Radioactivity of Water

the radioactivity caused by the presence of radioactive substances. These substances are introduced from the atmosphere or are washed out of soils and rocks. Both natural radioactive isotopes, such as ⁴⁰K, ²²²Rn, ²²⁶Ra, and ²³⁸U, and artificial isotopes arising from nuclear explosions, mainly ⁹⁰Sr, ⁹⁰Y, and ¹³⁷Cs, can be present in water. The content of natural radioactive substances in water depends on the origin of the substances and varies considerably (Table 1).

Artificial radioactive substances enter water together with precipitates from the atmosphere. Thus, as a result of the testing of nuclear weapons, the concentration of ⁹⁰Sr in natural water increased steadily until 1968, reaching 10 picocuries per liter in some cases. Another major source of artificial radioactive substances is the water discharged from plants that produce nuclear fuel.