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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.
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.
Ideally for equal amounts of water and hydrogen sulfide, the cold tower should output water with 12% more deuterium than it entered. Enriched water is output from the cold tower, while depleted water is output from the hot tower. An appropriate cascade system accomplishes enrichment: enriched water is fed into another separation unit and is ...
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.
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
DLW ('tagged' water) is traceable hydrogen (deuterium), and traceable oxygen (18 O). The 18 O leaves the body in two ways: (i) exhaled CO 2, and (ii) water loss in (mostly) urine, sweat, and breath. But the deuterium leaves only in the second way (water loss). From deuterium loss, we know how much of the tagged water left the body as water.
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.
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.