Agriculture Reference
In-Depth Information
fuel in soil. Agamuthu et al., (2010) recorded appreciable degradation of used lubricating oil
in soil when the growth of
Jatropha curcas
was enhanced with brewery spent grain.
Advantages
Disadvantages
Relatively low cost
Longer remediation time
Easily implemented and maintained
Climate dependent
Several mechanisms for removal
Effects to food web might be unknown
Ultimate contaminant fate might be
unknown
Environmentally friendly
Aesthetically pleasing
Results are variable
Reduces landfilled wastes
Harvestable plant materials
Costs 10 - 20% of mechanical treatments
Slower than mechanical treatments
Only effective for moderately hydrophobic
compounds
Faster than natural attenuation
Toxicity and bioavailability of
biodegradation products is not known.
High public acceptance
Contaminants may be mobilized into the
ground water
Fewer air and water emissions
Influenced by soil and climate conditions
of the site.
(Susarla et al., 2002; Kamath, et al., 2004)
Conserves natural resources
Table 1. Advantages and disadvantages of phytoremediation over traditional technologies.
3.3.1 Mechanisms of phytoremediation
Variety of pollutant attenuation mechanisms possessed by plants makes their use in
remediating contaminated land and water more feasible than physical and chemical
remediation (Glick, 2003; Huang et al., 2004, 2005; Greenberg, 2006; Gerhardt et al., 2009). As
a result of their sedentary nature, plants have evolved diverse abilities for dealing with toxic
compounds in their environment. Plants act as solar-driven pumping and filtering systems
as they take up contaminants (mainly water soluble) through their roots and
transport/translocate them through various plant tissues where they can be metabolized,
sequestered, or volatilized (Greenberg et al., 2006; Abhilash, 2009). Plants utilize different
types of mechanisms for dealing with environmental pollutants in soil. The mechanisms of
phytoremediation include biophysical and biochemical processes like adsorption, transport
and translocation, as well as transformation and mineralization by plant enzymes (Meagher,
2000). Plants have been shown to be able to degrade halogenated compounds like TCE by
oxidative degradation pathways, including plant specific dehalogenases (Nzengung, et al.,
1999). Dehalogenase activity was observed to be maintained after the plants death. Enzymes
can become bound to the organic matrix of the sediment as plants die, they decay and they
are buried in the sediment, thus contributing to the dehalogenase activity observed in
organic-rich sediments (Nzengung, et al., 1999).
