Iron Sulfides and Sulfur Species Produced at (001) Hematite Surfaces in the Presence of Sulfate-Reducing Bacteria
In the presence of sulfate-reducing bacteria (Desulfovibrio desulfuricans) hematite (a-Fe2O3) dissolution is affected and hydrogen sulfide, the product of sulfate reduction is released. As a consequence, ferrous ions are free to react with excess H2S to form insoluble iron sulfides. X-ray photoelectron spectra indicate binding energies consistent with the iron sulfides having a pyrrhotite structure (Fe2p3/2 708.4 eV; S2p3/2 161.5 eV). Other sulfur species identified at the surface include sulfate, sulfite and polysulfides. X-ray diffraction suggests an unidentifiable crystal structure at the hematite surface develops within 3 months, HRTEM confirms the presence of a hexagonal structure again suggesting the formation of pyrrhotite. The identification of pyrrhotite is inconsistent with previous reports in which mackinawite and greigite were products of biological sulfate reduction (Rickard 1969; Herbert et al 1998). The apparent differences in stoiciometries may be related to the availability of Fe2+(aq.) at the mineral surface through respiratory iron reduction by subsurface bacteria. The significance of pyrrhotite and polysulfide production in relation to the S- and Fe-cycles and to trace metal bioavailability is discussed.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1012323
- Report Number(s):
- PNNL-SA-33867; KP1704020; TRN: US201109%%787
- Journal Information:
- Geochimica et Cosmochimica Acta, 65(2):223-235, Vol. 65, Issue 2; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
60 APPLIED LIFE SCIENCES
AVAILABILITY
BACTERIA
CRYSTAL STRUCTURE
DESULFOVIBRIO
DISSOLUTION
HEMATITE
HYDROGEN SULFIDES
IRON
IRON SULFIDES
PRODUCTION
PYRRHOTITE
SPECTRA
SULFATE-REDUCING BACTERIA
SULFATES
SULFIDES
SULFITES
SULFUR
X-RAY DIFFRACTION
sulfate
hematite
ferrous ions
XPS
XRD
pyrrhotite
stoicimetries
iron
bacteria
polysulfide