Estimating the capacity for production of formamide by radioactive minerals on the prebiotic Earth

Zachary R. Adam, Yayoi Hongo, H. James Cleaves, Ruiqin Yi, Albert C. Fahrenbach, Isao Yoda, Masashi Aono

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32 Citations (Scopus)


Water creates special problems for prebiotic chemistry, as it is thermodynamically favorable for amide and phosphodiester bonds to hydrolyze. The availability of alternative solvents with more favorable properties for the formation of prebiotic molecules on the early Earth may have helped bypass this so-called "water paradox". Formamide (FA) is one such solvent, and can serve as a nucleobase precursor, but it is difficult to envision how FA could have been generated in large quantities or accumulated in terrestrial surface environments. We report here the conversion of aqueous acetonitrile (ACN) via hydrogen cyanide (HCN) as an intermediate into FA by γ-irradiation under conditions mimicking exposure to radioactive minerals. We estimate that a radioactive placer deposit could produce 0.1-0.8 mol FA km-2 year-1. A uraninite fission zone comparable to the Oklo reactors in Gabon can produce 0.1-1 mol m-2 year-1, orders of magnitude greater than other scenarios of FA production or delivery for which reaching sizeable concentrations of FA are problematic. Radioactive mineral deposits may be favorable settings for prebiotic compound formation through emergent geologic processes and FA-mediated organic chemistry.

Original languageEnglish
Article number265
JournalScientific reports
Issue number1
Publication statusPublished - 2018 Dec 1

ASJC Scopus subject areas

  • General


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