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Fig. 4.2 Phytoextraction process of lead contaminant (Source: United States Environmental
Protection Agency 2000)

Pennycress, has been found to grow in soils contaminated with lead (0.82 %) and
zinc from a mine. Bench-scale studies have also shown that certain tropical plants
are capable of phytoextraction. Corn, alfalfa, sorghum, cabbage, cauliflower,
tomato, rice, barley, oats, wheat, corn, pigeon pea, chickpea, soybean, peanut,
broccoli, lettuce, spinach, and amaranthus were found to be effective due to their
fast growth rate and large amount of biomass produced (United States Environ-
mental Protection Agency 2000).

4.3.2 The Roles of Sesbania drummondii
in the Phytoremediation of Lead

Sesbania drummondii is one of potential tropical plants that can remediate lead-
contaminated environment; it is a relatively large plant found growing naturally on
a site contaminated with Pb, along with other inorganic and organic contaminants.
For Sesbania to be useful in phytoremediation, it must not only accumulate large
amounts of Pb from soil, but also translocate the Pb to aerial parts for harvest. Pb,
however, is not very soluble in soil, and translocate poorly from roots to shoots