Scientists find ‘dark oxygen’ produced without light in deep ocean

Bo Barker Jørgensen, a marine biogeochemistry skilled who was not concerned within the analysis however peer-reviewed the examine, stated in an interview that it was a “very uncommon discovering.”

The findings might have implications for the deep-sea mining trade, whose gamers have sought to be allowed to discover the depths of the ocean and retrieve minerals like people who make up polymetallic nodules. Such minerals are seen as essential for the inexperienced vitality transition. Environmental activists and plenty of scientists imagine deep-sea mining is harmful as a result of it could possibly destabilize ecosystems in unpredictable methods and will have an effect on the ocean’s capability to assist include local weather change. The examine acquired funding from firms lively in seabed mining exploration.

When Andrew Sweetman, the lead writer of the examine, first recorded uncommon oxygen readings coming from the underside of the Pacific Ocean in 2013, he thought his analysis tools had malfunctioned.

“I mainly informed my college students, simply put the sensors again within the field. We’ll ship them again to the producer and get them examined as a result of they’re simply giving us gibberish,” Sweetman, head of the seafloor ecology and biogeochemistry analysis group on the Scottish Affiliation for Marine Science, informed CNN. “And each single time the producer got here again: ‘They’re working. They’re calibrated.’”

In 2021 and 2022, Sweetman and his group returned to the Clarion-Clipperton Zone, an space below the central Pacific recognized for having giant portions of polymetallic nodules. Assured that their sensors labored, they lowered a tool greater than 13,000 toes under the floor that positioned small containers into the sediment. The containers stayed in place for 47 hours, conducting experiments and measuring ranges of oxygen consumed by the microorganisms that reside there.

As a substitute of oxygen ranges taking place, they went up — suggesting that extra oxygen was being produced than consumed.

The researchers hypothesized that the electrochemical exercise of the completely different metals that make up polymetallic nodules have been answerable for the oxygen manufacturing measured by the sensors — like a battery wherein electrons stream from one electrode to a different, creating an electrical present, stated Tobias Hahn, one of many co-authors of the examine, in an interview.

This speculation would add a layer to our understanding of how organisms got here to exist below the ocean, stated Hahn, who targeted particularly on the sensors used within the examine experiments. “We thought that life started on Earth when photosynthesis kicked in, as oxygen was delivered to Earth via photosynthesis. It may very well be that really, this technique of electrochemically dividing water into oxygen and hydrogen equipped oxygen to the ocean,” he stated.

“This may very well be a sort of recreation changer within the story about how life began,” he added.

A information launch concerning the examine stated its findings problem “long-held assumptions that solely photosynthetic organisms, akin to crops and algae, generate Earth’s oxygen.”

But when that discovering is borne out, “we have to rethink mine” supplies like cobalt, nickel, copper, lithium and manganese underwater, “in order that we don’t deplete the oxygen supply for deep-sea life,” stated Franz Geiger, a professor of chemistry at Northwestern College and one of many co-authors of the examine, within the launch.

Mining carried out below the ocean within the Eighties serves as a cautionary story, Geiger stated. When marine biologists visited such websites a long time later, they “discovered not even micro organism had recovered.” However in areas that weren’t mined, “marine life flourished.”

“Why such ‘lifeless zones’ persist for many years continues to be unknown,” he stated. However the truth that they do means that mining the seafloor in areas with loads of polymetallic nodules may very well be particularly dangerous, as a result of these areas are inclined to have extra faunal variety than “probably the most various tropical rainforests,” he stated.

Although the examine has pointed to an fascinating new pathway for sustaining life deep below the ocean, many questions stay, Hahn stated. “We simply don’t know” how a lot “darkish oxygen” could be created via this course of, the way it impacts the polymetallic nodules or what portions of nodules are wanted to allow oxygen manufacturing, he stated.

Whereas the examine methodology is strong, “what’s missing is an understanding of what’s going on, what sort of course of that is,” stated Barker Jørgensen.