present

In phytoremediation, the plant removes

the contaminants by breaking down and
absorbing them and can contain and stabilize
them by acting as a filter or a trap. In order
to accumulate metals, plants must be able to

first, tolerate high concentrations of

Phytoremediation is the direct use of

living green plants to clean up polluted and
contaminated soils through removal,
degradation, or containment. This process is
used to clean up both organic and inorganic
contaminants in sites with shallow, low to
moderate levels of contamination along with, or
in place of, mechanical clean up (conventional
remediation). Conventional remediation is the
physical removal and burial of contaminated
soils. The primary application for
phytoremediation technology is the clean up of
heavily contaminated soils from abandoned
herbicide and pesticide manufacturing sites,
also known as brownfields. Phytoremediation
can be used to clean up metals, pesticides,
explosives, solvents, crude oil, pollyaromatic
hydrocarbons, and landfill leachates. It also has
the potential to restore agricultural soils
suffering from over-use and salt build-up from

irrigation.

Key physiological processes in

phytoremediation include:

(1)Stimulation of microorganism-based

transformation by plant exudates and
leachates, and by fluctuating oxygen regimes

(2) Slowing of contaminant transport from the

vegetated zone due to adsorption and
increased evapotranspiration

(3)Plant uptake, followed by metabolism or

accumulation

generally toxic metals, either by vascular

compartmentalization or chelaten. They must also be able
to translocate an element from the roots to the shoots
(normally,root concentrations of heavy metals exceed the
shoot concentration, but in hyperaccumulators the
opposite is true) as well as rapidly accumulate the element
from solution. The four mechanisms for the removal and
stabilization of non-organic pollutants are phytoextraction
(the use of plants to remove contaminants from soils),
rhizofiltration (the use of plants roots to remove
contaminants from running water), phytovolatilization (the
use of plants to make volatile chemical species of soil
elements) and phytostabilization (the use of plants to
convert toxic metals to less toxic forms). Similar methods
for the treatment of organic materials are respectively
phytodegradation, rhizodegradation, and phytovolatilization.
After the metals have been removed from the soil, the
plants may be harvested and then incinerated or
composted in order to retrieve the extracted metals.