Scientists have made a groundbreaking discovery that could revolutionise our understanding of life on Earth. Researchers have found that metallic minerals on the deep-ocean floor can produce oxygen in complete darkness, a process that challenges long-held beliefs about the origins of life and the role of photosynthesis.
This discovery was made by an international team, including researchers from the Scottish Association for Marine Science (SAMS) and Northwestern University, and published in the journal Nature Geoscience.
Andrew Sweetman, of SAMS, made the “dark oxygen” discovery while conducting ship-based fieldwork in the Pacific Ocean. Northwestern’s Franz Geiger led the electrochemistry experiments, which potentially explain the finding, said a press release by the Illinois-based university.
The big discovery
The study began when Sweetman, head of the Seafloor Ecology and Biogeochemistry research group at SAMS, recorded unusual oxygen readings from the bottom of the Pacific Ocean in 2013.
Initially suspecting equipment malfunction, Sweetman and his team repeatedly recalibrated their sensors, but the readings persisted. By 2021 and 2022, the team returned to the Clarion-Clipperton Zone, a mineral-rich area in the central Pacific, and confirmed their findings using different methods.
“We basically told my students, just put the sensors back in the box. We’ll ship them back to the manufacturer and get them tested because they’re just giving us gibberish,” Sweetman told CNN. “And every single time the manufacturer came back: ‘They’re working. They’re calibrated.’”
The role of polymetallic nodules
Polymetallic nodules, which are naturally occurring mineral masses found on the ocean floor, play a crucial role in this newly discovered process. These nodules, made up of metals like manganese, iron, cobalt, nickel, copper, and lithium, can generate oxygen through electrochemical activity even in the absence of light.
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“The polymetallic nodules that produce this oxygen contain metals such as cobalt, nickel, copper, lithium and manganese — which are all critical elements used in batteries,” said Geiger, who co-authored the study.
“Several large-scale mining companies now aim to extract these precious elements from the seafloor at depths of 10,000 to 20,000 feet below the surface. We need to rethink how to mine these materials, so that we do not deplete the oxygen source for deep-sea life.”
How this find will affect deep-sea mining
The discovery has significant implications for the deep-sea mining industry, which seeks to harvest these valuable minerals for green energy technologies. Environmentalists and scientists have expressed concerns about the impact of deep-sea mining on ocean ecosystems.
Past mining activities in the 1980s resulted in “dead zones” where even bacteria had not recovered decades later, highlighting the potential long-term damage to marine life.
“In 2016 and 2017, marine biologists visited sites that were mined in the 1980s and found not even bacteria had recovered in mined areas,” Geiger said.
“In unmined regions, however, marine life flourished. Why such ‘dead zones’ persist for decades is still unknown. However, this puts a major asterisk onto strategies for sea-floor mining as ocean-floor faunal diversity in nodule-rich areas is higher than in the most diverse tropical rainforests.”
The big question
The study challenges the traditional understanding that Earth’s oxygen supply began with photosynthetic organisms. The newly discovered process suggests that oxygen could have been produced in the deep ocean, supporting aerobic life before photosynthesis evolved.
This finding necessitates a reevaluation of how and where aerobic life may have begun on Earth.
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“This could be a kind of game changer in the story about how life started,” said Tobias Hahn, another co-author of the study, in an interview.
“We thought that life began on Earth when photosynthesis kicked in, as oxygen was brought to Earth through photosynthesis. It could be that actually, this process of electrochemically dividing water into oxygen and hydrogen supplied oxygen to the ocean.”
What the future holds…
While the discovery opens new avenues for understanding deep-sea ecosystems and the origins of life, many questions remain. Researchers are still trying to determine the extent of oxygen production by polymetallic nodules, the specific electrochemical processes involved, and the potential impacts on marine life if these nodules are disturbed.
Bo Barker Jørgensen, a marine biogeochemistry expert, who peer-reviewed the study told Washington Post“What is lacking is an understanding of what is going on, what kind of process this is.”
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Sweetman highlighted the need for further studies before any deep-sea mining activities commence. “If there’s oxygen being produced in large amounts, it’s possibly going to be important for the animals that are living there.”
With inputs from agencies