Deciphering Vanadium Speciation in Smelting Ash and Adaptive Responses of Soil Microorganisms.

Abundant smelting ash is discharged during pyrometallurgical vanadium (V) production. However, its associated V speciation and resultant ecological impact have remained elusive. In this study, V speciation in smelting ash and its influence on the metabolism of soil microorganisms were investigated. Smelting ashes from V smelters contained abundant V (19.6-115.9 mg/g). V(V) was the dominant species for soluble V, while solid V primarily existed in bioavailable forms. Previously unrevealed V nanoparticles (V-NPs) were prevalently detected, with a peak concentration of 1.3 × 10 particles/g, a minimal size of 136.0 ± 0.6 nm, and primary constituents comprising FeVO, VO, and VO. Incubation experiments implied that smelting ash reshaped the soil microbial community. Metagenomic binning, gene transcription, and component quantification revealed that sp. and sp. secreted extracellular polymeric substances through and gene regulation for V-NPs aggregation to alleviate toxicity under aerobic operations. The V K-edge X-ray absorption near-edge structure (XANES) spectra suggested that VO NPs were oxidized to VO NPs. In the anaerobic case, sp. and sp. reduced V(V) to V(IV) for detoxification regulated by the gene. This study provides a deep understanding of the V speciation in smelting ash and microbial responses, inspiring promising bioremediation strategies to reduce its negative environmental impacts.