Editing Archean Eon (section)

=== Archean Nitrogen Cycle ===
The cycling of nitrogen was also profoundly affected by the lack of atmospheric oxygen. Nitrogen is essential for life, serving as a fundamental component of '''amino acids''', '''nucleic acids''', and other '''biomolecules'''. With limited oxygen, '''ammonia''' (NH₃) was a significant form of nitrogen, more stable in the atmosphere and more soluble in water compared to nitrogen gas (N₂), and thus more '''bioavailable''' to early life forms.

Biological '''nitrogen fixation''' - the conversion of N₂ gas into biologically usable forms such as ammonia - was crucial. This process likely occurred in microbial mats and stromatolites, where early nitrogen-fixing bacteria and archaea resided. Modern processes like '''nitrification''' (the conversion of ammonia to nitrate) and '''denitrification''' (the reduction of nitrate to N₂) would have been minimal or absent in the Archean due to the lack of oxygen. 

The availability of fixed nitrogen in the form of ammonia could have influenced the development and diversity of early life. Ammonia and other nitrogen-containing gases like dinitrogen (N₂) and nitrous oxide (N₂O) could also have contributed to the greenhouse effect, affecting the Archean climate.