The layer of the atmosphere that has the highest level of oxygen is the troposphere. This is the lowest layer of the atmosphere, extending from the Earth's surface up to about 7-15 km. It contains about 78% nitrogen, 21% oxygen, and 1% other gases like argon and carbon dioxide. While the ozone layer in the stratosphere is known for its high concentration of ozone, which plays a crucial role in absorbing harmful ultraviolet radiation from the sun, it is not the layer with the most oxygen.
The ocean surface layer is also rich in oxygen due to photosynthesis by phytoplankton. These microscopic organisms produce oxygen as a byproduct of their energy production process.
However, the oxygen levels in the ocean decrease with depth, reaching a minimum layer where oxygen levels are very low. This is often referred to as the oxygen minimum zone.
