Phytoremediation of Cadmium, Lead and Zinc by Brassica juncea L. Czern and Coss

Objectives: To determine the potential of Brassica juncea to take up heavy metals (Cd, Pb and Zn) from aquatic environment. Methodology and results: The uptake of Cadmium (Cd), Lead (Pb) and Zinc (Zn) was studied at various concentrations, i.e. 0, 5, 10, 20 and 50 μg ml -1 in Steinberg’s solution over a period of 21 days. After 21 days, the plants were harvested, dried and the root and shoot biomass weighed. The uptake of each metal was studied in the root and shoot respectively, to determine the bioaccumulation coefficient of metals in B. juncea. The translocation factor was calculated so as to study the efficiency of the plants to bioaccumulate each metal in roots and shoot. The result showed that the heavy metals accumulated more in roots than in the shoots. When plants were exposed to the higher concentration (50 μg ml -1 ) of Cd or Pb, the metals were present at an average of 18.42 and 12.27 mg g -1 tissue in the root, respectively, and at 3.35 and 2.48 mg g -1 tissue in the shoots, respectively. The average concentration of zinc was 26.52 mg gm -1 and 2.59 mg g -1 in root and shoot respectively, when exposed to 50 μg ml -1 of zinc. Conclusions and application of findings : Brassica juncea has been found to have high potential to remediate Cd, Pb and Zn from aquatic environment with up to a maximum concentration of 50 μg ml -1 . This plant can therefore be grown in aquatic environment that are contaminated with heavy metals, after which the plant biomass can be harvested and burned to ash to recover the metals or to be disposed of appropriately and safely.