Dark oxygen is a term coined to describe oxygen produced in the absence of sunlight, a process previously thought impossible. This groundbreaking discovery was made by scientists who found that metallic nodules on the ocean floor are capable of generating oxygen through a chemical reaction. An interesting process to consider when thinking of environments!
This document from the Woods Hole Oceanographic Institution addresses the question of whether the ocean produces oxygen. It explains that while forests are often considered the primary source of oxygen due to the process of photosynthesis in trees, the majority of the planet’s breathable air actually originates from the world’s oceans. The key oxygen producers in the ocean are microscopic organisms such as phytoplankton, algae, and cyanobacteria, which also undergo photosynthesis, converting carbon dioxide and water into sugar and oxygen using sunlight. https://www.whoi.edu/know-your-ocean/did-you-know/does-the-ocean-produce-oxygen/#:~:text=So%20where%20did%20it%20come,They%20do%20this%20through%20photosynthesis.
The text provides historical context, noting that Earth’s atmosphere contained less than five percent oxygen until 600 million years ago, and land plants did not appear until 470 million years ago. The increase in atmospheric oxygen is attributed to the oceans. Over millions of years, tiny marine organisms produced oxygen through photosynthesis, and while much of it was consumed by cellular respiration and decomposition, some remained in the atmosphere, leading to a gradual buildup of oxygen and a decrease in carbon dioxide.
Here is a short video to further explore dark oxygen: https://youtube.com/shorts/vnVaE_1PUAs?si=uXofVotA1AmJidsp
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