Characterizing Redox Transformations of Antimony in Biologically Mediated Settings

Abstract

Antimony is a toxic element with increasing use in society and is therefore an increasingly pervasive anthropogenic pollutant. Antimony is a metalloid with properties similar to arsenic where behavior in the environment and toxicity is dependent on oxidation state. Microbial influences on antimony mobility and fate in the natural environment are poorly understood. In this study, batch oxidation and reduction experiments were conducted, with different microbial communities, to evaluate the redox transformation of antimony in controlled environments to better understand biologically mediated modifications of antimony. In the process, a new colorimetric method was developed to qualify antimonite presence and concentration during the microbial batch experiments. Results suggest microbial antimonate reduction is a ubiquitous microbial pathway, while microbial antimonite oxidation is not. Interactions between antimony and sediment chemistry, sediment type, mineral content, and ligand complexes impact results and mobility. This report provides the first assessment of the ability of wastewater treatment microbes to modify antimony and informs on possible biological remediation pathways for antimony contaminated waste streams.