- Researchers have identified a native roadside plant that can take up lead from the soil and thus help in removing the metal from the environment.
- The plant was found to accumulate lead at about 12,000 microgram/g of dry weight in the root and 7,000 microgram/g of dry weight in its shoot.
- These plants grow in soils that are continuously exposed to lead from vehicle exhausts.
- Though lead additives in petrol and diesel are banned now, some low-quality fuels still have a huge percentage of lead.
- The present study found that Eclipta prostrata had the highest lead tolerance.
- E. prostrata or ‘False Daisy’ is found across the Indian subcontinent. Known ‘Bhringraj’ (Karisalankanni in Tamil), it is used as a ‘hair-growth stimulant’ and in many ayurvedic preparations.
- The plant may be using the lead to protect itself from the pests, or other predators.
- Tribal people use it an antidote for snake bites and treatment of scorpion stings..
- Spectrophotometric studies showed increased levels of many enzymes that are known to induce tolerance in plants.
- Hi-tech microscopic analysis showed that the lead travelled to the leaves and was deposited as lead nanoparticles in its cell wall, cytoplasm, and chloroplast.
- Though we noticed a little distortion in the structure of these organelles no toxicity was seen,”
- The plants can be burned up after they have taken up the lead.
- In this way, the metal can be effectively contained and later disposed off safely.
- This study has provided evidence that the plant is a lead hyperaccumulator that has the suitable biochemical machinery.
- But as the present experiment was carried out using a soluble salt of lead (lead nitrate), more studies are needed in contaminated environments where lead is usually found in insoluble forms.
- To increase the solubility of lead so that it becomes bioavailable to the plant, some solubilising agents (metal chelators) need to be added to the soil; the plant must be tolerant to such chemicals as well.
- Made into a solution, solubilising agents will be added to the contaminated soil.
- As chelators have long residence time and can percolate well, they will react with the lead in the soil and make it in a form available to the plant.
- Such experiments using naturally contaminated soils are significant further steps in using the plant for bioremediation of lead-contaminated soil.
