Microbial sulfidogenesis in ferrihydrite-rich environments: Effects on iron mineralogy and arsenic mobility

Burton, Edward D; Johnston, Scott G; Bush, Richard T

doi:10.1016/j.gca.2011.03.001

Cited by 140 publications

(83 citation statements)

References 54 publications

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“…LCF does suggest, however, the formation of AsS (s) , despite the fact that the outflow of all FTRs is undersaturated by .2 orders of magnitudes with respect to AsS (s) . This apparent contradiction has been previously reported at circum-neutral pH [15] and can be ascribed to a surface reaction of As onto Fe sulfides which lead to a local As coordination that, using XAS, is indistinguishable from an AsS (s) -like solid phase. [6,7,12,17,51] In the FTRs A and B, where thiol formation was the dominant sink for reduced S, LCF suggests that thiol-bound As III accounts for a third of the total As.…”

Section: Discussioncontrasting

confidence: 88%

“…[9][10][11][12] In reducing soils and sediments, in the presence of complex mineral assemblages, [13][14][15][16] As sorption onto Fe sulfides is often of minor importance except at high As loading and slightly acidic pH. Under the latter conditions, As uptake by Fe monosulfide (FeS m(s) ) occurs through the formation of a sorption complex akin to realgar (AsS (s) ), as shown by Gallegos et al [17] In environments where all the reactive Fe is transformed into Fe sulfides, the remaining free sulfide (S thiolated As species.…”

Section: Introductionmentioning

confidence: 99%

“…-reducing microorganisms were depleting the readily available OM pool. We then added lactate, a substrate known to stimulate sulfate-reducing microorganisms, [15,43] Outflow SS ÀII was the only aqueous species that showed systematic differences between the As III and the As V -fed FTRs, being higher for As V (FTRs B and D) than for As III (FTRs A and C) by ,5 mM. Outflow SS (aq)…”

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confidence: 99%

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Arsenic binding to organic and inorganic sulfur species during microbial sulfate reduction: a sediment flow-through reactor experiment

et al. 2013

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Environmental context. The use of water contaminated with arsenic for drinking and irrigation is linked to water and food borne diseases throughout the world. Although reducing conditions in soils and sediments are generally viewed as enhancing arsenic mobility in subsurface environments, we show they can actually promote As sequestration in the presence of reduced sulfur species and labile organic matter. We propose that sulfurisation of organic matter and subsequent binding of As to thiol groups may offer an innovative pathway for As remediation.Abstract. Flow-through reactors (FTRs) were used to assess the mobility of arsenic under sulfate reducing conditions in natural, undisturbed lake sediments. The sediment slices in the FTRs were supplied continuously with inflow solutions containing sulfate and soluble As III or As V and, after 3 weeks, also lactate. The experiment ran for a total of 8 weeks. The dissolved iron concentration, pH, redox potential (E h ), as well as aqueous As and sulfur speciation were monitored in the outflow solutions. In FTRs containing surface sediment enriched in labile organic matter (OM), microbial sulfate reduction led to an accumulation of organically bound S, as evidenced by X-ray absorption spectroscopy. For these FTRs, the inflowing dissolved As concentration of 20 mM was lowered by two orders of magnitude, producing outflow concentrations of 0.2 mM monothioarsenate and 0.1 mM arsenite. In FTRs containing sediment collected at greater depth, sulfide and zero-valent S precipitated as pyrite and elemental S, while steady-state outflow arsenite concentrations remained near 5 mM. The observations thus suggest that As sequestration is enhanced when sediment OM buffers the free sulfide and zero-valent S concentrations. An updated conceptual model for the fate of As in the anoxic As-C-S-Fe system is presented based on the results of this study.

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Section: Discussioncontrasting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Arsenic binding to organic and inorganic sulfur species during microbial sulfate reduction: a sediment flow-through reactor experiment

et al. 2013

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“…A wide range of sulfurreducing bacteria exist that can use the different oxidized sulfur species as electron acceptors and therefore contribute to the formation of sulfide, which can then react abiotically with iron oxides (14). Sulfidogenesis by sulfate-reducing bacteria was found to lead to iron mineral transformation and arsenic mobilization (15,16). Straub and Schink (17) also investigated this reaction pathway of sulfur-mediated iron(III) mineral reduction in experiments with Sulfurospirillum deleyianum and ferrihydrite.…”

mentioning

confidence: 99%

Sulfur Species as Redox Partners and Electron Shuttles for Ferrihydrite Reduction by Sulfurospirillum deleyianum

Lohmayer

Kappler

Lösekann-Behrens

et al. 2014

Appl Environ Microbiol

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b Iron(III) (oxyhydr)oxides can represent the dominant microbial electron acceptors under anoxic conditions in many aquatic environments, which makes understanding the mechanisms and processes regulating their dissolution and transformation particularly important. In a previous laboratory-based study, it has been shown that 0.05 mM thiosulfate can reduce 6 mM ferrihydrite indirectly via enzymatic reduction of thiosulfate to sulfide by the sulfur-reducing bacterium Sulfurospirillum deleyianum, followed by abiotic reduction of ferrihydrite coupled to reoxidation of sulfide. Thiosulfate, elemental sulfur, and polysulfides were proposed as reoxidized sulfur species functioning as electron shuttles. However, the exact electron transfer pathway remained unknown. Here, we present a detailed analysis of the sulfur species involved. Apart from thiosulfate, substoichiometric amounts of sulfite, tetrathionate, sulfide, or polysulfides also initiated ferrihydrite reduction. The portion of thiosulfate produced during abiotic ferrihydrite-dependent reoxidation of sulfide was about 10% of the total sulfur at maximum. The main abiotic oxidation product was elemental sulfur attached to the iron mineral surface, which indicates that direct contact between microorganisms and ferrihydrite is necessary to maintain the iron reduction process. Polysulfides were not detected in the liquid phase. Minor amounts were found associated either with microorganisms or the mineral phase. The abiotic oxidation of sulfide in the reaction with ferrihydrite was identified as rate determining. Cysteine, added as a sulfur source and a reducing agent, also led to abiotic ferrihydrite reduction and therefore should be eliminated when sulfur redox reactions are investigated. Overall, we could demonstrate the large impact of intermediate sulfur species on biogeochemical iron transformations.

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“…Other researchers have observed the transformation of ferrihydrite to magnetite due to the presence of high local concentrations of an electron donor. Burton et al (2011) observed the transformation of As(III)-bearing ferrihydritecoated quartz sand to mackinawite, magnetite and goethite after 28 days of advective-flow column experiments. The columns were inoculated with Desulfovibrio vulgaris, a sulfate reducer.…”

Section: Resultsmentioning

confidence: 94%

Understanding abiotic ferrihydrite re-mineralization by ferrous ions

Raghav

Sáez

Ela

2014

Int. J. Environ. Sci. Technol.

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In this work, we study the abiotic re-mineralization of ferrihydrite under reducing conditions, obtained by adding zero-valent iron (ZVI) to a suspension of ferrihydrite particles. Under similar conditions, the system (ferrihydrite and ZVI) proceeded along two different transformation pathways differentiated by whether a magnetic stirrer or an overhead stirrer was used for mixing. X-ray diffraction characterization of the solid products showed that magnetite was the sole product of ferrihydrite transformation when a magnetic stirrer was used, whereas both goethite and magnetite were formed when an overhead stirrer was used. The system also behaved differently in terms of transformation kinetics and amount of magnetite formed. The quantification of magnetite generated was performed using a procedure developed in this study. The role of four mechanisms was investigated to explain these observed differences, namely-(1) presence/absence of high local Fe 2? concentrations, (2) mechanical abrasion, (3) presence/absence of a magnetic field, and (4) presence/ absence of a crystalline ZVI surface. Ferrous ions are expected to be concentrated near the magnetic bead on the magnetic stirrer as opposed to a more dispersed distribution with the overhead stirrer. This mechanistic study concluded that the presence of high local Fe 2? concentrations in the system leads to magnetite formation and the absence of the same leads to mixed goethite/magnetite or magnetite-free systems. These findings have significant implications for the mobilization of arsenic from iron (III) hydroxides as the conditions move from oxidizing to reducing, such as often occurs in engineered landfills and natural carbon-rich sediments.

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Microbial sulfidogenesis in ferrihydrite-rich environments: Effects on iron mineralogy and arsenic mobility

Cited by 140 publications

References 54 publications

Arsenic binding to organic and inorganic sulfur species during microbial sulfate reduction: a sediment flow-through reactor experiment

Arsenic binding to organic and inorganic sulfur species during microbial sulfate reduction: a sediment flow-through reactor experiment

Sulfur Species as Redox Partners and Electron Shuttles for Ferrihydrite Reduction by Sulfurospirillum deleyianum

Understanding abiotic ferrihydrite re-mineralization by ferrous ions

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