Geochemical fates and unusual distribution of arsenic in natural ferromanganese duricrust

Huan, Liu; Lu, Xiancai; Li, Juan; Chen, Xiaoye; Zhu, Xiangyu; Xiang, Wanli; Zhang, Rui; Wang, Xiaolin; Lu, Jianjun; Wang, Rucheng

doi:10.1016/j.apgeochem.2016.11.012

Cited by 10 publications

(8 citation statements)

References 88 publications

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“…Most of the hematite is disseminated in the clay-rich matrix, while minor occurrences as isolated amorphous aggregates are observed. The manganese generally occurs as the isomorphous Mn 3+/4+ substitution in the hematite lattice structure 50 , 51 at levels of 0.95–1.47 wt.% in the isolated hematite and 0.61–0.74 wt.% in the disseminated hematite in the form of Mn 2 O 3 (see Supplementary Note 3 and Supplementary Fig. 3 for detailed descriptions).…”

Section: Discussionmentioning

confidence: 99%

Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

Kang

Cao

et al. 2018

Nat Commun

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Thermochemical oxidation of methane (TOM) by high-valence metal oxides in geological systems and its potential role as a methane sink remain poorly understood. Here we present evidence of TOM induced by high-valence metal oxides in the Junggar Basin, located in northwestern China. During diagenesis, methane from deeper source strata is abiotically oxidized by high-valence Mn(Fe) oxides at 90 to 135 °C, releasing 13C-depleted CO2, soluble Mn2+ and Fe2+. Mn generally plays the dominant role compared to Fe, due to its lower Gibbs free energy increment during oxidation. Both CO2 and metal ions are then incorporated into authigenic calcites, which are characterized by extremely negative δ13C values (−70 to −22.5‰) and high Mn content (average MnO = 5 wt.%). We estimate that as much as 1224 Tg of methane could be oxidized in the study area. TOM is unfavorable for gas accumulation but may act as a major methane sink in the deep crustal carbon cycle.

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Section: Discussionmentioning

confidence: 99%

Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

Kang

Cao

et al. 2018

Nat Commun

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“…Based on this study, it is reasonable to expect that the Mn incorporation into iron oxides can similarly enhance the adsorption of other heavy metals, such as Cu, Cd, and Zn. It was also found that in natural Fe–Mn crusts, the incorporation of Mn into iron oxides enhances the retention of arsenic . Therefore, in subsurface environments with the coexistence of Mn and Fe, the precipitation of Mn-bearing iron oxides favors entrapping the heavy metals from contamination.…”

Section: Environmental Implications Of Mn Substitution In Goethitementioning

confidence: 99%

Structural Incorporation of Manganese into Goethite and Its Enhancement of Pb(II) Adsorption

Liu

et al. 2018

Environ. Sci. Technol.

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Natural goethite (α-FeOOH) commonly accommodates various metal elements by substituting for Fe, which greatly alters the surface reactivity of goethite. This study discloses the enhancement of Mn-substitution for the Pbadsorption capacity of goethite. The incorporated Mn in the synthesized goethite presents as Mn(III) and causes a slight decrease in the a and c of the unit cell parameters and an observable increase in the b direction due to the Jahn-Teller effect of the Mn(III)O octahedra. With the Mn content increasing, the particle size decreases gradually, and the surface clearly becomes roughened. The Pb adsorption capacity of goethite is observably enhanced by Mn substitution due to the modified surface complexes. And the increased surface-area-normalized adsorption capacity for Mn-substituted goethite indicated that the enhancement of Pb adsorption is not only attributed to the increase of surface area but also to the change of binding complexes. Extended X-ray absorption fine structure (EXAFS) analysis indicates that the binding structures of Pb on goethite presents as edge-sharing complexes with a regular R = 3.31 Å. In the case of Mn-goethite, Pb is also bound with the Mn surface site on the edge-sharing complex with a larger R = 3.47 Å. The mechanism for enhancing Pb adsorption on Mn-goethite can be interpreted as the preferred Pb binding on the Mn site of Mn-goethite surface. In a summary, the Mn-goethite has great potential for material development in environmental remediation.

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“…8 For the HT ferromanganese duricrusts obtained along the Yangtze River, the electron microprobe mapping and μ-XRF analyses revealed that As in the Fe-rich crusts was bound to the well-crystallized hematite phase via the bidentate binuclear linkage mode, while As in the Mn-rich samples was adsorbed on the pyrolusite surfaces by adopting the same complexation type. 9 Similar to As, the spatial partitions of Mo among the iron and manganese minerals in natural ferromanganese oxides are also of high complexity and inconsistency. Previous XRF measurements and element correction analyses showed that Mo was associated with the Mn phase in the DG ferromanganese crusts collected from the Pacific Ocean.…”

Section: ■ Introductionmentioning

confidence: 99%

“…With the aid of micro X-ray fluorescence (μ-XRF) mapping, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS) analyses, Marcus et al (2004) suggested that As was adsorbed on (via inner-sphere surface complexation) or co-precipitated with ferrihydrite in the DG ferromanganese samples collected from the Baltic Sea . For the HT ferromanganese duricrusts obtained along the Yangtze River, the electron microprobe mapping and μ-XRF analyses revealed that As in the Fe-rich crusts was bound to the well-crystallized hematite phase via the bidentate binuclear linkage mode, while As in the Mn-rich samples was adsorbed on the pyrolusite surfaces by adopting the same complexation type …”

Section: Introductionmentioning

confidence: 99%

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Comparison of Arsenate and Molybdate Speciation in Hydrogenetic Ferromanganese Nodules

Yang

Uesugi

Qin

et al. 2018

ACS Earth Space Chem.

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Marine ferromanganese oxides contain a large amount of trace elements, such as arsenic (As) and molybdenum (Mo). However, the host phases of tetrahedral AsO 4 3− and MoO 4 2− oxyanions therein have not been clearly identified thus far. In this work, we explored the mineralogical components of hydrogenetic (HG) ferromanganese nodules and compared the distribution behaviors of As and Mo. The X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analyses showed that the predominant manganese and iron phases were vernadite (δ-MnO 2 ) and ferrihydrite, respectively. According to the sequential extraction examination, both As and Mo were associated with the iron (oxyhydr)oxide phases. However, the XAS analyses indicated that As was retained by the ferrihydrite phase via double cornershared complexation, while Mo was preferentially adsorbed on δ-MnO 2 via edge-shared complexation. The immobilization of As and Mo by HG ferromanganese samples was attributed to specific chemical binding (ΔG chem ) rather than Coulombic interaction (ΔG coul ) as proposed in previous studies. The comparison of Mo XAS spectra before and after extraction revealed the unreliability of the sequential extraction approach to determine the host phase of trace elements as a result of the potential readsorption risk. The different distribution trends of As and Mo were due to their disparate intrinsic properties (e.g., averaged dissociation constants of conjugate acids) and the diverse properties (i.e., surface site densify, adsorption equilibrium constant, and crystalline structure) of ferrihydrite and δ-MnO 2 . These research findings would be significant for evaluating the geochemical behaviors and environmental fate of trace elements in marine systems.

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Geochemical fates and unusual distribution of arsenic in natural ferromanganese duricrust

Cited by 10 publications

References 88 publications

Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

Structural Incorporation of Manganese into Goethite and Its Enhancement of Pb(II) Adsorption

Comparison of Arsenate and Molybdate Speciation in Hydrogenetic Ferromanganese Nodules

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