Some plants are able to participate in the depollution of contaminated soils on which they grow. It's the phytoremediation. To achieve this, they implement different strategies.
In France, several hundred thousand industrial areas left fallow have polluted soils. In order to extract toxic substances, the use of mechanical or physico-chemical solutions is mainly used. They are relatively efficient and fast. On the other hand, they reduce the fertility and productivity of the treated soils.
A more environmentally friendly method of trying to eliminate pollutants through living organisms can also be used. And when we exploit the properties of certain plants, we talk about phytoremediation. The process is 100% natural. Its cost is more than reasonable and it is suitable for large areas. However, treatment times are long and decontamination can remain superficial.
Phytoremediation: Several modes of action
Depending on the situation, it is a particular plant rather than another one that will have to be used.
So some plants act by phytoextraction. Their roots extract pollutants from the soil. Pollutants that are then stored in the stems and leaves. This is the case with the culture of sunflower which can absorb metals as well as radioelements.
Other plants also act through their roots. These sequester the pollutants (arsenic, radioelements, etc.) in the soil, preserving the food chain and groundwater. This method of phytostabilisation can be implemented using Poplars for example.
The Weeping Willow, for its part, tends to accelerate the degradation of organic compounds (hydrocarbons, pesticides, etc.) through specific enzymes or live micro-organisms in the environment of its roots. It's the phytodegradation.
In the case of Phytovolatilisation, pollutants, which have become less harmful after a passage through the roots and leaves, are released into the atmosphere by the plant. This is how tobacco can treat certain pesticides or metals.
A great video regarding soil contamination can be watched following this link.