1:45 PM - 2:05 PM
[BBG01-01] The coupled evolution of life and the atmosphere during the early Archean
★Invited Papers
Keywords:Archean, Atmospheric chemistry, Biogeochemical cycles
The results suggest that net primary production (NPP) was ~0.1% and 1% that of the modern Earth for the non-photosynthetic (chemotrophic) ecosystem and anoxygenic photosynthetic ecosystem, respectively. The extremely low NPP fluxes produced by our model imply that geological fluxes of reductants, rather than light or nutrients, would have been the limiting factor for biological productivity. Despite the low biological productivity of the primitive biosphere, atmospheric methane abundances would have been relatively high (fCH4 = ~300 ppmv) because primitive biospheres efficiently recycle the material in the ocean-atmosphere system. Our results also demonstrate that the transition from a chemotrophic ecosystem to an anoxygenic photosynthetic ecosystem exerts minor impacts on atmospheric composition, making it difficult to diagnose both ecosystems based on atmospheric chemistry alone. While our results provide a comprehensive and statistically robust picture of the early-Archean Earth system that is consistent with available geologic records, further mechanistic understanding of the coupled H-C-Fe cycles is required to fully understand the stabilization mechanisms of atmospheric chemistry during the early-Archean. A better mechanistic understanding of the coupled evolution of primitive life and the atmosphere has great ramifications not only for the sustained habitability of Earth but for the search for life on Earth-like exoplanets with reducing atmospheres that may host primitive life.