Effect of wheat straw derived biochar on immobilization of Cd and Pb in single- and binary-metal contaminated soil

Abstract

Biochar is a promising adsorption amendment on reducing the bioavailability of heavy metals in contaminated soils. A greenhouse pot experiment was carried out to study the influence of wheat straw biochar (WSB) at different application rates (0%, 0.5%, 1%, and 5% w/w) on pH, electrical conductivity (EC) and toxicity characteristic leaching procedure (TCLP) extractable concentrations of Cd and Pb in single- and binary-metal contaminated soil. Ryegrass (Lolium perenne L.) was used as an indicator plant to evaluate the bioavailability of Cd and Pb. The results showed that the increase in addition of WSB from 0.5% to 5% significantly decreased the TCLP-Cd and Pb concentrations by 9.28–43.59% and 7.45–50.92%, respectively, as compared with control. Pb exhibited more competitive ability than Cd on WSB adsorption sites when coexisted in soil. The application of WSB alleviated the accumulation and uptake of Cd and Pb in the ryegrass shoot and root biomass and facilitated ryegrass growth. Overall, the application of WSB at a high application rate (e.g., 5%) with ryegrass cultivation is an effective method to immobilize Cd and Pb in single- and binary-metal contaminated soil. In the future, it is necessary to determine the long-term field effects of this application.

Keywords:

• Biochar
• Wheat straw
• Cd and Pb
• Ryegrass
• Competitive mechanism

Additional information

Funding

This work was supported by “111” Project (B08039) and the Opening Foundation of Shaanxi Key Laboratory of Exploration and Comprehensive Utilization of Mineral resources (2014HB004).