Phytoremediation

Phytoremediation
During the 20th century there has been an increasing environmental awareness. Heavy metal contamination has increased sharply since 1900 (Nriagu, 1979). Metal contamination poses a major environmental and human health problems worldwide according to Ensley, (2000). The heavy metal contaminated sites are estimated to cost $35 billion for remediation over the next five years. There are over 40,000 contaminated sites in the USA alone according to the EPA report. Plants are a potential environmental cleanup for heavy metal contaminated sites. This process is called Phytoremediation.Phytoremediation comes from the Greek prefix meaning plant and remedium, meaning to restore (Cunningham et al., 1996). Pytoremediation is the process of using plants to mitigate environmental problems and restore the area to its natural state. Either naturally occurring or genetically engineered plants are used for cleaning contaminated environments ( Flathman and Lanza, 1998).

__How Phytoremediation work?__ Phytoremediation is actually a genneric term for several ways in which plants can be used to clean up contaminated soils and water. Plants may break down or degrade organic pollutants, or remove and stabilize metal contaminants. This may be done through one of or a combination of the methods described in the link below called Processes of Phytoremediaition. The methods used to phytoremediate metal contaminants are slightly different to those used to remediate sites polluted with organic contaminants.

**Applications of Phytoremediation**
 * Processes of Phytoremediation**

__What is the biotechnology of Phytoremediation? __ The first step in phytoremediation is to find a plant species which is resistant to or tolerates a particular contaminant with a view to maximising it's potential for phytoremediation. Resistant plants are usually located growing on soils with underlying metal ores or on the boundary of polluted sites. Once a tolerant plant species has been selected traditional breeding methods are used to optimize the tolerance of a species to a particular contaminant. Agricultural methods such as the application of fertilisers, chelators, and pH adjusters can be utilised to further improve the potential for phytoremediation.

The figure below shows how the contaminants are being taken up by the roots of the trees, causing the contaminants to degrade and produce volatilization. []

The video shows the process of how a plant is being introduced to a uranium contaminated site. The tolerant plant absorbs the toxins to mitigate. [] media type="youtube" key="w99mGLfb4_g?fs=1" height="385" width="640"

The picture below shows the plants being grown for remediation of contaminated areas. [] []

__Advantages to Phytoremediation__ - Phytoremediaiton cost less. - The plants can be easily monitored - It is potentially the least harmful method because it is naturally occuring

__Limitations to Phytoremediation__ - Slow growth and low biomass require a long tiem commitment. - Survival of the plants is affected by the toxicity of the contaminated land and the general condition in the soil. - Bio-accumulation in the plants, which affects the food chain. - Not possible to stop leaching of contaminants into the ground water.

Phytoremediation is a fast developing field, since last ten years lot of field application were initiated all over the world, it includes Phytoremediation of Organic, Inorganic and Radionuclides. M ost of the phytoremediation experiments have taken place in the lab scale, where plants grown in hydroponic setting are fed heavy metal diets.The future of phytoremediation is still in research and development phase, and there are many technical barriers which need to be addressed. Both agronomic management practices and plant genetic abilities need to be optimised to develop commercially useful practices. Many hyperaccumulator plants remain to be discovered, and there is a need to know more about their physiology. Optimisation of the process, proper understanding of plant heavy metal uptake and proper disposal of biomass produced is still needed (kochian, 1996).

Rebecca D'Arcy