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Updated: Jun 23, 2026
06:52
Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron (Oxy)Hydroxides, Trace Elements, and Bacteria
Published on: December 19, 2017
FeS Colloids Trigger Antimony Redox Cycling, Colloid Formation, and Ultimate Fate during the Anoxic-Oxic Transition
Yanxiang Yuan1,2,3, John D Fortner4, Chenggang Ci5
1State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang550081, China.
Environmental Science & Technology
|June 20, 2026
Summary
Ferrous sulfide (FeS) colloids influence antimony (Sb) mobility by mediating redox transformations and colloidal formation at anoxic-oxic interfaces. FeS colloids initially enhance Sb transport but ultimately sequester it through iron (Fe) oxide formation.
Area of Science:
- Environmental Science
- Geochemistry
- Colloid Science
Background:
- Antimony (Sb) mobility in subsurface environments is linked to iron (Fe) geochemistry.
- The role of ferrous sulfide (FeS) colloids in controlling Sb fate at anoxic-oxic interfaces remains unclear.
Purpose of the Study:
- To elucidate how FeS colloids control Sb redox transformation, colloidal formation, and sequestration during anoxic-oxic transitions.
- To understand the mechanisms governing Sb mobility and fate in FeS-rich subsurface environments.
Main Methods:
- Experimental investigations and theoretical calculations.
- Spectroscopic analyses to confirm Sb sequestration mechanisms.
- Controlled experiments simulating anoxic-oxic transitions at circumneutral pH.
Main Results:
- FeS colloids mediate both Sb(V) reduction and Sb(III) oxidation, depending on redox conditions.
- Transient Fe(III) intermediates from FeS oxidation act as Sb(III) oxidants.
- Initially, Sb associates with FeS/ferrihydrite colloids (150-350 nm), enhancing mobility; upon complete oxidation, Sb is sequestered in larger aggregates (>1000 nm) via Fe(III) (oxyhydr-)oxides.
Conclusions:
- FeS colloids exhibit multifunctional roles in Sb fate at anoxic-oxic interfaces.
- FeS colloids influence Sb mobility through transient colloidal transport and ultimate sequestration.
- This study provides a mechanistic framework for predicting Sb behavior in redox-dynamic, FeS-rich subsurface environments.
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