Abstract
The early Earth's atmosphere, with extremely low levels of molecular oxygen and an appreciable abiotic flux of methane, could have been a source of organic compounds necessary for prebiotic chemistry. Here, we investigate the formation of a key RNA precursor, glycolaldehyde (2-hydroxyacetaldehyde, or GA) using a 1-dimensional photochemical model. Maximum atmospheric production of GA occurs when the CH4:CO2 ratio is close to 0.02. The total atmospheric production rate of GA remains small, only 1×107 mol yr-1. Somewhat greater amounts of GA production, up to 2 × 108 mol yr-1, could have been provided by the formose reaction or by direct delivery from space. Even with these additional production mechanisms, open ocean GA concentrations would have remained at or below ~1 μM, much smaller than the 1-2 M concentrations required for prebiotic synthesis routes like those proposed by Powner et al. (Nature 459:239-242, 2009). Additional production or concentration mechanisms for GA, or alternative formation mechanisms for RNA, are needed, if this was indeed how life originated on the early Earth.
Original language | English (US) |
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Pages (from-to) | 77-98 |
Number of pages | 22 |
Journal | Origins of Life and Evolution of Biospheres |
Volume | 43 |
Issue number | 2 |
DOIs | |
State | Published - Apr 2013 |
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Space and Planetary Science