Heavy metal hyper accumulation potential of local flora from polluted areas of Delhi

Phytoremediation is a cost-effective in-situ technique that exploits plant physiology for environmental remediation. Using local flora for phytoremediation has the advantage of successful revegetation and prevents leaching of the pollutants, such as heavy metals. The present study focused upon the hyperaccumulation potential of six local plants, namely Cannabis sativa, Datura metel, Amaranthus viridis, Parthenium hysterophorus, Oxalis corniculata, and Bryophyllum pinnatum, against copper, cadmium, zinc, chromium, and lead. P. hysterophorus was the most adapted hyper accumulator, as despite co-accumulation of Cu (331.45 mg/kg), Cd (243 mg/kg), and Zn (440.66 mg/kg), its phenols, superoxide dismutase (SOD), and peroxidase (POD) levels remained stable, indicating high metal tolerance. Similarly, stable antioxidant defense was also observed in O. corniculata despite Zn and Cr phytostabilization and Cd phytoextraction. Although D. metel accumulated the highest Cd and Cr levels, its elevated phenols, tannin, SOD, and POD indicated less adaptability to heavy metal stress. In contrast, B. pinnatum showed Cd phytoextraction (roots, 206.72 mg/kg; shoot, 248.80 mg/kg) and Cr phytostabilization (roots, 826.06 mg/kg), with a stable antioxidant response. A. viridis showed phytostabilization only for Cr, whereas C. sativa did not show significant hyperaccumulation potential. The results suggest that the phytoremediation capacity of tested plants on multi-contaminated sites is in the order P. hysterophorus > O. corniculate > D. metel > B. pinnatum > A. viridis > C. sativa.