State Environmental Protection Key Laboratory of Synergetic Control and Joint Remediation for Soil & Water Pollution, College of Ecology and Environment, Chengdu University of Technology, Chengdu, 610059, PR China.
State Environmental Protection Key Laboratory of Synergetic Control and Joint Remediation for Soil & Water Pollution, College of Ecology and Environment, Chengdu University of Technology, Chengdu, 610059, PR China.
Environ Pollut. 2022 Aug 1;306:119400. doi: 10.1016/j.envpol.2022.119400. Epub 2022 May 4.
The interaction of cadmium (Cd) pollution and acid rain stress has seriously threatened soil ecosystem and human health. However, there are still few effective amendments for the in-situ remediation in the Cd-contaminated acidified soil. In this study, the performance and mechanisms of palygorskite (PAL) and mercapto-functionalized PAL (MPAL) on Cd immobilization were investigated, and the stability as well as effects on soil micro-ecology under stimulated acid rain were also explored. Results showed that MPAL could react with Cd to form stable Cd-sulfhydryl and Cd-O complexes. The reduction of bioavailable Cd by MPAL was 121.19-164.86% higher than that by PAL. Notably, the Cd immobilization by MPAL remained stable within 90 days in which the concentrations of HOAc-extractable Cd were reduced by 18.28-25.12%, while the reducible and residual fractions were increased by 9.26-18.53% and 54.16%-479.01%, respectively. The sequential acid rain leaching demonstrated that soil after MPAL treatments had a strong H resistance, and the immobilized Cd showed prominent stability. In addition, activities of acid phosphatase, catalase and invertase in MPAL treated soil were significantly enhanced by 34.60%, 22.09% and 48.87%, respectively. After MPAL application, bacterial diversity was further improved with diversified sulfur metabolism biomarkers. The decreased abundance of Cd resistance genes including cadA, cadC, czcA, czcB, czcR and zipA also indicated that soil micro-ecology was improved by MPAL. These results showed that MPAL was an effective and eco-friendly amendment for the immobilization of Cd in contaminated soil.
镉（Cd）污染和酸雨胁迫的相互作用严重威胁着土壤生态系统和人类健康。然而，在受 Cd 污染的酸化土壤的原位修复中，仍然很少有有效的修复剂。在这项研究中，研究了坡缕石（PAL）和巯基功能化坡缕石（MPAL）对 Cd 固定化的性能和机制，以及在模拟酸雨下的稳定性及其对土壤微生态的影响。结果表明，MPAL 可以与 Cd 反应形成稳定的 Cd-巯基和 Cd-O 配合物。MPAL 降低生物可利用 Cd 的效率比 PAL 高 121.19-164.86%。值得注意的是，在 90 天内，MPAL 对 Cd 的固定化保持稳定，其中 HOAc 可提取 Cd 的浓度降低了 18.28-25.12%，而可还原和残留部分分别增加了 9.26-18.53%和 54.16%-479.01%。连续的酸雨淋洗表明，经 MPAL 处理后的土壤具有较强的 H 抗性，固定化的 Cd 表现出显著的稳定性。此外，MPAL 处理土壤中酸性磷酸酶、过氧化氢酶和转化酶的活性分别显著提高了 34.60%、22.09%和 48.87%。MPAL 应用后，细菌多样性进一步提高，出现多样化的硫代谢生物标志物。Cd 抗性基因 cadA、cadC、czcA、czcB、czcR 和 zipA 的丰度降低，也表明土壤微生态得到了改善。这些结果表明，MPAL 是一种有效且环保的修复剂，可用于固定污染土壤中的 Cd。
