Deep Secrets: Discovery of Dark Oxygen at Ocean Floor Challenges Theories on the Origin of Life

An Unexpected Discovery in the Depths of the Ocean

Researchers recently discovered dark oxygen in the depths of the ocean floor, where light finds it hard to reach. This finding in the Clarion-Clipperton Zone of the North Pacific Ocean has stunned scientists because light is a requirement for photosynthesis, which they believe to be the only way to produce oxygen, as noted by Science Alert. Biogeochemist Andrew Sweetman from the Scottish Association for Marine Science (SAMS) and his colleagues, who made the breakthrough that has challenged the belief about the production of oxygen, published their findings in the journal, Nature Geoscience. Here's a detailed breakdown of their findings. 

Polymetallic Nodules

Polymetallic nodules are a common presence on the ocean's abyssal plains, which are flat regions of the seafloor between depths of 10,000 and 20,000 feet below the ocean's surface, Live Science reported. These nodules contain oxides of iron and manganese and also carry metals like cobalt, nickel, and lithium, as well as rare earth elements such as cerium. These metals are in high demand in the electronics and low-carbon technology industries. Sweetman and his team were studying the impact of mining polymetallic nodules from the seafloor when they noticed the presence of oxygen.

Dark Oxygen

Researchers involved in the study believe that this oxygen is produced by the polymetallic nodules spread across the ocean floor, Live Science reported. The molecular oxygen produced by them has been dubbed 'dark oxygen' by researchers because the whole phenomenon takes place in the absence of light. During their assessment, the researchers measured oxygen concentration at different depths in the ocean. The team recorded a steady increase in oxygen beyond depths of more than 13,000 feet, despite minimal to zero availability of light for photosynthesis. This is the first time, that experts have found oxygen being generated in conditions where there is no presence of other living organisms and light.

How Dark Oxygen is Generated

Metallic nodules across the ocean floor are producing oxygen through seawater electrolysis, as per the study, according to Live Science. In this process, electric charges split seawater into oxygen and hydrogen. This charge is generated because of the difference in electric potential that is present between metal ions within the nodules, which leads to a redistribution of electrons, according to the study.

Raises Further Questions

This finding that light is not needed for oxygen production raises serious questions regarding everything that is known about the origin of life, as per researchers, Live Science reported. "For aerobic life to begin on the planet, there has to be oxygen and our understanding has been that Earth's oxygen supply began with photosynthetic organisms," Sweetman said. "But we now know that there is oxygen produced in the deep sea, where there is no light. I think we therefore need to revisit questions like: where could aerobic life have begun?" The result also puts into question whether these polymetallic modules should be mined extensively, as they are a valuable source of oxygen, according to researchers, Live Science reported.