remediation, biochar has been considered to be potentially effective.
Many reports provided sound data on the potential effectiveness
of biochar in removing heavy metal from aqueous solution and
soils.
The effect of the incorporation of biochar produced from rice
straw on the mobility and bioavailability of Cu(II), Pb(II) and Cd(II)
in an Ultisol was investigated by Jiang et al. (42). The acid
extractable Cu(II) and Pb(II) decreased by 19.7e100% and
18.8e77.0%, respectively with the increase of the biochar amendment
dose. When 5 mmol/kg of these heavy metals was added, the
reducible Pb(II) for treatments with 3% and 5% biochar was 2.0 and
3.0 times higher than that of samples without biochar. Another
study (43) explored the capability of biochar to immobilize and
retain As, Cd and Zn from a multi-element contaminated sedimentderived
soil with microanalyses techniques, which showed that
biochar reduced the concentration of Cd and Zn with 300- and 45-
fold, respectively, but the leachate concentration was not reduced.
With the immobilization of heavy metals in the soil, heavy metals
can be retained in the soil and will release in a slower rate which
exerts less impact on the environment.