不同土壤调理剂对Cd污染稻田修复效果

为验证不同土壤调理剂在轻度Cd污染稻田的修复效果，本研究于2021年和2022年在湖北大冶连续开展田间小区试验，研究了20种土壤调理剂对水稻产量、糙米Cd含量、土壤pH、土壤有效态Cd含量的影响，并选取2021年试验中具有代表性的4种调理剂（有机类：P3、P4，无机类：P11、P12），探究其对Cd在土壤-植株中转运累积和在土壤中5种赋存形态转化的影响。两年的结果表明：与对照组相比，各调理剂处理后水稻产量变化幅度为-9.80%~20.09%，糙米 Cd 降幅为 8.05%~79.57%，土壤 pH 提高了-0.01~1.13个单位，有效态Cd含量降低了4.79%~25.00%，且连续两年土壤pH值与有效态Cd含量均呈显著负相关关系。2021年试验中4种调理剂处理均能显著降低Cd从土壤到水稻根系的转运系数，且无机类调理剂（P11、P12）效果显著优于有机类（P3、P4）；各类调理剂（P3、P4、P11、P12）处理使土壤中可交换态Cd和碳酸盐结合态Cd占比分别降低5.91~17.77个百分点和6.33~8.88个百分点；使土壤中Fe-Mn结合态Cd、有机结合态Cd和残渣态Cd占比分别增加3.47~16.31、0.80~6.50个百分点和4.82~7.05个百分点。有机类调理剂（P3、P4）倾向于将土壤中Cd向有机结合态Cd转化，无机类调理剂（P11、P12）则更倾向将土壤中Cd向Fe-Mn结合态Cd转化。研究表明，选取适宜的调理剂能够实现Cd污染耕地安全利用，推荐无机类P12调理剂（主要成分CaO≥28%）作为湖北大冶轻度Cd污染修复调理剂。

Study on the remediation effect of different soil conditioners on Cd-contaminated paddy fields

To verify the remediation effects of different soil conditioners on lightly Cd-contaminated paddy fields, field plot experiments were conducted in 2021 and 2022 in Daye City, Hubei Province. The effects of 20 soil conditioners on rice yield, brown rice Cd contents, soil pH, and soil available Cd contents were studied. The results showed that compared with the control group, the rice yield changed from - 9.80% to 20.09%, the Cd reduction rate of brown rice was 8.05% to 79.57%, the soil pH increased by - 0.01 to 1.13 units, and the available Cd contents decreased by 4.79% to 25.00%. There was a significant negative correlation between soil pH value and available Cd content for two consecutive years. Meantime, four representative conditioning agents（organic：P3, P4, inorganic：P11, P12）in 2021 were further selected to explore their effects on the transfer and accumulation of Cd in soil-plant and the transformation of five types of occurrence forms in soil. In 2021, the transport coefficient of Cd from soil to root of rice were significantly decreased by all four treatments, and the effect of inorganic conditioners（P11, P12）were significantly better than that of organic conditioners（P3, P4）. The proportion of exchangeable Cd and carbonate-bound Cd in soil decreased by 5.91-17.77 percentage points and 6.33-8.88 percentage points, respectively, under the treatment of various conditioners（P3, P4, P11, P12）. The proportion of Fe-Mn bound Cd, organically bound Cd and residual Cd in soil were increased by 3.47-16.31, 0.80-6.50 percentage points and 4.82-7.05 percentage points, respectively. Organic conditioners（P3, P4）tend to convert soil Cd to organically bound Cd, while inorganic conditioners（P11, P12）tend to convert soil Cd to Fe-Mn bound Cd. Overall, two years of field experiments showed that the selection of suitable conditioners could realize the safe utilization of Cd-polluted farmland, and P12 conditioner（CaO≥28%）was recommended as the conditioner for the remediation of mild Cd pollution in Daye City, Hubei Province.