The research was carried out to assess the level of some trace metals in cucumber planted on contaminated soil in Nekede, Owerri. The mean concentrations of Pb, As, Ni, Hg and Fe in the fruits of the cucumber plant from the topsoil were 0.256, 78.82, 98.84, 3.49, and 96.63mg/kg, respectively while the values for the subsoil were 1.24, 49.77, 96.32, 2.58 and 162.66 mg/kg respectively. The mean concentration of Pb, As, Ni, Hg and Fe in the leaf of the cucumber plant from the topsoil were 1.24, 49.77, 96.32, 2.58, 162.66 mg/kg respectively while the mean concentration for the subsoil were 9.51, 0.00, 97.31, 0.00, 2.59 and 95.44mg/kg respectively. The mean values of Pb, As, Ni, Hg and Fe in the leaf for the control (topsoil) were 6.37, 2.22, 1.91, 2.99, 43.68 mg/kg respectively while the mean values for the control (subsoil) were 11.00, 1.34, 5.53, 3.01, 61.74 mg/kg respectively. The result indicated clear differences in heavy metal (Pb, As, Ni, Hg, and Fe) bioaccumulation among the various parts of the cucumber plant from the topsoil and subsoil. Except for Hg and Fe, the heavy metal concentrations in all the investigated cucumber fruits and leaves exceeded regulatory limits set by the World Health Organization, the Food and Agriculture Organization and other international standards. Soil–plant transfer factors indicated low accumulation of the heavy metals into the fruits and leaves of the cucumber, except for Ni in both the fruit and leaf. The pH values of the top soil samples ranged from 4.60 to 6.20. The range of As, Hg, Fe, Cr, Co, Zn, Cu, Cd, Ni and Pb for the topsoil samples were 0.114 - 1.441, 0.368 – 0.448, 8.483 – 9.826, 2.567 – 13.776, 0.00 – 0.131, 10.885 – 14.479, 0.375 – 18.915, 0.008 – 0.031, 0.00 – 0.00, 0.897 – 4.363 and 4.60 – 6.20 mg/kg respectively. The pH values of samples from the subsoil ranged from 4.40 to 4.80 with a mean value of 4.6. The range of As, Hg, Fe, Cr, Co, Zn, Cu, Cd, Ni and Pb for samples collected from the subsoil were 0.642 – 1.902, 0.322 – 0.897, 9.572 – 18.125, 0.00 – 10.430, 0.00 – 0.082, 10.849 -20.270, 0.199 – 22.340, 0.012 – 0.402, 0.00 -0.254 and 1.189 – 36.073mg/kg respectively. The result of the one-way analysis of variance revealed that there was no statistically significant difference (p > 0.05) in the mean level of heavy metals in the fruits and leaves of cucumber from the top soil and subsoil obtained from both the polluted and control sites. The Tukey post hoc test revealed that there was no statistically significant difference (p > 0.05) between the heavy metal accumulation in the cucumber of the topsoil and subsoil from the polluted and control sites. The BAFs of all the heavy metals were less than 1.0, except for Fe and Ni. Additionally, the BAFs of Fe, Ni and As were higher than the BAFs of Pb and Hg. The study recommended the articulation of strategies by the government to enforce proper management and disposal of solid waste through strict and dedicated implementation of waste management policies.
