For a long time, it was considered a common belief that all oxygen in the earth is due to photosynthesis, the process in which plants use sunlight energy to convert carbon dioxide and water into oxygen and sugars. All the oxygen found in dark ocean depths where sunlight could not penetrate was considered as defusing from the upper side. But currently scientists are closer to identifying the existence of “dark oxygen”, this is the oxygen which is not produced as the byproduct of photosynthesis.
“Dark oxygen” refers to the surprising discovery that oxygen can be produced in environments without sunlight, challenging the traditional belief that oxygen generation is solely tied to photosynthesis. This phenomenon has been observed in the deep ocean, particularly around polymetallic nodules on the seafloor. These nodules, rich in metals like manganese, cobalt, and nickel, can act like batteries, generating a small voltage that drives electrochemical reactions. These reactions split water molecules, producing oxygen through a process akin to electrolysis.
Scientists first encountered this in the Clarion-Clipperton Zone (CCZ) in the Pacific Ocean, where oxygen levels in deep seawater unexpectedly rose. Initially, they believed their instruments were faulty, but further research confirmed that the oxygen was being produced by the interaction of these metal-rich nodules with the surrounding water.
Dark oxygen production could play a previously unknown role in the global oxygen cycle. This has implications for climate models and our understanding of how deep-sea ecosystems contribute to overall oxygen levels on Earth. It suggests that oxygen generation in the deep sea could be more significant than previously thought.
The fact that oxygen can be produced in environments devoid of light raises intriguing possibilities about the origins of life on Earth and the potential for life on other planets or moons with similar conditions, such as Europa or Enceladus.
The polymetallic nodules responsible for dark oxygen production are also rich in rare earth metals crucial for green technologies. This presents a dilemma as these nodules are targeted for deep-sea mining. Understanding their role in oxygen production could influence decisions about how to manage and regulate deep-sea resource extraction.
