Introduction

The disposal of industrial effluents has become a serious problem due to rapid industrial development and urbanization. The application of industrial and city effluents to land has also become popular in recent years as an alternative means of treatment and disposal (Chhonkar et al. 2000a,b). Even they are useful sources of plant nutrients, these effluents often contain high amounts of various organic and inorganic materials as well as heavy metals, depending upon the industry from which they originate. The unscientific disposal of untreated or undertreated effluents has resulted in an accumulation of heavy metals in land and water bodies. Cultivated areas under peri-urban agriculture are worst affected by this problem. Heavy metals do not degrade in the environment and so can remain in soil and water bodies for long periods. Excessive metal accumulation in contaminated soils can result in decreased soil microbial activity, soil fertility, and overall soil quality, and reductions in yield (McGrath et al. 1995) and the entry of toxic materials into the food chain (Hann and Lubbers 1983). Although it is necessary to clean up contaminated sites, the application of environmental remediation strategies is often very expensive and intrusive (McGrath et al. 1995). Thus, it is important to develop low-cost and environmentally friendly strategies. Recently, the notion of using metal-accumulating plants for environmental clean-up has been vigorously pursued (Brown et al. 1995; Salt et al. 1995), giving birth to the philosophy of "phytoextrac-tion" within the broader concept of "phytoremediation" (Kumar et al. 1995).

Using the bioaccumulation capacities of specialized group of plants may provide an effective way of removing heavy metals from contaminated soils (Grispen et al. 2006; Meers et al. 2005; Salido et al. 2003). For the last one and half decades, extensive

Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi, 110012, India e-mail: [email protected]; [email protected]

I. Sherameti and A. Varma (eds.), Soil Heavy Metals, Soil Biology, Vol 19, DOI 10.1007/978-3-642-02436-8_18, © Springer-Verlag Berlin Heidelberg 2010

research has been done on various plant species in relation to the phytoextraction of metal from contaminated soils. However, the major limitation of phytoextraction is the reduced availability of metals due to their complexation with soil clays and organic matter. Therefore, the key to the successful phytoremediation of heavy metal contaminated soils lies in the optimization of soil and nutrient management practices for enhancing the availability of heavy metals to phytoremediating plants. Nevertheless, most phytoremediation studies confine themselves to using food crops as remediating plants. This approach is acceptable to farmers who are thus compensated for cleaning up their precious land. However, in developing countries, where compensation can sometimes be a burden on the government, phytoremediating research needs to consider other non-food crops such as timber and biodiesel-producing crops as phytoremediating plants, but very few research reports are available on this topic.

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