Deuterium

Abstract The hydrogen atom is believed to have been created during the “Big Bang” by proton–electron combinations (2). Together with an oxygen atom, it forms the water molecule and has three isotopes: 1 H (common hydrogen), 2 H (deuterium, D), and 3 H (tritium, T). Deuterium, discovered by Urey et al. (3) in 1932, is much heavier than 1 H. Common hydrogen has one proton, deuterium has one proton and one neutron, and tritium has one proton and two neutrons. Deuterium (also referred to as the heavy stable isotope of hydrogen) and common hydrogen are stable, but tritium is radioactive. In seawater, the relative abundances of hydrogen isotopes are H (99.984%), D (0.016%), and T (5 × 10 −5 %) (1). In the hydrosphere, there is only one deuterium atom per 6700 H atoms (4). Note that the arena of this article is limited to deuterium as it is a part of the water molecule. Hence, deuterium that may exist in other materials such as methane will not be dealt with here.