Interaction of FeII and Si under anoxic and reducing conditions: Structural characteristics of ferrous silicate co-precipitates

Francisco, Paul Clarence M.; Mitsui, Seiichiro; Ishidera, Takamitsu; Tachi, Yukio; Doi, Reisuke; Shiwaku, Hideaki

doi:10.1016/j.gca.2019.11.009

Cited by 18 publications

(16 citation statements)

References 70 publications

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“…Dehydration and structural rearrangement of the gel produced nanometer-sized particles of crystalline greenalite. The solubilities of dissolved ferrous iron and silica drop sharply with increasing pH, leading to rapid nucleation and precipitation of Fe(II)-silicates ( e.g., greenalite) in alkaline solutions (pH >7) (Tosca et al, 2016 ; Francisco et al, 2020 ).…”

Section: Experimental Growth Of Greenalite Nanoparticlesmentioning

confidence: 99%

Greenalite Nanoparticles in Alkaline Vent Plumes as Templates for the Origin of Life

2021

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Mineral templates are thought to have played keys roles in the emergence of life. Drawing on recent findings from 3.45-2.45 billion-year-old iron-rich hydrothermal sedimentary rocks, we hypothesize that greenalite (Fe 3 Si 2 O 5 (OH) 4) was a readily available mineral in hydrothermal environments, where it may have acted as a template and catalyst in polymerization, vesicle formation and encapsulation, and protocell replication. We argue that venting of dissolved Fe 2+ and SiO 2 (aq) into the anoxic Hadean ocean favored the precipitation of nanometer-sized particles of greenalite in hydrothermal plumes, producing a continuous flow of free-floating clay templates that traversed the ocean. The mixing of acidic, metal-bearing hydrothermal plumes from volcanic ridge systems with more alkaline, organic-bearing plumes generated by serpentinization of ultramafic rocks brought together essential building blocks for life in solutions conducive to greenalite precipitation. We suggest that the extreme disorder in the greenalite crystal lattice, producing structural modulations resembling parallel corrugations (*22 Å wide) on particle edges, promoted the assembly and alignment of linear RNA-type molecules (*20 Å diameter). In alkaline solutions, greenalite nanoparticles could have accelerated the growth of membrane vesicles, while their encapsulation allowed RNA-type molecules to continue to form on the mineral templates, potentially enhancing the growth and division of primitive cell membranes. Once self-replicating RNA evolved, the mineral template became redundant, and protocells were free to replicate and roam the ocean realm.

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Section: Experimental Growth Of Greenalite Nanoparticlesmentioning

confidence: 99%

Greenalite Nanoparticles in Alkaline Vent Plumes as Templates for the Origin of Life

2021

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“…Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) to measure Se, Fe, Na, and S concentrations, by ion chromatography (IC) to measure NH 4 + concentrations, and by UV–visible absorption spectrophotometry to qualitatively determine aqueous Se speciation. Saturation states were calculated by PHREEQC (v. 3.4) using stability constants given in Table S1 and activity corrections applied in our previous study. − The solids were characterized by X-ray diffraction (XRD) and relative phase proportions were estimated by Rietveld refinement using Profex (v. 4.3) . Morphological examination was carried out by scanning and transmission electron microscopy (SEM and TEM).…”

Section: Materials and Methodsmentioning

confidence: 99%

Selenide [Se(−II)] Immobilization in Anoxic, Fe(II)-Rich Environments: Coprecipitation and Behavior during Phase Transformations

Francisco

Matsumura

Kikuchi

et al. 2022

Environ. Sci. Technol.

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The radionuclide selenium-79 (Se-79) is predicted to be a key contributor to the long-term radiologic hazards associated with geological high-level waste (HLW) repositories; hence its release is of pertinent concern in the safety assessment of repositories. However, interactions of reduced Se species with aqueous Fe(II) species and solid phases arising from the corrosion of a steel overpack could play a role in mitigating its migration to the surrounding environment. In this study, we examined the immobilization mechanisms of Se(−II) during its interaction with aqueous Fe(II) and freshly precipitated Fe(OH)2 at circumneutral and alkaline conditions, respectively, its response to changes in pH, and its behavior during aging at 90 °C. Using microscopic and spectroscopic techniques, we observed β-FeSe precipitation, regardless of whether Se(−II) reacts with aqueous species or solid phases, and that modifying the pH following initial immobilization did not remobilize Se(−II). These observations indicate that Se(−II) migration beyond the overpack can be effectively and rapidly retarded via interactions with Fe(II) species arising from overpack corrosion. Thermodynamic calculations, however, showed that iron selenides became metastable at alkaline conditions and will dissolve in the long term. Aging experiments at 90 °C showed that Se(−II) can be completely retained via the crystallization of ferroselite at circumneutral conditions, while it will be largely remobilized at alkaline conditions. Our results show that Se(−II) mobility can be significantly influenced by its interactions with the corrosion products of the steel overpack and that these behaviors will have to be considered in repository safety assessments.

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“…(Patten and Byrne, 2017). Therefore, Fe (II) silica co-precipitates may play a role in stabilizing colloids (Mayer and Jarrell, 1996;Francisco et al, 2020). Findlay et al (2015) indicated that a substantial amount of Fe (in the mM level) would stay in the buoyant plume and might precipitate in and/or be adsorbed by silicate forms.…”

Section: Interplay Of Silicates Sulfur Oxygen and Iron In Controlling (Nano)particle Compositionmentioning

confidence: 99%

Soluble, Colloidal, and Particulate Iron Across the Hydrothermal Vent Mixing Zones in Broken Spur and Rainbow, Mid-Atlantic Ridge

2021

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The slow-spreading Mid-Atlantic Ridge (MAR) forms geological heterogeneity throughout the ridge system by deep crustal faults and their resultant tectonic valleys, which results in the existence of different types of hydrothermal vent fields. Therefore, investigating MAR hydrothermal systems opens a gate to understanding the concentration ranges of ecosystem-limiting metals emanating from compositionally distinct fluids for both near-field chemosynthetic ecosystems and far-field transport into the ocean interiors. Here, we present novel data regarding onboard measured, size-fractionated soluble, colloidal, and particulate iron concentrations from the 2018 R/V L’Atalante – ROV Victor research expedition, during which samples were taken from the mixing zone of black smokers using a ROV-assisted plume sampling. Iron size fractionation (<20, 20–200, and >200nm) data were obtained from onboard sequential filtering, followed by measurement via ferrozine assay and spectrophotometric detection at 562nm. Our results showed the persistent presence of a nanoparticulate/colloidal phase (retained within 20–200nm filtrates) even in high-temperature samples. A significant fraction of this phase was retrievable only under treatment with HNO3 – a strong acid known to attack and dissolve pyrite nanocrystals. Upon mixing with colder bottom waters and removal of iron in the higher parts of the buoyant plume, the larger size fractions became dominant as the total iron levels decreased, but it was still possible to detect significant (micromolar) levels of nanoparticulate Fe even in samples collected 5m above the orifice in the rising plume. The coolest sample (<10°C) still contained more than 1μM of only nitric acid-leachable nanoparticle/colloidal, at least 200 times higher than a typical Fe concentration in the non-buoyant plume. Our results support previous reports of dissolved Fe in MAR vent plumes, and we propose that this recalcitrant Fe pool – surviving immediate precipitation – contributes to maintaining high hydrothermal iron fluxes to the deep ocean.

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Interaction of FeII and Si under anoxic and reducing conditions: Structural characteristics of ferrous silicate co-precipitates

Cited by 18 publications

References 70 publications

Greenalite Nanoparticles in Alkaline Vent Plumes as Templates for the Origin of Life

Greenalite Nanoparticles in Alkaline Vent Plumes as Templates for the Origin of Life

Selenide [Se(−II)] Immobilization in Anoxic, Fe(II)-Rich Environments: Coprecipitation and Behavior during Phase Transformations

Soluble, Colloidal, and Particulate Iron Across the Hydrothermal Vent Mixing Zones in Broken Spur and Rainbow, Mid-Atlantic Ridge

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