Bioaccumulation of lead by pepper elder (Peperomia pellucida (l.) kunth) in a lead-contaminated hydroponic system

Abstract

Lead (Pb) has become one of the most common heavy metal contaminants, demanding research on economical remediation approaches with minimal ecological impacts. Pepper elder (Peperomia pellucida) is a fast-growing plant that can be a candidate for bioaccumulation and phyt oremediation. In this study, the lead bioaccumulation of P. pellucida was assessed by determining the growth response and absorptive capacity of the plant. Plants were grown in hydroponic solution spiked with 500 mg/L of Pb for 28 days. Growth response, absorptive capacity and tolerance of plants grown in contaminated nutrient solution were determined in comparison with control plants. After 28 days of exposure, lead phytotoxicity symptoms such as wilting, chlorosis and necrosis were observed on some plants. The control plants recorded 3.08 g total dry weight (DW) compared to the 1.35 g in Pb-contaminated plants. The tolerance index (TI) of P. pellucida was at 43.40%. The plants were able to absorb lead, with the concentration of lead in the roots (158.6 µg/g) being greater than the concentration of the metal in the shoots (43.2 µg/g). Meanwhile, bioconcentration factor (BCF) and translocation factor (TF) values were recorded at 0.40 and 0.27, respectively. BCF criterion indicates that the plant is not suitable for phytoextraction, but TF value shows that the plant can be a potential excluder. The findings of the study show that P. pellucida accumulated considerable amount of lead within its tissues, indicating that the plants may be further exploited for their capacity to absorb heavy metals by tweaking several factors that may affect its bioaccumulation ability.