Burton, E.Bush, R.Sullivan, L.Hocking, R.Mitchell, D.Johnston, S.Fitzpatrick, R.Raven, M.McClure, S.Jang, L.2010-07-222010-07-222009Environmental Science and Technology (Washington), 2009; 43(9):3128-31340013-936X0013-936Xhttp://hdl.handle.net/2440/59500Iron-monosulfide oxidation and associated S transformations in a natural sediment were examined by combining selective extractions, electron microscopy and S K-edge X-ray absorption near-edge structure (XANES) spectroscopy, The sediment examined in this study was collected from a waterway receiving acid-sulfate soil drainage. It contained a high acid-volatile sulfide content (1031 micromol g(-1)), reflecting an abundance of iron-monosulfide. The iron-monosulfide speciation in the initial sediment sample was dominated by nanocrystalline mackinawite (tetragonal FeS). At near-neutral pH and an 02 partial pressure of approximately 0.2 atm, the mackinawite was found to oxidize rapidly, with a half-time of 29 +/- 2 min. This oxidation rate did not differ significantly (P < 0.05) between abiotic versus biotic conditions, demonstrating that oxidation of nanocrystalline mackinawite was not microbially mediated. The extraction results suggested that elemental S (S8(0)) was a key intermediate S oxidation product Transmission electron microscopy showed the S8(0) to be amorphous nanoglobules, 100-200 nm in diameter. The quantitative importance of S8(0) was confirmed by linear combination XANES spectroscopy, after accounting for the inherent effect of the nanoscale S8(0) particle-size on the corresponding XANES spectrum. Both the selective extraction and XANES data showed that oxidation of S8(0) to SO4(2-) was mediated by microbial activity. In addition to directly revealing important S transformations, the XANES results support the accuracy of the selective extraction scheme employed here.enCopyright © 2009 American Chemical SocietyBacteriaSulfurFerrous CompoundsMicroscopy, ElectronSpectrum AnalysisOxidation-ReductionHydrogen-Ion ConcentrationGeologic SedimentsBiodegradation, EnvironmentalJournal article002009774510.1021/es80365480002657811000282-s2.0-6644912586434189Fitzpatrick, R. [0000-0002-9235-0360]