Plants Open the Future: Spreading Phytoremediation - December 2003

Plants Open the Future: Spreading Phytoremediation - December 2003

In December 2003, "phytoremediation" (environmental remediation technology using plants), which utilizes plants as a countermeasure against environmental pollution, attracted much attention.
Compared to conventional chemical and physical methods, phytoremediation is expected to be a low-cost and environmentally friendly technology, and its research and practical application are progressing in Japan.
In particular, its use is expanding as a purification technology for soil contaminated with heavy metals such as lead and cadmium.

There are several phytoremediation methods.
Phytoextraction (phytosorption) is a method that uses plants that accumulate heavy metals to absorb toxic substances in the soil, which are then properly treated after harvesting.
Phytostabilization (immobilization method) is a technique that uses plant roots to adsorb and immobilize pollutants and prevent their spread.
In addition, phytodegradation (decomposition method) utilizes the action of enzymes possessed by certain plants to break down harmful substances such as pesticides and organic solvents.

In Japan, phytoremediation demonstration experiments have been conducted in lead- and cadmium-polluted areas in Okayama and Ibaraki prefectures, and it was confirmed that ferns absorb high concentrations of certain heavy metals.
In addition, test cultivation utilizing sunflowers and marigolds has been conducted in Himeji City, Hyogo Prefecture, and is expected to have absorption effects.
Meanwhile, in the U.S., the application of this technology is already in the practical stage, as it is being applied to lead-contaminated soil in Illinois and petroleum-contaminated land in California.

However, there are many challenges to the widespread use of phytoremediation.
It has been pointed out that because of the long growing period of plants, phytoremediation is less immediately effective than conventional physical and chemical treatments.
There is also the risk of cross-contamination if absorbed toxic substances are not properly treated.
In Japan, there is a need to establish an assistance system led by the national and local governments and to strengthen the monitoring system for contaminated soil.

Phytoremediation is likely to become an important pillar of future environmental policy as a low-cost and sustainable contamination remediation technology.
As the technology advances, it is expected that more efficient plant species will be developed and that phytoremediation will be used in combination with other environmental remediation technologies.