USE OF SELECTED ORNAMENTAL PLANTS (TAGETES PATULA AND CALENDULA OFFICINALIS) TO REMOVE LEAD AND CADMIUM FROM SOIL

Abstract

Macro- or micro-elements that are known to harm plants and other living things if they exceed their allowed limits in soil are referred to as potentially toxic elements. Lead (Pb) and Cadmium (Cd) are two hazardous metals whose widespread use in many regions of the world has resulted in significant environmental contamination and health issues due to food chain contamination. This study aims to screen ornamental plant species exposed to Pb and Cd in spiked soils for determination of their phytoremediation potential in order to investigate approaches to repair contaminated soils with minimal impact on the environment and expenses. Two ornamental plant species (Tagetes patula and Calendula officinalis) were chosen to evaluate their capacity for Pb and Cd accumulation. For that purpose, pot experiments were carried out to assess the accumulative characteristics of the plant species in unspiked control (Pb=0, Cd=0) and spiked soils with various amounts of Pb (500, 1000, 1500, and 2000 mg/kg of soil) and Cd (50, 75, 100 and 125 mg/kg of soil). The maximum growth of Tagetes patula and Calendula officinalis was observed in the control after 10 weeks of exposure, and it decreased when the Pb concentration in the soil increased from 500 to 2000 mg/kg. The maximum growth of Tagetes patula and Calendula officinalis in the presence of Cd was likewise noted at the control, and it declined as the quantity of Cd in the soil increased from 50 to 125 mg/kg of Cd. At the soil contaminated with 1000 mg Pb/kg of soil, Tagetes patula roots and shoots showed the maximum Pb uptake, measuring 1101.7 and 206.3 mg Pb/kg, respectively. Calendula officinalis roots and shoots observed the highest uptake of 1411.2 and 592.4 mg Pb/kg, respectively in soil containing 500 mg Pb/kg. Against Cd exposure, both the plants showed the highest uptake in soil that was contaminated by 100 mg Cd/kg. Tagetes patula roots and shoots depicted the highest Cd uptake 1235.5 and 905.7 mg Cd/kg,respectively. Calendula officinalis roots and shoots showed the highest Cd uptake of 852.8 and 34.5 mg Cd/kg, respectively. Moreover, in Tagetes patula and Calendula officinalis bioconcentration factor (BCF) was ≥1 in all samples containing Pb, translocation factor (TF) ≤1 and enrichment factor (ECf) ≤.1. For Cd exposure, bioconcentration factor (BCF) of both plants was ≥1, translocation factor (TF) ≤1 and enrichment factor (ECf) ≥1. The results are promising, showing the potential for development of an integrated phytoremediation strategy using the selected plants.