ABSTRACT
Chlorine has three isotopes in nature: 35Cl-common and stable; 36Cl-very rare and radioactive, with a 301,000-year half-life; and 37Cl-less common and stable. Chlorine-36 concentrations are commonly expressed in units of 107 atoms/l of water. The measurement is performed in specialized laboratories with dedicated accelerators. Measurements can be done on 1-1 water samples.
