Extracting Rare Minerals From The Deep Sea Creates ‘Dark Oxygen,’ New Study Shows
A new study shows that extracting rare minerals from the deep sea creates ‘dark oxygen,’ which affects the deep seafloor environment. Extracting trace minerals from the deep sea and the seafloor miles below the surface could create ‘dark oxygen’ and potentially harmful changes to marine ecosystems, according to the research.
According to a paper published in the journal Nature Geoscience, dark oxygen—defined in this article as oxygen produced without the use of sunlight, as it is produced on Earth through photosynthesis—is produced when nodules made up of several trace minerals react on the deep, dark, salty seafloor.
Dark oxygen is created because mineral nodules act like batteries when disturbed, similar to how conventional batteries explode when placed in seawater. The nodules form over millions of years when minerals suspended in seawater gather around various fragments of material on the seafloor.
Many of the rare earth elements that make up these polymetallic nodules are important building blocks for advanced, low-carbon energy technologies. According to the study, this makes the deep seafloor an attractive target for mining companies.
Polymineral nodules are common on the deep seafloor, or abyssal plains, in oceans around the world, where sediments cover them. They are composed primarily of oxides of iron and manganese but may also contain metals such as cobalt, lithium, and copper, as well as trace elements and metals.
Mining activities could negatively impact seafloor ecosystems, scientists warn.
The researchers said extracting these elements from the seafloor could disturb the nodules. Causing them to produce more dark oxygen, which could negatively impact the environment of the deep seafloor.
The researchers used chambers placed on the seafloor at a depth of about 2.6 miles in the areas where the polymineral nodules were found to measure oxygen concentrations and organisms’ consumption of oxygen. The chambers were spread over several locations across thousands of miles in the Clarion-Clipperton Zone, an area between Hawaii and Mexico in the central Pacific Ocean. The electrical potential of each mineral nodule at the ocean surface was also measured.
The paper said that almost all experiments showed that oxygen concentrations increased steadily over two days. Indicating that more oxygen was produced than consumed. After subsequent analysis, the researchers speculated that the net oxygen production was due to the electrical properties of the nodules, which produce roughly the same voltage as an AA battery. Thus, the researchers called the result the “Earth Battery” hypothesis.
The study shows that it is difficult to estimate the amount of oxygen produced by polymineral nodules on a large scale. Still, if these nodules are mined, the ability of this oxygen source to support deep-seafloor ecosystems may be affected.
Final Thoughts
According to the National Oceanic and Atmospheric Administration, about half of the oxygen on Earth comes from the ocean. Most of it is produced by plankton and other marine life, such as plants, algae, and some bacteria that can photosynthesize.
More than 800 marine scientists have signed a petition calling for a halt to deep-sea mining activities. In contrast, more research is conducted on its potential impacts. Noting that deep-sea ecosystems are already affected by anthropogenic environmental pressures such as climate change and bottom fishing and pollution.
Mining polymetallic nodules in the Clarion-Clipperton Zone, where the discovery was made, “could result in the destruction of life and seafloor habitats in the mining area,” according to the National Oceanic and Atmospheric Administration.
