Ultrafine Magnetic Particles: A DIET-Proxy in Organic Rich Sediments?

Ustra, Andréa Teixeira; Mendonça, Carlos Alberto; Leite, Aruã; Macouin, Mélina; Doherty, Rory; Respaud, Marc; Tocuti, Giovana

doi:10.3389/feart.2020.608387

Cited by 2 publications

(2 citation statements)

References 53 publications

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“…Indeed, magnetite encrustations of Fe(III)-reducing or Fe(II)-oxidizing bacteria have been observed in culture (e.g., Miot et al, 2009 ). For instance, FORC signatures of non-interacting and interacting SD particles not produced by MTB have been identified in organic-rich methanogenic sediments ( Ustra et al, 2021 ). Both non-SD and clustered SD magnetite contributions are expected to lower the hysteresis squareness and might therefore be distinguishable from pure magnetofossil contributions.…”

Section: Discussionmentioning

confidence: 99%

Key Signatures of Magnetofossils Elucidated by Mutant Magnetotactic Bacteria and Micromagnetic Calculations

et al. 2022

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Magnetotactic bacteria (MTB) produce single‐stranded or multi‐stranded chains of magnetic nanoparticles that contribute to the magnetization of sediments and rocks. Their magnetic fingerprint can be detected in ancient geological samples and serve as a unique biosignature of microbial life. However, some fossilized assemblages bear contradictory signatures pointing to magnetic components that have distinct origin(s). Here, using micromagnetic simulations and mutant MTB producing looped magnetosome chains, we demonstrate that the observed magnetofossil fingerprints are produced by a mixture of single‐stranded and multi‐stranded chains, and that diagenetically induced chain collapse, if occurring, must preserve the strong uniaxial anisotropy of native chains. This anisotropy is the key factor for distinguishing magnetofossils from other populations of natural magnetite particles, including those with similar individual crystal characteristics. Furthermore, the detailed properties of magnetofossil signatures depend on the proportion of equant and elongated magnetosomes, as well as on the relative abundances of single‐stranded and multi‐stranded chains. This work has important paleoclimatic, paleontological, and phylogenetic implications, as it provides reference data to differentiate distinct MTB lineages according to their chain and magnetosome morphologies, which will enable the tracking of the evolution of some of the most ancient biomineralizing organisms in a time‐resolved manner. It also enables a more accurate discrimination of different sources of magnetite particles, which is pivotal for gaining better environmental and relative paleointensity reconstructions from sedimentary records.

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Section: Discussionmentioning

confidence: 99%

Key Signatures of Magnetofossils Elucidated by Mutant Magnetotactic Bacteria and Micromagnetic Calculations

et al. 2022

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“…The Raman spectra (Fig. 3(b)) suggests that SS from PR appears to contain a large amount of iron oxides and oxyhydroxides, being largely amorphous oxyhydroxides, known as Fe(OH)3, which could be retained as solid phases in the SS of PR [29,30]. The high temperature used in the Fe-BMG glasses manufacturing process causes Fe (OH)3 dehydration, forming -Fe2O3 and -Fe2O3, which are more thermodynamically stable.…”

Section: Structural Characterization Of Fe-bmg By Raman Spectroscopymentioning

confidence: 99%

Magneto-optical Properties of Iron-bulk Metallic Glasses Sustainably Produced from Iron-rich Sand Sludge

Queiroz,

Cavallaro,

Queiroz

2024

J. Appl. Phys. Sci. Int.

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A large amount of sand sludge (SS) from rivers polluted with heavy metals is continuously dredged and often dumped into landfills, resulting in environmental pollution of soil and water. This work examines the feasibility of the utilization of iron-enriched SS from dredged polluted rivers to produce Fe-based bulk metallic glasses (Fe-BMG). Fe-BMG was prepared from SS by melt-quenching technique, and their magnetic and photochromic properties were studied. The chemical composition of the Fe-BMG was determined by X-ray fluorescence (XRF). The structural properties have been analyzed using the Raman spectroscopy (RS), vibrating sample magnetometer (VSM) and ultraviolet-visible (UV-VIS) spectroscopy. XRF results shows that Fe-BMG contains an iron proportion of 38.8% (wt.) as the hematite (\(\alpha\)-Fe2O3), and magnetite (Fe3O4) phases. The Raman “fingerprints” of \(\alpha\)-Fe2O3 and Fe3O4 were identified at 1330 cm−1, and 300-600 cm-1, respectively. The measured saturation magnetization of Fe-BMG samples is 3.0 emu/g at 60 kOe. A UV-VIS analysis of the Fe-BMG exposed to sunlight simulator reveals an enhanced transmission of light in the 400-700 cm-1 region. These findings confirmed the successful conversion of the hazardous SS into Fe-BMG with promising magneto-optical characteristics for a wide variety of technological applications.

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Ultrafine Magnetic Particles: A DIET-Proxy in Organic Rich Sediments?

Cited by 2 publications

References 53 publications

Key Signatures of Magnetofossils Elucidated by Mutant Magnetotactic Bacteria and Micromagnetic Calculations

Key Signatures of Magnetofossils Elucidated by Mutant Magnetotactic Bacteria and Micromagnetic Calculations

Magneto-optical Properties of Iron-bulk Metallic Glasses Sustainably Produced from Iron-rich Sand Sludge

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