4种不同原料生物炭对镉污染土壤的钝化效果与稳定性比较

生物炭的性质与老化作用是影响生物炭钝化修复Cd污染土壤效果的重要因素。比较研究4种不同原料生物炭(污泥类、秸秆类、动禽粪便类和木本类)对Cd²⁺吸附作用和Cd污染土壤的钝化修复效果的差异。结果表明:施用生物炭显著提升土壤孔隙水pH(棕榈丝生物炭除外),降低孔隙水DOC和Cd浓度,从而减少水稻根系对孔隙水中Cd的吸收。同时,4种生物炭提高土壤pH,降低土壤有效态Cd、水稻根系和籽粒Cd含量。老化作用减弱稻秆生物炭的钝化效果,显著增强棕榈丝生物炭对土壤Cd的钝化作用,然而,老化作用对富含灰分的猪粪生物炭和污泥生物炭的影响较小。因此,选择生物炭钝化修复Cd污染稻田土壤时,必须考虑生物炭的原料及其老化作用。

Comparison of the Immobilization Effect and Stability of Four Different Raw Materials Biochar on Cadmium-Contaminated Soil

The properties and aging of biochar are important factors affecting the remediation effect of biochar in immobilizing Cd-contaminated soil. The differences of Cd²⁺ adsorption and Cd-contaminated soil immobilization efficiency of four different types biochar materials (sludge-based, straw-based, animal and poultry manure-based and wood-based) were comparatively investigated. The results showed that the application of biochar significantly increased the pH of soil pore-water (except palm fibers biochar), and decreased the concentrations of DOC and Cd in pore-water, and thus reduced the Cd uptake of rice roots in pore-water. At the same time, the application of four kinds of biochar increased soil pH value, but decreased soil available Cd, rice root and grain Cd content. However, aging weakened the immobilization effect of rice straw biochar and significantly enhanced the immobilization effect of palm fibers biochar on soil Cd, while aging had little effect on ash rich pig manure biochar and sludge biochar. Therefore, the raw materials and aging effects of biochar must be considered when choosing biochar immobilization to remediate Cd contaminated paddy soil.