Bioacumulation Potentials of Selected Tree Species in Heavy Metal Contaminated Soil

Abstract

Bioaccumulation potentials of some selected tree species (Tectona grandis, Gmelina arborea, Shorea roxburghii, Terminalia ivorensis and Terminalia superba) were assessed from heavy metal contaminated soils in a screen house study. The experiment was a 3 × 5 factorial treatment laid out in Completely Randomized Design. The factors were three levels of contamination (control, double permissible and triple permissible) and five tree species. Data collected include; physical and chemical properties of the soil and metal accumulation in roots, stems and the leaves of the tree species. These were subjected to analysis of variance, while, significantly different means were separated using Duncan Multiple Range Test (P ≤ 0.05). The results at 16 months after transplanting (MAT) showed that, S. roxborghi at the control level significantly (P ≤ 0.01) accumulated more Mn (76.38mgkg^-1) in its stem compared to other species. A significant level of Pb (0.006mgkg^-1) was also obtained in the leaves of Terminalia ivorensis at triple contamination level, while, Gmelina arborea accumulated highest concentrations (7.55mgkg^-1) in its stem at the control level compared to other species. Moreover, highest accumulation of Cu (7.65mgkg^-1) was obtained in Terminalia ivorensis at triple contamination level. Meanwhile, there was no significant difference between Zn and Cd accumulated in the leaves, stems and roots of the tree species throughout the period of investigation. Terminalia ivorensis, therefore, has been found to possess a high metal accumulation potential especially at toxic contamination levels compared to other species considered.