Molybdenum Stable Isotopes: Observations, Interpretations and Directions

Anbar, Ariel D.

doi:10.2138/gsrmg.55.1.429

Cited by 203 publications

(134 citation statements)

References 106 publications

(192 reference statements)

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“…Manheim and Landergren, 1974;Colodner et al, 1995;Morford and Emerson, 1999;Anbar, 2004). Of particular interest is the highly redox-sensitive behaviour of Mo that is accompanied by significant isotope fractionation, which results in oxic, suboxic, anoxic and euxinic sediments possessing isotopically distinct Mo-isotope compositions (Barling et al, 2001;Barling and Anbar, 2004;Siebert et al, 2003Poulson et al, 2006;Neubert et al, 2008a).…”

Section: Introductionmentioning

confidence: 99%

Molybdenum isotope behaviour accompanying weathering and riverine transport in a basaltic terrain

Pearce

Burton

Strandmann

et al. 2010

Earth and Planetary Science Letters

101

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Editor: M.L. DelaneyKeywords: molybdenum (Mo) isotopes basaltic weathering riverine inputs estuarine mixingThe application of the molybdenum (Mo) isotope system as a proxy for determining changes in the redox state of the oceans is predicated on the assumption that the composition of continental input can be characterised from crustal rock types, and remains constant. However, it has recently been shown that the δ 98/95 Mo composition of global rivers varies between 0.15‰ and 2.4‰ and is therefore systematically heavier than the average composition of the continental crust (∼ 0‰ 4‰).Systematic changes in the dissolved Mo-isotope composition are also observed within river catchments, with δ 98/95 Mo values increasing from ∼ 0‰ in glacial rivers (close to the source) to ∼ 1‰ downstream, consistent with Mo-isotopes being fractionated during weathering. Analysis of other riverine phases (bedload, colloids and iron-precipitates) demonstrates that these phases preferentially incorporate light Moisotopes, and remain coupled to the dissolved load during riverine transportation. A δ 98/95 Mo profile through the Borgarfjörður estuary exhibits a predominantly conservative mixing behaviour, but suggests that the release of isotopically light Mo from the particulate and/or colloidal phases may occur in the low salinity part of the estuarine mixing zone.

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Section: Introductionmentioning

confidence: 99%

Molybdenum isotope behaviour accompanying weathering and riverine transport in a basaltic terrain

Pearce

Burton

Strandmann

et al. 2010

Earth and Planetary Science Letters

101

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“…Molybdenum is one of these elements, that is, around 70% of output is presumed to be incorporated into ferromanganese oxides in the budget of Mo in the marine system (Bertine and Turekian, 1973;Siebert et al, 2003). This element is a redox-sensitive trace metal with seven stable isotopes and is essential in many bio-many studies have focused on this promising tool (Anbar, 2004;Barling and Anbar, 2004;Weeks et al, 2007;Wasylenki et al, 2008;Arnold et al, 2004;Pearce et al, 2008;Poulson et al, 2006;Voegelin et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

A XAFS study on the mechanism of isotopic fractionation of molybdenum during its adsorption on ferromanganese oxides

2009

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Due to its potential as a paleoredox proxy, there have been many studies on Mo isotopic fractionation during adsorption onto ferromanganese oxides in seawater. However, the mechanisms of both adsorption and isotopic fractionation are still under debate due to the lack of structural information on the adsorbed species. In this study, XAFS analyses were performed to reveal the mechanism, based on structural information at the molecular level, of Mo isotopic fractionation during adsorption onto ferromanganese oxides. Molybdenum L 3 -edge XANES and K-edge EXAFS revealed that Mo species adsorbed on the surface of ferrihydrite was a tetrahedrally coordinated outer-sphere complex, while that on δ-MnO 2 was an octahedrally coordinated inner-sphere complex. Additionally, it was also revealed that δ-MnO 2 was the dominant host phase of Mo in the hydrogenetic ferromanganese nodules from the comparison of their XAFS spectra. Previous studies reported that lighter isotopes of Mo were preferentially incorporated into ferromanganese oxides from seawater. This fractionation can be explained based on the structural difference between tetrahedral MoO 4 2-(=a major species in seawater) and the octahedral species adsorbed on the Mn oxide phase in ferromanganese nodules. In contrast, little change in Mo local structures during its adsorption onto ferrihydrite also suggested the little or no fractionation of Mo isotopes in the presence of Fe hydroxides without Mn oxides. These facts imply that the Mo isotopic composition in ancient marine sediments can distinguish redox boundaries of Fe 2+ /Fe(OH) 3 and of the more oxic Mn 2+ /MnO 2 .

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“…272 Also the corresponding amount of literature is impressive and does not only cover applications that can also be carried out using TIMS (but often in a faster way using ICP-MS), but also enables the exploitation of isotopic systems that could not -or only with great difficulty -be tackled using TIMS. Reviews dedicated to isotopic variation of a specific element and describing the applications based on its isotopic analysis have been published for Li, 273 Mg, 274 Si, 275 Ca, 276 Fe, 277 Cu, 278 Zn, 279 Se, 280 Mo, 281 Cd, 282 and Hg. 283 Interfered elements require high mass resolution settings especially if laser ablation analysis is involved.…”

Section: Geological Applicationsmentioning

confidence: 99%

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part II. Applications

Jakubowski

Prohaska

Vanhaecke

et al. 2011

J. Anal. At. Spectrom.

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Molybdenum Stable Isotopes: Observations, Interpretations and Directions

Cited by 203 publications

References 106 publications

Molybdenum isotope behaviour accompanying weathering and riverine transport in a basaltic terrain

Molybdenum isotope behaviour accompanying weathering and riverine transport in a basaltic terrain

A XAFS study on the mechanism of isotopic fractionation of molybdenum during its adsorption on ferromanganese oxides

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part II. Applications

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