复配钝化剂对镉污染稻田修复效果及其对土壤质量的提升

为评估复配钝化剂在真实环境下对Cd污染稻田的钝化修复效果及对土壤环境质量的影响，在安徽某地开展连续3 a的原位钝化修复实验，分析钝化剂对水稻Cd吸收、土壤理化性质、土壤酶活性、土壤微生物群落结构与功能的影响。结果表明：复配钝化剂[1%生物炭+0.2%硅肥（BS）和1%生物炭+0.2%石灰（BL）]显著降低土壤中DTPA提取态Cd含量（29.4%~40.1%）；复配钝化剂可使水稻籽粒Cd含量降低60%以上，优于2%的单独生物炭处理，且对水稻产量无不利影响。复配钝化剂使土壤pH、有机质含量（OM）、阳离子交换量（CEC）分别增加了0.77~1.25个单位、13.5%~52.0%、8.4%~38.5%，有效改善了土壤环境质量。土壤脲酶、磷酸酶、FDA水解酶的活性随着BS的施加分别提升了31.3%、38.7%、33.1%。同时，钝化剂还通过改变土壤理化性质（pH、CEC、DTPA提取态Cd含量等）显著改变了土壤微生物群落结构，但对微生物多样性无显著性影响，表明修复后土壤微生物群落生态系统稳定。微生物功能预测表明与碳代谢、能量代谢等新陈代谢相关基因簇的丰度在BS处理下明显提高，证明复配钝化剂降低了重金属的毒性，增加了土壤微生物活性。综上，复配钝化剂BS不仅可以实现Cd污染稻田的原位钝化修复，而且可以有效改善土壤环境质量，提升土壤生态功能。

In situ immobilization of Cd-polluted paddy soil and improvement of soil quality by combined ameliorants

The goal of the study was to assess the impact of combined ameliorants on Cd immobilization and soil environmental quality. A three-year field experiment was carried out in Anhui Province to investigate the effects of combined ameliorants on Cd uptake by rice, soil properties, enzyme activities, microbial community and function in a Cd-polluted paddy soil. The combined ameliorants（BS means 1% biochar+0.2% silicon fertilizer, BL means 1% biochar+0.2% lime） significantly reduced the concentrations of DTPA extractable Cd by 29.4%–40.1%. Similarly, combined ameliorants reduced Cd content in rice grains by more than 60% without reducing yields, and the immobilization efficiencies were higher than with 2% biochar treatment. The application of combined ameliorants also increased soil pH（0.77–1.25 units）, organic matter（13.5%–52.0%）, and cation exchange capacity（8.4%–38.5%）, which effectively improved the soil environmental quality. In addition, the urease, phosphatase and FDA hydrolase activities were improved by 31.3%, 38.7%, and 33.1% with BS application, respectively. Furthermore, such amendments significantly altered the soil microbial structure by changing soil properties（pH, CEC, DTPA extractable Cd, etc.）, but had no effect on microbial diversity, reflecting the stability of the soil microbial community''s ecosystem. Furthermore, microbial function prediction showed a significant increase in the abundance of gene clusters such as carbon metabolism following BS treatment, resulting in reduced heavy metals toxicity and increased soil microbial activity. Thus, combined ameliorants（particularly BS） can effectively immobilize Cd-polluted paddy soil, improving both soil environmental quality and ecological function.