Isotopic composition of CO2 in the atmosphere of Mars: fractionation by diffusive separation observed by the ExoMars Trace Gas Orbiter

Autor: Juan Alday, Colin F. Wilson, Patrick G. J. Irwin, Alexander Trokhimovskiy, Franck Montmessin, Anna A. Fedorova, Denis A. Belyaev, Kevin S. Olsen, O. Korablev, Franck Lefèvre, Ashwin S. Braude, Lucio Baggio, Andrey Patrakeev, Alexey Shakun
Přispěvatelé: Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford [Oxford], Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Journal of Geophysical Research. Planets
Journal of Geophysical Research. Planets, Wiley-Blackwell, 2021, 127 (12), pp.e2021JE006992. ⟨10.1029/2021je006992⟩
Journal of Geophysical Research. Planets, Wiley-Blackwell, 2021, (in press). ⟨10.1029/2021je006992⟩
ISSN: 2169-9097
2169-9100
DOI: 10.1029/2021je006992⟩
Popis: International audience; Isotopic ratios in atmospheric CO2 are shaped by various processes throughout Mars' history, and can help understand what the atmosphere of early Mars was like to sustain liquid water on its surface. In this study, we monitor the O and C isotopic composition of CO2 between 70 and 130 km for more than half a Martian year using solar occultation observations by the Atmospheric Chemistry Suite onboard the ExoMars Trace Gas Orbiter. We find the vertical trends of the isotopic ratios to be consistent with the expectations from diffusive separation above the homopause, with average values below this altitude being consistent with Earth-like fractionation (δ13C =-3 ± 37 ; δ18O =-29 ± 38 ; δ17O =-11 ± 41). Using these measurements, we estimate that at least 20-40% of primordial C on Mars has escaped to space throughout history. The total amount of C lost from the atmosphere is likely to be well in excess of this lower limit, due to carbonate formation and further sink processes. In addition, we propose a photochemical transfer of light O from H2O to CO2 to explain the larger enrichment in the 18O/16O ratio in H2O than in CO2.
Databáze: OpenAIRE
Externí odkaz: