High-precision measurement and standard calibration of triple oxygen isotopic compositions (δ18O, Δ17O) of sulfate by F2 laser fluorination

Cowie, B.; Johnston, David T.

doi:10.1016/j.chemgeo.2016.07.003

Cited by 22 publications

(21 citation statements)

References 56 publications

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“…. For two NBS127 measurements measured each day during 5 d (n = 10), we obtained a mean δ 18 O = −0.43 ± 0.54 (2σ ) and a mean I. Genot et al: Oxygen and sulfur mass-independent isotopic signatures 17 O = 0.044 ± 0.020 (2σ ) within error of the recent value reported by Cowie and Johnston (2016). Bao (2006) reported up to 2 ‰ variation in the correction factor that would result from sample impurity, but, as our samples were purified with an ion-exchange resin and the mean variation of the duplicates is lower than for NBS127, we applied a correction factor of 9.03 to δ 18 O for all analyzed samples based on the certified value of NBS127.…”

Section: Methodssupporting

confidence: 75%

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ33S reservoir of sulfate aerosols?

et al. 2020

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Abstract. To better understand the formation and the oxidation pathways leading to gypsum-forming “black crusts” and investigate their bearing on the whole atmospheric SO2 cycle, we measured the oxygen (δ17O, δ18O, and Δ17O) and sulfur (δ33S, δ34S, δ36S, Δ33S, and Δ36S) isotopic compositions of black crust sulfates sampled on carbonate building stones along a NW–SE cross section in the Parisian basin. The δ18O and δ34S values, ranging between 7.5 ‰ and 16.7±0.5 ‰ (n=27, 2σ) and between −2.66 ‰ and 13.99±0.20 ‰, respectively, show anthropogenic SO2 as the main sulfur source (from ∼2 % to 81 %, average ∼30 %) with host-rock sulfates making the complement. This is supported by Δ17O values (up to 2.6 ‰, on average ∼0.86 ‰), requiring > 60 % of atmospheric sulfates in black crusts. Negative Δ33S and Δ36S values between −0.34 ‰ and 0.00±0.01 ‰ and between −0.76 ‰ and -0.22±0.20 ‰, respectively, were measured in black crust sulfates, which is typical of a magnetic isotope effect that would occur during the SO2 oxidation on the building stone, leading to 33S depletion in black crust sulfates and subsequent 33S enrichment in residual SO2. Except for a few samples, sulfate aerosols mostly have Δ33S values > 0 ‰, and no processes can yet explain this enrichment, resulting in an inconsistent S budget: black crust sulfates could well represent the complementary negative Δ33S reservoir of the sulfate aerosols, thus solving the atmospheric SO2 budget.

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Section: Methodssupporting

confidence: 75%

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ33S reservoir of sulfate aerosols?

et al. 2020

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“…Sulfate 17 O/ 16 O ratios were measured by laser fluorination by F 2 coupled with isotope ratio mass spectrometry following ref. 63. Uncertainty (±1σ) was taken as the long-term reproducibility of a suite of primary sulfate standards (σ = 0.016).…”

Section: Methodsmentioning

confidence: 99%

Triple oxygen isotope insight into terrestrial pyrite oxidation

Hemingway

Olson

Turchyn

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The mass-independent minor oxygen isotope compositions (Δ′17O) of atmospheric O2andCO2are primarily regulated by their relative partial pressures,pO2/pCO2. Pyrite oxidation during chemical weathering on land consumesO2and generates sulfate that is carried to the ocean by rivers. The Δ′17O values of marine sulfate deposits have thus been proposed to quantitatively track ancient atmospheric conditions. This proxy assumes directO2incorporation into terrestrial pyrite oxidation-derived sulfate, but a mechanistic understanding of pyrite oxidation—including oxygen sources—in weathering environments remains elusive. To address this issue, we present sulfate source estimates and Δ′17O measurements from modern rivers transecting the Annapurna Himalaya, Nepal. Sulfate in high-elevation headwaters is quantitatively sourced by pyrite oxidation, but resulting Δ′17O values imply no direct troposphericO2incorporation. Rather, our results necessitate incorporation of oxygen atoms from alternative,17O-enriched sources such as reactive oxygen species. Sulfate Δ′17O decreases significantly when moving into warm, low-elevation tributaries draining the same bedrock lithology. We interpret this to reflect overprinting of the pyrite oxidation-derived Δ′17O anomaly by microbial sulfate reduction and reoxidation, consistent with previously described major sulfur and oxygen isotope relationships. The geologic application of sulfate Δ′17O as a proxy for pastpO2/pCO2should consider both 1) alternative oxygen sources during pyrite oxidation and 2) secondary overprinting by microbial recycling.

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“…Most reactions are "mass-dependent", meaning the isotopic fractionation relies on the mass differences between the isotopes; this 100 remains valid for most unidirectional (kinetic) and/or exchange (equilibrium) reactions. In a system with at least three isotopes, mass fractionation law at equilibrium and high temperature can be derived from its partition function (Bigeleisen and Mayer, 1947;Dauphas and Schauble, 2016;Urey, 1947;Young et al, 2002) as follows for instance with oxygen isotopes and SO 2 oxidation in sulfates:…”

Section: Mass-dependent and Independent Fractionationsmentioning

confidence: 99%

“…The high temperature approximation has been shown to be applicable for a wide range of temperature phases (Dauphas and Schauble, 2016) and isotope systems (S, Fe, Mg, O, Si…). Mass exponent value then depends on 110 the specific reaction considered but usually, 17 b, 33 b and 36 b-values used are close to 0.524, 0.515 and 1.889 respectively.…”

Section: Mass-dependent and Independent Fractionationsmentioning

confidence: 99%

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Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative ∆33S-reservoir of sulfate aerosols?

Genot¹,

Yang²,

Martin³

et al. 2019

Preprint

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Abstract. To better understand the formation and the oxidation pathways leading to gypsum-forming &#8220;black crusts&#8221; and investigate their bearing on the whole atmospheric SO2 cycle, we measured the oxygen (&#948;17O, &#948;18O and &#8710;17O) and sulfur (&#948;33S, &#948;34S, &#948;36S, &#8710;33S and &#8710;36S) isotopic compositions of black crust sulfates sampled on carbonate building stones along a NW-SE cross-section in the Parisian basin. The &#948;18O and &#948;34S, ranging between 7.5 and 16.7&#8201;&#177;&#8201;0.5&#8201;&#8240; (n&#8201;=&#8201;27, 2&#963;) and between &#8722;2.6 and 13.9&#8201;&#177;&#8201;0.2&#8201;&#8240; respectively, show anthropogenic SO2 as the main sulfur source (from 2 to 81&#8201;%, in average ~30&#8201;%) with host-rock sulfates making the complement. This is supported by &#8710;17O-values (up to 2.6&#8201;&#8240;, in average ~0.86&#8201;&#8240;), requiring >&#8201;60&#8201;% of atmospheric sulfates in black crusts. Both negative &#8710;33S-&#8710;36S-values between &#8722;0.34 and 0.00&#8201;&#177;&#8201;0.01&#8201;&#8240; and between &#8722;0.7 and &#8722;0.2&#8201;&#177;&#8201;0.2&#8201;&#8240; respectively were measured in black crusts sulfates, that is typical of a magnetic isotope effect that would occur during the SO2 oxidation on the building stone, leading to 33S-depletion in black crust sulfates and subsequent 33S-enrichment in residual SO2. Given that sulfate aerosols have mostly &#8710;33S&#8201;>&#8201;0&#8201;&#8240; and no processes can yet explain this enrichment, resulting in a non-consistent S-budget, black crust sulfates could well represent the complementary negative &#8710;33S-reservoir of the sulfate aerosols solving the atmospheric SO2 budget.

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High-precision measurement and standard calibration of triple oxygen isotopic compositions (δ18O, Δ17O) of sulfate by F2 laser fluorination

Cited by 22 publications

References 56 publications

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ<sup>33</sup>S reservoir of sulfate aerosols?

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ<sup>33</sup>S reservoir of sulfate aerosols?

Triple oxygen isotope insight into terrestrial pyrite oxidation

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative ∆<sup>33</sup>S-reservoir of sulfate aerosols?

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High-precision measurement and standard calibration of triple oxygen isotopic compositions (δ18O, Δ17O) of sulfate by F2 laser fluorination

Cited by 22 publications

References 56 publications

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ&lt;sup&gt;33&lt;/sup&gt;S reservoir of sulfate aerosols?

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ&lt;sup&gt;33&lt;/sup&gt;S reservoir of sulfate aerosols?

Triple oxygen isotope insight into terrestrial pyrite oxidation

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative ∆&lt;sup&gt;33&lt;/sup&gt;S-reservoir of sulfate aerosols?

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Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ<sup>33</sup>S reservoir of sulfate aerosols?

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ<sup>33</sup>S reservoir of sulfate aerosols?

Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative ∆<sup>33</sup>S-reservoir of sulfate aerosols?