Natural radioactivity of some spring and bottled mineral waters from several central Balkan sites, as a way of their characterization

Abstract

In this work, a study of the radioactive content of some spring and bottled mineral waters originating fi-om metamorphic rock areas was carried out. A high content of radium isotopes (Ra-226, Ra-228), was found by radiometric analysis in the spring waters: Studenica (Ra-226: 289 mBq/L), Cibutkovica (Ra-226: 92, 4 mBq/L, Ra-228: 610 mBq/L), and Crni Guber (Ra-226: 120 mBq/L, Ra-228: 1170 mBq/L). On the other hand, the radiochemical results showed a higher concentration of U-238 in the bottled mineral water samples (dissolved uranium concentrations were from 0.21 mBq[L, for Kopaonik to 71.5 mBq/L fo Skadarska) than in the spring water samples (dissolved uranium concentrations were very low approximate to 10 mBq/L). The concentrations of all the present naturally occuring radionuclides: U-238, U-234, Th-232, Th-230, Th-228, Ra-228 and Ra-226 were determined by alpha/gamma spectrometric analysis. The activity ratios U-234/U-238, Ra-226/Th-230 and Th-228/Th-232, Ra-228/Th-228 were calculated and are discussed as an indication of the radioactive disequilibrium in bothe the U-238 and Th-232 radioactive series. The high contents of radium isotopes with respect to the equilibrium values expected from the respective parents Th-232/(Th-232 series) and Th-230 (U-238 series) found in the spring water samples is the main evidence for the existence of significant radioactive disequilibrium in both the radioactive series.