In contaminated soil, pristine biochar has poor applicability for immobilizing vanadium (V), which mainly exists as oxyanions in soil. To elucidate the immobilization potential and biotic/abiotic stabilizing mechanisms of a ferrous sulfate (FS)-modified sludge biochar in a V-contaminated soil from a mining area, we investigated the effects of biochar addition on the soil characteristics, growth of alfalfa, leachability, bioavailability, speciation, and fractionation of V, and changes in the microbial community structure and metabolic response. The results showed that the water extractable, acid-soluble (F1), and pentavalent fractions of V in soil decreased by up to 99 %, 95 %, and 55 %, respectively, whereas the reducible and (F2) oxidizable (F3) fractions increased by up to 45 % and 76 %, respectively. After the soil was treated with the FS-modified biochar for 90 d, the V concentration in the roots and shoots of alfalfa (Medicago sativa L.) decreased by up to 81.5 % and 96 %, respectively. The changes in the speciation, fractionation, and efficient immobilization of V in the studied soil were due to the combined effects of the biochar-induced decrease in soil pH, adsorption and precipitation by elevated iron concentrations, reduction and complexation due to an increase in the organic matter content, and microbial reduction by Proteobacteria.

在污染土壤中，原始生物炭对钒（V）的固定化适用性较差，钒主要以氧阴离子形式存在于土壤中。为了阐明硫酸亚铁 (FS) 改性污泥生物炭在矿区 V 污染土壤中的固定化潜力和生物/非生物稳定机制，我们研究了添加生物炭对土壤特性、紫花苜蓿生长、可浸出性的影响、V 的生物利用度、物种形成和分馏，以及微生物群落结构和代谢反应的变化。结果表明，土壤中 V 的可水提、酸溶 (F1) 和五价部分分别减少了高达 99%、95% 和 55%，而可还原和 (F2) 可氧化 (F3) 部分分别增加了 45% 和 76%。Medicago sativa L.) 分别减少了高达 81.5 % 和 96 %。研究土壤中 V 的形态、分馏和有效固定化的变化是由于生物炭引起的土壤 pH 值降低、铁浓度升高引起的吸附和沉淀、还原和络合的综合影响。有机质含量和变形菌的微生物减少。