Strong Depletion of <sup>13</sup>C in CO Induced by Photolysis of CO<sub>2</sub> in the Martian Atmosphere, Calculated by a Photochemical Model - Sorbonne Université Access content directly
Journal Articles (Review Article) The Planetary Science Journal Year : 2023

Strong Depletion of 13C in CO Induced by Photolysis of CO2 in the Martian Atmosphere, Calculated by a Photochemical Model

Abstract

The isotopic signature of atmospheric carbon offers a unique tracer for the history of the Martian atmosphere and the origin of organic matter on Mars. The photolysis of CO 2 is known to induce strong isotopic fractionation of the carbon between CO 2 and CO. However, its effects on the carbon isotopic compositions in the Martian atmosphere remain uncertain. Here, we develop a 1D photochemical model to consider the isotopic fractionation via photolysis of CO 2 , to estimate the vertical profiles of the carbon isotopic compositions of CO and CO 2 in the Martian atmosphere. We find that CO is depleted in 13 C compared with CO 2 at each altitude, due to the fractionation via CO 2 photolysis: the minimum value of the δ 13 C in CO is about −170‰ under the standard eddy diffusion setting. This result supports the hypothesis that fractionated atmospheric CO is responsible for the production of the 13 C-depleted organic carbon in the Martian sediments detected by the Curiosity Rover, through the conversion of CO into organic materials and their deposition on the surface. The photolysis and transport-induced fractionation of CO that we report here leads to a ∼15% decrease in the amount of inferred atmospheric loss when combined with the present-day fractionation of the atmosphere and previous studies of carbon escape to space. The fractionated isotopic composition of CO in the Martian atmosphere may be observedby ExoMars Trace Gas Orbiter and ground-based telescopes, and the escaping ion species produced by the fractionated carbon-bearing species may be detected by the Martian Moons eXploration mission in the future.
Fichier principal
Vignette du fichier
Yoshida_2023_Planet._Sci._J._4_53.pdf (841.66 Ko) Télécharger le fichier
Origin Publisher files allowed on an open archive
Licence

Dates and versions

insu-04045592 , version 1 (24-03-2023)

Licence

Identifiers

Cite

Tatsuya Yoshida, Shohei Aoki, Yuichiro Ueno, Naoki Terada, Yuki Nakamura, et al.. Strong Depletion of 13C in CO Induced by Photolysis of CO2 in the Martian Atmosphere, Calculated by a Photochemical Model. The Planetary Science Journal, 2023, 4, 53 (8pp). ⟨10.3847/psj/acc030⟩. ⟨insu-04045592⟩
43 View
15 Download

Altmetric

Share

Gmail Mastodon Facebook X LinkedIn More