Heavy metal levels in fluted pumpkin (Telfairia occidentalis L.) leaf and soil from selected dumpsites in Port Harcourt Metropolis, Rivers State, Nigeria

Abstract

Composite samples were collected from three refuse dumpsites and a fourth one which served as control, and analyzed for heavy metals concentrations using Atomic Absorption Spectrometer (AAS VGB 210 system). The results of detectable concentrations of heavy metals in (mg/Kg dry weight) were as follows: Fe (11.308±0.034 - 9.479 ± 0.029), Pb (0.004±0.091 - 0.016 ± 0.017), Zn (1.084 ± 0.026 - 0.753±0.026), Ni (0.274±0.013 - 0.070 ± 0.013) in the leaf, while the soil recorded Fe (18.599±0.007 - 3.432±0.033), Pb (0.152±0.028 - 0.018±0.022), Zn (3.264±0.011 - 0.417±0.127), Ni (2.630±0.678 - 0.070±0.099). The levels in the soil were generally higher than those in the leaf. The trend which was attributable largely to anthropogenic inputs, and comparable with similar studies within and outside Nigeria, identified iron (Fe) to have a greater value of contaminant on both the soil and the leaf. The values of the heavy metals obtained at the different dumpsites were lower than their corresponding permissible limit. The values from the different dumpsites show some relationship between anthropogenic inputs and industrial activities. From each of the observed metals in the edible vegetable (Pumpkin leaf), and soil, the highest values were obtained in parts of Port Harcourt where there is the heavy presence of industrial discharge or activities. The transfer factor (tf) index revealed that Fe and Zn values from the dumpsites afforded greater than 1 value, while Pb indicated less than 1 value, Ni reported values within the normal range in the plant. It can therefore be argued that solid waste dumpsites in Port Harcourt Metropolis are laden with high concentrations of heavy metals which are later absorbed and assimilated by plants growing within such sites. The study, therefore, calls for regular monitoring to mitigate the dangers implicit in the continuous consumption of the leaf.