Phytoremediation and hyperaccumulator plants

Phytoremediation is a group of technologies that use plants to reduce, remove, degrade, or immobilize environmental toxins, primarily those of anthropogenic origin, with the aim of restoring area sites to a condition useable for private or public applications. Phytoremediation efforts have largely focused on the use of plants to accelerate degradation of organic contaminants, usually in concert with root rhizosphere microorganisms, or remove hazardous heavy metals from soils or water. Phytoremediation of contaminated sites is a relatively inexpensive and aesthetically pleasing to the public compared to alternate remediation strategies involving excavation/removal or chemical in situ stabilization/conversion. Many phytoremediation plans have multi-year timetables, but since most sites in need of remediatrion have been contaminated for more than ten years, as such a ten year remediation plan does not seem excessive. Seven aspects of phytoremediation are described in this chapter: phytoextraction, phytodegradation, rhizosphere degradation, rhizofiltration, phytostabilization, phytovolatization, and phytorestoration. Combining technologies offer the greatest potential to efficiently phytoremediate contaminated sites. The major focus of this chapter is phytoextraction of arsenic, cadmium, chromium, copper, mercury, nickel, lead, selenium, and zinc.