The term "Phytoremediation" is derived from the Greek word "phyto" (which means plant) and the Latin word "remedium" (which means restoring balance). This term was coined by Dr. Ilya Raskin of Rutgers University's Biotechnology Center for Agriculture and the Environment. He was a member of the task force sent by the IAEA to examine food safety at the infamous Chernobyl site.
The planet is polluted with xenobiotics and harmful metals. Phytoremediation is an innovative technology which uses various types of plants to remediate hazardous waste sites. This technology is cost-effective and environment-friendly.
Plants such as mustard, hemp, pigweed and alpine pennycress are known as hyperaccumulators. These plants have the ability to bioaccumulate pollutants in the soil water and air. Many phytoremediation projects have been successfully completed all over the world.
These projects have succeeded in mitigating concentration of harmful pollutants like crude oil and its derivatives, pesticides, metals, solvents and explosives. Phytoremediation is a clean technology and has gained in popularity over the last 20 years. It is very effective in cleaning soils contaminated with harmful chemicals like uranium, arsenic and lead.
Enhanced rhizosphere biodegradation, phyto-extraction, phyto-degradation and phyto-stabilization are some of the mechanisms of phytoremediation. Enhanced rhizosphere biodegradation is also known as phytostimulation, rhizodegradation and plant-assisted degradation. It breaks down organic contaminants in the soil via enhanced microbial activity in the plant root zone.
Phyto-extraction is the absorption of metal contaminants by plants through their roots. These pollutants are stored in the upper parts of the plants. Companies specialized in phyto-mining may recover and reuse the metals thus extracted.
Phyto-degradation (also referred to as phyto-transformation) is the process by which the substances absorbed by the plants from the environment are broken down. Enzymes produced by the plants (like dehalogenase and oxygenase) act as catalysts in the process. Phyto-stabilization focuses on reduction of the mobility of various heavy metals in the soil.
Phytoremediation has its limitations. It is confined to the area covered by the roots of the plants. It also depends on the healthy growth of the plants. High concentrations of harmful chemicals can be toxic to the plants. This technology it still in its infancy and is unfamiliar to the regulators.
Genetic engineering can play a major role in enhancing the natural phytoremediation capabilities of plants. Phytoremediation is a promising technology which needs long-term commitment and patience. Fortunately, many governments and commercial organizations are funding research activities in this field.