Natural radioactivity in the

Kawano, M. and S. Nakatani, Some properties of Natural Radioactivity in the Atnmosphere, in The natural Radiation Evviroment, (J. A. S. Adams and W. M. Lowder, ed) pp. 291-312, Univ. Chicago Press,... 

Nuclear dating has been most helpful in establishing the history of the earth and of the moon and of the meteorites. The fact is, there is no other way of measuring their ages. Prior to the discovery of natural radioactivity in the late 19th century, indirect methods were used to estimate the age of the earth, but there were no real answers until the radioactivity of thorium, uranium, and potassium were discovered and we began to understand atomic structure and to realize that nuclear transformation was essentially independent of the chemical form. 

Krey P, Fiseene I, Perry P, et al. n.d. Natural radioactivity in the biosphere. Environmental Measurements Laboratory, New York, NY. 

Reduction of background radiation owing to natural radioactivity in the metal parts of the detector chamber and shielding can be reduced as shown by using electrolytic quality metals. In addition, backscatter can be reduced significantly by improvements in the counting geometry. These improvements are worthy of consideration. 

Many natural radioelements are of great practical importance, in particular U with respect to its application as nuclear fuel, but also Th, Ra and Rn. Ra (T/2 = 1600 y) is found in many springs and the noble gas Rn is the main source of natural radioactivity in the air. 

Martinez-Aguirre et al. (1994) have performed an extensive study of the presence of natural radioactivity around a phosphate fertilizer factory complex situated in an estuarine area of southwest Spain. The study has concluded that the wastes from such industries are the cause of the enhancement of natural radioactivity in the immediate environment. Thus, significantly high levels of U and Th-isotopes and Ra are detected in water and sediment samples collected in this area. These conclusions, based on the enhanced isotopic concentrations, are further supported by the measured U, Th and Ra isotopic activity ratios being quite different from any observed elsewhere in undisturbed estuaries. These isotope activity ratios appear to be very sensitive indicators of waste disposal practices in such environments. 

Mastinu, G.G., Natural radioactivity levels in releases from coal-fired power plants in Italy. In Seminar on the radiological burden of man from natural radioactivity in the countries of the European Communities, pp. 429-436. CEC report V/2408/80, 1980. 

Whole-body counters were originally developed for investigation of poisoning by radioactive substances such as radium. They are now used diagnostically and consist of a large scintillation, or semiconductor, detector with the whole system, including the patient, placed in a heavily shielded room. The sensitivity is sufficient to measure natural radioactivity in the human body from such nuclides as... 

Natural radioactivity provides tracers in a wide range of characteristic timescales and reactivities, which can be used as tools to study the rate of reaction and transport processes in the ocean. Apart from cosmogenic nuclides and the long-lived radioisotope K-40, the natural radioactivity in the ocean is primarily derived from the decay series of three radionuclides that were produced in the period of nucleosynthesis preceding the birth of our solar system Uranium-238, Thorium-232, and Uranium-235 (a fourth series, including Uranium-233, has already decayed away). The remaining activity of these so-called primordial nuclides in the Earth s crust, and the range of half-lives and reactivities of the elements in their decay schemes, control the present distribution of U-series nuclides in the ocean. 

Natural radioactivity in the environment originates from two sources. First, primordial radionuclides which were incorporated into the Earth at the time of its formation are still present in it because of their long half-lives. Th and their decay... 

Radionuclide-tracer studies in natural marine environments obviously must rely on natural radioactivity in the environment or on radionuclides introduced from the activities of man such as fallout from nuclear-weapons testing or release of major amounts of nuclear waste such as from the Hanford Operations via the Columbia River. Some studies of this type have been discussed. We will conclude this section with those that are more closely related to investigations of com-plete ecosystems or subsystems. 

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