In the total darkness of the depths of the Pacific Ocean, scientists have discovered that oxygen is not produced by living organisms, but by strange potato-shaped lumps of metal that give off almost as much electricity as AA batteries.
The surprising finding has many potential implications and could even rethink how life first began on Earth, the researchers behind a study said Monday.
It was thought that only living things like plants and algae were capable of producing oxygen through photosynthesis – which requires sunlight.
But four kilometers (2.5 miles) below the surface of the Pacific Ocean, where no sunlight can reach, small mineral deposits are called polymetallic nodules was recorded making so-called dark oxygen for the first time.
The discovery was made in the Clarion-Clipperton Zone (CCZ), an abyssal plain that stretches between Hawaii and Mexico, where mining companies have plans to start harvesting the nodules.
The lumpy nodules – often called “batteries in a rock” – are rich in metals such as cobalt, nickel, copper and manganese, all of which are used in batteries, smartphones, wind turbines and solar panels.
The international team of scientists sent a small vessel to the floor of the CCZ with the aim of finding out how mining might affect the strange and little-understood animals that live where no light can reach.
“We tried to measure the rate of oxygen consumption by the seabed,” lead study author Andrew Sweetman of the Scottish Association for Marine Science (SAMS) told AFP.
To do this, they used a contraption called a benthic chamber, which scooped up a bunch of sediment.
Normally, the amount of oxygen trapped in the chamber “decreases as it is used up by organisms as they breathe,” Sweetman said.
But this time the opposite happened – the amount of oxygen increased. This was not supposed to happen in complete darkness where there is no photosynthesis.
It was so shocking that the researchers initially thought their underwater sensors must have been tripping. So they brought some nodules to their ship to repeat the test. Again the amount of oxygen increased.
They then noticed how the nodules carried a surprising electrical charge.
On the surface of the buttons, the team “surprisingly found voltages almost as high as in an AA battery,” Sweetman said. This charge can split seawater into hydrogen and oxygen in a process called seawater electrolysis, the researchers said.
This chemical reaction occurs at about 1.5 volts – about the charge of an AA battery.
Nicholas Owens, the SAMS director, said it was “one of the most exciting findings in marine science in recent times”.
The discovery of oxygen produced outside of photosynthesis “requires us to rethink how the evolution of complex life on the planet could have arisen”, he said.
“The conventional view is that oxygen was first produced about 3 billion years ago by ancient microbes called cyanobacteria and that there was a gradual development of complex life after that,” Owens said.
Sweetman said the team’s discovery showed that “life could have started elsewhere than on land”.
“And if the process occurs on our planet, could it help generate oxygen-rich habitats on other ocean worlds such as Enceladus and Europa and provide the opportunity for life to exist?” he said.
the study room, published in the journal Nature Geosciencewas partially funded by Canada’s The Metals Company, which aims to start mining the nodules in the CCZ next year.
