SO2 photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism

Shohei Hattori; Johan Albrecht Schmidt; Matthew Stanley Johnson; Sebastian O. Danielache; Akinori Yamada; Yuichiro Ueno; Naohiro Yoshida

doi:10.1073/pnas.1213153110

SO₂ photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism

Shohei Hattori, Johan Albrecht Schmidt, Matthew Stanley Johnson, Sebastian O. Danielache, Akinori Yamada, Yuichiro Ueno, Naohiro Yoshida

Kemisk Institut

42 Citationer (Scopus)

Abstract

Natural climate variation, such as that caused by volcanoes, is the basis for identifying anthropogenic climate change. However, knowledge of the history of volcanic activity is inadequate, particularly concerning the explosivity of specific events. Some material is deposited in ice cores, but the concentration of glacial sulfate does not distinguish between tropospheric and stratospheric eruptions. Stable sulfur isotope abundances contain additional information, and recent studies showa correlation between volcanic plumes that reach the stratosphere and mass-independent anomalies in sulfur isotopes in glacial sulfate. We describe a mechanism, photoexcitation of SO2, that links the two, yielding a useful metric of the explosivity of historic volcanic events. A plume model of S(IV) to S(VI) conversion was constructed including photochemistry, entrainment of background air, and sulfate deposition. Isotopologue-specific photoexcitation rates were calculated based on the UV absorption cross-sections of 32SO2, 33SO2, 34SO2, and 36SO2 from 250 to 320 nm. The model shows that UV photoexcitation is enhanced with altitude, whereasmass-dependent oxidation, such as SO2 + OH, is suppressed by in situ plume chemistry, allowing the production and preservation of amass-independent sulfur isotope anomaly in the sulfate product. The model accounts for the amplitude, phases, and time development of 33S/34S and 36S/33S found in glacial samples. We are able to identify the process controlling mass-independent sulfur isotope anomalies in the modern atmosphere. This mechanism is the basis of identifying the magnitude of historic volcanic events.

Originalsprog	Engelsk
Tidsskrift	Proceedings of the National Academy of Sciences of the United States of America
Vol/bind	110
Udgave nummer	44
Sider (fra-til)	17656-17661
Antal sider	6
ISSN	0027-8424
DOI	https://doi.org/10.1073/pnas.1213153110
Status	Udgivet - 29 okt. 2013

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10.1073/pnas.1213153110

Citationsformater

Hattori, S., Schmidt, J. A., Johnson, M. S., Danielache, S. O., Yamada, A., Ueno, Y., & Yoshida, N. (2013). SO₂ photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism. Proceedings of the National Academy of Sciences of the United States of America, 110(44), 17656-17661. https://doi.org/10.1073/pnas.1213153110

SO₂ photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism. / Hattori, Shohei; Schmidt, Johan Albrecht; Johnson, Matthew Stanley et al.
I: Proceedings of the National Academy of Sciences of the United States of America, Bind 110, Nr. 44, 29.10.2013, s. 17656-17661.

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review

Hattori, S, Schmidt, JA, Johnson, MS, Danielache, SO, Yamada, A, Ueno, Y & Yoshida, N 2013, 'SO₂ photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism', Proceedings of the National Academy of Sciences of the United States of America, bind 110, nr. 44, s. 17656-17661. https://doi.org/10.1073/pnas.1213153110

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abstract = "Natural climate variation, such as that caused by volcanoes, is the basis for identifying anthropogenic climate change. However, knowledge of the history of volcanic activity is inadequate, particularly concerning the explosivity of specific events. Some material is deposited in ice cores, but the concentration of glacial sulfate does not distinguish between tropospheric and stratospheric eruptions. Stable sulfur isotope abundances contain additional information, and recent studies showa correlation between volcanic plumes that reach the stratosphere and mass-independent anomalies in sulfur isotopes in glacial sulfate. We describe a mechanism, photoexcitation of SO2, that links the two, yielding a useful metric of the explosivity of historic volcanic events. A plume model of S(IV) to S(VI) conversion was constructed including photochemistry, entrainment of background air, and sulfate deposition. Isotopologue-specific photoexcitation rates were calculated based on the UV absorption cross-sections of 32SO2, 33SO2, 34SO2, and 36SO2 from 250 to 320 nm. The model shows that UV photoexcitation is enhanced with altitude, whereasmass-dependent oxidation, such as SO2 + OH, is suppressed by in situ plume chemistry, allowing the production and preservation of amass-independent sulfur isotope anomaly in the sulfate product. The model accounts for the amplitude, phases, and time development of 33S/34S and 36S/33S found in glacial samples. We are able to identify the process controlling mass-independent sulfur isotope anomalies in the modern atmosphere. This mechanism is the basis of identifying the magnitude of historic volcanic events.",

keywords = "Atmosphere, Climate Change, Light, Models, Chemical, Photochemistry, Sulfur Dioxide, Sulfur Isotopes, Volcanic Eruptions",

author = "Shohei Hattori and Schmidt, {Johan Albrecht} and Johnson, {Matthew Stanley} and Danielache, {Sebastian O.} and Akinori Yamada and Yuichiro Ueno and Naohiro Yoshida",

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T1 - SO2 photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism

AU - Hattori, Shohei

AU - Schmidt, Johan Albrecht

AU - Johnson, Matthew Stanley

AU - Danielache, Sebastian O.

AU - Yamada, Akinori

AU - Ueno, Yuichiro

AU - Yoshida, Naohiro

PY - 2013/10/29

Y1 - 2013/10/29

N2 - Natural climate variation, such as that caused by volcanoes, is the basis for identifying anthropogenic climate change. However, knowledge of the history of volcanic activity is inadequate, particularly concerning the explosivity of specific events. Some material is deposited in ice cores, but the concentration of glacial sulfate does not distinguish between tropospheric and stratospheric eruptions. Stable sulfur isotope abundances contain additional information, and recent studies showa correlation between volcanic plumes that reach the stratosphere and mass-independent anomalies in sulfur isotopes in glacial sulfate. We describe a mechanism, photoexcitation of SO2, that links the two, yielding a useful metric of the explosivity of historic volcanic events. A plume model of S(IV) to S(VI) conversion was constructed including photochemistry, entrainment of background air, and sulfate deposition. Isotopologue-specific photoexcitation rates were calculated based on the UV absorption cross-sections of 32SO2, 33SO2, 34SO2, and 36SO2 from 250 to 320 nm. The model shows that UV photoexcitation is enhanced with altitude, whereasmass-dependent oxidation, such as SO2 + OH, is suppressed by in situ plume chemistry, allowing the production and preservation of amass-independent sulfur isotope anomaly in the sulfate product. The model accounts for the amplitude, phases, and time development of 33S/34S and 36S/33S found in glacial samples. We are able to identify the process controlling mass-independent sulfur isotope anomalies in the modern atmosphere. This mechanism is the basis of identifying the magnitude of historic volcanic events.

AB - Natural climate variation, such as that caused by volcanoes, is the basis for identifying anthropogenic climate change. However, knowledge of the history of volcanic activity is inadequate, particularly concerning the explosivity of specific events. Some material is deposited in ice cores, but the concentration of glacial sulfate does not distinguish between tropospheric and stratospheric eruptions. Stable sulfur isotope abundances contain additional information, and recent studies showa correlation between volcanic plumes that reach the stratosphere and mass-independent anomalies in sulfur isotopes in glacial sulfate. We describe a mechanism, photoexcitation of SO2, that links the two, yielding a useful metric of the explosivity of historic volcanic events. A plume model of S(IV) to S(VI) conversion was constructed including photochemistry, entrainment of background air, and sulfate deposition. Isotopologue-specific photoexcitation rates were calculated based on the UV absorption cross-sections of 32SO2, 33SO2, 34SO2, and 36SO2 from 250 to 320 nm. The model shows that UV photoexcitation is enhanced with altitude, whereasmass-dependent oxidation, such as SO2 + OH, is suppressed by in situ plume chemistry, allowing the production and preservation of amass-independent sulfur isotope anomaly in the sulfate product. The model accounts for the amplitude, phases, and time development of 33S/34S and 36S/33S found in glacial samples. We are able to identify the process controlling mass-independent sulfur isotope anomalies in the modern atmosphere. This mechanism is the basis of identifying the magnitude of historic volcanic events.

KW - Atmosphere

KW - Climate Change

KW - Light

KW - Models, Chemical

KW - Photochemistry

KW - Sulfur Dioxide

KW - Sulfur Isotopes

KW - Volcanic Eruptions

U2 - 10.1073/pnas.1213153110

DO - 10.1073/pnas.1213153110

M3 - Journal article

C2 - 23417298

SN - 0027-8424

VL - 110

SP - 17656

EP - 17661

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

IS - 44