In Ocean's Depths, a Discovery of Dark Oxygen

To make oxygen during photosynthesis, plants need carbon dioxide and light. But what about places where there is no light, like the depths of the ocean? There's no oxygen, right?

Not so fast, a new study shows. There may be oxygen-producing batteries on the ocean floor.

Dr. Andrew Sweetman published his findings in the journal Nature Geoscience. He works at the Scottish Association for Marine Science. His findings are the result of more than a decade of research that began with what Sweetman thought were broken sensors. The sensors were designed to detect oxygen.  

“I basically told my students, just put the sensors back in the box. We’ll ship them back to the manufacturer and get them tested because they’re just giving us gibberish,” Sweetman told CNN. “And every single time the manufacturer came back: ‘They’re working. They’re calibrated.’”

Sweetman looked into it. He found lumpy rocks strewn across the ocean floor. They were about the size of potatoes. Some are as deep as 13,000 feet. Careful study of the rocks showed that they contained metals often found in batteries. The rocks contained lithium, cobalt, copper, and manganese. Clumped together, the stones produce an electric charge strong enough to cause electrolysis. That's the splitting of water molecules into hydrogen and oxygen.   

This so-called “dark oxygen” could be a key to ecosystems not yet explored. And it could be key to the world’s oxygen production, Sweetman says. The metals are also valuable to mining companies. Sweetman hopes that a balance can be reached to protect dark oxygen sources in the future. 

“I think that there’s more science that needs to be done,” Sweetman told CNN. “I hope it’s the start of something amazing.” 

Reflect: How do you think discoveries in science can change the way we understand the world around us?

Photo of ocean floor from Unsplash courtesy of Emmeli M.