Seasonal δ³⁴S variations in two high elevation snow pits measured by ³³S–³⁶S double spike thermal ionization mass spectrometry

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https://www.sciencedirect.com/science/article/pii/S0016703708003232?casa_token=T_PjP8HNJuIAAAAA:RxG97yGhR8wI4qzTQz7TBgZ9debjPN2H1Zfz1r_wJShH-eos8-EEO5VY365rl9RdzCQ1anVL1A

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https://doi.org/10.1016/j.gca.2008.05.036
 http://hdl.handle.net/11603/24287

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UMBC Joint Center for Earth Systems Technology (JCET)
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https://orcid.org/0000-0001-9606-767X

Date

2008-08-01

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journal articles
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Citation of Original Publication

Mann, Jacqueline L. et al. Seasonal δ34S variations in two high elevation snow pits measured by 33S–36S double spike thermal ionization mass spectrometry. Geochimica et Cosmochimica Acta 72 (Aug. 2008) 15, p 3907-3927. https://doi.org/10.1016/j.gca.2008.05.036.

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

δ³⁴S and sulfate concentrations were determined in snow pit samples using a thermal ionization mass spectrometric technique capable of 0.2‰ accuracy and requires ≈5 μg (0.16 μmol) natural S. The technique utilizes a ³³S–³⁶S double spike for instrumental mass fractionation correction, and has been applied to snow pit samples collected from the Inilchek Glacier, Kyrgyzstan and from Summit, Greenland. These δ³⁴S determinations provide the first high-resolution seasonal data for these sites, and are used to estimate seasonal sulfate sources. Deuterium (δD) and oxygen (δ¹⁸O) isotope data show that the Inilchek and Summit snow pit samples represent precipitation over ≈20 months. The δ³⁴S values for the Inilchek ranged from +2.6 ± 0.4‰ to +7.6 ± 0.4‰ on sample sizes ranging from 0.3 to 1.8 μmol S. δ³⁴S values for Greenland ranged from +3.6 ± 0.7‰ to +13.3 ± 5‰ for sample sizes ranging from 0.05 to 0.29 μmol S. The SO₄²⁻ concentration ranged from 92.6 ± 0.4 to 1049 ± 4 ng/g for the Inilchek and 18 ± 9 to 93 ± 6 ng/g for the Greenland snow pit. Anthropogenic sulfate dominates throughout the sampled time interval for both sites based on mass balance considerations. Additionally, both sites exhibit a seasonal signature in both δ³⁴S and SO₄²⁻ concentration. The thermal ionization mass spectrometric technique has three advantages compared to gas source isotopic methods: (1) sample size requirements of this technique are 10-fold less permitting access to the higher resolution S isotope record of low concentration snow and ice, (2) the double spike technique permits δ³⁴S and S concentration to be determined simultaneously, and (3) the double spike is an internal standard.