Abstract
Natural radio-nuclides; U-238, Th-232 and K-40 in rain, mine and tap water in Johor Bahru, Malaysia were measured by gamma-ray spectroscopy. Mean activity concentration of U-238, Th-232 and K-40 were found in rain water 2.34 +/- 0.11, 15.06 +/- 0.10, 4183.52 +/- 0.06 ppm, in mine water 3.32 +/- 0.10, 27.30 +/- 0.08, 6528 +/- 0.05 ppm and in tap water 2.18 +/- 0.11, 13.74 +/- 0.11 and 4435.97 +/- 0.06 ppm respectively. The mean estimated dose of U-238, Th-232 and K-40 in (mu Sv yr(-1)) to an adult from the rain, mine and tap water intake was 0.002 +/- 0.0001, 0.019 +/- 0.0001, 0.584 +/- 0.00004; 0.003 +/- 0.0001, 0.035 +/- 0.0001, 0.911 +/- 0.00004 and 0.002 +/- 0.0001, 0.017 +/- 0.0001, 0.619 +/- 0.00004 respectively.