Antimony Speciation and Environmental Behavior

Antimony (Sb) occurs naturally in soils and sediments and is produced by mining, smelting and various industrial processes. Its environmental behaviour is governed by speciation, predominantly between trivalent antimonite (Sb(III)) and pentavalent antimonate (Sb(V)). Sb(III) is more mobile and toxic, whereas Sb(V) forms stable oxyanions that adsorb strongly to mineral surfaces. Redox transformations between these states are mediated by both abiotic factors—such as pH, redox potential and reactive oxygen species—and by diverse microbial communities carrying specialised oxidase enzymes. These processes shape Sb mobility, bioavailability and ecological risk in soils, waters and biota. Co-occurrence with arsenic and other oxyanions further complicates speciation and transport, while plant uptake, microbial oxidation and precipitation govern the fate of dissolved Sb. Globally, antimony pollution poses threats to human health through drinking water and food-chain contamination, prompting research into novel remediation strategies. Bioremediation approaches exploit Sb-oxidising and immobilising microbes, engineered wetlands and phytoremediation by tolerant plants. Understanding the interplay of geochemical conditions, microbial metabolism and plant physiology is essential for predicting Sb behaviour, assessing risks and developing effective treatment technologies.

Research from Nature Portfolio

Recent studies have elucidated a coupled biotic–abiotic mechanism of microbial Sb(III) oxidation. In Agrobacterium tumefaciens GW4, cytoplasmic and periplasmic oxidases work in concert with elevated cellular hydrogen peroxide to convert Sb(III) to Sb(V). The periplasmic arsenite oxidase provides the primary oxidation pathway, while cellular H₂O₂—induced by Sb(III) exposure—acts as an abiotic oxidant that accelerates Sb(III) transformation and detoxifies reactive oxygen species. Knock-out and complementation analyses demonstrate that both enzymatic catalysts and endogenous H₂O₂ are essential for full oxidation efficiency and microbial resistance. This dual mechanism advances our understanding of microbial contributions to the Sb cycle and offers insights into how oxidative stress responses can be harnessed for bioremediation.

Antimony Speciation and Environmental Behavior publication trend

The graph below shows the total number of articles in antimony speciation and environmental behavior across all publications each year (not limited to Nature Index journals).

Technical terms

Speciation: The distribution of an element among chemical forms that affects its mobility and toxicity.

Sb(III) / Sb(V): Trivalent and pentavalent oxidation states of antimony, with differing solubility and toxicity profiles.

Denitrification: Microbial reduction of nitrate to gaseous nitrogen, often coupled to metal oxidation processes.

Biogeochemical cycle: The movement and transformation of elements through biological, geological and chemical compartments.

Oxidase: An enzyme that catalyses electron transfer from a substrate to an electron acceptor, typically oxygen or an oxyanion.

References

1. Nitrate-dependent antimony oxidase in an uncultured Symbiobacteriaceae member. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2024).
2. Anaerobic Bacterial Immobilization and Removal of Toxic Sb(III) Coupled With Fe(II)/Sb(III) Oxidation and Denitrification. Frontiers in Microbiology (2019).
3. Abiotic and biotic factors responsible for antimonite oxidation in Agrobacterium tumefaciens GW4. Scientific Reports (2017).
4. Bacteria responsible for nitrate-dependent antimonite oxidation in antimony-contaminated paddy soil revealed by the combination of DNA-SIP and metagenomics. Soil Biology and Biochemistry (2021).