Metallic minerals on the ocean floor about 4 km deep split water to generate oxygen in complete darkness

Amazing stuff! This discovery may impact future deep sea mining!

"The surprising discovery challenges long-held assumptions that only photosynthetic organisms, such as plants and algae, generate Earth's oxygen. But the new finding shows there might be another way. It appears oxygen also can be produced at the seafloor—where no light can penetrate—to support the oxygen-breathing (aerobic) sea life living in complete darkness. ...
“Several large-scale mining companies now aim to extract these precious elements from the seafloor at depths of 10,000 to 20,000 feet below the surface. We need to rethink how to mine these materials, so that we do not deplete the oxygen source for deep-sea life.” ...

To investigate this hypothesis, ... shipped several pounds of the polymetallic nodules collected from the ocean floor to ... laboratory ...

Just 1.5 volts — the same voltage as a typical AA battery — is enough to split seawater into hydrogen and oxygen. Amazingly, the team recorded voltages of up to 0.95 volts on the surface of single nodules. And when multiple nodules clustered together, the voltage can be much more significant, just like when batteries are connected in a series. ..."

From the abstract:

"Deep-seafloor organisms consume oxygen, which can be measured by in situ benthic chamber experiments. Here we report such experiments at the polymetallic nodule-covered abyssal seafloor in the Pacific Ocean in which oxygen increased over two days to more than three times the background concentration, which from ex situ incubations we attribute to the polymetallic nodules. Given high voltage potentials (up to 0.95 V) on nodule surfaces, we hypothesize that seawater electrolysis may contribute to this dark oxygen production."

Metallic minerals on the deep-ocean floor split water to generate 'dark oxygen,' new study finds An international team of researchers, including a Northwestern University chemist, has discovered that metallic minerals on the deep-ocean floor produce oxygen—[4.000 m) below the surface.

Deep-ocean floor produces its own ‘dark oxygen’ (original news release) New study finds metallic minerals act as geobatteries to split water

Evidence of dark oxygen production at the abyssal seafloor (open access)