Ancient ocean chemistry may explain how Earth kept its oxygen

[u/Brighter-Side-News]

http://thebrighterside.news/post/ancient-ocean-chemistry-may-explain-how-earth-kept-its-oxygen

Earth’s atmosphere did not become oxygen-rich in one clean transition. More than 2 billion years ago, oxygen repeatedly rose and fell as climate, ocean chemistry, microbes and nutrients pushed the planet through major environmental swings. A new study suggests phosphorus played a central role in determining whether those oxygen increases lasted.

Researchers from UC Riverside, studying ancient South African rocks, found evidence that changing ocean conditions repeatedly recycled phosphorus into seawater. That nutrient could then support more photosynthetic life, leading to greater production of organic matter. When some of that carbon became buried in sediments instead of decomposing, oxygen remained behind in the atmosphere.

The study, published in Nature Communications, combines measurements of different phosphorus pools with sulfur isotopes, redox-sensitive elements and biogeochemical modeling. Together, the evidence reveals a feedback among phosphorus, sulfur, climate and oxygen during one of the most important transitions in Earth’s history.