Attapulgite-supported nanoscale zero-valent iron promotes iron cycling and microbial synergy for the simultaneous remediation of cadmium and arsenic in paddy soils

The antagonistic environmental geochemical behaviors of cadmium (Cd) and arsenic (As) present a critical challenge for the simultaneous remediation of contaminated paddy soils. Here, we report the synthesis of attapulgite-supported nanoscale zero-valent iron (ATP-nZVI), and its remediation performance was systematically investigated. Batch adsorption kinetics studies showed that ATP-nZVI material exhibits superior adsorption capacity performance for Cd and As compared with its individual components. Importantly, the pot experiment demonstrated that ATP-nZVI application significantly increased soil pH and iron content, while concurrently enriching the soil microbiome, especially iron- and arsenic-reducing bacteria. This synergistic Fe-microbe interaction stimulated iron cycling, effectively reducing the bioavailability of Cd and As and promoting the formation of iron plaques in rice roots. Consequently, ATP-nZVI treatment decreased Cd and As accumulation in rice grains by 86.49% and 19.15%, respectively, while enhancing grain yield and essential micronutrient profiles (Zn, Mn, Cu, Fe and Mg). This work offers a cost-effective, eco-friendly and sustainable remediation strategy for the integrated management of multi-heavy metal contaminated agricultural soils.