Activities and activity ratios of U and Ra radioisotopes in drinking wells, springs and tap water samples in Morocco

Radiochemical results (U-234, U-238, Ra-226 and Ra-228 activities; U-234/U-238, Ra-228/Ra-226 and Ra-226/U-238 activity ratios) are reported for 31 drinking water samples collected from 8 wells, 12 hot mineral springs, 5 cold springs, and 6 tap water samples. Activities of the Ra isotopes were measured by gamma spectrometry using a low background and high efficiency well type germanium detector. The U isotopes were counted in an alpha spectrometer. The results show that U-238 activity varies between 4.46 and about 308 mBq l(-1) in wells, 0.59 and 17.88 mBq l(-1) in hot springs, 2.19 and 3.21 mBq l(-1) in cold springs, and between 2.5 and 15.70 mBq l(-1) in tap water samples. U-234/U-238 activity ratio is generally higher than 1 which is the equilibrium activity ratio value in closed systems. It varies in the ranges 0.79-2.11 in wells, 0.97-7.39 in hot springs, 2.53-8.30 in cold springs, and 1.14-3.35 in tap water. Unlike well waters, spring waters show low 238U activities and high (234)Ur/U-238 activity ratios. The highest activity of Ra measured in hot mineral water samples is about 150 and 352 times higher than the highest activity of Ra found in well waters and in cold springs, respectively. Ra-226/U-238 activity ratios are in the ranges: 0.07-1.14 in wells, 1.79-2115 in hot springs, 0.86-4.79 in cold springs, and 0.18-5.61 in tap water samples. The data are similar to those published for other regions of the world.