oxygen-16

isotope

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July 1, 2026

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Oxygen-16 is the most common isotope of oxygen, making up 99.759% of naturally occurring oxygen. Isotopes are atoms of the same element that have different numbers of neutrons. While all oxygen atoms have 8 protons, oxygen-16 has 8 neutrons, giving it an atomic weight of approximately 16.1

Oxygen itself is a nonmetallic chemical element essential for life, found abundantly in Earth's crust and atmosphere. It readily forms compounds, most notably water, and is crucial for processes like respiration and combustion.1

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glacier
Information from deep cores
…the ratio of oxygen-18 to oxygen-16. Oxygen-16 is the dominant isotope, making up more than 99 percent of all natural oxygen; oxygen-18 makes up 0.2 percent. However, the exact concentration of oxygen-18 in precipitation, particularly at high latitudes, depends on the temperature. Winter snow has a smaller oxygen-18–oxygen-16 ratio than…
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…the ratio of oxygen-18 to oxygen-16. Oxygen-16 is the dominant isotope, making up more than 99 percent of all natural oxygen; oxygen-18 makes up 0.2 percent. However, the exact concentration of oxygen-18 in precipitation, particularly at high latitudes, depends on the temperature. Winter snow has a smaller oxygen-18–oxygen-16 ratio than…
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isotopic fractionation
For example, oxygen-16 is enriched relative to the heavier oxygen isotopes in water evaporating from the sea. On the other hand, any precipitate is enriched in the heavy isotope, resulting in a further concentration of oxygen-16 in atmospheric water vapour. Because the processes of evaporation and condensation…
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For example, oxygen-16 is enriched relative to the heavier oxygen isotopes in water evaporating from the sea. On the other hand, any precipitate is enriched in the heavy isotope, resulting in a further concentration of oxygen-16 in atmospheric water vapour. Because the processes of evaporation and condensation…
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Quaternary
Sea-level changes
…occurs in three isotopes: ¹⁶O (99.763 percent), ¹⁷O (0.0375 percent), and ¹⁸O (0.1995 percent). Oxygen is found in all organisms and many minerals, including the aragonite and calcite that make up the shells of marine microfossils such as foraminifera. Oxygen isotopes are useful for geologic studies because the rate…
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…occurs in three isotopes: ¹⁶O (99.763 percent), ¹⁷O (0.0375 percent), and ¹⁸O (0.1995 percent). Oxygen is found in all organisms and many minerals, including the aragonite and calcite that make up the shells of marine microfossils such as foraminifera. Oxygen isotopes are useful for geologic studies because the rate…
Read More