Potato-sized lumps of metal on the seafloor are generating oxygen, a new study has found.
Scientists previously believed that oxygen was strictly formed as a byproduct of photosynthesizing plants. However, these oxygen-producing bits of metal, called polymetallic nodules, were found in the deep ocean, far beyond the reach of the sun’s rays.
Researchers made the discovery in the Clarion-Clipperton Zone, a long stretch of Pacific Ocean that extends from near Hawaii to off the coast of Mexico. Scientists had noted the presence of oxygen in the area more than a decade ago.
“I just ignored it, because I’d been taught – you only get oxygen through photosynthesis,” lead researcher Andrew Sweetman with the Scottish Association for Marine Science told the BBC.
Sweetman’s team took samples of the seafloor roughly 4,000 meters (13,000 feet) below the surface with an autonomous research lander that pushed a chamber into the sediment to create an enclosed microcosm of the seafloor. They used instruments mounted on the chambers to measure the oxygen inside them every 10 seconds.
They consistently found more oxygen accumulating in the chambers than was being consumed by deep-seafloor organisms, meaning it was being produced on sight. Before this work, deep sea oxygen was believed to come from ocean currents that deliver it from the surface to the depths.
Researchers hypothesize that the oxygen is produced via electrolysis. Essentially, the metal nodules produce electricity like a battery and with that energy they can split a water molecule, H2O, into its component parts, hydrogen and oxygen, thus producing oxygen in the dark ocean floor.
This discovery “challenges not only what we know about life in the ocean, but life on this planet and other planets,” Diva Amon wrote Mongabay in an email. Amon is a scientific advisor with the Benioff Ocean Science Laboratory at the University of California and was not involved with this study.
Historically scientists focused their search for life beyond Earth by looking for microbes that get their energy from chemicals. “That still may be the best approach, but this result shows that it might be wise to expand our perspective,” Jeff Marlow, a Boston University biologist and co-author of the paper, noted in a statement.
The battery-like properties that make these nodules effective at producing oxygen are the very same that make them valuable for people. They are a potentially huge source of copper, nickel, cobalt, iron, manganese, and rare earth elements that are essential for creating renewable energy technologies. Deep-sea mining companies have taken notice, and are developing the technology to harvest and process the nodules.
However, activist Sofia Tsenikli with the Deep Sea Conservation Coalition is calling for a moratorium on deep sea mining until the importance of this new source of oxygen is more well-understood.
“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,” Tsenikli said in a statement.
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