Not only that, the plants positively lap up the compounds, converting them to elemental mercury vapour which they exhale into the air . The plants were modified to include a gene, normally found in bacteria, that converts toxic mercury ions into elemental mercury. This is dangerous, often causes more disturbance than it alleviates, and is very expensive, especially if the area concerned is large. Bacteria seem to be able to come up with a metabolism to suit any occasion, and can offer species that absorb toxic materials of every kind. But researchers have lately been looking at plants, which offer many environmental advantages.
Plants have extensive root systems that find every crevice in the soil.
In addition to absorbing toxic chemicals, root systems stabilize the soil against erosion, preventing the kind of washout that transports soil-borne pollutants into rivers and drinking water. To top it all, plants look much more appealing than bacterial slime. But these plants are small and grow very slowly, so they would be of limited value for quick-fix bioremediation. Some trees, on the other hand, convert soil into biomass quickly and efficiently - but they'd be felled by toxic minerals. The answer is to find a tree that is resistant to toxins, by marrying a suitable tree with the metabolic virtuosity of bacterial genetics.