Can you imagine clearing up polluted water bodies with aquatic plants? Soon, it might be a reality as scientists of the University College in the city have found plants that have the capability to absorb heavy metals from water bodies and render them harmless.

With their focus back on nature now, many science labs had been looking around for organisms, from bacteria to plants, that can absorb the pollutants flushed into the environment, be it water or land. But even microbes were often found to be at a loss on how to deal with heavy metals such as cadmium and lead. That is when the research teams turned to plants.

Among the many such research groups in the city focusing on this area, the one at the Department of Botany, University College, has managed to zero in on several plants that have the ability to remove toxic substances from soil and water and thus detoxify them, in a process scientifically known as ‘phytoremediation.’

The University College group comprising Princymol Stephen, Devi Chinmayee M, Mary Sheeba A, Swapna T S and Mini I  recently found that the aquatic plant ‘Pistia stratiotes’ not only has a high tolerance level for toxic heavy metals but that it can also be used quite effectively in phytoremediation.

The little pond inside the University College was where Pistia was grown. It was later exposed to heavy metal-contaminated water in the lab for as long as ten whole days, after which the researchers analysed the enzymes of the plant to see how well it tolerated the stress.

 ’Only stress-tolerant plants can be effective in dealing with the heavy metals. We found the antioxidant defence mechanism in Pistia to be quite good,’’ said Swapna, who along with Mini, leads the phytoremediation studies at the Botany Department.

They found that Pistia could easily absorb copper, lead and cadmium from the surrounding water. ‘’It either nullifies these toxins or keeps them away in small bag-like structures called vacuoles, where they are rendered harmless. When the plant dies, some of the metals may return to the environment. Complete detoxification happens rarely, but we can bring down the levels of pollution,’’ said Swapna.

The other side of the story is that some of the commonly used leafy vegetables may have this accumulative bioremediation properties and that would be bad news for those who consume these vegetables regularly. A wild relative of our ‘Cheera’, the ‘mullan cheera’, was found to have a very high bioconcentration factor and it accumulates copper and lead much above the toxic limits.

‘’So, if you are consuming ‘mullan cheera’, you really need to know where it comes from. If coming from polluted sites, it may be harmful since the plant accumulates and translocates metals to the leaves,’’ said Swapna.

Since the ‘mullan cheera’ showed such high values for bioaccumulation, the research group is also studying the common green ‘cheera’, scientifically known as Amaranthus viridis. The group is also studying several aquatic plants such as Lemma, Spirodela, Hydrilla and Salvinia if they can clear up toxic matter from water bodies.

 Perhaps, our water bodies are already heaving a sigh of relief.