Determination and comparison of uranium and radium isotopes activities and activity ratios in samples from some natural water sources in Morocco

Radiochemical results (238U, 226Ra and 228Ra activities; 234U/238U, 228Ra/226Ra and 226Ra/238U activity ratios) are reported for 42 natural water samples collected from wells, hot mineral springs, rivers, tap water, lakes and irrigation water in 15 Moroccan locations. Results show that 238U activity varies between 4.5 and about 309 mBq l−1 in wells, 0.6 and 8.5 mBq l−1 in hot springs, 9.7 and 28 mBq l−1 in rivers, 2.5 and 16 mBq l−1 in tap waters and between 6 and 24 mBq l−1 in lakes. The 234U/238U activity ratio varies in the range 0.87–3.35 in all analyzed water samples except for hot springs where it reaches values higher than 7. Unlike well water, mineral water samples present low 238U activities and high 234U/238U activity ratios and 226Ra activities. The highest activity of radium in mineral water is 150 times higher than the highest activity of 226Ra found in well water. 226Ra/238U activity ratios are in the ranges 0.07–1.14 in wells, 0.04–0.38 in rivers, 0.04–2.48 in lakes, and 1.79–2115 in springs. The calculated equivalent doses to all the measured activities are inferior to the maximum contaminant levels recommended by the International Commission of Radioprotection and they do not present any risk for public health in Morocco.