Scientists discover ‘dark oxygen’ being produced by seabed metals in ground-breaking study

An international team of scientists has discovered that oxygen is being produced by potato-shaped metallic nodules thousands of feet below the surface of the Pacific Ocean.

The findings, which were published Monday in the Nature Geoscience journal, defy the scientific consensus of how oxygen is produced — and could even force a radical rethink of the origins of complex life on Earth.

Alongside implications for ocean science, the research raises fresh concerns about the risks of deep-sea mining.

A team of scientists led by Professor Andrew Sweetman at the U.K.'s Scottish Association for Marine Science found that oxygen is being produced in complete darkness approximately 4,000 meters (13,100 feet) below the ocean's surface.

It was previously thought that only living organisms such as plants and algae could use energy to create the planet's oxygen through a process called photosynthesis, which requires sunlight.

"For aerobic life to begin on the planet, there had to be oxygen and our understanding has been that Earth's oxygen supply began with photosynthetic organisms," Sweetman said.

"But we now know that there is oxygen produced in the deep sea, where there is no light. I think we therefore need to revisit questions like: where could aerobic life have begun?"

"Dark oxygen" was discovered while researchers conducted ship-based fieldwork in the Pacific Ocean. The team sampled the seabed of the Clarion-Clapperton Zone, an abyssal plain between Hawaii and Mexico, to assess the possible impacts of deep-sea mining.

Researchers analyzed multiple nodules and found many were carrying a "very high" electric charge, which they said could lead to the splitting of seawater into hydrogen and oxygen through a process called seawater