[Triumf-seminars] TRIUMF Accelerator Seminar today at 14:30

[TRIUMF Seminars]

Date/Time: Wed 2023-10-18 at 14:30

Location:  ISAC II Conf Room   

Speaker:   Min Song (University of Toronto)

Title:     Experimental study on the radiolytic organic synthesis and its implication for habitability on Earth and beyond

Abstract: The abiotic synthesis of organic compounds has been a subject of profound interest, offering crucial insights into the possible origins of life on Earth. In contrast to the complex biological processes prevalent on Earth's surface, deep subsurface environments provide natural laboratories for the study of abiotic chemistry. A notable discovery within these subsurface realms is the pivotal role played by radiation energy from natural radionuclides such as U, Th, and K within host rocks. Over geological timescales, this energy drives extensive radiolytic water-rock reactions, yielding potential energy sources important for subsurface life, including H2 and sulfate2-4. 
Recent investigations have proposed that radiolytic reactions involving carbonate minerals may be responsible for the production of volatile fatty acids (VFAs) in ancient fracture fluids found at a deep subsurface site (Kidd Creek, Timmins, ON)5. Most significantly, at Kidd Creek the acetate was the most abundant and 13C-enriched found in natural samples to date5. Experimental studies have shown that the radiolytic decomposition of calcite is a source of VFAs6,7. However, uncertainties remain that hinder the applicability of these experimental studies to natural systems like Kidd Creek. These uncertainties include the reaction pathways, reaction rates, and the radiolytic yield for VFAs and particularly for acetate. In addition, the associated isotope fractionation for the radiolytic reactions has not been completely explored, which could be useful in evaluating the relative contribution of radiolysis in organic synthesis in natural settings. 
Building upon previous efforts, our project aims to advance our understanding of radiolytic production of organic compounds including VFAs. This talk will provide a comprehensive overview of our research approach and objectives. We will employ an accelerated 4He+2 beam from the Off-Line Ion Sources (OLIS) facility at TRIUMF to irradiate carbonate solutions at up to 60 MeV under various conditions. We seek to unravel the mechanisms and rates governing the radiolytic reactions, and also explore the associated isotope fractionation. The outcomes of our research have implications for our understanding abiotic organic synthesis and its relevance to the potential habitability of subsurface environments on our planet and beyond.

References:
1	Lemmon, R. M. Chemical evolution. Chemical Reviews 70, 95-109 (1970).
2	Lin, L. H. et al. Radiolytic H2 in continental crust: nuclear power for deep subsurface     microbial communities. Geochemistry, Geophysics, Geosystems 6 (2005).
3	Lin, L.-H. et al. Long-term sustainability of a high-energy, low-diversity crustal biome. Science 314, 479-482 (2006).
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