Deuterium (symbol: Hydrogen-2, D or 2H), also known as heavy Hydrogen. is one of the two stable isotopes of hydrogen. The other one is Protium (symbol: Hydrogen-1, 1H). The nucleus of Deuterium, called Deuteron, contains one proton and one neutron, whereas the far more common, Protium has no neutron in the nucleus. Deuterium has a natural abundance in Earth’s oceans of about 1 atom to 6420 atoms of hydrogen. Thus deuterium accounts for approximately 0.0156% (or 0.0312%, on a mass basis) of all the naturally occurring hydrogen in the oceans, while Protium accounts for more than 99.98%. The abundance of deuterium changes slightly from one kind of natural water to another (see Vienna Standard Mean Ocean Water).
What is deuterium?
Deuterium is one of the three Hydrogen isotopes.
The nucleus of most Hydrogen atoms in nature contains one proton, but the nucleus of some hydrogen atoms can contain one proton and one neutron or one proton and two neutrons.
The first and the most common isotope of Hydrogen is call Protium (chemical symbol: 1H), the second is named Deuterium (chemical symbol: 2H or D), and the third one is Tritium (chemical symbol: 3H or T). Protium and Deuterium are a stable isotopes, but Tritium is an unstable one.
The abundance of deuterium in the water on Earth is approximately one deuterium atom to 6.400 hydrogen atoms (156,25 parts per million-ppm), or 0.0156%. This deuterium concentration changes very little from a natural water source to another.
The deuterium concentration in the adult human body is approximately of 120 to 140 ppm. Although it doesn’t seem much, if we compare this concentration with concentration in plasma of other vital elements, we can see that deuterium is present in an amount six times greater than calcium and ten times greater than magnesium.
Deuterium in nature
The deuterium content of waters, with minimal fluctuations:
- in the temperate climate area – 150 ppm (parts per million) D/(D+H),
- at the Equator – 155 ppm,
- in northern Canada – 135 ppm.
The deuterium quantity in water varies not only with latitude but also altitude (with a values ranging between 150 ppm at sea level and 130 ppm at heights above 3000 meters).
The deuterium concentration in an adult organism is of about 12-14 mmol/l (millimoles per liter). Although it doesn’t seems much, compared to the concentrations of other vital elements in the blood, deuterium is approximately six times more than calcium and ten times more than magnesium.
The deuterium quantity measured in the organisms that live in a certain geographic area is proportional with the deuterium concentration of the water in that area.
Deuterium properties
Deuterium can have kinetic isotopic effects different than hydrogen has, and the physical and chemical properties of the deuterium compounds differ from those of hydrogen compounds. For example, D2O (heavy water) is more viscous and heavier than H2O (normal water).
Heavy water is approximately 10% more dense than normal water, enough for the ice formed of heavy water to sink in normal water.
The differences in connection energies and lengths of hydrogen isotope compounds are greater than the isotopic differences for any other element. The bonds between deuterium and tritium are stronger than those with hydrogen, these differences being enough to produce important changes in biological reactions.
Heavy water is toxic to eukaryotic organisms. If 25% of the water in the organisms is replaced by heavy water, problems in cell division and reproduction appear. If 50% of the water is replaced, the eukaryotic organisms die.
Negative effects of Deuterium
Higher concentrations of heavy water kills fish, amphibians and insects.
Experiments conducted on rodents showed that a high level of deuterium of as much as 25% in the body water causes sterility, because neither the gametes nor the zygotes can develop.
Small mammals such as rodents die after approximately a week of consuming heavy water. The cause of death is similar to that of cytotoxic poisoning (the case of chemotherapy) or acute radiation syndrome.
