Reassessing the role of sulfur geochemistry on arsenic speciation in reducing environments

Handle URI:
http://hdl.handle.net/10754/599457
Title:
Reassessing the role of sulfur geochemistry on arsenic speciation in reducing environments
Authors:
Couture, Raoul-Marie; Van Cappellen, Philippe
Abstract:
Recent evidence suggests that the oxidation of arsenite by zero-valent sulfur (S(0)) may produce stable aqueous arsenate species under highly reducing conditions. The speciation of arsenic (As) in reducing soils, sediments and aquifers may therefore be far more complex than previously thought. We illustrate this by presenting updated Eh-pH diagrams of As speciation in sulfidic waters that include the most recently reported formation constants for sulfide complexes of As(III) and As(V). The results show that the stability fields of As(III) and As(V) (oxy)thioanions cover a large pH range, from pH 5 to 10. In particular, As(V)-S(-II) complexes significantly enhance the predicted solubility of As under reducing conditions. Equilibrium calculations further show that, under conditions representative of sulfidic pore waters and in the presence of solid-phase elemental sulfur, the S0 (aq)/HS- couple yields a redox potential (Eh)~0.1V higher than the SO4 2-/HS- couple. S(0) may thus help stabilize aqueous As(V) not only by providing an electron acceptor for As(III) but also by contributing to a more oxidizing redox state. © 2011 Elsevier B.V.
Citation:
Couture R-M, Van Cappellen P (2011) Reassessing the role of sulfur geochemistry on arsenic speciation in reducing environments. Journal of Hazardous Materials 189: 647–652. Available: http://dx.doi.org/10.1016/j.jhazmat.2011.02.029.
Publisher:
Elsevier BV
Journal:
Journal of Hazardous Materials
KAUST Grant Number:
KUK-C1-017-12
Issue Date:
May-2011
DOI:
10.1016/j.jhazmat.2011.02.029
PubMed ID:
21382662
Type:
Article
ISSN:
0304-3894
Sponsors:
We thank A. Tessier (INRS-ETE, University of Québec), Douglas E. LaRowe (Georgia Institute of Technology) and four anonymous reviewers for their comments and suggestions, which helped to improve the manuscript, and K. Mueller for editing the manuscript. R.-M. C. was financially supported by a postdoctoral fellowship from the Fonds québecois de recherche sur la nature et les technologies (FQRNT). This work was also supported in part by the Center for Soil, Water and Coastal Resources (SOWACOR), Award No. KUK-C1-017-12, made by King Abdullah University of Science and Technology.
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorCouture, Raoul-Marieen
dc.contributor.authorVan Cappellen, Philippeen
dc.date.accessioned2016-02-28T05:51:30Zen
dc.date.available2016-02-28T05:51:30Zen
dc.date.issued2011-05en
dc.identifier.citationCouture R-M, Van Cappellen P (2011) Reassessing the role of sulfur geochemistry on arsenic speciation in reducing environments. Journal of Hazardous Materials 189: 647–652. Available: http://dx.doi.org/10.1016/j.jhazmat.2011.02.029.en
dc.identifier.issn0304-3894en
dc.identifier.pmid21382662en
dc.identifier.doi10.1016/j.jhazmat.2011.02.029en
dc.identifier.urihttp://hdl.handle.net/10754/599457en
dc.description.abstractRecent evidence suggests that the oxidation of arsenite by zero-valent sulfur (S(0)) may produce stable aqueous arsenate species under highly reducing conditions. The speciation of arsenic (As) in reducing soils, sediments and aquifers may therefore be far more complex than previously thought. We illustrate this by presenting updated Eh-pH diagrams of As speciation in sulfidic waters that include the most recently reported formation constants for sulfide complexes of As(III) and As(V). The results show that the stability fields of As(III) and As(V) (oxy)thioanions cover a large pH range, from pH 5 to 10. In particular, As(V)-S(-II) complexes significantly enhance the predicted solubility of As under reducing conditions. Equilibrium calculations further show that, under conditions representative of sulfidic pore waters and in the presence of solid-phase elemental sulfur, the S0 (aq)/HS- couple yields a redox potential (Eh)~0.1V higher than the SO4 2-/HS- couple. S(0) may thus help stabilize aqueous As(V) not only by providing an electron acceptor for As(III) but also by contributing to a more oxidizing redox state. © 2011 Elsevier B.V.en
dc.description.sponsorshipWe thank A. Tessier (INRS-ETE, University of Québec), Douglas E. LaRowe (Georgia Institute of Technology) and four anonymous reviewers for their comments and suggestions, which helped to improve the manuscript, and K. Mueller for editing the manuscript. R.-M. C. was financially supported by a postdoctoral fellowship from the Fonds québecois de recherche sur la nature et les technologies (FQRNT). This work was also supported in part by the Center for Soil, Water and Coastal Resources (SOWACOR), Award No. KUK-C1-017-12, made by King Abdullah University of Science and Technology.en
dc.publisherElsevier BVen
dc.subjectEh-pH diagramsen
dc.subjectEquilibrium speciationen
dc.subjectSulfidic environmentsen
dc.subjectThioarsenic anionsen
dc.subjectZero-valent sulfuren
dc.titleReassessing the role of sulfur geochemistry on arsenic speciation in reducing environmentsen
dc.typeArticleen
dc.identifier.journalJournal of Hazardous Materialsen
dc.contributor.institutionGeorgia Institute of Technology, Atlanta, United Statesen
kaust.grant.numberKUK-C1-017-12en

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