precipitation, complex formation or metal valence reduction in the rhizosphere [99]. Organic pollutants
taken by plants are metabolized by enzymes such as dehalogenase and oxygenase, which are not
dependent on rhizospheric microorganisms [100]. However, several heavy metals absorbed by plants get
converted into volatile forms and subsequently released into the atmosphere by the process called
phytovolatilization. This process has been used for removal of some volatile heavy metals like Hg and
Se from polluted soils [101]. However, this is limited by the fact that it does not remove the metals
completely but rather transfers them from one medium (soil or water) to another (atmosphere) from
which they can reenter soil and water.