Dark Oxygen
A group of scientists has discovered a mysterious oxygen production in the deep ocean, called “Dark Oxygen”, where no sunlight can reach. The phenomenon was first observed in 2013 in a remote location of the Pacific Ocean, and contracts every concept about how oxygen is produced until now.
A mysterious phenomenon
As far as the human kind is concerned, half of the oxygen production on Earth is supplied by the Ocean, through photosynthetic organisms. Despite this common knowledge, an international team of researchers has discovered that by the seabed, even where light doesn’t penetrate, particles known as “polymetallic nodules” are able to provide the fundamental gas for aerobic organisms’ survival.
Scientist Andrew Sweetman, a professor at the Scottish Association for Marine Science and lead of the institution’s seafloor ecology and biogeochemistry group, declared: “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. And every single time the manufacturer came back: ‘They’re working. They’re calibrated.’”
The study published by Sweetman in the journal Nature Geoscience, evidences his discoveries concerning the theme, exploring the samples of sediment, seawater and polymetallic nodules collected from several locations in the Clarion-Clipperton Zone and taken to the lab afterwards.
Polymetallic Nodules
Polymetallic nodules are natural mineral deposits, formed over the course of a million years by precipitation of metallic components from the seawater. These particles can be found in most oceans and even lakes, but the areas selected by industrial explorers include mainly the Pacific Ocean, as the metals such as cobalt, nickel, copper, lithium and manganese contained in the nodules are in high demand for use in solar panels, electric car batteries and other green technology.
Franz Geiger, an electrochemist at Northwestern University in Evanston, Illinois, was approached by Sweetman to investigate the nodules’ behavior. Using a multimeter in order to measure the voltage of the surface of each metallic lump, readings of 0,95 volts were recorded, which is almost the same as an AA-sized battery. These studies show that the nodules sitting in the seabed may be able to split the water in hydrogen and oxygen through the electric current – a process known as seawater electrolysis, that occurs when a battery is placed under water.
“It appears that we discovered a natural ‘geobattery,’” Geiger said. “These geobatteries are the basis for a possible explanation of the ocean’s dark oxygen production.”. This discovery also raises new concerns about deep-sea mining, as the Clarion-Clipperton Zone, which is beyond the jurisdiction of any one country, is highly demanded by the industry. Some measures have already been taken to preserve the Clarion-Clipperton Zone, such as The International Seabed Authority, that recently designated some areas of it to be protected from deep-sea mining.
Unraveling the origins of life
Until then, there was general agreement that aerobic life began due to photosynthesis, so that this new discovery leaves endless questions about what role dark oxygen plays not only in the deep-sea ecosystem, but also in the whole biosphere. Beyond that, it suggests how human activities that disturb the deep sea are likely to affect processes and functions which humans are not even aware yet. In short, the discovery that seawater electrolysis could form oxygen in the deep could inspire fresh ways to think about how life began on Earth.
Referências
https://edition.cnn.com/2024/07/22/science/dark-oxygen-discovery-deep-sea-mining/index.html
https://www.bbc.com/news/articles/c728ven2v9eo
https://news.northwestern.edu/stories/2024/july/deep-ocean-floor-produces-its-own-dark-oxygen
