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The oxygen cycle is the biogeochemical cycle of oxygen atoms between different oxidation states in ions, oxides, and molecules through redox reactions within and between the spheres/reservoirs of the planet Earth. [ 1] The word oxygen in the literature typically refers to the most common oxygen allotrope, elemental/diatomic oxygen (O 2 ), as it ...
Geological history of oxygen. Before photosynthesis evolved, Earth's atmosphere had no free diatomic oxygen (O 2 ). [ 2] Small quantities of oxygen were released by geological [ 3] and biological processes, but did not build up in the atmosphere due to reactions with reducing minerals. Oxygen began building up in the atmosphere at approximately ...
Stages 4 and 5 (0.85 Ga – present): Other O 2 reservoirs filled; gas accumulates in atmosphere. [ 1] The Great Oxidation Event ( GOE) or Great Oxygenation Event, also called the Oxygen Catastrophe, Oxygen Revolution, Oxygen Crisis or Oxygen Holocaust, [ 2] was a time interval during the Earth 's Paleoproterozoic era when the Earth's ...
Scientists have discovered a new source of oxygen on the planet, originating from metal “batteries” deep beneath the Pacific Ocean. The “dark oxygen” phenomenon was observed at depths of ...
The study of extraterrestrial atmospheres is an active field of research, [1] both as an aspect of astronomy and to gain insight into Earth's atmosphere. [2] In addition to Earth, many of the other astronomical objects in the Solar System have atmospheres. These include all the giant planets, as well as Mars, Venus and Titan.
Cosmic rays ionize nitrogen and oxygen molecules in the atmosphere, which leads to a number of chemical reactions. Cosmic rays are also responsible for the continuous production of a number of unstable isotopes, such as carbon-14, in the Earth's atmosphere through the reaction: n + 14 N → p + 14 C.
One of the most important events of the Proterozoic was the accumulation of oxygen in the Earth's atmosphere. Though oxygen is believed to have been released by photosynthesis as far back as the Archean Eon, it could not build up to any significant degree until mineral sinks of unoxidized sulfur and iron had been exhausted. Until roughly 2.3 ...
Oxygenic photosynthesis is the main source of oxygen in the Earth's atmosphere, and its earliest appearance is sometimes referred to as the oxygen catastrophe. Geological evidence suggests that oxygenic photosynthesis, such as that in cyanobacteria, became important during the Paleoproterozoic era around two billion years ago.