Scientists discover hidden reservoir of oxygen inside Earth An international team of researchers has found that high-pressure magma can hold much more oxygen than previously thought, writes the National Science Review. As the magma rises to the surface, the pressure decreases, causing a decrease in its ability to hold oxygen. The authors of the work suggest that the gas released in this way can participate in the oxidation of the upper mantle and the Earth's crust, and under suitable conditions affect the composition of the atmosphere. Photo: Russian Space Systems.