REMEDIATION OF AS–CD CO-CONTAMINATED MINING SOIL BY ATTAPULGITE-SUPPORTED NANOSCALE ZERO-VALENT IRON: STABILIZATION PERFORMANCE, LEACHING RISK, AND PLANT RESPONSE

Abstract

Attapulgite-supported nanoscale zero-valent iron (nZVI@ATP) was synthesized and applied as an in situ stabilization amendment for As–Cd co-contaminated mining soil. A 60-day incubation experiment combined with a ryegrass pot trial was conducted to evaluate changes in contaminant availability, leaching risk, operationally defined fractions, and plant uptake. All amendments reduced the available and TCLPextractable fractions of As and Cd, with nZVI@ATP showing the strongest immobilization performance. After 60 days, 2% and 4% nZVI@ATP decreased available As by 43.87% and 48.23%, and available Cd by 72.15% and 77.22%, respectively. Sequential extraction indicated that nZVI@ATP promoted the transformation of As and Cd from labile fractions to less mobile fractions. Amendment application also increased soil pH and cation exchange capacity, improved ryegrass growth, and reduced As and Cd accumulation in plant tissues. These results suggest that nZVI@ATP is a promising mineral-based amendment for reducing the mobility and bioavailability of As and Cd in mining soils.