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Acid production by FeSO4·nH2O dissolution and implications for terrestrial and martian aquatic systems

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Published/Copyright: April 1, 2015
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American Mineralogist
From the journal American Mineralogist Volume 94 Issue 2-3

Abstract

Combined experimental, modeling, and analytical results indicate that the rapid acidification of dilute waters in contact with nominally Fe2+-sulfate minerals (FeSO4·nH2O) is caused by Fe3+ hydrolysis, which occurs when low levels (<1 mol%) of a contaminant Fe3+-sulfate phase are dissolved along with the FeSO4·nH2O. This rapid acidification has previously been attributed to hydrolysis by Fe2+. However, dissolution experiments performed using ZnSO4·nH2O, in which the Zn2+ cation has a higher hydrolysis constant (log K = -8.96) than Fe2+ (log K = -9.5), failed to produce significant changes in solution pH. We present the results of geochemical modeling simulations confirming that FeSO4·nH2O dissolution alone cannot explain the experimentally observed change in pH from 5.65 to 3.50. Nor can the experimental observations be explained by oxidation of Fe2+ to Fe3+ in solution. Instead, our experimental results can be best explained by modeling the incorporation of <1 mol% Fe3+ contamination from any number of Fe3+ or mixed valence Fe-sulfate phases, including anhydrous Fe3+2 (SO4)3, coquimbite, kornelite, römerite, bilinite, copiapite, or ferricopiapite, all of which are reasonable candidate phases for oxidative breakdown products of FeSO4·nH2O. Laboratory Mössbauer spectra are consistent with up to 0.6 mol% of the total Fe in the sample to be present as Fe3+. Although the doublet has parameters that are not diagnostic of any specific Fe3+-sulfate, they do help constrain its identification. These results demonstrate that minor contamination of labile Fe2+ sulfates by Fe3+ can have dramatic effects on solution chemistry that should be considered when studying reactions relevant to acid mine drainage waste sites and other localities where Fe-sulfate minerals occur, such as the surface of Mars.

Keywords : Mars; AMD; melanterite; pH; Mössbauer
Received: 2008-9-5
Accepted: 2008-11-7
Published Online: 2015-4-1
Published in Print: 2009-2-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Determination of high-pressure phase equilibria of Fe2O3 using the Kawai-type apparatus equipped with sintered diamond anvils
  2. Suhailite, a new ammonium trioctahedral mica
  3. First record of K-cymrite in North Qaidam UHP eclogite, Western China
  4. Stability of uranium (VI) peroxide hydrates under ionizing radiation
  5. Heat capacities and thermodynamic functions of TiO2 anatase and rutile: Analysis of phase stability
  6. The behavior of Co and Ni in olivine in planetary basalts: An experimental investigation
  7. Partitioning of Ni between olivine and an iron-rich basalt: Experiments, partition models, and planetary implications
  8. The application of Lorentz transmission electron microscopy to the study of lamellar magnetism in hematite-ilmenite
  9. A Monte Carlo study of short- and long-range order of tetrahedral cations in sapphirine and khmaralite
  10. High-pressure ammonium-bearing silicates: Implications for nitrogen and hydrogen storage in the Earth’s mantle
  11. Formation of aragonite mesocrystals and implication for biomineralization
  12. U-Pb age, trace-element, and Hf-isotope compositions of zircon in a quartz vein from eclogite in the western Dabie Mountains: Constraints on fluid flow during early exhumation of ultrahigh-pressure rocks
  13. Interaction of phosphate-bearing solutions with gypsum: Epitaxy and induced twinning of brushite (CaHPO4·2H2O) on the gypsum cleavage surface
  14. Fukalite: An example of an OD structure with two-dimensional disorder
  15. Chemical control of 3T stacking order in a Li-poor biotite mica
  16. Site preference of U and Th in Cl, F, and Sr apatites
  17. High-pressure structural behavior of ingersonite, Ca3Mn2+Sb5+4O14: An in-situ single-crystal X-ray study
  18. Crystal chemistry of Fe32+Cr2Si3O12–Fe32+Fe23+Si3O12 garnet solid solutions and related spinels
  19. A method to synthesize large fluid inclusions in quartz at controlled times and under unfavorable growth conditions
  20. The stability of methane hydrate intercalates of montmorillonite and nontronite: Implications for carbon storage in ocean-floor environments
  21. Structure and carbonate orientation of vaterite (CaCO3)
  22. Qusongite (WC): A new mineral
  23. Nanoscale “liquid” inclusions of As-Fe-S in arsenian pyrite
  24. Water speciation in hydrous silicate and aluminosilicate glasses: Direct evidence from 29Si-1H and 27Al-1H double-resonance NMR
  25. Acid production by FeSO4·nH2O dissolution and implications for terrestrial and martian aquatic systems
https://doi.org/10.2138/am.2009.3085
Keywords for this article
Mars; AMD; melanterite; pH; Mössbauer

Articles in the same Issue

  1. Determination of high-pressure phase equilibria of Fe2O3 using the Kawai-type apparatus equipped with sintered diamond anvils
  2. Suhailite, a new ammonium trioctahedral mica
  3. First record of K-cymrite in North Qaidam UHP eclogite, Western China
  4. Stability of uranium (VI) peroxide hydrates under ionizing radiation
  5. Heat capacities and thermodynamic functions of TiO2 anatase and rutile: Analysis of phase stability
  6. The behavior of Co and Ni in olivine in planetary basalts: An experimental investigation
  7. Partitioning of Ni between olivine and an iron-rich basalt: Experiments, partition models, and planetary implications
  8. The application of Lorentz transmission electron microscopy to the study of lamellar magnetism in hematite-ilmenite
  9. A Monte Carlo study of short- and long-range order of tetrahedral cations in sapphirine and khmaralite
  10. High-pressure ammonium-bearing silicates: Implications for nitrogen and hydrogen storage in the Earth’s mantle
  11. Formation of aragonite mesocrystals and implication for biomineralization
  12. U-Pb age, trace-element, and Hf-isotope compositions of zircon in a quartz vein from eclogite in the western Dabie Mountains: Constraints on fluid flow during early exhumation of ultrahigh-pressure rocks
  13. Interaction of phosphate-bearing solutions with gypsum: Epitaxy and induced twinning of brushite (CaHPO4·2H2O) on the gypsum cleavage surface
  14. Fukalite: An example of an OD structure with two-dimensional disorder
  15. Chemical control of 3T stacking order in a Li-poor biotite mica
  16. Site preference of U and Th in Cl, F, and Sr apatites
  17. High-pressure structural behavior of ingersonite, Ca3Mn2+Sb5+4O14: An in-situ single-crystal X-ray study
  18. Crystal chemistry of Fe32+Cr2Si3O12–Fe32+Fe23+Si3O12 garnet solid solutions and related spinels
  19. A method to synthesize large fluid inclusions in quartz at controlled times and under unfavorable growth conditions
  20. The stability of methane hydrate intercalates of montmorillonite and nontronite: Implications for carbon storage in ocean-floor environments
  21. Structure and carbonate orientation of vaterite (CaCO3)
  22. Qusongite (WC): A new mineral
  23. Nanoscale “liquid” inclusions of As-Fe-S in arsenian pyrite
  24. Water speciation in hydrous silicate and aluminosilicate glasses: Direct evidence from 29Si-1H and 27Al-1H double-resonance NMR
  25. Acid production by FeSO4·nH2O dissolution and implications for terrestrial and martian aquatic systems
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