Chemical methods and phytoremediation of soil contaminated with heavy metals

The effects of chemical amendments (calcium carbonate (CC), steel sludge (S S) and furnace slag (FS)) on the growth and uptake of cadmium (Cd) by wetla nd rice, Chinese cabbage and wheat grown in a red soil contaminated with Cd were investigated using a pot experiment. The phytoremediation of heavy me tal contaminated soil with vetiver grass was also studied in a field plot e xperiment. Results showed that treatments with CC, SS and FS decreased Cd u ptake by wetland rice, Chinese cabbage and wheat by 23-95% compared with th e unamended control. Among the three amendments, FS was the most efficient at suppresing Cd uptake by the plants, probably due to its higher content o f available silicon (Si). The concentrations of zinc (Zn), lead (Pb) and Cd in the shoots of vetiver grass were 42-67%, 500-1200% and 120-260% higher in contaminated plots than in control, respectively. Cadmium accumulation b y vetiver shoots was 218 g Cd/ha at a soil Cd concentration of 0.33 mg Cd/k g. It is suggested that heavy metal-contaminated soil could be remediated w ith a combination of chemical treatments and plants. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.