Scientists have discovered a previously unknown source of oxygen at a depth of over 4,000 meters below the surface of the Pacific Ocean, in the Clarion-Clipperton Zone. This phenomenon, called “dark oxygen,” challenges the existing belief that oxygen on Earth comes exclusively from photosynthesis by organisms living in sunlight. 

The mechanism of oxygen production without light 

Research conducted by a team led by Andrew Sweetman of the Scottish Association for Marine Science has shown that polymetallic nodules on the ocean floor can generate oxygen in complete darkness. Experiments conducted both in situ and in the laboratory have shown an increase in oxygen concentration in closed chambers containing these nodules. It is believed that this process occurs as a result of the electrolysis of seawater, initiated by small electrical voltages generated by minerals contained in the nodules, such as manganese, cobalt, nickel, and copper. 

Significance for deep-sea ecosystems 

This discovery has important implications for understanding the functioning of deep-sea ecosystems. Until now, it was believed that in such conditions, oxygen is only consumed and not produced. New data suggest that polymetallic nodules may be a local source of oxygen, supporting life in these extreme environments. This discovery may also shed new light on the origins of life on Earth, indicating that oxygen may have been available in the deep ocean early in the development of the biosphere. 

Challenges of ocean floor exploitation 

Polymetallic nodules are also of interest to the mining industry because of their content of metals used in technology, such as batteries. However, their potential role in oxygen production raises questions about the safety of their exploitation. Scientists are calling for caution and thorough research before beginning large-scale mining operations, so as not to disturb delicate deep-sea ecosystems. 

Although the mechanism of “dark oxygen” production is not yet fully understood, this discovery opens up new avenues of research in oceanography and marine biology. Understanding this process could be crucial for the protection of the marine environment and for the search for life in extreme conditions, both on Earth and on other planets. 

Sources: Nature