Glossary

Send

Phytoremediation

Cleaning contaminated soil, water or air with the use of plants

Many plants are able to grow in contaminated media (soil, water or air). Although the plants absorb pollutants in the water or air, they have developed mechanisms to protect themselves against their toxic effect. They then store the pollutants in specific cell areas in the roots, stems or leaves, or convert them into non-toxic substances. Examples of contaminants include heavy metals, metalloids (arsenic), pesticides, explosives, solvents, salts and oils. Pollutants which have accumulated in the plants are removed by harvesting. The growth and harvest cycle must often be repeated to completely remove the contaminants from the soil.

Suitable plants for removing heavy metal contamination include oilseed rape, mustard, sunflowers, barley and various varieties of grass.

Genetic engineering is also used to give plants the capability of absorbing contaminants and converting them into non-toxic substances. For example, poplars have been genetically modified to contain increased levels of glutathione. Glutathione is needed in the cells to bind heavy metals, causing them to lose their toxic effects. Poplars store the heavy metals, which have been rendered harmless, in their leaves.