Discovery of ‘Dark Oxygen’ in the Deep Sea and Its Potential for Mars Terraforming
Scientists have discovered that certain deep-sea metallic nodules are producing significant amounts of oxygen through an unknown process. This phenomenon, dubbed ‘dark oxygen’ production, could play a crucial role in shaping ocean ecosystems and even have applications for making Mars more habitable.
A Breakthrough in Oxygen Production
Chaornin Sun and his research team at the Chinese Academy of Sciences in Beijing have identified two species of deep-sea bacteria capable of generating large amounts of oxygen. This discovery challenges the long-standing belief that all oceanic oxygen is produced through photosynthesis—where light energy splits water molecules into oxygen and hydrogen.
For decades, scientists believed that oxygen production in the ocean only occurred in the sunlit upper layers, driven by photosynthetic organisms. However, in recent years, researchers have found that certain bacteria and archaea can produce oxygen in darkness, though only in small, seemingly insignificant amounts.
Revisiting an Earlier Controversy
In 2013, Andrew Sweetman from the Scottish Association for Marine Science detected oxygen production at extreme depths on the abyssal plain. Initially, he dismissed it as an instrument error. However, after repeated findings, his team began investigating further. Last year, they published a controversial study claiming that metallic nodules found on the seabed were producing enough oxygen to influence local ecosystems and potentially play a role in the evolution of life.
Critics raised objections, particularly pointing out that the nodules contain manganese oxide, a compound that can only form in the presence of oxygen. This cast doubt on whether these nodules were genuinely a source of oxygen or merely interacting with existing oxygen in the environment.
A Newly Discovered Biological Process
Now, Sun’s team has identified a new biological process that may explain the mystery. They found that when two specific strains of deep-sea bacteria are exposed to nitrate ions, they convert the nitrates into ammonia while simultaneously releasing oxygen. This process, independent of light, could be responsible for the unexpected oxygen levels found in deep-sea environments.
“The amount of oxygen produced is astonishing,” says Sun. “This mechanism does not rely on sunlight or traditional photosynthesis, making it a significant discovery.”
Their experiments showed that the concentration of dissolved oxygen produced through this reaction is over 300 times higher than previously known ammonia-oxidizing archaea. This means that the process could be widespread in nitrate-rich ocean environments and may support various oxygen-dependent microorganisms and even small marine animals.
Implications for Terraforming Mars
One of the most exciting implications of this discovery is its potential for Mars. Scientists have already detected nitrates on Mars, meaning that this bacterial process could theoretically be used to generate oxygen on the planet. Sun’s research suggests that Mars’ conditions may be sufficient to support microbial nitrate-dependent oxygen production, providing a new strategy for long-term terraforming efforts.
“This microbial oxygen production could serve as a significant oxygen source in environments where sunlight is scarce,” the study notes. This could be a crucial step in making Mars habitable for future human exploration.
Are Deep-Sea Bacteria Creating Metallic Nodules?
Another fascinating aspect of Sun’s research is the potential connection between these bacteria and the formation of metallic nodules. His team observed that when manganese is present in the environment, it precipitates out as manganese oxide, suggesting that bacteria might be actively involved in the formation of these nodules.
This supports Sweetman’s earlier findings, where his team observed that oxygen seemed to be produced in the presence of metallic nodules. However, their attempts to rule out microbial involvement by using chemical agents to kill bacteria were inconclusive. Sweetman acknowledges that their approach may not have effectively reached all the bacteria present in the deep-sea sediments.
Further Research Needed
While the discovery is promising, scientists like Don Canfield from the University of Southern Denmark remain skeptical. He believes that while the results are intriguing, more research is needed to determine if this process is truly a significant source of oxygen in deep-sea environments.
“If this discovery holds up, it would be groundbreaking,” says Canfield. “But I have concerns about how widespread and impactful this process really is.”
Sweetman agrees that more research is necessary, noting that scientists continue to uncover new microbial processes that challenge previous assumptions about deep-sea ecosystems.
The Impact on Deep-Sea Mining
The debate over deep-sea oxygen production has significant environmental implications. Many companies are interested in mining metallic nodules from the ocean floor, as they contain valuable minerals such as manganese, nickel, and cobalt. However, Sweetman warns that removing these nodules and the top layers of sediment could have long-lasting consequences.
“If the nodules and the top 10 centimeters of sediment are removed, it would take approximately 100,000 years for the ecosystem to return to its previous state,” he says. “We need to be mindful of how long these systems take to recover before engaging in large-scale mining operations.”
Conclusion
The discovery of dark oxygen production in the deep sea is a major scientific breakthrough, with implications ranging from oceanic ecosystems to potential Mars colonization. While more research is needed to fully understand this process, it challenges conventional wisdom about oxygen production and opens up new possibilities for both Earth’s deep-sea environments and space exploration.
