Exploring the Mystery of ‘Dark’ Oxygen: Is It More Abundant Than We Realized?

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A surprising discovery was announced in July: metallic rocks on the seabed of the Pacific Ocean are producing oxygen, even where sunlight can’t reach. This shocking finding has sparked interest in the scientific community.

Researchers found that small, potato-sized nodules rich in metals, located about 4,000 meters (13,100 feet) underwater in the Clarion-Clipperton Zone, can create an electrical charge. This charge breaks seawater into oxygen and hydrogen through a process called electrolysis. This challenges the belief that oxygen production is only possible through sunlight and photosynthesis.

Andrew Sweetman, a professor at the Scottish Association for Marine Science, is leading a three-year project to study this “dark” oxygen further. His team is using specialized equipment to explore depths of up to 11,000 meters (36,089 feet). This research project, funded by the Nippon Foundation at $2.7 million, aims to uncover more about this phenomenon.

The discovery of dark oxygen highlights how little we know about the deep ocean, particularly the Clarion-Clipperton Zone. This area is being examined for deep-sea mining of rare metals, crucial for modern technologies.

Sweetman described the finding as a significant shift in understanding deep-sea ecosystems and the potential for life on Earth. He also noted that this new research could help answer many questions raised by their discovery.

The project aims to figure out whether dark oxygen exists in other areas of the CCZ and determine how it is produced. This understanding may also assist scientists in their quest to find life beyond Earth.

While oxygen is typically generated by plants reliant on sunlight, other scientists have found unexpected oxygen in dark environments. Sweetman believes dark oxygen might be a more common occurrence than previously thought.

Research by microbiologist Emil Ruff revealed oxygen in groundwater samples deep beneath the Canadian prairie, isolated for tens of thousands of years. This suggests that microbes may have developed unique ways to produce oxygen in the absence of light.

Ruff’s studies showed these microbes could break down nitrites to create oxygen, supporting other life forms in the groundwater. His work emphasizes that nature often surprises us, revealing processes once thought impossible.

Ruff and his team have also sampled ancient water trapped in a South African mine that is about 3 kilometers deep (9,500 feet). They are investigating how oxygen forms in this setting, which contains known oxygen but unclear origins.

Potential explanations include radiolysis, a process where radioactive decay splits water molecules, or microbial activity similar to what Ruff observed in Canada. Sweetman’s project will explore whether microbial reactions play a role in dark oxygen production on the seafloor, specifically how hydrogen is generated during oxygen creation.

Nasa has shown interest in this research, as it relates to how life might exist on other planets without sunlight. By understanding energy needs for oxygen production in extreme environments, like the icy moons of Saturn and Jupiter, they hope to inform future missions.

Deep-sea mining companies aim to extract valuable metals from the seabed, which raises environmental concerns. Critics warn that such activities could damage fragile ecosystems and disrupt carbon storage in the ocean, potentially worsening climate change.

Sweetman believes it is crucial to fully understand the seabed ecosystem before exploiting its resources. He acknowledges the critical responses to his research and plans to address these through proper scientific channels.

Despite ongoing investigations, some scientists, like Amy Gartman from the US Geological Survey, have not seen the electrical activities reported by Sweetman. She emphasizes that scientific inquiry is a process, and it may take time to reach conclusive answers.