Environmental Impact and Health Effects of Hydrogen(2)

Deuterium
Deuterium is the stable, nonradioactive isotope of hydrogen, commonly called heavy hydrogen because its atomic weight is approximately doubles that of ordinary hydrogen, but it has identical chemical properties. Deuterium has about twice the atomic weight of normal hydrogen because its nucleus contains a proton and a neutron, instead of just a proton. Hydrogen as it occurs in nature contains approximately 0.02 percent of deuterium that was the first isotope to be separated in a pure form from an element. Several methods have been used to separate the isotope from natural hydrogen. The two processes that have been most successful have been fractional distillation of water and a catalytic exchange process between hydrogen and water. In the latter system, when water and hydrogen are brought together in the presence of a suitable catalyst, about three times as much deuterium appears in the water as in hydrogen. Deuterium has also been concentrated by electrolysis, centrifuging, and fractional distillation of liquid hydrogen. The nuclei of deuterium atoms, called deuterons, are much used in research in physics because they can be readily accelerated by cyclotrons and similar machines and used as “atomic bullets” to transform an atom of one element into another element. Deuterium also has important uses in biological research as a tracer element for studying problems of metabolism.

Regular hydrogen and deuterium are not normally metallic, meaning they are not shiny or malleable. Scientists have used pressure and heat, however, to force deuterium to act like a metal, making it shinier and easier to compress. Studying deuterium in compressed and highly hot conditions can help scientists understand how hydrogen behaves in the hot, heavily pressurized interiors of planets and in the interiors of stars. The use of heavy water as a moderator in atomic piles has been suggested and Deuterium, either in deuterium oxide or in lithium deuteride, and tritium are essential components of nuclear fusion weapons, or hydrogen bombs.

Tritium
Tritium is the radioactive hydrogen isotope of atomic mass 3 and symbol 1H3 or T. The nucleus of a tritium atom consists of a proton and two neutrons. It undergoes decay by beta emission to give a helium nucleus of mass 3; it has a half-life of 12.26 years. Tritium is produced in a number of ways, including the bombardment of deuterium compounds with high-energy deuterons and by the absorption of neutrons by the lithium isotope of mass 6. Some tritium is produced in the upper levels of the atmosphere by the bombardment of nitrogen with energetic neutrons produced by cosmic rays; rainwater is usually found to contain minute amounts of tritium. The enormous amount of energy released when tritons react with deuterons in the so-called nuclear-fusion process makes tritium an important constituent of hydrogen bombs. Tritium is also used as a tracer in chemical and biochemical research.