Scientists May Have Discovered That ‘Black Oxygen’ Is Created Without Photosynthesis

 

A deep-sea shark and several eels are attracted to bait placed atop Cook Seamount, located off the coast of the Big Island of Hawaii, on September 6, 2016. The long, serpentine eels are dark gray to black, and the shark is gray. Rocks cover the seafloor.

A deep-sea shark and several eels are attracted to bait placed atop Cook Seamount, as seen from the Pisces V submersible during a dive to the previously unexplored seamount off the Big Island of Hawaii, September 6, 2016.

Caleb Jones/AP

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Caleb Jones/AP

Researchers scouring the lightless landscape of the Pacific Ocean floor believe they have observed the creation of “dark oxygen,” potentially challenging commonly held beliefs about how oxygen is produced on Earth.

Until now, it was thought that oxygen was created solely through photosynthesis, a process that requires sunlight. But this discovery challenges that theory and raises new questions about the origins of life itself.

“I think we therefore need to ask ourselves questions again such as: where could aerobic life have started?” Andrew Sweetman, a professor at the Scottish Marine Science Association in Oban, Scotland, said in a press release.

The research team led by Sweetman published its findings Monday in a paper in the journal Geosciences of nature.

Scientists aren’t sure exactly how oxygen is created at such dark depths, but they think it’s produced by electrically charged minerals called polymetallic nodules, which range in size from tiny particles to about the size of a potato.

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

“The conventional wisdom is that oxygen was first produced about three billion years ago by ancient microbes called cyanobacteria and that complex life gradually evolved thereafter,” Nicholas Owens, director of the Scottish Marine Science Association, said in the press release. “The possibility that there is an alternative source requires us to radically rethink our thinking.”

The researchers conducted tests on the seafloor and also collected samples for surface testing, and they came to the same conclusion: oxygen levels increased near the polymetallic nodules.

Seawater can be split into hydrogen and oxygen with 1.5 volts of electricity, about the amount of electricity in a AA battery. The researchers found that some nodules had up to 0.95 volts of electricity, and several nodules together produced even higher voltages.

This discovery could have an impact on 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, household appliances and electric vehicles.

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

But he also said mining should be conducted in a way that does not remove oxygen needed by life forms in that part of the ocean.

“We have to be very careful if deep-sea mining becomes an opportunity that continues…at a level and frequency that is not detrimental to life there,” Geiger told NPR.

Companies conducted deep-sea mining exploration missions in the 1970s and 1980s, he said, and recent research suggests those missions may have impacted marine life in the region for decades.

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