凹凸棒石组配硫酸锌对土壤Cd的钝化效果及生态风险评价

为明确凹凸棒石组配硫酸锌作为修复材料在钝化土壤Cd以及促进玉米生长方面的应用潜力，以凹凸棒石为原料，通过液相浸渍制备凹凸棒石组配硫酸锌作为钝化剂开展钝化试验与盆栽试验，研究了凹凸棒石与硫酸锌配比分别为3∶1、5∶1、7∶1、9∶1、11∶1时对土壤Cd有效性、玉米生长状况及其对Cd富集能力的影响，并采用扫描电镜初步探讨钝化剂的表面特征. 结果表明:与对照相比，添加凹凸棒石组配硫酸锌钝化处理使Cd的DTPA(二乙基三胺五乙酸)有效态含量降低了5.22%~32.77%，TCLP(毒性浸出方法)有效态含量降低了12.43%~35.65%，Cd的钝化效率随硫酸锌添加量的增加而显著提高(P<0.05). 钝化处理可显著降低玉米植株中Cd的含量，其茎部Cd含量的最大降幅为60.06%，根部Cd含量的最大降幅为32.69%，Cd主要集中分布在根部；同时，钝化剂的加入缓解了Cd对玉米生长的胁迫，随硫酸锌用量的增加，玉米生物量显著提升. 研究显示，凹凸棒石组配硫酸锌可作为对Cd污染农田修复的钝化剂，在钝化剂同等剂量水平下，凹凸棒石与硫酸锌配比为3:1时，对土壤中Cd的钝化效果最佳. 

Stabilization Effect of Attapulgite and ZnSO4 on Cd in Soil and Ecological Risk Assessment

In order to understand the application potential of attapulgite and ZnSO₄ as remediation materials in soil Cd stabilization and corn growth, attapulgite was prepared by liquid impregnation with ZnSO₄ as stabilizer to carry out stabilization tests and pot experiments. The effects of Cd availability, corn growth and uptake of Cd were studied at the attapulgite: ZnSO₄ ratios of 3∶1, 5∶1, 7∶1, 9∶1 and 11∶1. The surface characteristics of the stabilizers were imaged by scanning electron microscopy. The results show that compared with the control, the leachable Cd in the attapulgite and ZnSO₄ treated samples determined by the DTPA and TCLP tests decreased by 5.22%-32.77% and 12.43%-35.65%, respectively. The stabilization efficiency of Cd increased significantly (P<0.05) with the increase of ZnSO₄ addition. The stabilization treatment significantly reduced the content of Cd in corn plants. The largest reduction of Cd content in the shoots and roots was 60.06% and 32.69%, respectively, and Cd was mainly distributed in the roots. At the same time, the addition of the stabilizers alleviated the stress of Cd on corn growth, and the biomass of corn increased significantly with the increase of ZnSO₄. The stabilizers reduced the availability of Cd mainly through adsorption, interlayer ion exchange, surface hydroxyl coordination and anaerobic reduction precipitation. The study shows that the combination of attapulgite and ZnSO₄ (with 3:1 ratio) can be used to remediate Cd contaminated soil as an efficiency amendment.