How does organic matter constrain the nature, size and availability of Fe nanoparticles for biological reduction?

Pédrot, Mathieu; Boudec, Ange Le; Davranche, Mélanie; Dia, Aline; Hénin, Odile

doi:10.1016/j.jcis.2011.03.067

Cited by 107 publications

(66 citation statements)

References 75 publications

(106 reference statements)

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“…The low degree of polymerization (i.e. crystal growth), evidenced by the TEM and XAS analyses, could be explained by the high amount of OM which impairs the crystal growth of the Fe(III)-oxyhydroxides (Cornell and Schwertmann, 2003;Pédrot et al, 2011). Scarce well-formed Fe crystals were assumed to have been inherited from the soil and therefore preserved from the reductive dissolution.…”

Section: As Speciation As a Function Of The Size Fractionmentioning

confidence: 99%

Highlighting the wide variability in arsenic speciation in wetlands: A new insight into the control of the behavior of arsenic

Guénet

Davranche

Vantelon

et al. 2017

Geochimica et Cosmochimica Acta

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Highlighting the wide variability in arsenic speciation in wetlands: a new insight into the control of the behavior of arsenic. Geochimica et Cosmochimica Acta, Elsevier, 2017, 203, pp.284-302 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1Highlighting the wide variability in arsenic speciation in wetlands: AbstractAlthough the behavior of Arsenic (As) under reducing conditions in periods of high water levels in wetlands is well understood and documented, there is a lack of information under oxidizing conditions when the water level decreases. In this study, we were interested in the first stage of the oxidizing period, when oxidation products are still in suspension. A soil sample from the Naizin Kervidy wetland (France) was incubated in the laboratory to produce a reduced soil solution. The reduced solution was subsequently oxidized, filtered and ultrafiltered using decreasing pore size membranes (5 µm, 3 µm, 0.2 µm, 30 kDa and 5 kDa). The distribution of As and Fe was investigated in each size fraction of the oxidized solution and their speciations were studied using XAS, HPLC and SEC-ICP-MS. Organic matter was characterized using thermally assisted hydrolysis and methylation gas chromatography-mass spectrometry (THM-GC-MS) and fluorescence spectroscopy. The majority of the As was present as As(V) but a small amount of As(III) still remained despite the advanced oxidized conditions. In the > 0.2 µm fractions, the XAS analyses showed that As was associated, in the second shell, with Fe (As-Fe = 3.35 Å) as bidentate binuclear complexes and C (As-C = 2.90 Å), suggesting the integration of As in biological objects. In the < 30 kDa fraction, As was directly bound to C (As-C = 1.96 Å) in the first shell indicating the presence of organic As species. In the second shell, an As-Fe distance of 3.35 Å was found showing that 2 part of the As was still complexed with Fe. The 0.2 µm-30 kDa fraction was a transitional fraction in terms of the Fe species and OM composition. In this fraction, organic matter exhibited a more humic character (aromatic molecules) inducing an increasing cation binding capacity. As a consequence, in this fraction and in the smallest one, As, Fe and OM seemed to form ternary complexes in which the Fe or nano-oxides in the > 30 kDa fraction and as monomer, or cluster in < 30 kDa fraction acted as a bridge. In all of the fractions, a proportion of As(V) was present as organic methylated species. These organic species might be produced by several organisms (animal or plant) via a detoxification process. They seemed to be bound to the particulate and colloidal Fe/OM phases as well as integ...

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Section: As Speciation As a Function Of The Size Fractionmentioning

confidence: 99%

Highlighting the wide variability in arsenic speciation in wetlands: A new insight into the control of the behavior of arsenic

Guénet

Davranche

Vantelon

et al. 2017

Geochimica et Cosmochimica Acta

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“…Neither a release of the mineralassociated organic matter nor a mineral transformation was observed during reduction. Pédrot et al (2011) produced nanometer-sized lepidocrocite and Fe-humic acid coprecipitates and compared its reduction by Shewanella putrefaciens. They found the reduction of the coprecipitates to be about eight times faster than that of pure lepidocrocite.…”

Section: K Eusterhues Et Al: Fh-associated Om Inhibits Fe(iii) Redumentioning

confidence: 99%

“…We assume that these effects dominate over the surface passivation effect due to associated organic matter in case of the fast and extensive reduction of CFhA. A systematically different aggregate structure between ferrihydrite with adsorbed organic matter and coprecipitated ferrihydrites may also have influenced the availability of the mineral surface (Pédrot et al, 2011). A possibly different composition of the mineral-bound organic matter in coprecipitates compared to adsorption complexes is a further aspect, which has to be taken into account.…”

Section: Microbial Fe(iii) Reduction By Geobacter Bremensismentioning

confidence: 99%

“…Comparison to the studies of Pédrot et al (2011) and Shimizu et al (2013), let us assume that the electron transfer mechanism of a microorganism controls whether or not mineral-bound organic matter decreases or increases microbial reduction. Whereas Shewanella may use own redoxactive products to enhance electron shuttling, direct contact requiring Geobacter may not be able to reach the oxide surface when blocked by organic matter.…”

Section: Summary and Environmental Implicationsmentioning

confidence: 99%

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Reduction of ferrihydrite with adsorbed and coprecipitated organic matter: microbial reduction by <i>Geobacter bremensis</i> vs. abiotic reduction by Na-dithionite

et al. 2014

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Abstract. Ferrihydrite is a widespread poorly crystalline Fe oxide which becomes easily coated by natural organic matter in the environment. This mineral-bound organic matter entirely changes the mineral surface properties and therefore the reactivity of the original mineral. Here, we investigated 2-line ferrihydrite, ferrihydrite with adsorbed organic matter, and ferrihydrite coprecipitated with organic matter for microbial and abiotic reduction of Fe(III). Ferrihydrite-organic matter associations with different organic matter loadings were reduced either by Geobacter bremensis or abiotically by Na-dithionite. Both types of experiments showed decreasing initial Fe-reduction rates and decreasing degrees of reduction with increasing amounts of mineral-bound organic matter. At similar organic matter loadings, coprecipitated ferrihydrites were more reactive than ferrihydrites with adsorbed organic matter. The difference can be explained by the smaller crystal size and poor crystallinity of such coprecipitates. At small organic matter loadings the poor crystallinity of coprecipitates led to even faster Fe-reduction rates than found for pure ferrihydrite. The amount of mineral-bound organic matter also affected the formation of secondary minerals: goethite was only found after reduction of organic matter-free ferrihydrite and siderite was only detected when ferrihydrites with relatively low amounts of mineral-bound organic matter were reduced. We conclude that direct contact of G. bremensis to the Fe oxide mineral surface was inhibited by attached organic matter. Consequently, mineral-bound organic matter shall be taken into account as a factor in slowing down reductive dissolution.

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“…Iron minerals such as Fe(III) oxides exhibit a high reactivity towards dissolved organic matter (OM); thus Fe(III) oxides are either partially or completely covered by OM in natural environments (Eusterhues et al, 2005;Kaiser and Zech, 2000;Lalonde et al, 2012;Torn et al, 1997). Fe(III) oxides enveloped by OM potentially lead to changes in the surface properties in comparison to non-modified Fe(III) oxides, which ultimately may influence mobility, solubility, and aggregation (Eusterhues et al, 2014;Narvekar et al, 2017;Pédrot et al, 2011;Vindedahl et al, 2016). The poorly crystalline ferrihydrite is one of the most common Fe(III) oxides and typically forms aggregates of nanometer-sized individual crystals (Bigham et al, 2002;Cornell and Schwertmann, 2003;Jambor and Dutrizac, 1998).…”

Section: Introductionmentioning

confidence: 99%

Ferrihydrite-associated organic matter (OM) stimulates reduction by <i>Shewanella oneidensis</i> MR-1 and a complex microbial consortia

et al. 2017

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Abstract. The formation of Fe(III) oxides in natural environments occurs in the presence of natural organic matter (OM), resulting in the formation of OM-mineral complexes that form through adsorption or coprecipitation processes. Thus, microbial Fe(III) reduction in natural environments most often occurs in the presence of OM-mineral complexes rather than pure Fe(III) minerals. This study investigated to what extent does the content of adsorbed or coprecipitated OM on ferrihydrite influence the rate of Fe(III) reduction by Shewanella oneidensis MR-1, a model Fe(III)-reducing microorganism, in comparison to a microbial consortium extracted from the acidic, Fe-rich Schlöppnerbrunnen fen. We found that increased OM content led to increased rates of microbial Fe(III) reduction by S. oneidensis MR-1 in contrast to earlier findings with the model organism Geobacter bremensis. Ferrihydrite-OM coprecipitates were reduced slightly faster than ferrihydrites with adsorbed OM. Surprisingly, the complex microbial consortia stimulated by a mixture of electrons donors (lactate, acetate, and glucose) mimics S. oneidensis under the same experimental Fe(III)-reducing conditions suggesting similar mechanisms of electron transfer whether or not the OM is adsorbed or coprecipitated to the mineral surfaces. We also followed potential shifts of the microbial community during the incubation via 16S rRNA gene sequence analyses to determine variations due to the presence of adsorbed or coprecipitated OM-ferrihydrite complexes in contrast to pure ferrihydrite. Community profile analyses showed no enrichment of typical model Fe(III)-reducing bacteria, such as Shewanella or Geobacter sp., but an enrichment of fermenters (e.g., Enterobacteria) during pure ferrihydrite incubations which are known to use Fe(III) as an electron sink. Instead, OM-mineral complexes favored the enrichment of microbes including Desulfobacteria and Pelosinus sp., both of which can utilize lactate and acetate as an electron donor under Fe(III)-reducing conditions. In summary, this study shows that increasing concentrations of OM in OM-mineral complexes determines microbial Fe(III) reduction rates and shapes the microbial community structure involved in the reductive dissolution of ferrihydrite. Similarities observed between the complex Fe(III)-reducing microbial consortia and the model Fe(III)-reducer S. oneidensis MR-1 suggest electron-shuttling mechanisms dominate in OM-rich environments, including soils, sediments, and fens, where natural OM interacts with Fe(III) oxides during mineral formation.

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How does organic matter constrain the nature, size and availability of Fe nanoparticles for biological reduction?

Cited by 107 publications

References 75 publications

Highlighting the wide variability in arsenic speciation in wetlands: A new insight into the control of the behavior of arsenic

Highlighting the wide variability in arsenic speciation in wetlands: A new insight into the control of the behavior of arsenic

Reduction of ferrihydrite with adsorbed and coprecipitated organic matter: microbial reduction by <i>Geobacter bremensis</i> vs. abiotic reduction by Na-dithionite

Ferrihydrite-associated organic matter (OM) stimulates reduction by <i>Shewanella oneidensis</i> MR-1 and a complex microbial consortia

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How does organic matter constrain the nature, size and availability of Fe nanoparticles for biological reduction?

Cited by 107 publications

References 75 publications

Highlighting the wide variability in arsenic speciation in wetlands: A new insight into the control of the behavior of arsenic

Highlighting the wide variability in arsenic speciation in wetlands: A new insight into the control of the behavior of arsenic

Reduction of ferrihydrite with adsorbed and coprecipitated organic matter: microbial reduction by &lt;i&gt;Geobacter bremensis&lt;/i&gt; vs. abiotic reduction by Na-dithionite

Ferrihydrite-associated organic matter (OM) stimulates reduction by &lt;i&gt;Shewanella oneidensis&lt;/i&gt; MR-1 and a complex microbial consortia

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Reduction of ferrihydrite with adsorbed and coprecipitated organic matter: microbial reduction by <i>Geobacter bremensis</i> vs. abiotic reduction by Na-dithionite

Ferrihydrite-associated organic matter (OM) stimulates reduction by <i>Shewanella oneidensis</i> MR-1 and a complex microbial consortia