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A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle , the nitrogen cycle and the water cycle .
The values below are standard apparent reduction potentials (E°') for electro-biochemical half-reactions measured at 25 °C, 1 atmosphere and a pH of 7 in aqueous solution. [1] [2] The actual physiological potential depends on the ratio of the reduced (Red) and oxidized (Ox) forms according to the Nernst equation and the thermal voltage.
Agricultural interest in 18th-century soil chemistry led to better understanding of nutrients and their connection to biochemical processes. This relationship between the cycles of organic life and their chemical products was further expanded upon by Dumas and Boussingault in a 1844 paper that is considered an important milestone in the development of biogeochemistry.
Bromine's chemistry is linked to other halogens such as chlorine and iodine amplify atmospheric cycling that contributes to troposphere and stratosphere ozone layer destruction. Figure modified from Saiz-Lopez, A., von Glasow, R., 2012. Reactive halogen chemistry in the troposphere.
A stirred BZ reaction mixture showing changes in color over time. The discovery of the phenomenon is credited to Boris Belousov.In 1951, while trying to find the non-organic analog to the Krebs cycle, he noted that in a mix of potassium bromate, cerium(IV) sulfate, malonic acid, and citric acid in dilute sulfuric acid, the ratio of concentration of the cerium(IV) and cerium(III) ions ...
In animals, the processes of alternating cycles of biochemical reactions of ATP synthesis and cleavage occur automatically. Moreover, the processes of alternating cycles of biochemical reactions at the levels of organs, systems and the whole organism, for example, respiration , heart contractions and others occur with different periods and ...
There are biogeochemical cycles for the elements calcium, carbon, hydrogen, mercury, nitrogen, oxygen, phosphorus, selenium, and sulfur; molecular cycles for water and silica; macroscopic cycles such as the rock cycle; as well as human-induced cycles for synthetic compounds such as polychlorinated biphenyl (PCB). In some cycles there are ...
An example chemical cycle, a schematic representation of a Nitrogen cycle on Earth. This process results in the continual recycling of nitrogen gas involving the ocean. Chemical cycling describes systems of repeated circulation of chemicals between other compounds, states and materials, and back to their original state, that occurs in space ...