The Stable Isotopic Composition of Atmospheric O2

Oxygen isotopes in atmospheric O₂ have been studied since the early days of isotope geochemistry. In Sections 4.19.1 and 5.14.2 of this chapter, the subject and stable isotope methodology relevant to processes affecting atmospheric O₂ are introduced. In Section 5.14.3, major processes affecting ¹⁸O/¹⁶O of atmospheric O₂ known as Dole effect (DE) are reviewed. These include biological oxygen consumption and production, hydrology, and photochemistry. Temporal DE variations are then discussed. In Section 5.14.4, ¹⁷O/¹⁶O and ¹⁸O/¹⁶O of atmospheric O₂ and how these are modified by stratospheric photochemistry, biological, and hydrologic processes are dealt with. Finally, ¹⁷O/¹⁶O and ¹⁸O/¹⁶O ratios during glacial and interglacial variations and in deeper geological time are discussed.