Life unlocks nitrogen
The air was full of nitrogen nobody could use
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The triple bond in N₂ is among the strongest in chemistry. The enzyme nitrogenase breaks it at room temperature, something industry managed only in 1913 with 400 degrees and 200 atmospheres of pressure. Isotope data from South African rocks suggest biological nitrogen fixation was running around 3.2 billion years ago. It moved the ceiling on how much life the planet could carry: before nitrogenase the biosphere was limited to whatever nitrogen lightning and volcanoes happened to supply. Nitrogenase is destroyed by oxygen, and the bacteria that use it must still shield it — a fossil from a world without air.
For children
Almost 80 per cent of the air is nitrogen, and every living thing needs it to build its body. But the nitrogen molecule is bound so tightly that almost nothing can pull it apart. Some bacteria found a way — and without them life would still be a thin film.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org