Phytoremediation of heavy metals - Progresses and perspectives

Heavy metals are metallic elements which have a high atomic weight and a density much greater (at least 5 times) than water. There are more than 20 heavy metals, but four are of particular concern to human health: lead (Pb), cadmium (Cd), mercury (Hg), and inorganic arsenic (As). Phytoremediation, an eco-friendly technology which is both ecologically and economically viable is an attractive alternative to the current clean-up methods that are very expensive. This technology involves efficient use of aquatic plants to remove, detoxify or immobilize heavy metals. It is best applied at sites with shallow contamination of organic, nutrient or metal pollutants that are amenable to one of the five applications; phytotransformation, rhizosphere bioremediation, phytostabilization, phytoextraction and rhizofiltration. Phytoremediation of heavy metals and its effect on plants have been compiled to provide a wide applicability of phytoremediation.