Towards high-precision isotopic analysis of CO2 from ice-core gas bubbles using quantum cascade laser spectroscopy

International audience The paleo-climate archive provided by gas stored in bubbles in the ice provides a powerful means to study the ~40% increase in the atmospheric CO2 concentration between glacial and interglacial climates, in combination with numerical modeling studies, to elucidate the underlyi...

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Bibliographic Details
Main Authors: Shah, Miral, Gorrotxategi Carbajo, Paula, Kerstel, Erik, Chappellaz, Jerome
Other Authors: LAsers, Molécules et Environnement (LAME-LIPhy), Laboratoire Interdisciplinaire de Physique Saint Martin d’Hères (LIPhy), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )
Format: Conference Object
Language:English
Published: HAL CCSD 2013
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Online Access:https://hal.archives-ouvertes.fr/hal-00996055
Description
Summary:International audience The paleo-climate archive provided by gas stored in bubbles in the ice provides a powerful means to study the ~40% increase in the atmospheric CO2 concentration between glacial and interglacial climates, in combination with numerical modeling studies, to elucidate the underlying physical mechanisms. Of particular interest is, considering the strong correlation between the carbon cycle and climate, and in light of the post-industrial revolution anthropogenic increase of the CO2 concentration. The source of the CO2 released into the atmosphere during previous deglaciations can be constrained from 13CO2 isotopic measurements on CO2 gas stored in bubbles in the ice-cores by the fact that the different CO2 reservoirs (terrestrial biosphere, oceans) and associated mechanisms (biological or physical) have different isotopic signatures. Unfortunately, conventional IRMS measurements on the small quantity of gas available are difficult, tedious, and time-consuming. We report here on the design of an alternative method based on Optical Feedback Cavity Enhanced Absorption Spectrometry (OF-CEAS) using a quantum cascade laser operating near 4.36 μm. The aim of this instrument design is to achieve the measurement of the 13C/12C isotopic ratio (δ13C) with a precision better than 0.05 ‰ on small quantities of the trapped atmospheric CO2. We describe the instrument and show preliminary results.