The discovery of “dark oxygen” on the Pacific Ocean floor is a challenge to the notion of the origins of life in marine biology
A few years ago, a team of marine biologists went back to the areas that were mined four decades ago and found no life. “And then a few hundred meters over to the left and right, where the nodules were intact, plenty of life.”
The researchers think they have discovered “dark oxygen” being created on the Pacific Ocean floor, which could challenge traditional beliefs about how oxygen is produced.
Seawater can be split into hydrogen and oxygen with 1.5 volts of electricity, which is the amount in a AA battery. Researchers found out that some of the nodules possessed higher-than-normal voltages and that there were many more of them.
Nicholas Owens, the director of the Scottish Association for Marine Science said that the conventional view is that oxygen was produced around three billion years ago by ancient microbes, and that there was a progression of complex life thereafter. “The potential that there was an alternative source requires us to have a radical rethink.”
Sweetman first noticed something strange in 2013. He and his team had been working to measure the oxygen flow in confined areas. The flow of oxygen seemed to increase at the seafloor, despite the fact that there were no photosynthesizing organisms nearby, so much so that the researchers thought it was an instrumental anomaly.
Where Did Oxygen Start on Earth? Scientists Revisiting Polymetal Nodules in the Clarion-Clipperton Zone
The metals in polymetallic nodules can be used to make batteries for consumer electronics, appliances and electric vehicles.
Franz Geiger, a Northwestern University chemistry professor who worked on the study, said in a separate news release that there may be enough polymetallic nodules in an area of the Pacific Ocean called the Clarion-Clipperton Zone to meet global energy demands for decades after.
If deep-sea mining becomes an opportunity that is being pursued, it needs to be done on a level and not detrimental to life down there, Geiger told NPR.
Some research indicates that missions for deep-sea mining in the 70s and ’80s may have had repercussions on the marine life in the area for decades.
“I think we therefore need to revisit questions like: where could aerobic life have begun?” said Andrew Sweetman, a professor with the Scottish Association for Marine Science in Oban, Scotland, in a news release.
The issue needed to be investigated. First, the team ascertained with certainty that any microorganisms capable of producing oxygen weren’t present. The scientists speculated that polymetallic nodules were captured in the benthic chamber. After several laboratory tests, Sweetman says, they found that the nodules act like a geobattery: They generate a small electric current (about 1 volt each) that splits water molecules into their two components, hydrogen and oxygen, in a process called electrolysis.
How the nodules produce oxygen, however, is not entirely clear: It’s not known what generates the electric current, whether the reaction is continuous, and crucially, whether the oxygen production is significant enough to sustain an ecosystem.
It is possible that the spark that started life on Earth was caused by the ionization of the polymetallic nodules. According to Sweetman, this is an exciting hypothesis that should be explored further. It is possible that this could happen on another world, and be a potential source of alien life.
But with many questions unanswered, some are casting doubt on the findings. The biggest criticisms have come from within the seabed-mining world: Patrick Downes of the Metals Company, a seabed-mining company that works in deep water—the same waters Sweetman studied and that partly funded Sweetman’s research—says the results are the result of oxygen contamination from outside sources, and that his company will soon produce a paper refuting the thesis put forward by Sweetman’s group.