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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.
Since one in about every 6,400 hydrogen atoms is deuterium, a 50-kilogram (110 lb) human containing 32 kilograms (71 lb) of body water would normally contain enough deuterium (about 1.1 grams or 0.039 ounces) to make 5.5 grams (0.19 oz) of pure heavy water, so roughly this dose is required to double the amount of deuterium in the body.
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.
Hypoxia can occur throughout the water column and also at high altitudes as well as near sediments on the bottom. It usually extends throughout 20–50% of the water column, but depends on the water depth and location of pycnoclines (rapid changes in water density with depth). It can occur in 10–80% of the water column.
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.
The deuterium used in the experiment was a generous gift of heavy water from UC Berkeley physicist Gilbert N. Lewis. [4] Bombarding deuterium produced two previously undetected isotopes, helium-3 (3 He) and 3 H. Rutherford and his colleagues successfully created 3 H, but incorrectly assumed that 3 He was the radioactive
In 1964, the concept of deuterium excess d (d = δ 2 H - 8δ 18 O) [3] was proposed. Later, a parameter of deuterium excess as a function of humidity has been established, as such the isotopic composition in local meteoric water can be applied to trace local relative humidity, [10] study local climate and used as a tracer of climate change. [6]
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.