In a groundbreaking discovery, scientists have revealed that oxygen is being produced in the deep sea through a process associated with polymetallic nodules on the seafloor of the Pacific Ocean, in the complete absence of sunlight. This finding challenges what is known about how oxygen reaches the deep ocean and how oxygen is produced. There may also be important implications for how deep-sea mining could impact this extraordinary process.
Until now, it has been understood that the deep ocean is oxygenated by the global conveyor-belt-like system of ocean currents that transport oxygen-rich waters from the surface to the deep sea. The findings of a new study published today in Nature Geoscience challenge this notion, documenting oxygen production at the abyssal seafloor. The discovery was made during experiments conducted in the Clarion-Clipperton Zone CCZ , the first target area for deep-sea mining, at over 4, meters below the surface.
While studying biological activity around polymetallic nodules in the CCZ, scientists made the surprising discovery that instead of oxygen levels decreasing over time, in some places they tripled in just two days.
Further investigation discovered that these polymetallic nodules may be able to produce enough voltage to split water molecules into hydrogen and oxygen, a process known as seawater electrolysis. This phenomenon, never before observed in the deep ocean, appears to be unique to these deep-sea nodules. This research emphasizes just how much we still have to discover and learn about the deep sea and raises more questions about how deep-sea mining could impact deep-sea life and processes.
It is human arrogance to continue to push to mine these nodules that are producing potential life-sustaining oxygen in an extraordinarily important and unique ecosystem. It is currently unknown how the removal or smothering of these nodules from deep-sea mining operations and the associated sediment plumes could influence seafloor oxygen production and what the impacts on deep-sea life and processes, including carbon cycling, could be.
