Abstract EANA2026-47

Ionizing radiation is one of the major factors that reaches across the disciplines of astrobiology, such as star formation, generation of biogenic elements, or synthesis of organic molecules and driving of prebiotic chemistry [1]. Nitrogen is one of the elements necessary for life, and one of the requirements for the origin and early evolution of life on any potentially habitable planet, is the existence of some abiotic process that provides a source of fixed nitrogen in a biochemically available form. A source of energy like ionizing radiation, could break the strong bond of N2 in the atmosphere and use the resulting nitrogen atoms to create relevant molecules such as ammonia, one of the building blocks essentials for life. In previous studies reported by our group, pyrite (FeS2) mineral has shown remarkable photo-catalytic properties, fixing atmospheric nitrogen as ammonium salt under exposure of the mineral surface to UV radiation [2]. On the other hand, some studies shown that gamma radiation can change the oxidation pathway of pyrite mineral and promote its reactivity, with strong implications in geochemistry processes [3,4].

Our main goal, in the prebiotic chemistry and planetary habitability context, is to explore the catalytic properties of pyrite mineral under exposure to high doses of gamma radiation. Furthermore, the role of this radiation on the fixation of molecular nitrogen from the atmosphere is compared with the nitrogen fixation process described in previous UV radiation studies. The experimental set-up for the gamma irradiation experiment was performed inside the Nayade Co-60 irradiation facility of CIEMAT (Madrid, Spain), a pool-type facility with water as biological shield. Different samples of pyrite were encapsulated in nitrogen atmosphere and exposed to gamma radiation in a dose of 2.7 MGy. The spectroscopic characterization of pyrite surfaces before and after radiation was performed by X-ray photoemission spectroscopy (XPS), a highly sensitive surface physics technique.

Our preliminary results show the successful fixation of nitrogen from the atmosphere on pyrite surface after high dose of gamma radiation. The formation of oxides and sulphates on the pyrite surface was also identified. Furthermore, the nature and ratio of the different nitrogen species determined by XPS depends on the presence of absent of chemisorbed water on the pyrite surface. These findings contribute to the understanding of the role of ionizing radiation and the surface reactivity of pyrite mineral, as a catalyst in the process of fixing atmospheric nitrogen. Unravelling these mechanisms provides a better understanding of the prebiotic chemistry pathways, as well as for future planetary exploration missions.

 

References:

[1] Dartnell LR. Astrobiology. (2011) 11(6), 551.

[2] E. Mateo-Marti, S. Galvez-Martinez, C. Gil-Lozano and María-Paz Zorzano. Scientific Reports (2019) 9, 15311.

[3] Mingliang Kang, Yixiao Kang, Wujian Jin, Jingye She, Danwen Qin, Hanyu Wu, Hanqin Weng, Chao Chen, Jiuqiang Li. Chemical Engineering Journal (2024) 489, 151473.

[4] Jingye She, Danwen Qin, Andreas C. Scheinost, Mingliang Kang, Wujian Jin, Hanqin Weng, Hanyu Wu, Jianrong Zeng. Geochimica et Cosmochimica Acta (2025) 391, 237.