With pressure that crushes most underwater rovers, water below freezing, and pitch-black conditions, the deep ocean has scarcely been explored. Only a select few scientists have traveled to the deepest trench in the world’s oceans and little is known about the organisms that dwell there. Approximately 26% of the seafloor has been mapped, leaving the vast majority of the ocean to explore.
Scientists don’t know much about the deepest parts of the Earth’s oceans, but Andrew K. Sweetman from The Scottish Association for Marine Science and his team uncovered new information that has rocked the science community. They found evidence that chunks of metal are producing dark oxygen in the depths of the Pacific Ocean’s Clarion-Clipperton Zone (CCZ).
At 5,500 meters underwater, the CCZ is under 550 atmospheres of pressure (that’s 8,085 pounds of pressure per square inch) and it’s completely void of light. Yet, oxygen is produced here. Before this finding, scientists believed oxygen production from the ocean came solely from photosynthesizers, like algae or phytoplankton. The oxygen produced by photosynthesizers on the surface eventually travels down the water column to the seafloor.
Oxygen is in high demand at the bottom of the ocean. It travels several thousand meters to the seafloor; over the course of this journey, most of the oxygen gets used up. The finite amount of oxygen that reaches the sea floor decreases as organisms consume it, generating a deficit. This is the first time scientists have found an inanimate object producing oxygen, even in complete darkness.
These chunks of metal are called polymetallic nodules and contain various metals such as magnesium and cobalt. These nodules are mined within the CCZ for their minerals and their use in electronics, batteries, and other devices.
The study showed that in deeper waters where oxygen levels are expected to be low if the nodules were present, oxygen levels were actually elevated. These chunks of metal produce more oxygen than the organisms can consume, leaving elevated oxygen levels where there should be a deficiency.
Sweetman and his team believe that polymetallic nodules generate dark oxygen by splitting seawater molecules into hydrogen and oxygen. This process, known as seawater electrolysis, occurs when an electric current is shot into the water and destabilizes seawater molecules. Similar to a battery, these nodules hold a certain voltage that creates electrical currents. The more clumped together the nodules, the higher the voltage and the more oxygen generated.
Seawater electrolysis is gaining attention in the sustainability movement for its potential to produce green hydrogen which is used as a clean energy source. But the process of creating this so-called clean energy takes a lot of electricity sourced from unsustainable carbon-based energy sources, like fossil fuels. These obscure chunks of metal found deep in the ocean could significantly enhance this process, making it more efficient and environmentally friendly.
Deep-sea ecosystems function in ways that challenge our previous understanding of nature, revealing opportunities for discovery and innovation that could benefit humans and the environment. But, with mining in the CCZ increasing, scientists are worried about the future of these nodules and the fragile ecosystems they support. It is crucial to find a balance between resource extraction and the preservation of such valuable and unexplored environments.
