Simultaneous measurement of 226Ra and 228Ra in natural water by liquid scintillation counting

Several types of bottled drinking water originating from three different areas in Egypt are studied through measurement of radium activity, assessment of related annual dose for adults and finally to define the role of water quality on radium levels. The mean levels of 226Ra activity range from 0.44 to 0.92 Bq/L and the mean levels of 228Ra from 0.30 to 0.78 Bq/L, with related 226Ra/228Ra ratios ranging from 2.61 to 0.56. Water types originating from the Eastern Nile Delta area are characterized by low 226Ra levels and relatively high 228Ra activity, presumably due to the muddy agricultural nature of this area, which is subject to water from several surface resources for irrigation. In general, the mean activity levels for both 226Ra and 228Ra are within those in drinking water in several other countries and the annual ingested dose is comparable with the typical range reported by UNSCEAR. Also, the effect of TDS, pH, calcium, bicarbonate, sulphate and chloride ion concentrations on radium levels is studied and discussed.