Uranium has both radioactive and chemical hazards and risk assessments must address both types. Its environmental distribution depends on natural occurrence and has been influenced by human activities such as energy production, coal, and phosphate fertilizer exploration, which may impact freshwater ecosystems. In this book, the authors present current research in the study of the characteristics, occurrence and human exposure to uranium. Topics include the anthropogenic sources of uranium in Serbia; uranium mining in Portugal; laser-induced nuclear decays in uranium isotopes; uranium hydrothermal deposits; and geophysical studies to evaluate geological and hydro-geological features in old uranium mines.