Radioactive nuclides of cosmogenic and terrestrial origin. Radioactivity of the atmosphere. Atmospheric dispersion of radioactive nuclides. Radioactivity in marine environment, rivers and lakes, tap water and thermal springs. Radioactivity in soil and plants. Radioactive nuclides of man-made origin. Uranium mines, enrichment and depleted uranium, radioactive wastes. Nuclear accidents and radioactive fallout. Radiation dosimetry