Gamma and alpha spectrometry for natural radioactive nuclides in the spa waters of Extremadura (Spain)

Gamma and alpha spectrometry of waters from several spas of Extremadura (Spain) were performed in order to determine their radioactivity. For the gamma spectrometry, the sample was measured directly using an HpGe detector with a Marinelli beaker. The nuclide 222Rn was determined by measuring the emissions from its daughters 214Pb and 214Bi and assuming transient equilibrium. Each sample was measured for several days in order to check that 214Pb and 214Bi decay with the half-life of 222Rn. Concentrations of 222Rn ranged from 3.5 to 234 Bq/l. Alpha spectrometry of uranium, thorium and 226Ra was performed by chemical separation of these elements from the samples and then using PIPS detectors for the measurement of the sources. Uranium concentrations were in general below 1 μg/l (with one exception), thorium specific activities were of the order of 10−5 Bq/l, and 226Ra activity ranged from 4.5 to 71 mBq/l. These results allow some conclusions to be established about the environmental behaviour of these radionuclides.