On the Clarion-Clipperton Zone (CCZ), which spans 4.5 million square kilometres (1.7 million square miles) in the Pacific Ocean, there are coal-like mineral rocks, called polymetallic nodules, which typically contain manganese and iron. Scientists have found that these nodules produce oxygen without the process of photosynthesis.
At the depths of the Pacific Ocean where sunlight is absent, a significant quantity of oxygen is being released from an unknown source. The oxygen levels surpass those found in surface waters abundant with algae, indicating a unique phenomenon referred to as 'dark oxygen'. The presence of polymetallic nodules in this area, not found in other surveyed regions, implies that these rocks play a crucial role in this oxygen production.
At a depth of twelve thousand feet below the ocean's surface lies a realm of perpetual darkness. Without sunlight reaching this depth for photosynthesis, there are no plants generating oxygen. Surprisingly, in this dark expanse, oxygen is plentiful, courtesy of small, "battery rocks" on the seafloor. Recent findings published in the journal Nature Geoscience unveil nature's unique method of oxygen production independent of plants.
According to a study published in the journal Nature Geoscience, it is proposed that tiny metallic nodules discovered in the Clarion-Clipperton Zone (CCZ) in the north Pacific generate oxygen by means of seawater electrolysis. This process involves the separation of seawater into oxygen and hydrogen when exposed to an electric charge. The study suggests that this electric charge is likely generated by the variance in electric potential among the metal ions present in the nodules, causing an electron redistribution.
Polymetallic nodules, also known as manganese nodules, are frequently found on the flat seabed areas of the ocean known as abyssal plains, located at depths ranging from 10,000 to 20,000 feet (3,000 to 6,000 m) below the ocean surface. These nodules predominantly consist of iron and manganese oxides, but they also contain valuable metals like cobalt, nickel, and lithium, in addition to rare earth elements like cerium, which play a crucial role in electronics and environmentally friendly technologies.
Researchers are intrigued by the potential of deep-sea mining, viewing the nodules as a possible source of answers. These nodules, often described as "a battery in a rock" by Gerard Barron, CEO of the Metals Company, have sparked curiosity among researchers. They are contemplating whether the metals within these nodules could function as natural geobatteries, capable of splitting seawater into hydrogen and oxygen using seawater electrolysis. You can replicate this experiment at home by placing a small battery into salted water and observing the resulting bubbles of hydrogen and oxygen gas.
The expression "Batteries in a rock" was merely a metaphor, according to the scientists, indicating that although the nodules housed metals utilized in batteries, they were not inherently electrically charged. In order to generate a charge, there would need to be a partial separation of positive and negative ions within a nodule, resulting in an electrical potential difference. To investigate this possibility, scientists conducted tests on the nodules' electric charge with the assistance of Franz Geiger, a physical chemist from Northwestern University.
"Surprisingly, there was a voltage of nearly one volt detected on the surface of these nodules," stated Head researcher Sweetman. To put it into perspective, a AA battery typically holds around 1.5 volts. The primary hypothesis of the researchers is that this voltage is responsible for splitting seawater to generate oxygen. However, they have not conducted experiments to verify if stopping the electric charge of the nodules would cease oxygen production. This aspect will be investigated in upcoming research by the scientists.
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