Bioremediation of Heavy Metal Polluted Soils

Phytoremediation of heavy metal contaminated soils, by using plants to make soil contaminants nontoxic, offers a cost effective “green” method for soil remediation. There are now four subsets of this technology applicable to soil remediation: (1) phytoextraction, using hyperaccumulator plants or high biomass metal accumulating plants to remove toxic metals from soil; (2) phytovolatilization, using plants to stimulate volatilization of metals from soil or plant surface; (3) phytofiltration, using plants to absorb, precipitate and concentrate toxic metals from water; and (4) phytostabilization, using plants to transform soil metals from toxic forms to less toxic forms. The use of plants to clean soils contaminated by toxic metals shows great potentiality. Also discussed are some important advances, made in the past few years, in making use of microorganisms for remediation of heavy metal contaminated soils.