Zinc isotope fractionation during adsorption onto Mn oxyhydroxide at low and high ionic strength

Bryan, Allison; Dong, Shikui; Wilkes, Elise B.; Wasylenki, Laura E.

doi:10.1016/j.gca.2015.01.026

Cited by 113 publications

(96 citation statements)

References 51 publications

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“…The global mean δ 66 Zn value of modern seawater is ~0.5‰, while sources of Zn to the oceans, including riverine, aerosol, and hydrothermal inputs, are close to the average crustal value of ~0.3‰ (Little, Vance, Walker‐Brown, & Landing, ). Iron and manganese oxides scavenge isotopically heavy Zn (Δ 66 Zn ~0.3 to 0.5‰) (Bryan, Dong, Wilkes, & Wasylenki, ; Little, Sherman, Vance, & Hein, ; Maréchal, Nicolas, Douchet, & Albarède, ; Pokrovsky, Viers, & Freydier, ). Carbonates appear to be unfractionated from seawater; however, isotopically heavy carbonates have been observed within the geologic record (e.g., Pichat, Douchet, & Albarède, ).…”

Section: Global Zinc Isotope Mass Balance: Organic Biomass a Large Amentioning

confidence: 99%

Tracking the rise of eukaryotes to ecological dominance with zinc isotopes

et al. 2018

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The biogeochemical cycling of zinc (Zn) is intimately coupled with organic carbon in the ocean. Based on an extensive new sedimentary Zn isotope record across Earth's history, we provide evidence for a fundamental shift in the marine Zn cycle ~800 million years ago. We discuss a wide range of potential drivers for this transition and propose that, within available constraints, a restructuring of marine ecosystems is the most parsimonious explanation for this shift. Using a global isotope mass balance approach, we show that a change in the organic Zn/C ratio is required to account for observed Zn isotope trends through time. Given the higher affinity of eukaryotes for Zn relative to prokaryotes, we suggest that a shift toward a more eukaryote-rich ecosystem could have provided a means of more efficiently sequestering organic-derived Zn. Despite the much earlier appearance of eukaryotes in the microfossil record (~1700 to 1600 million years ago), our data suggest a delayed rise to ecological prominence during the Neoproterozoic, consistent with the currently accepted organic biomarker records.

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Section: Global Zinc Isotope Mass Balance: Organic Biomass a Large Amentioning

confidence: 99%

Tracking the rise of eukaryotes to ecological dominance with zinc isotopes

et al. 2018

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“…The stable isotopes of Zn provide the potential to better understand interactions between Zn and soil constituents, including metal oxides (Juillot et al, 2008;Balistrieri et al, 2008;Bryan et al, 2015;Pokrovsky et al, 2005), phyllosilicates (Guinoiseau et al, 2016), and organic matter (Jouvin et al, 2009;Gélabert et al, 2006;Kafantaris and Borrok, 2014;John and Conway, 2014). Heavy Zn isotopes are preferentially adsorbed on to the surface of Mn-oxides (birnessite; Bryan et al, 2015) and Fe-oxides, with a higher fractionation factor for poorly crystalline Fe-oxides (ferrihydrite) than for crystalline Fe-oxides (goethite) (Juillot et al, 2008;Balistrieri et al, 2008). Heavy Zn isotopes are also preferentially retained by sorption onto kaolinite (Guinoiseau et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

The influence of weathering and soil organic matter on Zn isotopes in soils

et al. 2017

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“…Gélabert et al (2006) and John et al (2007) Weiss et al (2005Weiss et al ( , 2007, Viers et al (2007), Moynier et al (2009b) and Aucour et al (2011) have found roots to be enriched in heavy isotopes with respect to leaves and shoots. Studies by Pokrovsky et al (2005), Balistrieri et al (2008), Juillot et al (2008), Bryan et al (2015) and Veeramani et al (2015) investigated isotopic fractionation induced by adsorption on oxides and hydroxides and have reported a preferential sorption of heavy isotopes on minerals surface. Guinoiseau et al (2016) measured enrichment in heavy isotopes at phyllosilicates surface with ∆ 66 Zn adsorbed-solution ranging from 0.11 at low pH and low ionic strength to 0.49 at high pH and high ionic strength.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium zinc isotope fractionation in Zn-bearing minerals from first-principles calculations

2016

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Isotopic composition analysis contributes significantly to the investigation of the biogeochemical cycle of zinc with its economical, environmental and health implications. Interpretation of isotopic measurements is however hindered by the lack of a set of equilibrium isotopic fractionation factors between Zn-bearing minerals. In this study, equilibrium mass-dependent Zn isotope fractionation factors in Zn-bearing minerals are determined from first-principles calculations within the density functional theory (DFT) scheme. A wide range of minerals belonging to sulfide, carbonate, oxide, silicate, sulfate and arsenate mineral groups are modelled to account for the natural diversity of Zn crystal-chemical environment. Calculated reduced partition function ratios (β-factors) span a range smaller than 2 at 22 • C. All studied secondary minerals (adamite, gahnite, gunningite, hemimorphite, hydrozincite, zincite) but zinc carbonate (smithsonite) are isotopically heavier than zinc sulfide minerals (sphalerite and wurtzite) from which they could form through supergene processes. Zinc-aluminium spinel and zinc silicate are the isotopically heaviest minerals. The investigation of the crystalchemical parameters at the origin of differences in isotopic properties shows an excellent linear correlation between ln β and Zn interatomic force constants. β-factors are also observed to increase when the Zn-first neighbour bond lengths decrease and charges on atoms involved in the bonding increase and vice versa. These findings are in line with the observation of heavy isotope enrichment in systems having the largest bond strength.

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Zinc isotope fractionation during adsorption onto Mn oxyhydroxide at low and high ionic strength

Cited by 113 publications

References 51 publications

Tracking the rise of eukaryotes to ecological dominance with zinc isotopes

Tracking the rise of eukaryotes to ecological dominance with zinc isotopes

The influence of weathering and soil organic matter on Zn isotopes in soils

Equilibrium zinc isotope fractionation in Zn-bearing minerals from first-principles calculations

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