Mobilization and transformation of antimony in stibnite by microbial induced oxidation in mining environment

Elevated concentrations of antimony (Sb) in environmental and biological systems due to mining activities are of particular global concern. Microorganisms play a crucial role in the oxidation process of metallic sulfide minerals, leading to the release of metal ions into surrounding soil or water systems. However, the mechanisms and potential environmental effects of microbial induced oxidation of stibnite (Sb2S3) in mine environment remain unclear. In this study, compared with the abiotic controls, the microbial community screened from the highly contaminated soil of the Xikuangshan antimony mine in aerobic experiments did not promote Sb mobilization as expected. However, they had a significant effect on the morphology and species of oxidation products of Sb2S3 by mediating the oxidation of Sb(III) and sulfide on surface and in solution. These naturally coexisting bacteria could partially oxidize Sb2S3 to Sb(V) and SO42- directly on the mineral surface, completely oxidize the dissolved Sb(III) to Sb(V), facilitate the oxidation of S-0 to S2O32-, and form the secondary Sb(V)-bearing mineral [NaSb (OH)(6)]. These findings support the important role of microorganisms in the mobilization and transformation of Sb from minerals/rocks in the mining environment and provide further insight into their potential environmental impacts and effective mitigation strategies.