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While there are many abiotic sources and sinks for O 2, the presence of the profuse concentration of free oxygen in modern Earth's atmosphere and ocean is attributed to O 2 production from the biological process of oxygenic photosynthesis in conjunction with a biological sink known as the biological pump and a geologic process of carbon burial involving plate tectonics.
The increase in oxygen concentrations had wide ranging and significant impacts on Earth's biosphere. Most significantly, the rise of oxygen and the oxidative depletion of greenhouse gases (especially atmospheric methane ) due to the GOE led to an icehouse Earth that caused a mass extinction of anaerobic microbes , but paved the way for the ...
The common allotrope of elemental oxygen on Earth is called dioxygen, O 2, the major part of the Earth's atmospheric oxygen (see Occurrence). O 2 has a bond length of 121 pm and a bond energy of 498 kJ/mol. [42] O 2 is used by complex forms of life, such as animals, in cellular respiration. Other aspects of O
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.
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 atmosphere and shallow seas first experienced a rise in the concentration of free oxygen. [3]
Some sources of a trace gas are biogenic processes, outgassing from solid Earth, ocean emissions, industrial emissions, and in situ formation. [1] A few examples of biogenic sources include photosynthesis, animal excrements, termites, rice paddies, and wetlands. Volcanoes are the main source for trace gases from solid earth.
The oxygen cycle involves biogeochemical transitions 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. [36] The word oxygen in the literature typically refers to molecular oxygen (O 2) since it is the common product or reactant ...
Photosynthesis provided a source of free oxygen, but the loss of reducing agents such as hydrogen is thought to have been a necessary precondition for the widespread accumulation of oxygen in the atmosphere. [239] Hence the ability of hydrogen to escape from the atmosphere may have influenced the nature of life that developed on Earth. [240]