Composition and structural aspects of naturally occurring ferrihydrite

Cismasu, A. Cristina; Michel, F. Marc; Tcaciuc, A. Patricia; Tyliszczak, Tolek; Brown, Gordon E.

doi:10.1016/j.crte.2010.11.001

Cited by 174 publications

(138 citation statements)

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“…Studies of DOM Fe (hydr)oxide structures have found greater structural disorder in the coprecipitated Fe phases vs. organic-free or synthetic ferrihydrite (Eusterhues et al, 2008;Mikutta et al, 2008;Cismasu et al, 2011;Mikutta, 2011). The implications of these structural changes on biogeochemical processes remain unresolved.…”

Section: Introductionmentioning

confidence: 99%

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

Henneberry

Kraus

Nico

et al. 2012

Organic Geochemistry

147

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a b s t r a c tThe objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Febased coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc) was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. There was no evidence that exposure to reducing conditions led to release of DOM from the floc, indicating that coprecipitation with complex natural DOM in aquatic environments may stabilize Fe (hydr)oxides against crystallization upon reaction with reduced species and lead to long term sequestration of the DOM. STXM analysis identified spatially distinct regions with remarkable functional group purity, contrary to the model of DOM as a relatively uniform complex polymer lacking identifiable organic compounds. Polysaccharide-like OM was strongly and directly correlated with the presence of Fe but showed different Fe binding strength depending on the presence of carboxylic acid functional groups, whereas amide and aromatic functional groups were inversely correlated with Fe content.

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Section: Introductionmentioning

confidence: 99%

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

Henneberry

Kraus

Nico

et al. 2012

Organic Geochemistry

147

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“…The coprecipitation of OM with Fe results in the adsorption and occlusion of organic molecules within the interstices between individual ferrihydrite crystals, while adsorption of OM occurs on pre-existing ferrihydrite surfaces (Eusterhues et al, 2014). Moreover, the presence of dissolved OM impedes ferrihydrite growth (Cismasu et al, 2011;Eusterhues et al, 2008;Mikutta et al, 2008;Schwertmann et al, 2005); therefore, ferrihydrite with coprecipitated OM have smaller crystal sizes and more crystallographic defects. Since ferrihydrite is formed usually in OMrich environments coprecipitation is the more common process in nature (Eusterhues et al, 2008).…”

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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“…Additionally, the presence of dissolved organic matter inhibits ferrihydrite growth Published by Copernicus Publications on behalf of the European Geosciences Union. (Schwertmann et al, 2005;Mikutta et al, 2008;Eusterhues et al, 2008;Cismasu et al, 2011), and so coprecipitated ferrihydrites tend to develop smaller crystal sizes and more crystallographic defects. Likewise, the aggregation behavior of ferrihydrites may be affected.…”

Section: Introductionmentioning

confidence: 99%

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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Composition and structural aspects of naturally occurring ferrihydrite

Cited by 174 publications

References 52 publications

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

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

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

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Composition and structural aspects of naturally occurring ferrihydrite

Cited by 174 publications

References 52 publications

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

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

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

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

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