Photo for representational purposes only. Source: Unsplash
Paris: In the total darkness of the depths of the Pacific Ocean, scientists have discovered oxygen being produced not by living organisms but by strange potato-shaped metallic lumps that give off almost as much electricity as AA batteries.
The surprise finding has many potential implications and could even require rethinking how life first began on Earth, the researchers behind a new study said on Monday.
It had been thought that only living things such as plants and algae were capable of producing oxygen via photosynthesis -- which requires sunlight.
But four kilometres (2.5 miles) below the surface of the Pacific Ocean, where no sunlight can reach, small mineral deposits called polymetallic nodules have been recorded making so-called dark oxygen for the first time.
The discovery was made in the Clarion-Clipperton Zone (CCZ), an abyssal plain stretching 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, which are all used in batteries, smartphones, wind turbines and solar panels.
The international team of scientists sent a small vessel to the floor of the CCZ aiming to find out how mining could impact the strange and little understood animals living where no light can reach.
No sunlight required
"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.
To do so, they used a contraption called a benthic chamber which snatched up a bunch of sediment.
Normally, the amount of oxygen trapped in the chamber "decreases as its used up by organisms as they respire," 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.
This was so shocking that the researchers initially thought their underwater sensors must have been on the blink.
So they brought up some nodules to their ship to repeat the test. Once again, the amount of oxygen increased.
They then noticed how the nodules were carrying a startling electric change.
On the surface of the nodules, the team "amazingly found voltages almost as high as are in an AA battery," Sweetman said.
This charge could split seawater into hydrogen and oxygen in a process called seawater electrolysis, the researchers said.
This chemical reaction occurs at around 1.5 volts -- around the charge of a AA battery.
