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JoeMerchant [soylentnews.org] writes:

https://www.sciencealert.com/mysterious-dark-oxygen-discovered-at-bottom-of-ocean-stuns-scientists [sciencealert.com]

Chugging quietly away in the dark depths of Earth's ocean floors, a spontaneous chemical reaction is unobtrusively creating oxygen, all without the involvement of life.

"The discovery of oxygen production by a non-photosynthetic process requires us to rethink how the evolution of complex life on the planet might have originated," says SAMS marine scientist Nicholas Owens.

Scatterings of polymetallic nodules carpet vast areas of the ocean's bottom. We value these exact metals for their use in batteries, and it turns out that's exactly how the rocks may be spontaneously acting on the ocean floor. Single nodules produced voltages of up to 0.95 V. So when clustered together, like batteries in a series, they can easily reach the 1.5 V required to split oxygen from water in an electrolysis reaction.

This discovery offers a possible explanation for the mysterious stubborn persistence of ocean 'dead zones' decades after deep sea mining has ceased.

"In 2016 and 2017, marine biologists visited sites that were mined in the 1980s and found not even bacteria had recovered in mined areas. In unmined regions, however, marine life flourished," explains Geiger.

"Why such 'dead zones' persist for decades is still unknown. However, this puts a major asterisk onto strategies for sea-floor mining as ocean-floor faunal diversity in nodule-rich areas is higher than in the most diverse tropical rainforests."

As well as these massive implications for deep-sea mining, 'dark oxygen' also sparks a cascade of new questions around the origins of oxygen-breathing life on Earth.

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