Scientists have made a surprising discovery of dark oxygen in the deep sea nodules! Instead of just consuming oxygen, as previously thought, certain areas of the seafloor are actually producing it! This unexpected finding challenges our understanding of the deep ocean’s ecosystem. Researchers studying the Clarion–Clipperton Zone (CCZ) found that polymetallic nodules – mineral-rich rocks on the seabed – seem to be the key.
Unexpected Dark Oxygen Production
The team used special underwater chambers to measure oxygen levels near these nodules. Much to their surprise, they discovered a net dark oxygen production (DOP) rather than the expected consumption. This means more oxygen was appearing than disappearing in the experimental chambers! This net oxygen production ranged from 1.7 to 18 mmol O2 m−2 d−1.
The Geo-Battery Hypothesis
So, what’s causing this oxygen production? The scientists propose a fascinating geo-battery hypothesis. They suggest that the nodules themselves act like a battery, creating a potential difference which drives the electrolysis of seawater – splitting water molecules into oxygen and hydrogen. This process is normally energy-intensive, but it seems the nodules’ unique composition of metal ions helps to make this reaction possible.
Nodules: Tiny Deep Sea Powerhouses?
Measurements taken of the electrical potential across different points on the nodules revealed voltages as high as 0.95 V. This voltage difference, which varies across the different nodule surfaces, is a possible driver of the observed dark oxygen production. Although further research is needed to confirm this “geo-battery” theory, it certainly adds a new layer of complexity to deep ocean processes.
Further Research Needed
While this discovery is exciting, more research is needed. Scientists are eager to find out more about how much oxygen is produced, how long this production lasts and how this impacts the entire deep sea ecosystem. The role of various metals in these nodules also requires further investigation. This research opens up exciting new fields of inquiry and may impact how we understand the deep sea environment.
Revolutionizing Our Understanding of the Deep Ocean
This unexpected finding challenges our current understanding of how oxygen cycles in the deep ocean. The discovery of dark oxygen production from polymetallic nodules adds a new dimension to our understanding, implying that the deep ocean may be much more dynamic than previously assumed. This has potential ramifications for a range of studies involving the deep sea. This incredible discovery could also have implications for marine ecosystems and geological processes in the deep sea.
Reference
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
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