Dark Oxygen Discovered in Deep Sea in Pioneering Study

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

The results, published Monday in Natural Sciences and Geology These findings challenge the scientific consensus about how oxygen is produced, and may even force us to radically rethink the origins of complex life on Earth.

In addition to the implications for ocean science, the research raises new concerns about the risks of deep-sea mining.

A team of scientists led by Professor Andrew Sweatman of the Scottish Association for Marine Science in the UK has discovered that oxygen is produced in complete darkness at a depth of about 4,000 metres (13,100 feet) below the ocean surface.

It was previously believed that only living organisms such as plants and algae were able to use energy to create oxygen on the planet through a process called photosynthesis, which requires sunlight.

“For aerobic life to begin on the planet, oxygen had to be present, and our understanding is that the oxygen supply to Earth began with photosynthetic organisms,” says Sweetman. He said.

“But we now know that oxygen is produced in the deep sea, where there is no light. So I think we need to revisit questions like: Where did aerobic life begin?”

The “dark oxygen” was discovered while researchers were conducting fieldwork aboard ships in the Pacific Ocean. The team took samples from the seafloor in the Clarion-Clapperton Zone, an abyssal plain between Hawaii and Mexico, to assess the potential impacts of deep-sea mining.

The researchers analyzed a number of nodules and found that many of them carried an “extremely high” electrical charge, which they said could lead to the splitting of seawater into hydrogen and oxygen through a process called seawater electrolysis.

“With this discovery, we have generated a lot of unanswered questions, and I think we have a lot to think about in terms of how we extract these nodules, which are like batteries in the rocks,” Sweetman said.

He added that more research would be needed into the production of “dark oxygen.”

The study was partly funded by the Canadian Deep Sea Mining Corporation. The metals company, which aims to mine in the Clarion-Clapperton area by late 2025.

Meanwhile, environmental groups say the practice cannot be done sustainably and will inevitably lead to ecosystem destruction and species extinction.

“The discovery that a process linked to polymetallic nodules is producing oxygen, in an area targeted by the deep sea mining industry, provides further support for the urgent need for a moratorium,” said Sophia Tsinikli, global campaign leader for deep sea mining at the Deep Sea Conservation Alliance, an environmental non-governmental group.

“This research underscores how much we still have to discover and learn about the deep sea, and raises more questions about how deep-sea mining may impact deep-sea life and processes,” Tsinikli said Monday.