不同钝化剂对稻田镉污染修复和迁移的影响

通过对镉污染稻田的原位修复治理试验，对比研究了改性电厂灰（BFA）、生石灰（CaO）、石灰石（CaCO₃）、稻壳生物炭（BC）、硫酸亚铁（FeSO₄）和零价铁粉（Fe）对镉污染稻田土壤钝化修复效果及Cd在土壤—水稻体系迁移的影响。结果表明：6种钝化材料处理对土壤总Cd及有效态Cd降低率变化范围分别为0.519～6.25 mg·kg^-1（-5.31%～14.5%）、0.290～0.330 mg·kg^-1（-3.13%～12.5%），但处理之间无显著性差异。在200～600 kg·acre^-1施加量下CaO和CaCO₃处理可以使土壤pH值分别提高0.38～0.80、0.25～0.48个单位，施加改性电厂灰能够使土壤pH提升0.21～0.28个单位，生物质炭和铁粉处理对土壤pH无明显影响。与对照组相比，6种材料可使水稻产量增幅-6.20%～32.2%，籽粒Cd含量降低3.35%～61.0%，其中400 kg·acre^-1 CaO、600 kg·acre^-1 FeSO₄、600 kg·acre^-1 BFA处理对水稻籽粒中Cd含量降幅最大，分别达到61.0%、55.4%、44.2%；在土壤-水稻体系中，水稻不同部位对Cd的富集表现为根>茎叶>籽粒，其中400 kg·acre^-1 CaO、600 kg·acre^-1 FeSO₄、600 kg·acre^-1BFA处理均可降低水稻各部位对Cd的富集系数。

Effects of different passivators on immobilization and translocation of Cd in paddy fields

The effects of modified biofuel ash (BFA), lime (CaO and CaCO₃), rice biochar (BC), FeSO₄ and Fe on the effect of passivation remediation and Cd migration in soil-rice system of Cd-contaminated paddy soils were comparatively investigated through in situ remediation treatment trials. The results showed that the six passivation material treatments had a range of 0.519 to 6.25 mg·kg^-1 (-5.31% to 14.5%) and 0.290 to 0.330 mg·kg^-1 (-3.13% to 12.5%) on the reduction rate of total Cd and effective state Cd in soil, respectively, but there was no significant differences between treatments. CaO and CaCO₃ treatments at application rates of 200 to 600 kg·acre^-1 could raise soil pH by 0.38 to 0.80 and 0.25 to 0.48 units, respectively, and application of modified power plant ash could raise soil pH by 0.21 to 0.28 units, while biomass char and iron powder treatments had no significant effect on soil pH. Compared with the control, the six materials could increase the rice yield by -6.20% to 32.2% and reduce the seed Cd content by 3.35% to 61.0%, with the 400 kg·acre^-1 CaO, 600 kg·acre^-1 FeSO₄, and 600 kg·acre^-1 BFA treatments having the greatest reduction by 61.02%, 55.4%, 44.2% respectively. In the soil-rice system, the enrichment of Cd in different parts of rice showed that root > stem > seed , where 400 kg·acre^-1 CaO, 600 kg·acre^-1 FeSO₄, and 600 kg·acre^-1 BFA treatments could reduce the enrichment coefficient of Cd in all parts of rice.