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Oceans and Seas: Radionuclides

  1. Michio Aoyama

Published Online: 15 JUN 2010

DOI: 10.1002/0470862106.ia743

Encyclopedia of Inorganic Chemistry

Encyclopedia of Inorganic Chemistry

How to Cite

Aoyama, M. 2010. Oceans and Seas: Radionuclides. Encyclopedia of Inorganic Chemistry. .

Author Information

  1. Meteorological Research Institute, Tsukuba, Japan

Publication History

  1. Published Online: 15 JUN 2010


The main sources of anthropogenic radioactivity of the world ocean are fallout from atmospheric nuclear weapon testing and the releases from nuclear fuel reprocessing plants and from the Chernobyl accident in 1986. This article summarizes the numbers of tests and the annual fission and fusion yields for the atmospheric weapon tests. The artificial radionuclides 137Cs, 239, 240Pu, 90Sr, and other transuranics are used for monitoring and study by many institutes and organizations in many countries for the following reasons: (i) 137Cs and 90Sr are conservative in the open sea, the most abundant anthropogenic radionuclides, and the main contributors to biological exposure; and (ii) the very long-lived 239, 240Pu is nonconservative and the most abundant among transuranics. The number of observations of these radionuclides in each sea area is summarized. Global distribution of 137Cs decay corrected for accumulative deposition as of January 1, 1970 is described as the initial condition of 137Cs inventory in the world ocean. The collective effective dose commitment to the world population from artificial and natural radionulides in the marine food is described. The current radionuclide levels in the world ocean are low and therefore of no concern from the radiological point of view.


  • artificial radionuclides;
  • global fallout;
  • nuclear weapons tests;
  • nuclear fuel reprocessing;
  • SNAP-9A;
  • global database;
  • effective dose;
  • fish;
  • shellfish