An approach to determination of 226 Ra and 228 Ra in the ground water and its impact on the population dose

The concentrations of naturally occurring radionuclides of Ra and Ra were determined in the groundwater samples in three areas near Riyadh city in Saudi Arabia. The waters of these areas are supplied for the city consumption. A total of thirty water samples of the three areas were analyzed for Ra and Ra. The concentration of Ra was found in the range from 2.1 – 6.3, 7.2 14.1 and 16.7 – 33.5 mBq·L and the concentration of Ra ranged from 3.2 – 8.4, 17.2 26.8 and 22.9 34.7 mBq·L for the site 1, site 2 and site 3, respectively. A radiochemical separation technique was followed which is based on co-precipitation of radium with barium-133 tracer (1x10 dpm·ml). For measuring radium in water, the intended radioisotope was coprecipitated with barium as Ba(RaSO4) and radium-226 activity was finally measured by α-spectrometry. For measurement of radium-228, high resolution and low background γ-spectrometry was used. The committed effective dose for the different age groups based on the water consumption of 1.5 L·day has been estimated and found to be not more than 0.003 mSv·yr for adults and 0.014 mSv·yr for critical age group (12-17 years old), for Ra. While it is not more than 0.007 mSv·yr for adults and 0.056 mSv·yr for critical age group, for Ra. The results obtained were compared with the World Health Organization (WHO) drinking water directive [6]. We have also evaluated the suitability of the ground water for drinking purposes on the basis of national standards. It appears that the waters of the three regions under investigation do not pose any significant threat to the population health if used for drinking purposes.