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Oxygen (chemical symbol O) has three naturally occurring isotopes: 16 O, 17 O, and 18 O, where the 16, 17 and 18 refer to the atomic mass.The most abundant is 16 O, with a small percentage of 18 O and an even smaller percentage of 17 O. Oxygen isotope analysis considers only the ratio of 18 O to 16 O present in a sample.
O, samples enriched with the other stable isotopes can be used for isotope labeling. For example, it was proven that the oxygen released in photosynthesis originates in H 2 O, rather than in the also consumed CO 2, by isotope tracing experiments. The oxygen contained in CO 2 in turn is used to make up the sugars formed by photosynthesis.
In geochemistry, paleoclimatology and paleoceanography δ 18 O or delta-O-18 is a measure of the deviation in ratio of stable isotopes oxygen-18 (18 O) and oxygen-16 (16 O). It is commonly used as a measure of the temperature of precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotopic fractionation, like methanogenesis.
Paleoclimatologists measure the ratio of oxygen-18 and oxygen-16 in the shells and skeletons of marine organisms to determine the climate millions of years ago (see oxygen isotope ratio cycle). Seawater molecules that contain the lighter isotope , oxygen-16, evaporate at a slightly faster rate than water molecules containing the 12% heavier ...
Oxygen isotopic ratios, which may be measured very precisely, yield a unique and distinct signature for each Solar System body. [40] Different oxygen isotopic signatures can indicate the origin of material ejected into space. [41] The Moon's titanium isotope ratio (50 Ti/ 47 Ti) appears close to the Earth's (within 4 ppm).
The Dole effect, named after Malcolm Dole, describes an inequality in the ratio of the heavy isotope 18 O (a "standard" oxygen atom with two additional neutrons) to the lighter 16 O, measured in the atmosphere and seawater. This ratio is usually denoted δ 18 O.
The ratio 18 O / 16 O (δ 18 O) can ... however oxygen isotope paleothermometry has also been done of ... An example of the production cycle is a 90-minute ...
The isotopic composition of the oxygen in a core can be used to model the temperature history of the ice sheet. Oxygen has three stable isotopes, 16 O, 17 O and 18 O. [66] The ratio between 18 O and 16 O indicates the temperature when the snow fell. [67] Because 16 O is lighter than 18 O, water containing 16