Radon and radium concentrations in drinkable water supplies of the Thu Duc region in Ho Chi Minh City, Vietnam.

The results of (222)Rn and (226)Ra activity measurements in drinkable water supplies of the Thu Duc region in Ho Chi Minh City, Vietnam, are presented in this paper. The measurements were performed using a RAD 7 radon detector manufactured by Durridge Company, Inc. Mean concentrations of (222)Rn and (226)Ra were found to be 0.11±0.01Bql(-1) and 0.11±0.02Bql(-1) in 14 drinking water samples. They are 0.12±0.01Bql(-1) and 0.10±0.02Bql(-1) in 15 tap water samples, respectively. The mean (222)Rn concentration of 1.40±0.03Bql(-1) in the 20 groundwater samples of this study is also lower than the WHO advised level of 100Bql(-1). Fifty percent of groundwater samples analysed have (226)Ra levels in excess of the USEPA recommended maximum contaminant level of 0.185Bql(-1). The occurrence of elevated concentrations of (226)Ra in groundwater samples was explained by pH and alkaline conditions.