It calls into question the theory on the origins of life on Earth: a strange “black oxygen” discovered in the abysses of the Pacific Ocean

Cet “oxygène noir” a été détecté à plus de 4 kilomètres de profondeur, au centre du Pacifique. Illustration Unsplash – Jeremy Bishop

A strange "black oxygen" was discovered in the abyss of the Pacific Ocean, according to a study published this Monday, July 22, 2024.

In the abyss of the Pacific Ocean and the utter darkness, scientists have discovered with amazement oxygen coming not from oxygen. living organisms but of sorts of pebbles containing metals, which questions the theory on the origins of life on Earth.

At 4 km depth 

This strange "black oxygen" was detected at a depth of more than 4 kilometers, in the abyssal plain of the Clarion-Clipperton geological fracture zone, in the central Pacific, according to a study published Monday.

A target of choice for underwater mining due to the presence of polymetallic nodules, mineral concretions rich in metals (manganese, nickel, cobalt, etc.) necessary in particular for the manufacture of batteries for electric vehicles, wind turbines, photovoltaic panels and mobile phones.

It was in this area that a vessel from the Scottish Association for Marine Sciences (SAMS) carried out samples, financed by The Metals Company and UK Seabed Resources who covet these precious nodules.

"The oxygen level increased in the water'

Objective of the research: evaluate the impact of such prospecting on an ecosystem where the absence of light prevents photosynthesis and therefore the presence of plants, but which is full of species unique animals.

"We were trying to measure the oxygen consumption" of the ocean floor, by putting its sediments under bells called benthic chambers, Andrew Sweetman, first author of the work published in Nature Geoscience, explains to AFP.

Logically, the seawater thus imprisoned should have seen its oxygen concentration decrease, as the latter was consumed by living organisms at these depths.

However, the opposite was observed: "the oxygen level increased in the air ;water above the sediments, in complete darkness and therefore without photosynthesis", explains Professor Sweetman, head of the research group on the ecology and biogeochemistry of the seabed of the SAMS association.

"Rethinking how life appeared on Earth"

The surprise was such that the researchers initially thought their underwater sensors had made a mistake. They carried out experiments on board their ship to see if the same thing happened on the surface, by incubating these same sediments and the nodules they contained in the dark. And noted once again that the oxygen level was increasing.

"On the surface of the nodules, we detected an electrical voltage almost as high as in an AA battery", describes Professor Sweetman, comparing these nodules to "batteries in the rock".

"The discovery of oxygen production by a process other than photosynthesis prompts us to rethink how life appeared on Earth&quot ;, linked to the appearance of oxygen, comments Professor Nicholas Owens, director of SAMS.

"Life could have started elsewhere than on dry land"

The view "conventional" being that oxygen &quot ;was first made about 3 billion years ago by cyanobacteria which led to the development of more complex organisms", develops the scientist.

"Life could have started elsewhere than on dry land and near the surface of the ocean", argues Professor Sweetman. "Since this process exists on our planet, it could generate oxygenated habitats in other "ocean worlds" like Enceladus or Europa ( of the moons of Saturn and Jupiter)" and create the conditions for the appearance of extra-terrestrial life.

He hopes that his conclusions will make it possible to "better regulate" deep-sea mining, based on more accurate environmental information.