Abstract:
Lead being toxic and the most widely present heavy metal, causes different problems in the environment. Various technologies have been developed for the removal of Pb from soil. Microbes and synthetic chelate-assisted phytoextraction have been used for the remediation of Pb contaminated soils. The present study focused on the integration of synthetic chelates along with biological systems for enhanced phytoextraction of Pb by Pelargonium hortorum. Pb resistant fungal and bacterial strains capable of Pb solubilization were selected by growing them individually with five different metal chelators and the growth (optical density) of each strain was checked using U.V/Visible Spectrophotometer. Laboratory results showed that Aspergillus flavus & Klebsiella quasipneumoniae subsp. Similipneumoniae had significantly better growth in citric acid after 48 and 24 h, respectively. Disc diffusion method confirmed the growth compatibility of these two strains. The finally selected bacterial and fungal combination along with citric acid was applied to the pilot scale setup of Pb phytoextraction using Pelargonium hortorum. Three plots having different levels of Pb (13, 1187 and 2292 mg kg-1, respectively) were transplanted by one-month old seedlings of Pelargonium hortorum and were provided with selected chelates combination under natural conditions for four months. The growth parameters of plants as well as Pb uptake by each plant grown in soil with the highest exposure level (2292 mg kg-1 Pb) were significantly higher as compared to the plants in 1187 mg kg-1 Pb and 13 mg kg-1 Pb. The results suggested that integration of biological and chemical amendment can be a better solution for plant growth and performance in high Pb contaminated soils.
