Deep Oxygen

The world has a huge appetite for the batteries that power electric vehicles. Many of the elements needed to make batteries are spread across the ocean floor—especially in the Pacific. They form nodules the size of potatoes that contain a lot of manganese, nickel, and other key metals. But some of the nodules may already be acting as batteries—generating an electric current that produces oxygen.

Most oxygen in the oceans comes from tiny organisms near the surface that use photosynthesis—a process that requires sunlight. But researchers recently found a possible new source of oxygen on the ocean floor, between Mexico and Hawaii.

They nestled small chambers into the sediment and filled them with seawater. Then, they monitored the amount of oxygen in the water over a period of two days. They expected to see the level drop as organisms in the sediments used the oxygen. Instead, the level went up. There’s no sunlight that deep, so the oxygen could not have come from photosynthesis.

It may come from the nodules. In seawater, a nodule generates a small electric current on its surface. It’s not enough to split the water molecules into hydrogen and oxygen. But if several nodules are touching, the combined current might do the job.

The scientists said this source of oxygen could be important for life in that region. So mining operations could disrupt things—not an appetizing prospect for the ecosystem at the bottom of the Pacific Ocean.