How ocean chemistry helped life keep breathing
Scientists have helped solve a longstanding mystery about how Earth remained habitable after oxygen first accumulated in its atmosphere more than 2 billion years ago, providing evidence that ancient ocean chemistry sustained life-friendly conditions.
Scientists have unraveled an ancient process that helped maintain Earth's oxygen-rich atmosphere and support life after oxygen first emerged about 2.3 billion years ago. Research led by UC Riverside geologist Andrey Bekker reveals that rising ocean sulfate levels, triggered by microbes breaking down organic matter, spurred a self-perpetuating cycle of phosphorus recycling.
This recycling boosted biological productivity and allowed more organic carbon to sink, continuously replenishing oxygen in the atmosphere. Until now, scientists could only gauge total phosphorus amounts in ancient rocks, but new techniques now separate phosphorus available to life from what's locked away. This nuanced understanding shows oxygen levels fluctuated more than previously thought after the Great Oxidation Event, reshaping ocean chemistry over time.
The findings may reshape ideas about early life evolution, suggesting other factors could have limited complex oxygen-dependent organisms' emergence. Today, declining ocean oxygen due to climate change could similarly reduce marine productivity if phosphorus becomes less available. The research also aids the search for extraterrestrial life by illustrating how oxygen, nutrients, and life co-evolved on Earth.
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