Ancient South African rocks show how oxygen stayed high
A team including geologist Andrey Bekker of the University of California, Riverside, studied ancient rocks from South Africa. They found a self-sustaining ocean cycle that kept oxygen high after the Great Oxidation Event about 2.3 billion years ago.
In the cycle, more oxygen raised sulfate in the sea. Microbes used the sulfate to break down organic matter and released phosphorus, which fed new growth and more carbon burial. The team used a new technique that separates phosphorus that living things could use from phosphorus locked in minerals. The study is peer-reviewed and appears in Nature Communications. Bekker says the results suggest oxygen swung more than scientists once believed.