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Deuterium-depleted water has less deuterium (2 H) than occurs in nature at sea level. [1] Deuterium is a naturally-occurring, stable (non-radioactive) isotope of hydrogen with a nucleus consisting of one proton and one neutron. A nucleus of normal hydrogen (protium, 1 H) consists of one proton only, and no neutron.
Thus heavy water as defined by the Gold Book includes semiheavy water (hydrogen-deuterium oxide, HDO) and other mixtures of D 2 O, H 2 O, and HDO in which the proportion of deuterium is greater than usual. For instance, the heavy water used in CANDU reactors is a highly enriched water mixture that is mostly deuterium oxide D
Deuterium occurs in trace amounts naturally as deuterium gas (2 H 2 or D 2), but most deuterium atoms in the Universe are bonded with 1 H to form a gas called hydrogen deuteride (HD or 1 H 2 H). [12] Similarly, natural water contains deuterated molecules, almost all as semiheavy water HDO with only one deuterium.
Semiheavy water is the result of replacing one of the protium (normal hydrogen, 1 H) in normal water with deuterium (2 H; or less correctly, [1] D). [2] It exists whenever there is water with 1 H and 2 H in the mix. This is because hydrogen atoms (1,2 H) are rapidly exchanged between water molecules.
Due to confusion over multiple water standards, the Commission on Isotopic Abundances and Atomic Weights recommended in 1994 that all future isotopic measurements of oxygen-18 (18 O) and deuterium (2 H) be reported relative to VSMOW, on a scale such that the δ 18 O of SLAP is −55.5‰ and the δ 2 H of SLAP is −428‰, relative to VSMOW.
Global meteoric water line. Data are global annual average 18 O and 2 H values from precipitation monitored at IAEA network stations distributed globally (n=420). [1]The Global Meteoric Water Line (GMWL) describes the global annual average relationship between hydrogen and oxygen isotope (oxygen-18 [18 O] and deuterium [2 H]) ratios in natural meteoric waters.
Semiheavy water, a form of water in which one of the protium atoms in light water is replaced with deuterium atoms; Heavy water, a form of water that contains a larger than usual amount of deuterium molecules; Super-heavy water, a form of water in which both protium atoms in light water are replaced with tritium atoms
For water, the condensed phase is more enriched while the vapor is more depleted. For example, rain condensing from a cloud, is heavier than the vapor starting point. Generally, the large variations in deuterium concentration in water are from fractionations between liquid, vapor, and solid reservoirs.