posted on 2024-01-10, 14:41authored byJinxi He, Baogang Zhang, Wenyue Yan, Yujian Lai, Yang Tang, Yawei Han, Jingfu Liu
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 × 1013 particles/g, a
minimal size of 136.0 ± 0.6 nm, and primary constituents comprising
FeVO4, VO2, and V2O5.
Incubation experiments implied that smelting ash reshaped the soil
microbial community. Metagenomic binning, gene transcription, and
component quantification revealed that Microbacterium sp. and Tabrizicola sp. secreted extracellular
polymeric substances through epsB and yhxB 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 VO2 NPs were oxidized to
V2O5 NPs. In the anaerobic case, Comamonas sp. and Achromobacter sp. reduced V(V) to V(IV)
for detoxification regulated by the napA 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.