Discovering a Hidden Source of Oxygen on the Deep Seafloor
Scientists have found surprising evidence that mineral-rich rocks called polymetallic nodules on the deep seabed may produce oxygen—even without sunlight.
What Did the Researchers Do?
The team placed special devices called benthic chambers on the ocean floor in an area filled with rocks that were high rich in valuable metals and rare earth elements. They measured oxygen levels over a couple of days and found that oxygen increased a lot—up to three times more than expected. Even when they added chemicals to stop biological activity, the oxygen still increased. This suggests that the nodules themselves might be responsible.
The nodules sometimes show high voltage readings, up to 0.95 volts. The researchers think that these electrical properties might drive a reaction similar to electrolysis, turning seawater into oxygen.
Why Is This Important?
This discovery is important because it could provide a new oxygen source for deep-sea life and influence how we understand the ocean’s chemistry. The extra oxygen produced by these nodules might help support life in areas where oxygen is otherwise limited. In addition, the study raises questions about the potential impacts of deep-sea mining; if mining disturbs these nodules, it could change the natural process of oxygen production on the seafloor. Understanding this process may also offer clues about how oxygen levels on Earth have changed over millions of years, linking deep-sea geochemistry with broader environmental and evolutionary processes.
This finding also bridges a gap between oceanography and physics. The proposed “geo-battery” mechanism, where electrical potentials on polymetallic nodules drive seawater electrolysis, is fundamentally an electrochemical process—one that is of great interest in the field of physics. Research into natural battery systems can offer insights into energy conversion, electron transfer, and catalysis, areas that are critical in condensed matter physics and materials science. Furthermore, understanding how these natural processes work might inspire new approaches in renewable energy technologies, by mimicking nature’s own methods of harnessing and transforming energy.
Strengths and Questions
The study from Nature Geoscience has several strengths that make its findings reliable. The experiments were well-designed and carefully controlled, with multiple tests and methods used to ensure that the oxygen increases were real. However, there are still some open questions. The exact details of how the “geo-battery” mechanism works need further investigation, and it is not yet clear if the same process occurs in other deep-sea areas. Moreover, even though the experiments tried to rule out the influence of living organisms, the complex nature of deep-sea environments means that more research is needed to fully understand any potential biological contributions.
Reference Material – Sweetman, A.K., Smith, A.J., de Jonge, D.S.W. et al. Evidence of dark oxygen production at the abyssal seafloor. Nat. Geosci. 17, 737–739 (2024). https://doi.org/10.1038/s41561-024-01480-8
Image Rights – Hunt, K. (2025). Scientists discover ‘dark’ oxygen being produced more than 13,000 feet below the ocean surface. [online] Cnn.com. Available at: https://media.cnn.com/api/v1/images/stellar/prod/cerianthid-hires.jpg?c=16×9&q=h_653
