In the waters of Karlovy Vary thermal structure were measured activity of all natural isotopes of radium (223Ra, 224Ra, 226Ra, 228Ra). Set volume activity of radium isotopes are high, the highest activity of the primary Vřídlo (3.05 Bq l-1).
On the basis of the ratio can be calculated 228Ra/226Ra for ekvilibrace with rocks (granite Carlsbad), the situation is complicated by secondary processes.