Assessment of the phytoremediation capabilities of bracken fern (Pteridium aquilinum) for the remediation of heavy metals (Pb, Ni and Cd) contaminated water

Abstract

This study was carried out to investigate the potential uptake of heavy metals (Pb, Ni, and Cd) by Pteridium aquilinum plant from aqueous solutions. The whole plant strands were cultured in 36 experimental pots containing 5, 10 and 15 (mg/L) of Pb2+, Ni2+ and Cd2+ aqueous solutions. The plants were harvested after 24, 48, 72 and 96 hours of exposure and segmented into leaves, stem and root, respectively. The heavy metals content in the plant parts were analyzed using Atomic Absorption Spectrophotometer version VGP 210. The highest actual accumulations for Pb, Ni and Cd were recorded in the root at 15 mg/L of the aqueous solution after 96 hours of exposure with mean values of 4.29±0.04, 4.06±0.01 and 0.65±0.00 mg/kg, respectively. The highest total actual accumulations recorded in the plant were 9.19±0.14, 10.80±0.03, and 1.23±0.04 mg/kg for Pb, Ni and Cd, respectively. The accumulation of the heavy metals in the plant parts was in this order; root > stem > leaves. The results reveal that, the accumulation of heavy metals in the plant increases with increase in the concentration of the aqueous solutions and the duration of exposure to the aqueous solutions. The uptake of heavy metals by the plant is in this order; Ni > Pb > Cd. The translocation factor (TF) recorded for Pb, Ni and Cd in the plant were all greater than 1 (>1) except for Cd at exposure duration of 96 h in the 15 mg/L Cd2+ aqueous solutions, with the highest TF values of 2.500, 1.886 and 1.601, respectively. This indicates that more of the heavy metals were stored in the shoot. P. aquilinum is therefore described as a good accumulator plant, which could be used for phytoextraction of Pb, Ni and Cd in aqueous solutions of the metals. Key words: Phytoremediation, Pteridium aquilinum, heavy metals, contamination, translocation factor.