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Degradation of amino acids on Mars by UV irradiation in the presence of chloride and oxychlorine salts

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Title: Degradation of amino acids on Mars by UV irradiation in the presence of chloride and oxychlorine salts
Authors: Liu, D
Kounaves, SP
Item Type: Journal Article
Abstract: The degradation of glycine (Gly), proline (Pro), and tryptophan (Trp) was studied under simulated Mars conditions during UV-driven production of oxychlorines and compared under Mars ambient and humid conditions, as films, and with addition of sodium chloride (NaCl), sodium chlorate (NaClO3), and sodium perchlorate (NaClO4) salts. It was shown that glycine sustained no significant destruction in either of the non-salt samples under Mars ambient or humid conditions. However, its degradation increased in the presence of any of the three salts and under both conditions though more under humid conditions. Proline degradation followed the order No Salt > NaCl > NaClO3 > NaClO4 under Mars ambient conditions but the reverse order under Mars humid conditions. A mechanism is proposed to explain how water and silica participate in these degradation reactions and how it is strongly influenced by the identity of the salt and its ability to promote deliquescence. No difference was observed for tryptophan between Mars ambient and humid conditions, or for the different salts, suggesting its degradation mechanism is different compared to glycine and proline. The results reported here will help to better understand the survival of amino acids in the presence of oxychlorines and UV on Mars and thus provide new insights for the detection of organic compounds on future Mars missions.
Issue Date: 6-Jul-2021
Date of Acceptance: 27-Feb-2021
URI: http://hdl.handle.net/10044/1/88428
DOI: 10.1089/ast.2020.2328
ISSN: 1531-1074
Publisher: Mary Ann Liebert
Start Page: 793
End Page: 801
Journal / Book Title: Astrobiology
Volume: 21
Issue: 7
Copyright Statement: © 2021, Mary Ann Liebert, Inc., publishers.
Keywords: Science & Technology
Physical Sciences
Life Sciences & Biomedicine
Astronomy & Astrophysics
Geosciences, Multidisciplinary
Life Sciences & Biomedicine - Other Topics
Amino acids
Amino acids
Amino acids. Astrobiology 21, xxx–xxx
0201 Astronomical and Space Sciences
0402 Geochemistry
0403 Geology
Astronomy & Astrophysics
Publication Status: Published
Conference Place: United States
Online Publication Date: 2021-03-30
Appears in Collections:Earth Science and Engineering
Faculty of Engineering