A deep-sea shark and several eels are attracted to bait placed on the summit of Cook Sea Mount, photographed from the Pisces V submersible during a September 6, 2016 dive to the previously unexplored Cook Sea Mount off the coast of Hawaii.
Caleb Jones/AP
Hide caption
Toggle caption
Caleb Jones/AP
Researchers studying light-deprived features on the Pacific Ocean floor believe they have observed the production of “dark oxygen” there, potentially calling into question commonly held ideas about how oxygen is produced on Earth.
Until now, it was thought that oxygen could only be produced through photosynthesis, which requires sunlight, but this discovery calls into question that theory and raises new questions about the origin of life itself.
“So I think we need to rethink questions like where aerobic life began.” Andrew Sweetman says:“The continent is a very different place,” said a professor at the Scottish Institute for Marine Science in Oban, Scotland, in a news release.
Sweetman and his research team The survey results were announced Monday magazine article Nature Chemistry.
Scientists aren’t sure how oxygen is produced in such dark depths, but they think it’s produced by electrically charged minerals called polymetallic nodules. Size range From tiny particles to the size of a potato.
These nodules are “effectively batteries in the rocks,” Sweetman said, and they could use their electrical charge to split seawater into hydrogen and oxygen in a process called seawater electrolysis.
“The conventional view is that oxygen was first produced around 3 billion years ago by ancient microorganisms called cyanobacteria, and that complex life developed gradually thereafter,” Nicholas Owens, president of the Scottish Association for Marine Science, said in a news release. “The possibility of alternative sources requires a fundamental rethink.”
The researchers conducted tests on the ocean floor and also took samples to test on land, and came to the same result: elevated oxygen levels near the polymetallic nodules.
Seawater can be split into hydrogen and oxygen with just 1.5 volts of electricity, the power of a single AA battery, and the researchers found that some nodules could produce as much as 0.95 volts, and that multiple nodules together could produce even higher voltages.
The discovery could have implications for deep-sea mining
The polymetallic nodules contain metals such as manganese, nickel and cobalt, which can be used to make lithium-ion batteries used in consumer electronics and electric vehicles.
Franz Geiger, a chemistry professor at Northwestern University who worked on the study, said in a separate news release that an area of the Pacific Ocean known as the Clarion-Clipperton Zone could contain enough polymetallic nodules to meet global energy needs for decades to come.
But he also said mining must be done in a way that doesn’t deplete oxygen for the area’s creatures.
“If deep sea mining proves to be an opportunity to be pursued, we really need to be careful … it should be done to an extent and with a frequency that doesn’t harm life on the seafloor,” Geiger told NPR.
He said companies conducted deep-sea mining research missions in the 1970s and ’80s, and recent studies suggest those missions may have affected marine life in the area for decades.
“A few years ago, a team of marine biologists revisited the area that had been mined 40 years ago and found essentially no life,” Geiger said, “but the veins on either side, a few hundred metres away, still had intact nodules and were abundant with life.”
