Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/25827
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dc.contributor.authorWan, Molien_UK
dc.contributor.authorSchröder, Christianen_UK
dc.contributor.authorPeiffer, Stefanen_UK
dc.date.accessioned2017-10-05T23:07:03Z-
dc.date.available2017-10-05T23:07:03Z-
dc.date.issued2017-11-15en_UK
dc.identifier.urihttp://hdl.handle.net/1893/25827-
dc.description.abstractThe formation of pyrite has been extensively studied because of its abundance in many anoxic environments. Yet, there is no consensus on the underlying pathways and kinetics of its formation. We studied the formation of pyrite during the reaction between reactive ferric hydroxides (goethite and lepidocrocite) and aqueous sulfide in an anoxic glove box at neutral pH. The formation of pyrite was monitored with Mössbauer spectroscopy using 57Fe isotope-enriched ferric (hydr)oxides. The initial molar ratios of Fe(III):S(-II) were adjusted to be ‘high’ with Fe(III) concentrations in excess of sulfide (HR) and ‘low’ (LR) with excess of sulfide. Approximately the same surface area was applied in all HR runs in order to compare the mineral reactivity of ferric hydroxides. Electron transfer between aqueous sulfide and ferric hydroxides in the first 2 hours led to the formation of ferrous iron and methanol-extractable oxidized sulfur (MES). Metastable FeSx formed in all of the experiments. Pyrite formed at a different rate in HR and LR runs although the MES and ferrous iron concentrations were rather similar. In all HR runs, pyrite formation started after 48 hours and achieved a maximum concentration after 1 week. In contrast, pyrite started to form only after 2 months in LR runs (Fe(III):S(-II) ∼ 0.2) with goethite and no pyrite formation was observed in LR with lepidocrocite after 6 months. Rates in LR runs were at least 2-3 orders of magnitude slower than in HR runs. Sulfide oxidation rates were higher with lepidocrocite than with goethite, but no influence of the mineral type on pyrite formation rates in HR runs could be observed. Pyrite formation rates in HR runs could not be predicted by the classical model ofRickard (1975). We therefore propose a novel ferric-hydroxide-surface (FHS) pathway for rapid pyrite formation that is based on the formation of a precursor species >FeIIS2-. Its formation is competitive to FeSx precipitation at high aqueous sulfide concentrations and requires that a fraction of the ferric hydroxide surface not be covered by a surface precipitate of FeSx. Hence, pyrite formation rate decreases with decreasing Fe(III):S(-II)aq ratio. In LR runs, pyrite formation appears to follow the model ofRickard (1975) and to be kinetically controlled by the dissolution of FeS. The FHS-pathway will be prominent in many aquatic systems with terrestrial influence, i.e. abundance of ferric iron. We propose that the Fe(III):S(-II)aqratio can be used as an indicator for rapid pyrite formation during early diagenesis in anoxic/suboxic aquatic systems.en_UK
dc.language.isoenen_UK
dc.publisherElsevieren_UK
dc.relationWan M, Schröder C & Peiffer S (2017) Fe(III):S(-II) Concentration Ratio Controls the Pathway and the Kinetics of Pyrite Formation during Sulfidation of Ferric Hydroxides. Geochimica et Cosmochimica Acta, 217, pp. 334-348. https://doi.org/10.1016/j.gca.2017.08.036en_UK
dc.rightsThis item has been embargoed for a period. During the embargo please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study. Accepted refereed manuscript of: Wan M, Schröder C & Peiffer S (2017) Fe(III):S(-II) Concentration Ratio Controls the Pathway and the Kinetics of Pyrite Formation during Sulfidation of Ferric Hydroxides, Geochimica et Cosmochimica Acta, 217, pp. 334-348. DOI: 10.1016/j.gca.2017.08.036 © 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/en_UK
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/en_UK
dc.subjectrapid pyrite formationen_UK
dc.subjectpathwayen_UK
dc.subjectpolysulfidesen_UK
dc.subjectreactive ferrous ironen_UK
dc.subjectiron-sulfur interactionen_UK
dc.subjectferric hydroxidesen_UK
dc.subjectMössbauer spectroscopyen_UK
dc.titleFe(III):S(-II) Concentration Ratio Controls the Pathway and the Kinetics of Pyrite Formation during Sulfidation of Ferric Hydroxidesen_UK
dc.typeJournal Articleen_UK
dc.rights.embargodate2018-09-02en_UK
dc.rights.embargoreason[1-s2.0-S0016703717305380-main.pdf] Publisher requires embargo of 12 months after formal publication.en_UK
dc.identifier.doi10.1016/j.gca.2017.08.036en_UK
dc.citation.jtitleGeochimica et Cosmochimica Actaen_UK
dc.citation.issn0016-7037en_UK
dc.citation.volume217en_UK
dc.citation.spage334en_UK
dc.citation.epage348en_UK
dc.citation.publicationstatusPublisheden_UK
dc.citation.peerreviewedRefereeden_UK
dc.type.statusAM - Accepted Manuscripten_UK
dc.author.emailchristian.schroeder@stir.ac.uken_UK
dc.citation.date01/09/2017en_UK
dc.contributor.affiliationUniversity of Bayreuthen_UK
dc.contributor.affiliationBiological and Environmental Sciencesen_UK
dc.contributor.affiliationUniversity of Bayreuthen_UK
dc.identifier.isiWOS:000411362000020en_UK
dc.identifier.scopusid2-s2.0-85028955677en_UK
dc.identifier.wtid520711en_UK
dc.contributor.orcid0000-0002-7935-6039en_UK
dc.date.accepted2017-08-27en_UK
dcterms.dateAccepted2017-08-27en_UK
dc.date.filedepositdate2017-09-03en_UK
rioxxterms.apcnot requireden_UK
rioxxterms.typeJournal Article/Reviewen_UK
rioxxterms.versionAMen_UK
local.rioxx.authorWan, Moli|en_UK
local.rioxx.authorSchröder, Christian|0000-0002-7935-6039en_UK
local.rioxx.authorPeiffer, Stefan|en_UK
local.rioxx.projectInternal Project|University of Stirling|https://isni.org/isni/0000000122484331en_UK
local.rioxx.freetoreaddate2018-09-02en_UK
local.rioxx.licencehttp://www.rioxx.net/licenses/under-embargo-all-rights-reserved||2018-09-01en_UK
local.rioxx.licencehttp://creativecommons.org/licenses/by-nc-nd/4.0/|2018-09-02|en_UK
local.rioxx.filename1-s2.0-S0016703717305380-main.pdfen_UK
local.rioxx.filecount1en_UK
local.rioxx.source0016-7037en_UK
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