO/FAO/DPR (2018) except Cd which were recorded as 0.057 (Control), 0.375 (Location 1), 0.061 (Location 2) and 0.126 (Location 3) for Leaf.0.345 (Control), 0.661 (Location 1), 0.348 (Location 2) and 0.191 (Location 3) for Stem and 0.924 (Control), 1.461 (Location 1), 0.893 (Location 2) and 0.393 (Location 3) for Tuber, in the wet season. This indicated that Cd levels in leaf, stem and tuber in the wet season were above the permissible limit of 0.02mg/kg for food crops. The elevated levels of Cd in cassava tissues implied consequences of oil-related activities and other anthropogenic contaminants in the study area. The pollution consequences of Cd together with its imminent hazards on human and animals have been discussed based on the result; therefore constant monitoring programs should be put in place to further safeguard the environment from other contaminants.