Jul 22. () –
An international team of researchers, including a chemist from Northwestern University (United States), has discovered that Metallic minerals from the deep ocean floor produce oxygen, 13,000 feet below the surfaceThe study is published in the journal ‘Nature Geoscience’.
The surprising discovery challenges long-held assumptions that only photosynthetic organisms, such as plants and algae, generate Earth’s oxygen. The new finding shows there could be another way. It appears that oxygen can also be produced on the seafloor, where light cannot penetrate, to support oxygen-breathing (aerobic) marine life that lives in complete darkness.
Specifically, Andrew Sweetman, from the Scottish Association for Marine Science (SAMS), made the discovery of the “dark oxygen”“while doing field work from a ship in the Pacific Ocean. Franz Geiger of Northwestern led the electrochemistry experiments, which possibly explain the finding.”For aerobic life to begin on the planet, there had to be oxygen, and until now we knew that the supply of oxygen to the Earth began with photosynthetic organisms.“, says Sweetman, who heads the Deep Sea Ecology and Biogeochemistry research group at SAMS.
“But now we know that oxygen is produced in the deep sea, where there is no light. So I think we need to ask ourselves again questions like: Where could aerobic life have started?”
Polymetallic nodules (natural mineral deposits that form on the ocean floor) are the basis of the discovery. These nodules, which are a mixture of various minerals, range in size from tiny particles to the size of an average potato.
“The polymetallic nodules that produce this oxygen contain metals such as cobalt, nickel, copper, lithium and manganese, all of which are essential elements used in batteries,” says Geiger, co-author of the study.
“Several large-scale mining companies are now looking to extract these precious elements from the seabed at depths of between 3,000 and 6,000 metres below the surface. We need to rethink how to extract these materials, so as not to deplete the source of oxygen for life in the deep sea.”
Sweetman made the discovery while sampling the seafloor of the Clarion-Clipperton Zone, a mountainous underwater ridge that stretches nearly 4,500 miles across the northeast quadrant of the Pacific Ocean. When his team initially detected oxygen, he assumed the equipment must be faulty..
“When we first got this data, we thought the sensors were faulty because all the deep-sea studies had only looked at oxygen being consumed rather than produced,” Sweetman said. “We would go back home and recalibrate the sensors, but over the course of 10 years, these strange oxygen readings kept coming back. We decided to use an alternative method that worked differently than the optode sensors we were using. When both methods yielded the same result, we knew we were onto something groundbreaking and unthinkable.”
In the summer of 2023, Sweetman reached out to Geiger to discuss possible explanations for the source of the oxygen. In his previous work, Geiger found that rust, when combined with saltwater, can generate electricity. The researchers wondered if the polymetallic nodules in the deep ocean generated enough electricity to produce oxygen. This chemical reaction is part of a process called seawater electrolysis, which strips electrons from the oxygen atom in water.
To investigate this hypothesis, Sweetman sent several kilograms of polymetallic nodules, which were collected from the ocean floor, to Geiger’s lab at Northwestern. Sweetman also visited Northwestern last December and spent a week in Geiger’s lab. Just 1.5 volts (the same voltage as a regular AA battery) is enough to split seawater. Amazingly, The team recorded voltages of up to 0.95 volts on the surface of individual nodules.And when several nodes are grouped together, the voltage can be much more significant, as when batteries are connected in series.
“We seem to have discovered a natural ‘geobattery,'” Geiger says. “These geobatteries are the basis for a possible explanation of dark oxygen production in the ocean.” The researchers agree that the mining industry should take this discovery into account before planning deep-sea mining activities. According to Geiger, the total mass of polymetallic nodules in the Clarion-Clipperton zone alone is enough to meet global energy demand for decades. But Geiger sees the mining activities of the 1980s as a warning.
“In 2016 and 2017, marine biologists visited sites that were mined in the 1980s and found that not even bacteria had recovered in the mined areas.“, Geiger points out.
“However, in unexploited regions, marine life flourished. It is still unknown why such ‘dead zones’ persist for decades. However, This puts a major asterisk on strategies for deep seabed mining, as the diversity of ocean floor fauna in nodule-rich areas is greater than in more diverse rainforests.“, he concludes.
Add Comment