Abstract

Ever-increasing urban expansion, industrial development, and anthropogenic activities are major sources of polluting environment with heavy metals and organic substances. Phytoremediation is a broad term which covers several plant-based approaches for cleaning up such contaminated environments. The six subsets of this technology include: a) phytoextraction, in which roots of hyperaccumulator plants take up contaminants and translocate and concentrate chemical elements from the soil to above ground shoots and leaves; b) phytofiltration, in which plant roots are used to precipitate and concentrate contaminants from effluents; c) phytovolatilization, in which plants uptake volatile pollutants from soil, transform them into volatile form and transpire them into the atmosphere; d) phytostabilization, which occurs through the sorption, precipitation, complexation, or metal valence reduction by plants to stabilize pollutants in soils; e) phytodegradation, in which plants transform, break down, stabilize, or volatilize contaminants from soil and groundwater; and f) dendroremediation, in which living trees remove, sequester, or chemically decompose the pollutants from environments. Recently, genetic engineering has played a great role in enhancing the efficiency of phytoremediation by manipulating genes for uptake, transport, and sequestering pollutants. Various phytoremediation techniques, their advantages, and disadvantages are discussed in this entry. Further recent advances and future trends in phytoremediation are briefly reviewed.