What is the dark oxygen found in the Pacific and how can it change our understanding of the origin of life?

Scientists have discovered metallic lumps at the bottom of the ocean that could well provide a new explanation to the question of how life on Earth began.

A team of experts exploring the Clarion-Clipperton Zone (CCZ), between Hawaii and Mexico, have found a substance - not a living organism - that can produce oxygen and give off almost as much electricity as AA batteries. Before this discovery, it was believed that only algae and plants could produce oxygen using photosynthesis, a process which requires light in order to work.

However, at the depths of the discovery, some 4km below the surface, dwells another option. This new information could well have scientists back at the drawing board to expand the (already lengthy) list of questions as to how life on our planet began. Time to buy another whiteboard.

What is the ‘dark oxygen’ discovery?

The scientists were poking around the CCZ looking for deep-sea creatures and the effects a potential mining expedition could have on them. The area is rich in what the people in white coats call ‘polymetallic nodules’, small pieces of potato-shaped rock that are filled with metals such as nickel, copper and cobalt, substances used to make batteries and solar panels. CNN explains that “the nodules form over the course of millions of years through chemical processes that cause metals to precipitate out of water around shell fragments, squid beaks and shark teeth and cover a surprisingly large area of the seafloor.”

As a result, the area is seen as haven for companies looking to exploit the natural resources that the animals down there have called home for millions of years. While there are concerns that the mining may well irrevocably damage the perfect ecosystem and have climate change effects, money talks.

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‘One of the most exciting finds in recent times’

“We were trying to measure the rate of oxygen consumption by the seafloor,” lead study author Andrew Sweetman of the Scottish Association for Marine Science (SAMS) told AFP. Normally, the amount of oxygen collected in the chamber (which literally grabs lumps of the seabed like a claw machine at an arcade) “decreases as its used up by organisms as they respire”, he explained.

And so, when the oxygen levels in the sample began to increase, the scientists thought that their machines had crumbled under pressure. Oxygen cannot be produced here, they thought. We are in total blackness, there is no light for photosynthesis.

But when the nodules were brought to the surface, to their amazement, the results were confirmed: they were “amazingly” carrying an electric charge similar to that of a battery you can find in the back of your TV remote or PlayStation controller. The electric charge produced by the nodules was splitting the hydrogen and oxygen in the water in a process known as electrolysis.

“I basically told my students, just put the sensors back in the box. We’ll ship them back to the manufacturer and get them tested because they’re just giving us gibberish, and every single time the manufacturer came back: ‘They’re working. They’re calibrated.’”

Nicholas Owens, the SAMS director, said that this ‘dark oxygen’ was “one of the most exciting findings in ocean science in recent times”, adding that the discovery “requires us to rethink how the evolution of complex life on the planet might have originated.

“The conventional view is that oxygen was first produced around 3 billion years ago by ancient microbes called cyanobacteria and there was a gradual development of complex life thereafter,” Owens added, “and, if the process is happening on our planet, could it be helping to generate oxygenated habitats on other ocean worlds such as Enceladus and Europa and providing the opportunity for life to exist?” The research paper was published in Nature Geoscience.