Every second breath a person takes depends on oxygen generated not by forests or grasslands, but by microscopic organisms ...

Microscopic ocean algae produce a huge share of Earth’s oxygen—but they need iron to do it. New field research shows that when iron is scarce, phytoplankton waste energy and photosynthesis falters.

We think of oxygen as life, sustenance, a literal breath of fresh air. But it's actually a very reactive element. Anyone who's burned a log has witnessed this firsthand. So why do so many life-forms ...