"Discovery of 'Dark Oxygen' in Deep-Sea Metal Nodules May Challenge Theories on the Origins of Life"
In a pioneering breakthrough, researchers studying the Clarion-Clipperton Zone in the North Pacific Ocean have uncovered a fascinating phenomenon: metallic nodules on the ocean floor are capable of producing their own form of oxygen, known as "dark oxygen."
These intriguing polymetallic nodules, roughly the size of potatoes, are made up of iron and manganese oxides and also harbor precious metals such as cobalt and rare earth elements.
Potato-sized metallic nodules scattered across the Pacific Ocean seafloor are generating oxygen in total darkness, without any biological assistance, new research shows.
This groundbreaking discovery of "dark oxygen" is the first instance where scientists have observed oxygen production independent of living organisms, potentially reshaping our understanding of how life may have originated on Earth.
“When we first analyzed the data, we suspected the sensors were malfunctioning, as all previous deep-sea studies have only observed oxygen being consumed, not produced,” said Andrew Sweetman, lead author of the study and a professor at the Scottish Association for Marine Science (SAMS).
“However, when the instruments consistently showed the same results, we realized we had stumbled upon something truly groundbreaking and unexpected,” he added.
The findings, published on Monday (July 22) in *Nature Geoscience*, indicate that small metallic nodules in the Clarion-Clipperton Zone of the North Pacific produce oxygen through a process called seawater electrolysis. This occurs when seawater splits into oxygen and hydrogen due to an electric charge.
The charge likely arises from the difference in electric potential between metal ions within the nodules, leading to a redistribution of electrons, according to the study.
Polymetallic knobs, usually tracked down on the deep fields of the sea — level ocean bottom locales situated between 10,000 and 20,000 feet (3,000 to 6,000 meters) profound — are wealthy in iron and manganese oxides. These knobs additionally contain significant metals like cobalt, nickel, and lithium, as well as uncommon earth components like cerium, which are indispensable for hardware and maintainable innovations.
Sweetman and his team initially set out to explore how mining polymetallic nodules might impact the seafloor ecosystem in the (CCZ), an immense abyssal plain stretching about 1.7 million square miles (4.5 million square kilometers) between Hawaii and Mexico. To assess this, they used specialized experimental chambers to track changes in oxygen levels at various locations.
Traditionally, oxygen levels diminish with depth due to reduced light and a decline in photosynthetic life, leading to lower oxygen production. Surprisingly, their findings showed a steady emission of oxygen from the seabed, defying the expected decline.
The discovery of dark oxygen 13,000 feet (4,000 meters) beneath the ocean's surface, where no light reaches, challenges the long-held belief that Earth's oxygen is solely produced through photosynthesis (and, to a lesser extent, through the oxidation of ammonia, which yields only minimal amounts of oxygen that are quickly used up). This finding prompts new questions about the origins of life on Earth, which dates back roughly 3.7 billion years, according to Sweetman.
“For aerobic life to have started on Earth, there must be oxygen, and we’ve always believed that this oxygen originated from photosynthetic organisms,” he explained. “However, with the discovery of oxygen production in the deep sea, where no light is present, we need to reconsider some fundamental questions, such as: where could aerobic life have first emerged?”
The findings also bring up new concerns about the potential mining of polymetallic nodules, which may be crucial for providing oxygen to deep-sea ecosystems, Sweetman noted.
“This discovery has raised numerous unanswered questions,” he said. “We now have much to consider regarding how we mine these nodules, which function like batteries within rocks.”
