Chemical effects of large impacts on the Earth's primitive atmosphere.

摘要: Intense bombardment of the moon and terrestrial planets ˜3.9–4.0 × 109 years ago1,2 could have caused chemical reprocessing Earth's primitive atmosphere3. In particular, shock heating rapid quenching by impact large bodies into atmosphere produce molecules such as HCN H2CO4 which are important precursors for abiotic synthesis complex organic molecules5–7. Here we model production H2CO thermochemical equilibrium kinetic calculations composition shocked air parcels a wide range temperatures, pressures initial compositions. For atmospheres with C/O ≥1, our results suggest that bolide impacts cause volume mixing ratios approximately 10−3 to 10−5 in region global average 10−12. The corresponding 10−7 10−9; no-global can occur, however, is rapidly destroyed or rained out within days hours. Rainout oceans 3–15% produced provide ˜(3–14) 1011 mol per year. This somewhat larger than other predicted sources HCN8 H2CO9 on Earth.