Lognormal distribution of natural radionuclides in freshwater sediments and coal-ash repositories

The distribution of natural radionuclides, K-40, Ra-226 and Th-232, in freshwater sediments and in coal-fired power-plant ash repositories has been tested for lognormality. Thereafter, lognormality for natural radionuclide concentration frequency distribution was accepted with a high probability. The log-normal natural radionuclide distribution in sediments and coal-ash indicated single population groups. The anthropogenic modifications of the natural radionuclide concentrations in the environment are indicated. The adsorbed dose rates, in mGy y(-1), in air from gamma field of the natural radionuclides were calculated.