Eiler, John M. and Schauble, Edwin (2004) ^(18)O^(13)C^(16)O in Earth’s atmosphere. Geochimica et Cosmochimica Acta, 68 (23). pp. 4767-4777. ISSN 0016-7037. http://resolver.caltech.edu/CaltechAUTHORS:20121031-071703520
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The chemistry and budgets of atmospheric gases are constrained by their bulk stable isotope compositions (e.g., δ^(13)C values), which are based on mixing ratios of isotopologues containing one rare isotope (e.g., 16O13C16O). Atmospheric gases also have isotopologues containing two or more rare isotopes (e.g., ^(18)O^(13)C^(16)O). These species have unique physical and chemical properties and could help constrain origins of atmospheric gases and expand the scope of stable isotope geochemistry generally. We present the first measurements of the abundance of ^(18)O^(13)C^(16)O from natural and synthetic sources, discuss the factors influencing its natural distribution and, as an example of its applied use, demonstrate how its abundance constrains the sources of CO_2 in the Los Angeles basin. The concentration of ^(18_O^(13)C^(16)O in air can be explained as a combination of ca. 1‰ enrichment (relative to the abundance expected if C and O isotopes are randomly distributed among all possible isotopologues) due to enhanced thermodynamic stability of this isotopologue during isotopic exchange with leaf and surface waters, ca. 0.1‰ depletion due to diffusion through leaf stomata, and subtle (ca. 0.05‰) dilution by ^(18)O^(13)C^(16)O-poor anthropogenic CO_2. Some air samples are slightly (ca. 0.05‰) lower in ^(18)O^(13)C^(16)O than can be explained by these factors alone. Our results suggest that ^(18)O^(13)C^(16)O abundances should vary by up to ca. 0.2‰ with latitude and season, and might have measurable sensitivities to stomatal conductances of land plants. We suggest the greatest use of Δ_(47) measurements will be to “leverage” interpretation of the δ^(18)O of atmospheric CO_2.
|Additional Information:||© 2004 Elsevier Ltd. Received December 3, 2003; accepted in revised form May 5, 2004. Associate editor: M. Bar-Matthews. We thank Nami Kitchen for assistance with laboratory work associated with the measurements presented here. We gratefully acknowledge comments on an early draft of this manuscript by Jess Adkins, Ken Farley, Jim Randerson, Alex Sessions, Zhengrong Wang, and Paul Wennberg. We thank Michael Bender, Boaz Luz and an anonymous reviewer for their insightful comments, and Miryam Bar-Matthews for editing this paper. We gratefully acknowledge the financial support of the Packard Foundation (grant 2001–19030) and NSF (grants EAR-0095897 and EAR-0220066).|
|Official Citation:||John M. Eiler, Edwin Schauble, 18O13C16O in Earth’s atmosphere, Geochimica et Cosmochimica Acta, Volume 68, Issue 23, 1 December 2004, Pages 4767-4777, ISSN 0016-7037, 10.1016/j.gca.2004.05.035. (http://www.sciencedirect.com/science/article/pii/S0016703704004363)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||31 Oct 2012 14:35|
|Last Modified:||23 Aug 2016 10:20|
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