Observation of “dark” oxygen on the Pacific Ocean floor: a possible explanation of the sudden increase in oxygen flow in the confined areas

“A few years ago, a team of marine biologists went back to those areas that were mined 40 years ago and found essentially no life,” Geiger said. “And then a few hundred meters over to the left and right, where the nodules were intact, plenty of life.”

Researchers scouring the lightless landscape of the Pacific Ocean floor think they’ve observed “dark oxygen” being created there, potentially challenging commonly held beliefs about how oxygen is produced on Earth.

These nodules — “effectively batteries in a rock,” Sweetman said — may use their electric charge to split seawater into hydrogen and oxygen in a process called seawater electrolysis.

The director of the Scottish Association for Marine Science said that the conventional view was that oxygen first came from ancient cyanobacteria and that there was a gradual development of complex life thereafter. “The potential that there was an alternative source requires us to have a radical rethink.”

Sweetman first noticed a strange thing. He and his team had been working to measure the oxygen flow in the confined areas. Despite the fact that there was no photosynthesing organisms nearby, the researchers thought that the increase in oxygen flow was due to an abnormality.

Where Did Aerobic Life Start in the Clarion-Clipperton Zone? The Case of Polymetallic Nodules in a Deep Ocean Environment

The metals used in polymetallic nodule can be used to make the batteries used in consumer electronics, appliances and electric vehicles.

Franz Geiger, a Northwestern University chemistry professor who worked on the study, said in a separate news release that there may be enough polymetallic nodules in an area of the Pacific Ocean called the Clarion-Clipperton Zone to meet global energy demands for decades after.

These possibilities add weight to the argument that the deep seabed is a delicate environment that needs to be protected from industrial exploitation. (There is already a petition, signed by more than 800 marine scientists from 44 different countries, that highlights the broader environmental risks of deep sea mining and calls for a pause on its development.)

Companies conducted exploratory missions for deep-sea mining in the 1970s and ’80s, he said, and recent research suggests that those missions may have had repercussions on marine life in the area for decades.

“I think we need to revisit questions like: where could aerobic life have begun?” said Andrew Sweetman in a news release.

The same finding was made in 2021, despite a different measurement approach. The scientists were assessing changes in oxygen levels inside a benthic chamber, an instrument that collects sediment and seawater to create enclosed samples of the seabed environment. They were able to analyze, among other things, how Oxygen was being consumed within the sample environment. Oxygen in the benthic chamber should have decreased over time as organisms in the water consumed it, but it did the opposite: Oxygen in the benthic chamber increased despite the dark conditions.

It is not known how the electric current is generated and whether the reaction is continuous or if it produces enough oxygen to sustain an ecology.

There is a bigger question about whether the polymetallic nodules caused the electrolysis that started the life on Earth. According to Sweetman, this is an exciting hypothesis that should be explored further. It might even be possible that this could take place on other worlds, and be a potential source of alien life.

But with many questions unanswered, some are casting doubt on the findings. Patrick Downes, the founder of the Metals Company, a company that works in deep water and partly funded Sweetman’s research, says that the results are the result of oxygen contamination.