Cadmium isotope variations in Neoproterozoic carbonates - A tracer of biologic production?

Hohl, Simon V.; Galer, S. J. G.; Gamper, Antonia; Becker, H.

doi:10.7185/geochemlet.1704

Cited by 38 publications

(23 citation statements)

References 23 publications

(38 reference statements)

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“…With advances in instrumentation, increasingly high precision Cd isotope measurement results have been reported using different chemical purification procedures and different instrumental analysis methods (e.g., Wombacher et al , Cloquet et al , Ripperger and Rehkämper , Gao et al , Schmitt et al , Xue et al , Li et al ). The Cd isotopes of different types of samples with low Cd mass fractions including organic materials, plants, carbonates, silicate rocks, river sediments, seawater and meteorites have been determined precisely and accurately (e.g., Rosman and De Laeter , Cloquet et al , Ripperger and Rehkämper , Gao et al , Wombacher et al , Schmitt et al , Abouchami et al , Pallavicini et al , Georgiev et al , Wei et al , Wiggenhauser et al , Wen et al , Hohl et al , John et al , Imseng et al , Li et al , Viehman et al ). The mass bias produced by the instrument has been corrected by different methods including sample‐calibrator bracketing, and the Ag doping and double spike method (Wombacher et al , Cloquet et al , Ripperger and Rehkämper , Schmitt et al , Li et al ).…”

Section: Methodsmentioning

confidence: 99%

“…The double spike technique can effectively correct isotope fractionation from chemical separation and mass discrimination of the instrument (e.g., Compston and Oversby , Galer , Ripperger and Rehkämper , Rudge et al , Schmitt et al ). Recent studies have shown that the use of double spike is beneficial for determining the Cd isotope compositions in different types of samples with low Cd mass fractions (e.g., Ripperger and Rehkämper , Schmitt et al , Horner et al , Georgiev et al , Wiggenhauser et al , Hohl et al , John et al , Imseng et al ). Schmitt et al () and Rehkämper et al () have mentioned that when choosing a Cd double spike correction method, two factors should be considered: (a) isobaric and molecular interferences, and (b) limitations imposed by the collector configuration and the maximum mass dispersion that can be accommodated by the collectors.…”

Section: Methodsmentioning

confidence: 99%

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High‐Precision Cd Isotope Measurements of Soil and Rock Reference Materials by MC‐ICP‐MS with Double Spike Correction

Liu

Zhang

et al. 2019

Geostandard Geoanalytic Res

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This study presents a high‐precision Cd isotope measurement method for soil and rock reference materials using MC‐ICP‐MS with double spike correction. The effects of molecular interferences (e.g., 109Ag1H+, 94Zr16O+, 94Mo16O+ and 70Zn40Ar+) and isobaric interferences (e.g., Pd, In and Sn) to Cd isotope measurements were quantitatively evaluated. When the measured solution has Ag/Cd ≤ 5, Zn/Cd ≤ 0.02, Mo/Cd ≤ 0.4, Zr/Cd ≤ 0.001, Pd/Cd ≤ 5 × 10−5 and In/Cd ≤ 10−3, the measured Cd isotope data were not significantly affected. The intermediate measurement precision of pure Cd solutions (BAM I012 Cd, Münster Cd and AAS Cd) was better than ± 0.05‰ (2s) for δ114/110Cd. The δ114/110Cd values of soil reference materials (NIST SRM 2709, 2709a, 2710, 2710a, 2711, 2711a and GSS‐1) relative to NIST SRM 3108 were in the range of −0.251 to 0.632‰, the δ114/110Cd values of rock reference materials (BCR‐2, BIR‐1, BHVO‐2, W‐2, AGV‐2, GSP‐2 and COQ‐1) varied from −0.196‰ to 0.098‰, and that of the manganese nodule (NOD‐P‐1) was 0.163 ± 0.040‰ (2s, n = 8). The large variation in Cd isotopes in soils and igneous rocks indicates that they can be more widely used to study magmatic and supergene processes.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

High‐Precision Cd Isotope Measurements of Soil and Rock Reference Materials by MC‐ICP‐MS with Double Spike Correction

Liu

Zhang

et al. 2019

Geostandard Geoanalytic Res

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“…Cadmium isotopes in marine environments are a promising new tool for studying (bio)geochemical cycling of micronutrients in the oceans [53][54][55] and in sedimentary archives, such as Fe-Mn crusts [56], carbonates [57,58], microbialites [30], mudstones, and black shales [57][58][59]. Cd concentrations in seawater show a nutrient-like behaviour, with surface depletion and deep water enrichments.…”

Section: Status Quo Of CD Isotopes In Marine Lithologiesmentioning

confidence: 99%

“…Under incomplete oxidative OM recycling, biological uptake may act as an effective Cd sink and authigenic minerals may store the ambient seawater Cd isotope composition. Consequently, stable Cd isotope compositions show broad variations in ancient sediments that may be linked to variations in paleo productivity and redox state [30,57,58,[61][62][63]. Many more processes govern the Cd isotopic compositions of sediments than in seawater.…”

Section: Status Quo Of CD Isotopes In Marine Lithologiesmentioning

confidence: 99%

“…Therefore, when applying Cd isotopes in ancient marine sediments, additional fractionation processes with different fractionation factors have to be evaluated very carefully. Besides biological utilization, partitioning into calcite [64] or authigenic sulphides [45,46] and variable uptake under changing salinity [57,65,66] may play a role. Unlike the aforementioned processes, inorganic adsorption onto Mn oxides has been shown experimentally to have no significant isotope fractionation at long time scales (>24 h) [67].…”

Section: Status Quo Of CD Isotopes In Marine Lithologiesmentioning

confidence: 99%

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Trace Metal and Cd Isotope Systematics of the Basal Datangpo Formation, Yangtze Platform (South China) Indicate Restrained (Bio)Geochemical Metal Cycling in Cryogenian Seawater

et al. 2020

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The behaviour of bioavailable trace metals and their stable isotopes in the modern oceans is controlled by uptake into phototrophic organisms and adsorption on and incorporation into marine authigenic minerals. Among other bioessential metals, Cd and its stable isotopes have recently been used in carbonate lithologies as novel tracer for changes in the paleo primary productivity and (bio)geochemical cycling. However, many marine sediments that were deposited during geologically highly relevant episodes and which, thus, urgently require study for a better understanding of the paleo environment are rather composed of a mixture of organic matter (OM), and detrital and authigenic minerals. In this study, we present Cd concentrations and their isotopic compositions as well as trace metal concentrations from sequential leachates of OM-rich shales of the Cryogenian basal Datangpo Formation, Yangtze Platform (South China). Our study shows variable distribution of conservative and bioavailable trace metals as well as Cd isotope compositions between sequential leachates of carbonate, OM, sulphide, and silicate phases. We show that the Cd isotope compositions obtained from OM leachates can be used to calculate the ambient Cryogenian surface seawater of the restricted Nanhua Basin by applying mass balance calculations. By contrast, early diagenetic Mn carbonates and sulphides incorporated the residual Cd from dissolved organic matter that was in isotopic equilibrium with deep/pore waters of the Nanhua Basin. Our model suggests that the Cd isotopic composition of surface seawater at that time reached values of modern oxygenated surface oceans. However, the deep water Cd isotope composition was substantially heavier than that of modern fully oxygenated oceans and rather resembles deep waters with abundant sulphide precipitation typical for modern oxygen minimum zones. This argues for incomplete recycling of Cd and other bioavailable metals shortly after the Sturtian glaciation in the redox stratified Cryogenian Nanhua Basin. Our study highlights the importance of sequential leaching procedures when dealing with impure authigenic sediments such as OM-rich carbonates, mudstones, or shales to achieve reliable trace metal concentrations and Cd isotope compositions as proxies for (bio)geochemical metal cycling in past aquatic systems.

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Bioactive trace metals and their isotopes as paleoproductivity proxies: An assessment using GEOTRACES-era data

Horner

Little

Conway

et al. 2020

Preprint

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The ocean plays host to three carbon 'pumps' that redistribute climatically-significant quantities of carbon dioxide (CO2) from the atmosphere to the ocean interior and seafloor (Volk & Hoffert, 1985). These ocean carbon pumps-biological, carbonate, and solubility-influence Earth's climate over timescales ranging from decades to millions of years (e.g., Volk & Hoffert, 1985; Sigman et al., 2010; Khatiwala et al., 2019). The biological pump is of particular interest as it connects the cycles of C to those of O2, (micro)nutrients, and marine biology, and today accounts for as much as 70 % of the 'contribution ' of all three carbon pumps (Sarmiento & Gruber, 2006). The biological pump redistributes atmospheric carbon in two steps. First, phytoplankton, photoautotrophic microbes, use sunlight to transform ambient DIC (dissolved inorganic carbon) into POC (particulate organic carbon), represented here by CO2 and glucose, respectively, by the simplified reaction: CO2 + H2O + hv → CH2O + O2 [1] The second step requires that some fraction of the newly-formed POC sinks into the ocean interior through a combination of biological and physical aggregation processes (e.g., Alldredge & Silver 1988). The resulting surface ocean DIC deficit promotes the invasion of atmospheric CO2 into seawater to maintain air-sea CO2 equilibrium, driving an overall reduction in atmospheric pCO2. (This definition of the biological pump neglects dissolved organic carbon export, which is comparatively understudied, though may account for as much as one-third of C export; e.g., Carlson et al., 2010; Giering et al., 2014.) Importantly, Reaction [1] requires sunlight and can only occur in the euphotic layer of the ocean. In contrast, aerobic heterotrophic respiration can occur wherever POC and O2 are present: CH2O + O2 → CO2 + H2O [2] (There are a number of O2-independent respiration pathways that are reviewed in detail elsewhere; e.g., Froelich et al., 1979.) While the representation of all POC as glucose (CH2O) is instructive for illustrating an important biotic transformation in the ocean, it is also simplistic; microbial biomass consists of dozens of bioactive elements that serve many essential functions (e.g., da Silva & Williams, 1991). The elemental stoichiometry of POC can thus be expanded to include a number of major and micronutrient elements, as illustrated by the extended Redfield ratio reported by Ho et al.

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Cadmium isotope variations in Neoproterozoic carbonates - A tracer of biologic production?

Cited by 38 publications

References 23 publications

High‐Precision Cd Isotope Measurements of Soil and Rock Reference Materials by MC‐ICP‐MS with Double Spike Correction

High‐Precision Cd Isotope Measurements of Soil and Rock Reference Materials by MC‐ICP‐MS with Double Spike Correction

Trace Metal and Cd Isotope Systematics of the Basal Datangpo Formation, Yangtze Platform (South China) Indicate Restrained (Bio)Geochemical Metal Cycling in Cryogenian Seawater

Bioactive trace metals and their isotopes as paleoproductivity proxies: An assessment using GEOTRACES-era data

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