RadonToxic elements RAD-7 a b s t r a c tThe radon activity concentration and toxic elements have been assessed in drinking and irrigated water samples collected from different locations of Sungai Petani, Kedah, Malaysia. The water samples were collected from wells, streams and taps. A calibrated alpha spectrometer RAD-7 (Model 2890) and Atomic Absorption Spectrometers (Perkin eElmer, Model AAnalyst 200, Shimadzu, Model AA-700) were used to estimate radon activity concentration and toxic elements, respectively. Maximum average value of radon concentration among the various types of water sources was found 14.7 ± 1.44 Bq/l in well water used for drinking and irrigation and minimum was found 5.37 ± 0.58 Bq/l in tap water used for drinking. Contribution of radon in drinking water to indoor air and age dependent associated annual effective doses were calculated from the measured radon concentration and were found less than lower limit of recommended action level. The activity concentrations of Ni > Pb > Cd > As > Cr were found higher for streams water as compared to wells and tap water. Values of radon concentration in well water were found higher than EPA recommended level and lower than WHO action level while the annual effective doses and level of toxic elements in water reported in this study were found lower than recommended level.

Available online xxxKeywords: Radioactivity Soil RiceTransfer factor Physico-chemical effects a b s t r a c t Radioactivity distribution and transfer factor (TF) in plants are crucial parameters used to assess radioactive contamination in the environment and its risks to humans. In this study, the activities of 226 Ra, 232 Th, and 40 K were successfully measured via gamma-ray spectrometry on rice plant components (root, straw, husk, and grain) and on corresponding soil samples collected from paddy fields in Penang, Malaysia. Soil physicochemical characteristics (pH, citation exchange capacity, electrical conductivity, organic matter, and soil texture) were also analyzed for their estimated effects on soilegrain TF. A major fraction of the total 226 Ra and 232 Th activities measured at 47% and 57%, respectively, were concentrated in the roots, whereas only about 9% and 8% were distributed in the grains, correspondingly. 40 K activity accumulation was about 59% in the straw and 7% in the grains. Rice soilegrain TFs were observed in the ranges of (0.06e0.36) Â 10 À1 for 226 Ra, (0.04e0.14) Â 10 À1 for 232 Th, and (0.74e4.72) Â 10 À1 for 40 K. Results showed that the selected radionuclide distributions in rice are dependent on component type, and their grain concentrations are not linearly related to their soil concentrations. These findings indicated that uptake predominantly depends on soil physico-chemical characteristics.