Isotope abundances: periodicity
The isotopic abundances are representative isotopic compositions of chemicals most likely to be encountered in the laboratory.
The abundances need not necessarily correspond to the most common source of the material. So, the values quoted for hydrogen is for fresh water in a temperate climate rather than ocean water.
Values in parentheses represent ranges for probable variations in the materials as well as experimental errors.
- K.J.R. Rosman and P.D.P. Taylor for International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1997, Pure and Applied Chemistry, 1998, 70, 217. [Copyright 1997 IUPAC]