Forty-First Lauriston S. Taylor Lecture: Environmental Radiation and Life-A Broad View

Since Earth's creation some 4.5 billion years ago, primordial radioactivity has been part of the planet, and radiations from space have continuously impinged on its surface. Primordial radioactivity has helped shape Earth's surface through the heat from radioactive decay energy, and omnipresent natural radiation has likely influenced the origin, and certainly the evolution, of all life forms in our biosphere today. This paper offers a brief discussion of our natural radiation environment and its impacts, from the beginning of life to the present, and provides a broad overview of present day radioecology, which includes the use of radioactive tracers to study ecosystem functions, the fate and transport of radionuclides in the biosphere, and radiation effects on plants and animals. Large releases of radioactivity, although tragic and regrettable, have been studied to increase our knowledge of Earth's basic processes and of radionuclide transport and accumulation in the environment. On a much smaller scale, purposeful use of natural and anthropogenic radioactive tracers has contributed further knowledge. This information has solidified basic concepts and provided data for constructing dynamic models to calculate concentrations of radionuclides in, and radiation doses to, plants and animals. Sealed radiation sources have been used to study effects of chronic exposure on natural biotic communities. Existing transport models and knowledge of radiation effects provide tools to evaluate human health risks and environmental impacts of radioactive releases. Applications have included guidance for environmental protection, radiation litigation, environmental cleanup decisions and informed responses to releases of radioactivity. This paper concludes with a brief discussion of the more urgent knowledge gaps and potential new research approaches.