Phytovolatilization
In this mechanism, the contaminants are adsorbed from the soil into the body of the
plant to transform them into volatile products. Finally, the volatile degradation form
is transpired with water vapor from the leaves, stems or other parts of plant, which
the pollutants cross before attaining the leaves (Muthusaravanan et al. 2018). The
method is applicable for contaminated soil, sediment, and water. The metal contaminants such as mercury, volatile organic materials like trichloroethene, and volatile
forms of inorganic chemicals such as selenium and arsenic can be treated by
phytovolatilization (Yadav et al. 2018; Muthusaravanan et al. 2018).
Phytostabilization
Plants immobilize pollutants of groundwater and soil through absorption and accumulation by precipitation or roots in the rhizosphere (the root zone of plants). The
processes via reducing the mobility of the pollutant prevent migration to the groundwater and it in turn decreases metal bioavailability in the food chain
(Muthusaravanan et al. 2018). Phytostabilization is useful to treat lead, cadmium,
arsenic, zinc, chromium, and copper, and takes advantage of the soil chemical and
environmental changes induced by the presence of the plant (Yadav et al. 2018). The
mechanism is highly effective and treats a broad variety of contaminations. Additional resolution of phytostabilization includes the stabilization of waste and
decreasing the next complications, hydraulic control, and reducing erosion via
wind and water (Yadav et al. 2018).
Phytodegradation
In phytodegradation, which is also referred to as phytotransformation (Trap et al.
2005), either complex organic compounds are degraded to simple molecules or they
are incorporated into the tissues of plant. First, the contaminants are taken up by the
plants and then they are broken down by plants utilizing enzymes (Yadav et al.
2018). The enzymes are dehalogenase, peroxidase, oxygenase, nitrilase, phosphatase, and nitroreductase (Jabeen et al. 2009). Because the heavy metals are
nonbiodegradable, this mechanism is limited to treat organic pollutions.
Hydraulic Control
In this mechanism, plant (tree) is used to control the movement of pollutions from
the polluted site through groundwater. Large amount of water is utilized by trees
with long roots and therefore they act as pumps to pull out the water. So the
pollutions are absorbed along with water in this process (Muthusaravanan et al.
2018). Hydraulic control has been reported in some plants (reader is referred to the
Table 12.6 of Muthusaravanan et al. 2018).
472
M. Fatehi et al.
In this mechanism, the contaminants are adsorbed from the soil into the body of the
plant to transform them into volatile products. Finally, the volatile degradation form
is transpired with water vapor from the leaves, stems or other parts of plant, which
the pollutants cross before attaining the leaves (Muthusaravanan et al. 2018). The
method is applicable for contaminated soil, sediment, and water. The metal contaminants such as mercury, volatile organic materials like trichloroethene, and volatile
forms of inorganic chemicals such as selenium and arsenic can be treated by
phytovolatilization (Yadav et al. 2018; Muthusaravanan et al. 2018).
Phytostabilization
Plants immobilize pollutants of groundwater and soil through absorption and accumulation by precipitation or roots in the rhizosphere (the root zone of plants). The
processes via reducing the mobility of the pollutant prevent migration to the groundwater and it in turn decreases metal bioavailability in the food chain
(Muthusaravanan et al. 2018). Phytostabilization is useful to treat lead, cadmium,
arsenic, zinc, chromium, and copper, and takes advantage of the soil chemical and
environmental changes induced by the presence of the plant (Yadav et al. 2018). The
mechanism is highly effective and treats a broad variety of contaminations. Additional resolution of phytostabilization includes the stabilization of waste and
decreasing the next complications, hydraulic control, and reducing erosion via
wind and water (Yadav et al. 2018).
Phytodegradation
In phytodegradation, which is also referred to as phytotransformation (Trap et al.
2005), either complex organic compounds are degraded to simple molecules or they
are incorporated into the tissues of plant. First, the contaminants are taken up by the
plants and then they are broken down by plants utilizing enzymes (Yadav et al.
2018). The enzymes are dehalogenase, peroxidase, oxygenase, nitrilase, phosphatase, and nitroreductase (Jabeen et al. 2009). Because the heavy metals are
nonbiodegradable, this mechanism is limited to treat organic pollutions.
Hydraulic Control
In this mechanism, plant (tree) is used to control the movement of pollutions from
the polluted site through groundwater. Large amount of water is utilized by trees
with long roots and therefore they act as pumps to pull out the water. So the
pollutions are absorbed along with water in this process (Muthusaravanan et al.
2018). Hydraulic control has been reported in some plants (reader is referred to the
Table 12.6 of Muthusaravanan et al. 2018).
472
M. Fatehi et al.