Abstract_EANA2024-59

Abstract EANA2024-59

The Role of Clay Structure and Ions in Amino Acid Preservation on Nontronite Clays

Hannah Pollak (1), Xunyi Zhu (2), Valentina Erastova (1, 2)

(1) University of Edinburgh, University of Edinburgh, UK (2) UK Centre for Astrobiology, University of Edinburgh, UK

The quest to discover signs of ancient life on Mars faces numerous challenges, including the planet's harsh and inhospitable environment. Mars is exposed to high levels of ionising radiation, and the oxidising compounds in the regolith and atmosphere can rapidly destroy any exposed biomolecules. Despite these obstacles, research has shown that certain mineral surfaces can adsorb and effectively protect these biomarkers from degrading conditions, making mineral matrices prime target locations in the search for biosignatures on Mars.

To better understand the effectiveness of mineral protection, we examined the interactions of 21 proteinogenic amino acids with two nontronite clays in the presence of four cations: Na+, K+, Ca2+, and Mg2+. Through a large-scale molecular modelling study, we characterised and classified the adsorption mechanisms specific to each combination. We found that both clay composition and counterions play crucial roles in amino acid retention.

This work reveals the impact of changing environmental conditions on biomarker adsorption and desorption mechanisms, highlighting the importance of accounting for the unique ion and clay compositions in extraterrestrial environments. Additionally, we demonstrate how molecular simulations can guide the search for biosignatures on Earth and beyond.