Heavy water

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Not to be confused with hard water or tritiated water.
Heavy water
Spacefill model of heavy water
IUPAC name
[2H]2-Water[citation needed]
Other names
  • Deuterium oxide[1]
  • Water-d2[2]
Molar mass 20.0276 g mol−1
Appearance Very pale blue, transparent liquid
Odor Odorless
Density 1.107 g mL−1
Melting point 3.82 °C; 38.88 °F; 276.97 K
log P −1.38
Viscosity 1.25 mPa s (at 20 °C)
Dipole moment 1.87 D
NFPA 704
 N verify (what isYesY/N?)
Infobox references

Heavy water (deuterium oxide (2
) or D
), is a form of water that contains a larger than normal amount of the hydrogen isotope deuterium, (also known as heavy hydrogen, which can be symbolized as 2
or D) rather than the common hydrogen-1 isotope (called protium, symbolized as 1


Some or most of the hydrogen atoms in heavy water contain a neutron, making those heavy water hydrogen atoms about twice as heavy as normal hydrogen. However, the weight of the heavy water molecule as a whole is not substantially different from that of a normal water molecule because about 89% of the molecular weight of water comes from the single oxygen atom rather than the two hydrogen atoms. The additional neutron in each hydrogen atom does not change the volume of the water noticeably. The increased molecular weight does make the water slightly more dense. The colloquial term heavy water is often also used to refer to a highly enriched water mixture that contains mostly deuterium oxide but also contains some ordinary water molecules as well: for instance heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction, meaning that 99.75% of the hydrogen atoms are of the heavy type. In comparison, in ordinary water, which is the "ordinary water" used for a deuterium standard on Earth, there are only about 156 deuterium atoms per million hydrogen atoms.



Other heavy forms of water[edit]

Semiheavy water[edit]


Heavy-oxygen water[edit]

Water enriched in the heavier oxygen isotopes 17O and 18O is also commercially available, e.g., for use as a non-radioactive isotopic tracer. It is "heavy water" as it is denser than normal water (H218O is approximately as dense as D2O, H217O is about halfway between H2O and D2O)—but is rarely called heavy water, since it does not contain the deuterium that gives D2O its unusual nuclear and biological properties. It is more expensive than D2O due to the more difficult separation of 17O and 18O.[8]

Tritiated water[edit]

Tritiated water contains tritium in place of protium or deuterium.

Physical properties (with comparison to light water)[edit]

Properties[9] D2O (Heavy water) HDO (Semiheavy water) H2O (Light water)
Freezing point 3.82 °C (38.9 °F) 2.04 °C (35.7 °F) 0.0 °C (32 °F)
Boiling point 101.4 °C (214.5 °F) 100.7 °C (213.3 °F) 100.0 °C (212 °F)
Density at STP (g/mL) 1.1056 1.054 0.9982
Temp. of maximum density 11.6 °C 3.98 °C[10]
Heat of fusion (kJ/mol) 6.132 6.227 6.00678
Heat of vaporisation (kJ/mol) 41.521 40.657
pH (at 25 °C) 7.43 (sometimes "pD") 7.266 (sometimes "pHD") 6.9996
Refractive index (at 20 °C, 0.5893 μm)[11] 1.32844 1.33335

Physical properties obvious by inspection: Heavy water is 10.6% denser than ordinary water, a difference not immediately obvious. One of the few ways to demonstrate heavy water's physically different properties without equipment is to freeze a sample and drop it into normal water (it sinks). If the water is ice-cold the higher melting temperature of heavy ice can also be observed: it melts at 3.7 °C, and thus endures very well in ice-cold normal water.[12]

An early experiment[13] reported not the "slightest difference" in taste between ordinary and heavy water. On the other hand, rats given a choice between distilled normal water and heavy water were able to avoid the heavy water based on smell, and it may be possible that it has a different taste.[14]



Harold Urey discovered the isotope deuterium in 1931 and was later able to concentrate it in water.[15] Urey's mentor Gilbert Newton Lewis isolated the first sample of pure heavy water by electrolysis in 1933.[16] George de Hevesy and Hoffer used heavy water in 1934 in one of the first biological tracer experiments, to estimate the rate of turnover of water in the human body. The history of large-quantity production and use of heavy water in early nuclear experiments is given below.[17] Emilian Bratu and Otto Redlich studied the autodissociation of heavy water in 1934.[18]

Effect on biological systems[edit]



To perform their tasks, enzymes rely on their finely tuned networks of hydrogen bonds, both in the active center with their substrates, and outside the active center, to stabilize their tertiary structures. As a hydrogen bond with deuterium is slightly stronger[20] than one involving ordinary hydrogen, in a highly deuterated environment, some normal reactions in cells are disrupted.

Particularly hard-hit by heavy water are the delicate assemblies of mitotic spindle formation necessary for cell division in eukaryotes. Plants stop growing and seeds do not germinate when given only heavy water, because heavy water stops eukaryotic cell division.[21][22] The deuterium cell is larger and a modification of the direction of division.[23][24] The cell membrane also changes, and it reacts first to the impact of heavy water. In 1972 it was demonstrated that an increase in the percentage content of deuterium in water reduces plant growth.[25] Research conducted on the growth of prokaryote microorganisms in artificial conditions of a heavy hydrogen environment showed that in this environment, all the hydrogen atoms of water could be replaced with deuterium.[26][27][28] Experiments showed that bacteria can live in 98% heavy water.[29] However, all concentrations over 50% of deuterium in the water molecules were found to kill plants.

Effect on animals[edit]

Experiments in mice, rats, and dogs[30] have shown that a degree of 25% deuteration causes (sometimes irreversible) sterility, because neither gametes nor zygotes can develop. High concentrations of heavy water (90%) rapidly kill fish, tadpoles, flatworms, and Drosophila. Mammals, such as rats, given heavy water to drink die after a week, at a time when their body water approaches about 50% deuteration.[31] The mode of death appears to be the same as that in cytotoxic poisoning (such as chemotherapy) or in acute radiation syndrome (though deuterium is not radioactive), and is due to deuterium's action in generally inhibiting cell division. It is more toxic to malignant cells than normal cells but the concentrations needed are too high for regular use.[30] As in chemotherapy, deuterium-poisoned mammals die of a failure of bone marrow (bleeding and infection) and intestinal-barrier functions (diarrhea and fluid loss).




Toxicity in humans[edit]

Because it would take a very large amount of heavy water to replace 25% to 50% of a human being's body water (water being in turn 50% - 75% of body weight[33]) with heavy water, accidental or intentional poisoning with heavy water is unlikely to the point of practical disregard. Poisoning would require that the victim ingest large amounts of heavy water without significant normal water intake for many days to produce any noticeable toxic effects.

Oral doses of heavy water in the range of several grams, as well as heavy oxygen 18O, are routinely used in human metabolic experiments. See doubly labeled water testing. Since one in about every 6400 hydrogen atoms is deuterium, a 50 kg human containing 32 kg of body water would normally contain enough deuterium (about 1.1 gram) to make 5.5 grams of pure heavy water, so roughly this dose is required to double the amount of deuterium in the body.

The American patent U.S. Patent 5,223,269 is for the use of heavy water to treat hypertension (high blood pressure). A loss of blood pressure may partially explain the reported incidence of dizziness upon ingestion of heavy water. However, it is more likely that this symptom can be attributed to altered vestibular function.[34]

Heavy water radiation contamination confusion[edit]









Production was first started in 1934[citation needed] in Dnepropetrovsk, but was interrupted during Operation Barbarossa. After 1946, five plants were constructed, with an annual production of 20 tons.

United States[edit]

During the Manhattan Project the United States constructed three heavy water production plants as part of the P-9 Project at Morgantown Ordnance Works, near Morgantown, West Virginia; at the Wabash River Ordnance Works, near Dana and Newport, Indiana; and at the Alabama Ordnance Works, near Childersburg and Sylacauga, Alabama. Heavy water was also acquired from the Cominco plant in Trail, British Columbia (Canada). The Chicago Pile-3 experimental reactor used heavy water as a moderator and went critical in 1944. The three domestic production plants were shut down in 1945 after producing around 20 metric tons of product[citation needed] (around 20,000 litres).[38] The Wabash plant was reopened and began resumption of heavy water production in 1952.






"Heavy water" made by Norsk Hydro

In 1934, Norsk Hydro built the first commercial heavy water plant at Vemork, Tinn, with a capacity of 12 tonnes per year.[39] From 1940 and throughout World War II, the plant was under German control and the Allies decided to destroy the plant and its heavy water to inhibit German development of nuclear weapons. In late 1942, a planned raid by British airborne troops failed, both gliders crashing. The raiders were killed in the crash or subsequently executed by the Germans. On the night of 27 February 1943 Operation Gunnerside succeeded. Norwegian commandos and local resistance managed to demolish small, but key parts of the electrolytic cells, dumping the accumulated heavy water down the factory drains. Had the German nuclear program followed similar lines of research as the United States Manhattan Project, the heavy water would not have been crucial to obtaining plutonium from a nuclear reactor, but the Germans did not discover the graphite reactor design used by the allies for this purpose.






The Atomic Energy of Canada Limited (AECL) design of power reactor requires large quantities of heavy water to act as a neutron moderator and coolant. AECL ordered two heavy water plants, which were built and operated in Atlantic Canada at Glace Bay (by Deuterium of Canada Limited) and Port Hawkesbury, Nova Scotia (by General Electric Canada). These plants proved to have significant design, construction and production problems and so AECL built the Bruce Heavy Water Plant (44°19′38″N 81°35′32″W﻿ / ﻿44.3273°N 81.5921°W﻿ / 44.3273; -81.5921), which it later sold to Ontario Hydro, to ensure a reliable supply of heavy water for future power plants. The two Nova Scotia plants were shut down in 1985 when their production proved unnecessary.

The Bruce Heavy Water Plant in Ontario was the world's largest heavy water production plant with a capacity of 700 tonnes per year. It used the Girdler sulfide process to produce heavy water, and required 340,000 tonnes of feed water to produce one tonne of heavy water. It was part of a complex that included eight CANDU reactors, which provided heat and power for the heavy water plant. The site was located at Douglas Point near Tiverton, Ontario on Lake Huron where it had access to the waters of the Great Lakes.

The Bruce plant was commissioned in 1979 to provide heavy water for a large increase in Ontario's nuclear power generation. The plants were significantly more efficient than planned and only three of the planned four units were eventually commissioned. In addition, the nuclear power programme was slowed down and effectively stopped due to a perceived oversupply of electricity, later shown to be temporary, in 1993. Improved efficiency in the use and recycling of heavy water plus the over-production at Bruce left Canada with enough heavy water for its anticipated future needs. Also, the Girdler process involves large amounts of hydrogen sulfide, raising environmental concerns if there should be a release. The Bruce heavy water plant was shut down in 1997, after which the plant was gradually dismantled and the site cleared.

Atomic Energy of Canada Limited (AECL) is currently researching other more efficient and environmentally benign processes for creating heavy water. This is essential for the future of the CANDU reactors since heavy water represents about 20% of the capital cost of each reactor.


Since 1996 a plant for production of heavy water was being constructed at Khondab near Arak.[42] On 26 August 2006, Iranian President Ahmadinejad inaugurated the expansion of the country's heavy-water plant. Iran has indicated that the heavy-water production facility will operate in tandem with a 40 MW research reactor that had a scheduled completion date in 2009.[43][44]



Other countries[edit]

Argentina is a declared producer of heavy water, using an ammonia/hydrogen exchange based plant supplied by Switzerland's Sulzer company.

Romania produces heavy water at the Drobeta Girdler sulfide plant and exports it occasionally.

France operated a small plant during the 1950s and 1960s.

Exists in elevated concentration in Lake Tanganyika[46]


Nuclear magnetic resonance[edit]

Deuterium oxide is used in nuclear magnetic resonance spectroscopy when the solvent of interest is water and the nuclide of interest is hydrogen. This is because the signal from the water solvent would interfere with the signal from the molecule of interest. Deuterium has a different magnetic moment from hydrogen and therefore does not contribute to the 1H NMR signal at the hydrogen-1 resonance frequency.

For some experiments, it may be desirable to identify the labile hydrogens on a compound, that is hydrogens that can easily exchange away as H+ ions on some positions in a molecule. 1H NMR shows natural abundance hydrogens in a molecule. With addition of D2O, sometimes referred to as a D2O shake, labile hydrogens exchange away and are substituted by deuterium (2H) atoms from D2O and not show up at those positions in the molecule in an 1H NMR spectrum.

Organic chemistry[edit]


Fourier transform spectroscopy[edit]


Neutron moderator[edit]






Neutrino detector[edit]

The Sudbury Neutrino Observatory (SNO) in Sudbury, Ontario used 1000 tonnes of heavy water on loan from Atomic Energy of Canada Limited. The neutrino detector is 6,800 feet (2,100 m) underground in a mine, to shield it from muons produced by cosmic rays. SNO was built to answer the question of whether or not electron-type neutrinos produced by fusion in the Sun (the only type the Sun should be producing directly, according to theory) might be able to turn into other types of neutrinos on the way to Earth. SNO detects the Cherenkov radiation in the water from high-energy electrons produced from electron-type neutrinos as they undergo reactions with neutrons in deuterium, turning them into protons and electrons (only the electrons move fast enough to be detected in this manner). SNO also detects the same radiation from neutrino↔electron scattering events, which again produces high energy electrons. These two reactions are produced only by electron-type neutrinos. The use of deuterium is critical to the SNO function, because all three "flavours" (types) of neutrinos[47] may be detected in a third type of reaction, neutrino-disintegration, in which a neutrino of any type (electron, muon, or tau) scatters from a deuterium nucleus (deuteron), transferring enough energy to break up the loosely bound deuteron into a free neutron and proton. This event is detected when the free neutron is absorbed by 35Cl present from NaCl deliberately dissolved in the heavy water, causing emission of characteristic capture gamma rays. Thus, in this experiment, heavy water not only provides the transparent medium necessary to produce and visualize Cherenkov radiation, but it also provides deuterium to detect exotic mu type (μ) and tau (τ) neutrinos, as well as a non-absorbent moderator medium to preserve free neutrons from this reaction, until they can be absorbed by an easily detected neutron-activated isotope.

Metabolic rate testing in physiology/biology[edit]

Heavy water is employed as part of a mixture with H218O for a common and safe test of mean metabolic rate in humans and animals undergoing their normal activities. This metabolic test is usually called the doubly labeled water test.

Tritium production[edit]



Deuterium's absorption cross section for thermal neutrons is 0.52 millibarns (barn=10−28 m2, milli=1/1000), while oxygen-16's is 0.19 millibarns and oxygen-17's is 0.24 barns. 17O makes up 0.038% of natural oxygen, making the overall cross section 0.28 millibarns. Therefore in D2O with natural oxygen, 21% of neutron captures are on oxygen, rising higher as 17O builds up from neutron capture on 16O. Also, 17O may emit an alpha particle on neutron capture, producing radioactive carbon-14.

See also[edit]



  1. ^ Parpart, Arthur K. (December 1935). "The permeability of the mammalian erythrocyte to deuterium oxide (heavy water)". Journal of Cellular and Comparative Physiology 7 (2): 153–162. doi:10.1002/jcp.1030070202. Retrieved 29 December 2014. 
  2. ^ Svishchev, I. M.; Kusalik, P. G. (January 1994). "Dynamics in liquid water, water-d2, and water-t2: a comparative simulation study". The Journal of Physical Chemistry 98 (3): 728–733. doi:10.1021/j100054a002. Retrieved 29 December 2014. 
  5. ^ Harold Clayton Urey (1893–1981)
  6. ^ http://www-pub.iaea.org/MTCD/publications/PDF/ngwm-cd/PDF-Files/paper%2017%20(Holt).pdf
  7. ^ http://cigr.ageng2012.org/images/fotosg/tabla_137_C0371.pdf
  9. ^ Physical property comparison
  11. ^ "RefractiveIndex.INFO". Retrieved 2010-01-21. 
  12. ^ Gray, Theodore (2007). "How 2.0". Popular Science. Retrieved 2008-01-21. 
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  14. ^ "ScienceDirect – Physiology & Behavior : Taste responses to deuterium oxide". Dx.doi.org. doi:10.1016/0031-9384(79)90124-0. 
  15. ^ H. C. Urey, Ferdinand G. Brickwedde, G. M. Murphy (1932). "A Hydrogen Isotope of Mass 2". Physical Review 39: 164–165. Bibcode:1932PhRv...39..164U. doi:10.1103/PhysRev.39.164. 
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  22. ^ Bild,, W, Năstasă V, Haulică, I. . (2004) In Vivo and in Vitro Research on the Biological Effects of Deuterium-depleted water: Influence of Deuterium-depleted water on Cultured Cell Growth, Rom J. Physiol. Vol. 41, N 1-2, pp. 53-67.
  24. ^ Mosin, O. V., I. Ignatov, I. (2013) Microbiological Synthesis of 2H-Labeled Phenylalanine, Alanine, Valine, and Leucine/Isoleucine with Different Degrees of Deuterium Enrichment by the Gram-Positive Facultative Methylotrophic Bacterium Вrevibacterium Methylicum, International Journal of BioMedicine, Vol. 3, N 2, pp. 132-138.
  25. ^ Katz J., Crespy H. L. (1972) Pure Appl. Chem., Vol. 32, pp. 221–250.
  26. ^ Mosin O. B., Skladnev D. A., Egorova T. A., Shvets V. I. (1996) Biological Effects of Heavy Water, Bioorganic Chemisytry , Vol. 22, N 10–11, pp. 861–874.
  29. ^ Skladnev D. A., Mosin O. V., Egorova T. A., Eremin S. V., Shvets V. I. (1996) Methylotrophic Bacteria as Sourses of 2H-and 13C-amino Acids. Biotechnology, pp. 14–22.
  31. ^ Thomson J.F. (1960) Physiological Effects of D2O in Mammals. Deuterium Isotope Effects in Chemistry and Biology. Annals of the New York Academy of Sciences, Vol. 84, pp. 736-744.
  33. ^ Watson, P. E. et al.(1980) Total body water volumes for adult males and females estimated from simple anthropometric measurements, The American Journal for Clinical Nutrition, Vol. 33, No 1, pp.27-39.
  34. ^ Money, K. E.; Myles (February 1974). "Heavy water nystagmus and effects of alcohol". Nature 247 (5440): 404–405. Bibcode:1974Natur.247..404M. doi:10.1038/247404a0. PMID 4544739. 
  35. ^ "Point Lepreau in Canada". NNI (No Nukes Inforesource). Archived from the original on 2007-07-10. Retrieved 2007-09-10. 
  36. ^ Associated Press (6 March 1990). "Radiation Punch Nuke Plant Worker Charged With Spiking Juice". Philadelphia Daily News. Retrieved 2006-11-30. 
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  38. ^ http://convert-to.com/conversion/water-weight-volume/convert-metric-tonne-t-water-weight-to-liter-l-of-water-volume.html
  39. ^ See Norsk Hydro Rjukan
  41. ^ "3 Scandals Oslo Must Put to Rest". International Herald Tribune, 1988-10-07, p. 6 (1988-09-14). Retrieved from Wisconsinproject.org on 2012-04-20.
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  46. ^ Limnology and hydrology of Lake Tanganyika and Malawi, Ruud C. M. Crul - http://unesdoc.unesco.org/images/0010/001085/108584eb.pdf
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External links[edit]