Radiological characterization of drinking waters in Central Italy

The quality of drinking water, due to the importance in the human diet, must be strictly controlled. In this study, a monitoring of radioactivity content was performed in tap waters collected in a region of Central Italy to check the compliance with recent European and Italian regulations. Gross alpha and beta activities, 238U, 234U, 226Ra, 222Rn, and 3H concentrations were measured. Gross alpha and beta activities were determined by standard ISO 9696 and ISO 9697; for 226Ra, 222Rn and 3H determination, liquid scintillation was used. 238U and 234U concentrations were determined by alpha spectrometry after separation from the matrix by extraction chromatography and electroplating. The results obtained revealed that, in most samples, gross alpha and gross beta were lower than the parameter value indicated in the international regulations. An attempt was also made to find a correlation between these results and the chemical parameters of waters. The results indicate, as expected, a good correlation between gross beta activity and 40K concentration. In all samples uranium isotopes represent the principal radioactivity source. As the isotopic equilibrium is not always attained, all isotopes should be individually quantified. 226Ra usually exhibits a lower concentration than uranium, however its determination is very important due to its higher radiotoxicity. 222Rn concentration is very low in all the samples . All the samples presented a 3H concentration lower than MDA. As far as the compliance with international regulations is concerned, recommended WHO guideline activity concentrations for drinking water were exceeded in 2 cases for gross alpha activity and were not exceeded in any case for gross beta activity. In the two samples with an alpha activity higher than 100 mBq L-1, the sum of uranium and radium concentrations agrees well enough with the total alpha value.