Biochar for remediation of alkaline soils contaminated with toxic elements

Toxic elements (TEs) are generally less available in alkaline soils as considerable portions of TEs are precipitated with carbonates/hydroxides or presented in metal–organic complexes. However, intensive anthropogenic activity, the high total concentration of TEs, geochemical behavior of some TEs (e.g., Mo and V), and soil dynamic redox conditions could dramatically increase the TE bioavailability and risks in alkaline soils. This chapter introduces the potential of biochar to immobilize TEs in alkaline soils. It highlights the different factors that affect the adsorption capacity of biochar for TEs in alkaline soils. The possible mechanisms of TEs immobilization process and the development in biochar production and modification methods that could enhance the immobilization capacity of biochar for TEs in alkaline soils are also discussed.