Scientists may have found dark oxygen being created
High Voltage Production of Polymetallic Nodules in Seawater and its Possible Effect on the Origin of Oxygen Flow at the Seafloor
“A few years ago, a team of marine biologists went back to those areas that were mined 40 years ago and found essentially no life,” Geiger said. “And then a few hundred meters over to the left and right, where the nodules were intact, there was plenty of life.”
The scientists are not sure how oxygen is created at such dark depths, but they believe it is being produced by minerals called polymetallic nodules, which range in size from a small particle to about the size of a potato.
Seawater can be split into hydrogen and oxygen with 1.5 volts of electricity, which is the amount in a AA battery. Researchers found that some of the nodules possessed as much as 0.95 volts of electricity, and multiple nodules together produced even higher voltages.
Oxygen was thought to be created through a process called photosynthesis. But the discovery casts doubt on that theory and raises new questions about the origins of life itself.
Sweetman first noticed something strange in 2013. He and his team had been trying to measure the amount of oxygen in the air in nodule-rich areas. The researchers thought that the increase in oxygen flow at the seafloor was due to a photosynthesizing organisms not being nearby.
Ocean floor pollution in the Clarion-Clipperton Zone: Oxygen changes in a benthic chamber in 2021
The polymetallic nodules contain some of the metals that can be used for batteries in consumer electronics, appliances and electric vehicles.
Over the course of a decade, Andrew Sweetman and his colleagues have been studying the ocean floor and its communities, especially in the Pacific’s Clarion-Clipperton Zone. The valuable metals in the rocks are used to make batteries. They are considered a bounty for deep-sea mining companies, which are developing technologies that can bring them to the surface.
There is an argument to be made that the deep seabed is delicate and needs to be protected from exploitation. (There is already a petition, signed by more than 800 marine scientists from 44 different countries, that highlights the broader environmental risks of deep sea mining and calls for a pause on its development.)
Companies conducted exploratory missions for deep-sea mining in the 1970s and ’80s, he said, and recent research suggests that those missions may have had repercussions on 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 same finding, however, was repeated in 2021, albeit using a different measurement approach. The scientists were assessing changes in oxygen levels inside a benthic chamber, an instrument that collects sediment and seawater to create enclosed samples of the seabed environment. The instrument allowed them to analyze, among other things, how oxygen was being consumed by microorganisms within the sample environment. Oxygen trapped in the chamber should have decreased over time as organisms in the water and sediment consumed it, but it did the opposite: Despite the dark conditions preventing any photosynthetic reactions, oxygen levels in the benthic chamber increased.
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.
If the polymetallic nodules caused an electrical charge, then what if it was the start of life on Earth? This is an exciting hypothesis that should be explored further. It’s possible this could take place on another world, and give rise to 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.
Researchers from the UK have found that polymetallic nodules on the seafloor, which contain metals that can be used for electric vehicles and consumer electronics, produce high levels of oxygen. Polymetallic nodules range in size from a small particle and about the size of a potato. Scientists believe they may be producing oxygen through an electrical charge generated by the nodules.