oxygen cycle

the process by which oxygen released into the atmosphere by photosynthetic organisms is taken up by aerobic organisms while the carbon dioxide released as a by-product of repiration is taken up for photosynthesis.
[1930-35]

* * *

      circulation of oxygen in various forms through nature. Free in the air and dissolved in water, oxygen is second only to nitrogen in abundance among uncombined elements in the atmosphere. Plants and animals use oxygen to respire and return it to the air and water as carbon dioxide (CO2). CO2 is then taken up by algae and terrestrial green plants and converted into carbohydrates during the process of photosynthesis, oxygen being a by-product. The waters of the world are the main oxygen generators of the biosphere; their algae are estimated to replace about 90 percent of all oxygen used. Oxygen is involved to some degree in all the other biogeochemical cycles. For example, over time, detritus from living organisms transfers oxygen-containing compounds such as calcium carbonates into the lithosphere.

      Despite the burning of fossil fuel and the reduction of natural vegetation (on land and in the sea), the level of atmospheric oxygen appears to be relatively stable because of the increase in plant productivity resulting from agricultural advances worldwide.

* * *


Universalium. 2010.

Look at other dictionaries:

  • Oxygen cycle — The oxygen cycle. The Oxygen cycle is the biogeochemical cycle that describes the movement of oxygen within its three main reservoirs: the atmosphere (air), the total content of biological matter within the biosphere (the global sum of all… …   Wikipedia

  • oxygen cycle — noun : the cycle whereby atmospheric oxygen is converted to carbon dioxide in animal respiration and regenerated by green plants in photosynthesis * * * Ecol. the process by which oxygen released into the atmosphere by photosynthetic organisms is …   Useful english dictionary

  • oxygen cycle — noun Date: 1935 the cycle whereby atmospheric oxygen is converted to carbon dioxide in animal respiration and regenerated by green plants in photosynthesis …   New Collegiate Dictionary

  • Ozone-oxygen cycle — in the ozone layer. The ozone oxygen cycle is the process by which ozone is continually regenerated in Earth s stratosphere, all the while converting ultraviolet radiation into heat. In 1930 Sydney Chapman resolved the chemistry involved. The… …   Wikipedia

  • carbon-nitrogen-oxygen cycle — anglies, azoto ir deguonies ciklas statusas T sritis chemija apibrėžtis Žvaigždžių gelmėse vykstančių termobranduolinių vandenilio virtimo heliu reakcijų seka (katalizatoriai – C ir N). atitikmenys: angl. Bethe cycle; Bethe Weizsäcker cycle;… …   Chemijos terminų aiškinamasis žodynas

  • carbon-nitrogen-oxygen cycle — noun A group of nuclear reactions, that involve the interaction of protons with carbon, nitrogen and oxygen nuclei, thought to be the main source of energy in main sequence stars of greater than 1.4 solar mass …   Wiktionary

  • Carbon-Nitrogen-Oxygen Cycle —    This is when the nuclear reactions in a star s core, using carbon as a catalyst, transform hydrogen into helium. Also called CNO Cycle …   The writer's dictionary of science fiction, fantasy, horror and mythology

  • Oxygen evolution — is the process of generating molecular oxygen through chemical reaction. Mechanisms of oxygen evolution include the oxidation of water during oxygenic photosynthesis, electrolysis of water into oxygen and hydrogen, and electrocatalytic oxygen… …   Wikipedia

  • Oxygen — This article is about the chemical element and its most stable form, O2 or dioxygen. For other forms of this element, see Allotropes of oxygen. For other uses, see Oxygen (disambiguation). nitrogen ← oxygen → fluorine ↑ O ↓ …   Wikipedia

  • Oxygen isotope ratio cycle — Oxygen isotope ratio cycles are cyclical variations in the ratio of the abundance of oxygen with an atomic mass of 18 to the abundance of oxygen with an atomic mass of 16 present in some substances, such as polar ice or calcite in ocean core… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.