2024-07-22 15:21:23
Image of the seabed in the Clarion-Clipperton fracture zone in the Pacific Ocean, provided by the National Oceanography Centre on July 24, 2023 ( National Oceanography Centre / Smartex project (NERC) / Handout )
In the depths of the Pacific Ocean and complete darkness, scientists have astonishingly discovered oxygen coming not from living organisms but from types of pebbles containing metals, which calls into question the theory about the origins of life on Earth.
This strange “black oxygen” was detected at more than 4 kilometers deep, in the abyssal plain of the Clarion-Clipperton geological fracture zone in the central Pacific, according to a study published on Monday.
A prime target for deep-sea mining due to the presence of polymetallic nodules, mineral concretions rich in metals (manganese, nickel, cobalt…) necessary for the manufacturing of batteries for electric vehicles, wind turbines, solar panels, and mobile phones.
It is in this area that a ship from the Scottish Association for Marine Science (SAMS) conducted sampling, funded by The Metals Company and UK Seabed Resources, who are vying for these precious nodules.
The aim of the research: to assess the impact of such exploration on an ecosystem where the absence of light prevents photosynthesis and thus the presence of plants, but which is teeming with unique animal species.
“We were trying to measure the oxygen consumption” of the ocean floor, by placing its sediments under bells called benthic chambers, explains Andrew Sweetman, the lead author of the work published in Nature Geoscience, to AFP.
Logically, the trapped seawater should have seen its oxygen concentration decrease as it was consumed by living organisms at these depths.
Instead, the opposite was observed: “the oxygen level increased in the water above the sediments, in complete darkness and therefore without photosynthesis,” elaborates Professor Sweetman, head of the marine ecology and biogeochemistry research group at SAMS.
– Batteries in the rock –
The surprise was such that the researchers initially thought their underwater sensors had malfunctioned.
They conducted experiments on board their ship to see if the same thing occurred at the surface, by incubating these same sediments and the nodules they contained in the dark. Once again, they found that the oxygen levels increased.
“At the surface of the nodules, we detected an electric potential almost as high as that of an AA battery,” describes Professor Sweetman, comparing these nodules to “batteries in the rock.”
These astonishing properties could be the origin of a water electrolysis process that separates its molecules into hydrogen and oxygen using an electric current. This chemical reaction occurs at around 1.5 volts – the voltage of a battery – that the nodules could reach when grouped together, according to a statement from SAMS attached to the study.
“The discovery of oxygen production through a process other than photosynthesis encourages us to rethink how life arose on Earth,” linked to the appearance of oxygen, comments Professor Nicholas Owens, director of SAMS.
The “conventional” view being that oxygen “was first produced about 3 billion years ago by cyanobacteria, which led to the development of more complex organisms,” elaborates the scientist.
“Life could have started elsewhere than on dry land and near the ocean surface,” suggests Professor Sweetman. “Since this process exists on our planet, it could generate oxygenated habitats in other ‘ocean worlds’ like Enceladus or Europa (moons of Saturn and Jupiter)” and create the conditions for the emergence of extraterrestrial life.
He hopes that his findings will allow for “better regulation” of deep-sea mining, based on more precise environmental information.