abundance was probably less than half of the present day value. However, this study fits into a larger body of work that generally constrains the prebiotic N₂ abundance to be between half and double the present level.

Oxygen

Oxygen in the form of O₂ makes up 21% of Earth's modern atmosphere by volume. Earth's modern atmospheric O₂ is due almost entirely to biology (e.g. it is produced during oxygenic photosynthesis), so

1.Previous
3.Next