Scientists May Have Discovered 'Dark Oxygen' Created Without Photosynthesis: NPR

Researchers scouring the lightless landscape at the bottom of the Pacific Ocean believe they have observed “dark oxygen” being created there, which may challenge common beliefs about how oxygen is produced on Earth.

Until now, it was thought that oxygen could only be created through photosynthesis, a process that requires sunlight. But the discovery casts doubt on that theory and raises new questions about the origins of life itself.

“I think we need to rethink questions like: Where could aerobic life begin?” Andrew Sweetman saidProfessor John Matthews, a professor at the Scottish Association for Marine Science in Oban, Scotland, said in a press release:

The research team led by Sweetman Published its results Monday in a magazine article Natural Sciences and Geology.

Scientists don't know for sure how oxygen is created at such dark depths, but they believe it is produced by electrically charged minerals called polymetallic nodules, which vary in size From a tiny particle to about the size of a potato.

These nodules, which act as “batteries in rocks,” may use their electrical charge to split seawater into hydrogen and oxygen in a process called seawater electrolysis, Sweetman said.

“The conventional view is that oxygen was first produced about three billion years ago by ancient microbes called cyanobacteria, and that there was a gradual evolution of complex life after that,” said Nicholas Owens, director of the Scottish Society for Oceanography, in the press release. “The possibility of an alternative source requires us to fundamentally rethink.”

The researchers conducted tests on the seafloor and also collected samples to test above ground, and came to the same conclusion: higher oxygen levels near polymetallic nodules.

Seawater can be split into hydrogen and oxygen with 1.5 volts of electricity, about the same as a AA battery. The researchers found that some nodes had as much as 0.95 volts of electricity, and that many nodes together produced even higher voltages.

This discovery could impact deep sea mining.

Polymetallic nodules contain metals such as manganese, nickel and cobalt, which can be used to make lithium-ion batteries used in consumer electronics, home appliances and electric vehicles.

There may be enough polymetallic nodules in the Pacific Ocean region called the Clarion-Clipperton Zone to meet global energy demand for decades after that, Franz Jaeger, a Northwestern University chemistry professor who worked on the study, said in a separate news release.

But he also said mining must be done in a way that does not eliminate oxygen for life forms in that part of the ocean.

“We need to be very careful if it turns out that deep-sea mining is going to be an opportunity that is being exploited … and it's being done at a level and at a frequency that doesn't harm the life there,” Geiger told NPR.

He said companies conducted deep-sea mining exploration missions in the 1970s and 1980s, and recent research suggests those missions may have had repercussions on marine life in the area for decades.

“A few years ago, a team of marine biologists went back to the areas where the mines had been mined 40 years ago and found no life at all,” Jaeger said. “And then, a few hundred meters to the left and right, where the nodules were intact, there was a lot of life.”