Phytoremediation: Role of plants in contaminated site management

Abstract

Bioengineering is a new branch of civil engineering which integrates live materials, mainly plants and microorganisms, to address the problems of environmental management and sustainable development. The technology originated in Germany in the 1930s, but gained importance in the 1980s, when researches in environmental biotechnology discovered the environmental virtues of some specially adapted plants and microbes. Bioengineering is the green or soft cheaper alternative to the hard and costly civil engineering works for environmental reconstruction. Phytoremediation (Greek: phyton =plant; Latin: remediare =remedy) is emerging green bioengineering technology that uses plants to remediate environmental problems. A number of green plants-trees, herbs, grasses and shrubs, both aquatic and terrestrial, have been discovered to have been endowed with the wonderful properties of environmental restoration, such as decontamination of polluted soil and water, stabilization of engineered slopes and embankments on highways, railways, bridges and dams, and prevention of soil erosion. They are aesthetically pleasing, passive, solar-energy driven and pollution abating natures (green) technology meeting the same objectives of fossil-fuel driven and polluting conventional technology. They thrive in very harsh environmental conditions of soil and water; absorb, tolerate, transfer, assimilate, degrade and stabilise highly toxic materials (heavy metals and organics such as solvents, crude oil, pesticides, explosives and polyaromatic hydrocarbons) from the polluted soil and water; and firmly holds the soil in place by their extensive root network to prevent any erosion. The plants act both as accumulators, and excluders. Accumulators survive despite concentrating contaminants in their aerial tissues. They biodegrade or biotransform the contaminants into inert forms in their tissues. The excluders restrict contaminant uptake into their biomass. The plant biomass eventually becomes valuable biological source for the community or for the plant-based industries. © 2007 Springer-Verlag Berlin Heidelberg.