Immobilization of cadmium by mercapto-functionalized palygorskite under stimulated acid rain: Stability performance and micro-ecological response. (1st August 2022)

• Record Type: Journal Article
• Authors: Li, Jia; Wu, Bin; Luo, Zhi; Lei, Ningfei; Kuang, Hongjie; Li, Ziqing
• Is Part Of: Environmental pollution. Volume 306(2022)
• Publication Date: 2022-08-01
• Subjects: Immobilization -- Cadmium -- Mercapto-functionalized palygorskite -- Micro-ecology -- Acid rain; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.119400
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: 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 cad A, cad C, czc A, czc B, czc R and zip A 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. Graphical abstract: Image 1 Highlights: Mercapto modification enhanced the Cd immobilization of palygorskite. Cd immobilization by MPAL kept stability under the acid rain stimulation. Cd immobilization by MPAL was controlled by Cd 2+ and mercapto complexation. MPAL increased enzyme activities, bacterial diversity and sulfur metabolism. MPAL reduced the abundance of Cd resistance genes in soils.