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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 ...
Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust, and after hydrogen and helium, it ...
Oxygen began building up in the atmosphere at approximately 1.85 Ga. At current rates of primary production, today's concentration of oxygen could be produced by photosynthetic organisms in 2,000 years. [ 4] In the absence of plants, the rate of oxygen production by photosynthesis was slower in the Precambrian, and the concentrations of O 2 ...
Sensor readings seemed to show that oxygen was being made on the seabed 4,000 meters (about 13,100 feet) below the surface, where no light can penetrate. The same thing happened on three ...
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.
Cellular respiration is the process of which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Anaerobic respiration is used by microorganisms either bacteria or archaea in which neither oxygen (aerobic respiration) nor pyruvate ...
Sulfur dioxide is an intermediate in the production of sulfuric acid, being converted to sulfur trioxide, and then to oleum, which is made into sulfuric acid. Sulfur dioxide for this purpose is made when sulfur combines with oxygen. The method of converting sulfur dioxide to sulfuric acid is called the contact process.
The rate of change of oxygen can be calculated from the difference between global sources and sinks. [26] The oxygen sinks include reduced gases and minerals from volcanoes, metamorphism and weathering. [26] The GOE started after these oxygen-sink fluxes and reduced-gas fluxes were exceeded by the flux of O 2 associated with the burial of ...