The potential of Berkheya coddii for phytoextraction of nickel, platinum, and palladium contaminated sites

Abstract

The study involved assessing the potential of the native plant species (Berkheya coddii) for the phytoextraction of nickel, palladium, and platinum contaminated sites. Plant and soil samples were randomly collected from Barberton area, near Agnes mine, Mpumalanga Province, South Africa. Samples were analysed for total nickel, palladium, and platinum concentrations together with other elements found in the soil and in the plants' roots, and leaves. Soil versus leaves and soil versus roots uptake of these metals by the plant were compared. The mean concentration of nickel in the leaves/canopy was found to be 13,980 ± 10,780 mg kg−1 dry mass, in the roots it was 2046 ± 789 mg kg−1 dry mass, and in the soil it was 1040 ± 686 mg kg−1 dry mass. This resulted in a mean concentration ratio in the leaves to soil of 13.44. The platinum mean concentration in the leaves was 0.22 ± 0.15 mg kg−1 dry mass, in the roots it was 0.14 ± 0.04 mg kg−1 dry mass, and in the soil it was 0.04 ± 0.03 mg kg−1 dry mass. This resulted in a mean concentration ratio in the leaves to soil of 5.5. Palladium was found to have a mean soil concentration of 0.07 ± 0.045 mg kg−1 dry mass. The mean concentrations in the roots and in the leaves were 0.18 ± 0.07 dry mass and 0.71 ± 0.52 mg kg−1 dry mass, respectively. This gave a mean concentration ratio in the leaves to soil of 10.1 for palladium. Other elements that were found to have a mean concentration ratio in the leaves to soil of around 2.5 or above are sodium, potassium, magnesium, calcium, and sulfur. Berkheya coddii was found to be most efficient in accumulating nickel, palladium, and platinum from the soil. The results for the first time revealed that the plant may have the potential to uptake platinum and palladium; both metals are in the same group of the periodic table as nickel.