James' World 2

Click the link below the picture

.

The flat, pitch-black seabed of the Pacific Ocean’s Clarion-Clipperton Zone (CCZ) is littered with what looks like hunks of charcoal. These unassuming mineral deposits, called polymetallic nodules, host a unique deep-sea ecosystem, much of which scientists have yet to catalog. And the deposits are also a key target for companies that are looking to mine the deep sea because they contain metals, such as manganese and cobalt, that are used to make batteries.

Now researchers have discovered that these valuable nodules do something remarkable: they produce oxygen and do so without sunlight. “This is a totally new and unexpected finding,” says Lisa Levin, an emeritus professor of biological oceanography at the Scripps Institution of Oceanography, who was not involved in the research. The oxygen gas on planet Earth is typically understood to come from living organisms that convert sunlight, carbon dioxide and water into oxygen and sugar. The idea that some of the gas may come from these inanimate minerals and be produced in total darkness “really strongly goes against what we traditionally think of as where oxygen is made and how it’s made,” says Jeffrey Marlow, a microbiologist at Boston University and a co-author of the study, which was published on Monday in Nature Geoscience.

The story of discovery goes back to 2013, when deep-sea ecologist Andrew Sweetman was facing a frustrating problem. He was part of a research team that had been trying to measure how much oxygen organisms on the CCZ seafloor consumed. The researchers sent landers down more than 13,000 feet to create enclosed chambers on the seabed that would track how oxygen levels in the water fell over time.

But oxygen levels did not fall. Instead they rose significantly. Thinking the sensors were broken, Sweetman sent the instruments back to the manufacturer to be recalibrated. “This happened four or five times” over the course of five years, says Sweetman, who studies seafloor ecology and biogeochemistry at the Scottish Association for Marine Science. “I literally told my students, ‘Throw the sensors in the bin. They just do not work.’”

Then, in 2021, he was able to go back to the CCZ on an environmental survey expedition sponsored by a deep-sea mining firm called the Metals Company. Again, his team used deep-sea landers to make enclosed chambers on the seafloor. The chambers enclosed encased sediment, nodules, living organisms and seawater and monitored oxygen levels. Sweetman and his team used a different technique to measure oxygen this time, but they observed the same strange results: oxygen levels increased dramatically.

“Suddenly I realized that … I’d been ignoring this hugely significant process, and I just kicked myself,” Sweetman says. “My mindset completely changed [to] focus on what is causing this.”

“My first thought was microbiology, and that’s because I’m a microbiologist,” Marlow says. It wasn’t a far-fetched idea: scientists had recently uncovered some ways that microbes such as bacteria and archaea could generate “dark oxygen” in the absence of sunlight. In lab tests that reproduced conditions on the seafloor in the new study, the researchers poisoned the seawater with mercury chloride to kill off microbes. Yet the oxygen levels still increased.

If this dark oxygen didn’t come from a biological process, then it must have come from a geological one, the researchers reasoned. They tested and ruled out a few possible hypotheses—such as that radioactivity in the nodules was separating oxygen out of the seawater or that some other environmental factor was separating oxygen gas out of the manganese oxide in the nodules.

.

.

.

Click the link below for the article:

.

__________________________________________