DARK OXYGEN GENERATED BY BATTERY-LIKE METALS UNDERWATER

The process by which plants use sunlight to create oxygen is known as photosynthesis. However, are you familiar with "dark oxygen"? This phrase refers to a phenomenon where oxygen is created on the ocean floor without the usual photosynthesis process. In a recent study published in Nature Geoscience, scientists discovered that metal nodules on the Pacific Ocean's abyssal plains separate seawater into hydrogen and oxygen.

Andrew Sweetman, the head researcher at the Scottish Association for Marine Science, initially discovered this phenomenon in 2013. Sweetman discovered that unusually high levels of oxygen are being produced at the sea floor in the absence of light. Until recently, scientists thought that photosynthesis by marine plants produced all of the oxygen in the ocean.

Rather, the study clarifies that "dark oxygen" is produced by seawater electrolysis, which is brought on by the high voltage on each nodule's surface. Throughout millions of years, dissolved metal in saltwater accumulates on shell fragments and other ocean debris to form these nodules.

The Pacific Ocean lies between Hawaii and Mexico, thousands of feet below the surface where the scientists conducted their research. After gathering and examining the nodules, the researchers calculated their voltages, which were comparable to those of an ordinary AA battery. Additionally, scientists measured the oxygen levels and their utilisation from chambers on the seafloor a few miles from the nodule fields. The polymetallic nodules, the researchers concluded, functioned like batteries because the voltage of the individual nodules on the seafloor added up to produce currents strong enough to split water molecules into hydrogen and oxygen. 

Since this discovery, deep-sea mining companies have developed a strong interest in these lumps, which are made of iron and manganese oxides and contain elements like cobalt, copper, and lithium that are used in batteries. Deep-sea mining companies are currently working on plans to remove the nodules. Scientists and marine biologists, however, are gravely concerned that mining operations could disrupt the nodule formation process and potentially destroy the habitat.

Professor Murray Roberts, a marine biologist from the University of Edinburgh, told BBC News that "there is already overwhelming evidence that strip mining deep-sea nodule fields will destroy ecosystems we barely understand." Approximately eight hundred marine scientists worldwide have signed a petition demanding a halt to mining operations, including Professor Murray.

"It would be crazy to push forward with deep-sea mining knowing they may be a significant source of oxygen production, given how vast these fields are on our planet."

This finding has multiple ramifications: it casts doubt on the long-held notion that photosynthesis was the only process used by ocean organisms to produce oxygen, and it also raises concerns about the utilisation of this recently discovered oxygen source by deep-sea creatures. Even though there are currently no regulations in place to safeguard the nodule sea beds, more investigation is required to ascertain whether development operations and the preservation of these ecosystems can coexist.