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  • 1
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    Authigenic Formation of Clay Minerals in the Abyssal North Pacific (2022)
    Details
    Publication Date: 2023-07-19
    Description: Present estimates of the biogeochemical cycles of calcium, strontium, and potassium in the ocean reveal large imbalances between known input and output fluxes. Using pore fluid, incubation, and solid sediment data from North Pacific multi‐corer cores we show that, contrary to the common paradigm, the top centimeters of abyssal sediments can be an active site of authigenic precipitation of clay minerals. In this region, clay authigenesis is the dominant sink for potassium and strontium and consumes nearly all calcium released from benthic dissolution of calcium carbonates. These observations support the idea that clay authigenesis occurring over broad regions of the world ocean may be a major buffer for ocean chemistry on the time scale of the ocean overturning circulation, and key to the long‐term stability of Earth's climate.
    Description: Key Points: North Pacific red clay sediments are a sink for marine calcium, strontium, and potassium. Authigenic formation of clay minerals is prevalent in pelagic sediments throughout the North Pacific. The main mechanism for clay formation is recrystallization of aluminosilicates, neoformation can occur in biogenic silica rich sediments.
    Description: EC H2020 PRIORITY “Excellent science” H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Description: Blavatnik Family Foundation http://dx.doi.org/10.13039/100011643
    Description: Isaac Newton Trust http://dx.doi.org/10.13039/501100004815
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.pangaea.de/10.1594/PANGAEA.946881
    Keywords: ddc:549 ; reverse weathering ; clay authigenesis ; calcium ; potassium ; porewater ; strontium
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 2
    Electronic Resource
    Electronic Resource
    Mössbauer spectroscopy study on double rare-earth orthoferrites Eu0.2R0.8FeO3 (R=rare earth) (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5111-5114 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Double rare-earth ferrites Eu0.2R0.8FeO3 (R=rare earth) are synthesized by a high-temperature method. X-ray-diffraction determinations show that all the compounds possess orthorhombic structure. Both 151Eu and 57Fe Mössbauer spectra are measured. The results indicate that the isomer shift of the 151Eu nucleus depends on the unit-cell volume of Eu0.2R0.8FeO3, and the quadrupole interaction of 151Eu Mössbauer spectra is relative to the inverse of the unit-cell volume. The hyperfine field parameter of 57Fe Mössbauer spectra increases linearly with increasing unit-cell volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351379
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  • 3
    Electronic Resource
    Electronic Resource
    A Coupled Riverine-Marine Fractionation Model for Dissolved Rare Earths and Yttrium (1998)
    Springer
    Aquatic geochemistry 4 (1998), S. 103-121 
    Details
    ISSN: 1573-1421
    Keywords: Rare earth ; Rare earth ; fractionation ; model ; riverine ; oceanic ; estuarine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Fractionation of yttrium (Y) and the rare earth elements (REEs) begins in riverine systems and continues in estuaries and the ocean. Models of yttrium and rare earth (YREE) distributions in seawater must therefore consider the fractionation of these elements in both marine and riverine systems. In this work we develop a coupled riverine/marine fractionation model for dissolved rare earths and yttrium, and apply this model to calculations of marine YREE fractionation for a simple two-box (riverine/marine) geochemical system. Shale-normalized YREE concentrations in seawater can be expressed in terms of fractionation factors (λ ij ) appropriate to riverine environments ( $$\lambda _{ij}^{river}$$ ) and seawater ( $$\lambda _{ij}^{ocean}$$ ): $$\log \frac{{\left( {M_i } \right)_T^{ocean} }}{{\left( Y \right)_T^{ocean} }} = log\;\lambda _{ij}^{ocean} + ((\lambda _{ij}^{river} )^{ - 1} - 1)\;log\frac{{[Y]_T^{river} }}{{[Y^0 ]_T^{river} }}$$ where $$\left( {M_i } \right)_T^{ocean}$$ and $$\left( Y \right)_T^{ocean}$$ are input-normalized total metal concentrations in seawater and $$[Y]_T^{river} /[Y^0 ]_T^{river}$$ is the ratio of total dissolved Y in riverwater before $$([Y^0 ]_T^{river} )$$ and after $$([Y]_T^{river} )$$ commencement of riverine metal scavenging processes. The fractionation factors (λ ij ) are calculated relative to the reference element, yttrium, and reflect a balance between solution and surface complexation of the rare earths and yttrium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009651919911
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  • 4
    Electronic Resource
    Electronic Resource
    Comprehensive Investigation of Yttrium and Rare Earth Element Complexation by Carbonate Ions Using ICP–Mass Spectrometry (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 803-815 
    Details
    ISSN: 1572-8927
    Keywords: Rare earth ; complexation ; carbonate ; ICP–MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Carbonate stability constants for yttrium and all rare earth elements have been determined at 25°C and 0.70 molal ionic strength by solvent exchange and inductively coupled plasma–mass spectrometry (ICP–MS). Measured stability constants for the formation of $${\text{MCO}}_3^ +$$ and $${\text{M}}\left( {{\text{CO}}_{\text{3}} } \right)_2^--$$ from M3+ are in good agreement with previous direct measurements, which involved the use of radio-chemical techniques and trivalent ions of Y, Ce, Eu, Gd, Tb, and Yb. Direct ICP–MS measurements of $${\text{MCO}}_3^ +$$ and $${\text{M}}\left( {{\text{CO}}_{\text{3}} } \right)_2^--$$ formation constants are also in general agreement with modeled stability constants for the metals La, Pr, Nd, Sm, Dy, Ho, Er, Tm, and Lu, based on linear-free energy relationship (LFER). The experimental procedures developed in this work can be used for assessing the complexation behavior of other geochemically important ligands such as phosphate, sulfate, and fluoride.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022677119835
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  • 5
    Electronic Resource
    Electronic Resource
    Comparative Coprecipitation of Phosphate and Arsenate with Yttrium and the Rare Earths: The Influence of Solution Complexation (1997)
    Springer
    Journal of solution chemistry 26 (1997), S. 1187-1198 
    Details
    ISSN: 1572-8927
    Keywords: Coprecipitation ; rare earths ; lanthanides ; yttrium ; phosphate ; arsenate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Coprecipitation of yttrium (Y) and rare earth elements (REEs) with phosphate and arsenate removes these elements from solution in variable proportions. During both phosphate and arsenate Coprecipitation, middle REEs (Sm and Eu) are progressively depleted in solution relative to heavier and lighter elements. Solution complexation by oxalate (Ox 2-) influences Y and REE removal patterns by strongly enhancing the retention of Y and the heaviest REEs in solution. The extent of this enhancement is well described by a quantitative account of the comparative solution complexation of Y and REEs as M(Ox)+ and M(Ox) $$_{\text{2}}^ - $$ . The comparative behavior of phosphate and arsenate coprecipitation exhibits both similarities and differences. During arsenate coprecipitation the light REEs are retained in solution, relative to the heavy REEs, to a greater extent than is the case for phosphate coprecipitation. Notable irregularities are observed in the comparative coprecipitation behavior of nearest-neighbor elements (e.g., Eu–Gd–Tb and Tm–Yb–Lu). Such irregularities are very similar for phosphate and arsenate coprecipitation in the absence and in the presence of solution complexation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022933224074
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  • 6
    Electronic Resource
    Electronic Resource
    151Eu and57Fe Mössbauer effect studies of magnetic interactions in europium transition element oxides solution (1992)
    Springer
    Hyperfine interactions 68 (1992), S. 237-240 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The solid state solutions of europium transition element oxides Eu (Fe0.8M0.2)O3 (M=Sc,Cr,Mn,Co) are synthesized. The X-ray diffraction of the compound shows that all the compounds possess the perovskite structures. Both the151Eu Mössbauer spectra and the57Fe Mössbauer spectra are measured. The hyperfine magnetic field and non-axisymmetric electric field gradient are observed in the151Eu Mössbauer spectrum. The57Fe Mössbauer spectrum shows that there are four components of hyperfine fields corresponding to four kinds of different neighbours of the Fe ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02396480
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  • 7
    Electronic Resource
    Electronic Resource
    Mössbauer spectroscopic study on (Eu1−x Gd x )FeO3 (1992)
    Springer
    Hyperfine interactions 68 (1992), S. 241-244 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Europium gadolinium ferrites (Eu1−xGdx)FeO3 (X=0, 0.2, 0.4, 0.6, 0.8) are synthesized. The results of the X-ray diffraction show that all the compounds possess a perovskite structure. Both the151Eu Mössbauer spectra and the57Fe Mössbauer spectra are measured. The151Eu Mössbauer spectra are considered to be the pure quadrupole spectra. The results show that the isomer shift and the quadrupole splitting of the151Eu spectra vary with x. The hyperfine filed of the57Fe Mössbauer spectrum depends on the unit-cell volume. The57Fe spectra of the samples synthesised by the high-pressure and high-temperature mothod show a part of paramagnetic structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02396481
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  • 8
    Electronic Resource
    Electronic Resource
    Mössbauer spectroscopic study on nanocrystalline LaFeO3 materials (1992)
    Springer
    Hyperfine interactions 69 (1992), S. 851-854 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Perovskite-type nanocrystalline materials LaFeO3 with different crystal size were synthesized. These samples with different compacted pressure were investigated by Mössbauer spectroscopy at room temperature. The results showed that the LaFeO3 crystal in size of 70nm possessed an antiferromagnetic structure, that of 12nm was the superposition of the weaker antiferromagnetic structure and the stronger superparamagnetic structure. The rate of interface atoms to crystal atoms and the hyperfine field in nanocrystals varied with the compacted pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401960
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  • 9
    Electronic Resource
    Electronic Resource
    Iron distribution in chevkinite (1992)
    Springer
    Hyperfine interactions 70 (1992), S. 1057-1059 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper Mössbauer spectra of chevkinite at 283K and 83K are presented for the first time. The spectra consist of two Fe2+ and two Fe3+ doublets, and the assignments were made according to the structure of chevkinite. Iron distribution obtained from the spectrum at 83 K is consistent with that at 283 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397511
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  • 10
    Electronic Resource
    Electronic Resource
    The study of Mössbauer effect in EuBa2Cu3O7-y (1992)
    Springer
    Hyperfine interactions 70 (1992), S. 1211-1214 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract EuBa2(Cu1-xFex)3O7-x has been investigated by the57Fe and151Eu Mössbauer effect. The57Fe Mössbauer spectra of the EuBa2(Cu1xFex)3O7-y without or with DC electric current (the current strength I=0.5A) around the superconducting transition temperature have been measured. The results indicate that the isomer shift (IS) and the quadrupole splitting (QS) of the Fe replacing the Cu(2) vary neither with increasing the Fe content nor with the small DC eletric, current passing the superconductor and that the IS and the QS of the Fe replacing the Cu(1) vary with the Fe content. Especially, the IS and the QS of the Fe (D3) replacing the Cu(1) are changed when the small electric current passes the superconductor at 80K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397547
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