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The adjective anoxic (from the Greek an- = “not”, oxys = “sour”), also outdated anoxysch , basically designates an oxygen-free area, i.e. an area that does not contain oxygen ( anoxia ). It is the opposite of oxic .


The term “anoxic” is used in particular to characterize the environment of living beings such as bodies of water , water sediments , soils and artificial structures. In an anoxic environment, oxygen is only present in bound form, e.g. B. in water as carbon dioxide , nitrate or sulfate . Anoxic systems have a low redox potential . Only organisms that are not dependent on oxygen ( anaerobes ) can be active in such a system . In such a milieu, there are oxidized compounds which, instead of oxygen, can be used as electron acceptors in anaerobic respiration as energy suppliers for the metabolism . Examples of this are sulfate respiration or nitrate respiration .

Sewage technology

In wastewater technology and engineering too , “anoxic” describes an oxygen-free environment. The bacteria have no oxygen at their disposal, only terminal electron acceptors with a lower redox potential ( anaerobic respiration ). In a sewage treatment plant, these are mainly nitrate or nitrite ( denitrification ), as well as sulfur and iron compounds.

Medicine and physiology

In medicine and animal physiology , one speaks of anoxia in the presence of an oxygen deficiency, which leads to an insufficient supply of the organs.

supporting documents

  1. a b c d e Keyword “anoxic” in: Herder-Lexikon der Biologie. Spectrum Akademischer Verlag GmbH, Heidelberg 2003. ISBN 3-8274-0354-5 .