Topic outline

  • Abundance of natural radionuclides in the ocean

    Many natural radionuclides are soluble in seawater, so here we calculated the abundance of nuclides that are soluble in seawater.

     The figure below shows the abundance when the amount of seawater is 1.4 billion km3. Units are PBq (1015 becquerels) or trillions of becquerels. The most common of these is potassium 40 (40K), 1022 becquerels (Bq). Compared to rubidium 87 (87Rb) and uranium 238 (238U), the amount of becquerel is about two orders of magnitude higher. Potassium 40 (40K) weighs about 40 billion tons. Uranium-238 (238U) is about 4 billion tons. It can be imagined that seawater as a whole contains a considerable amount of natural radionuclides.


    Abundance of major natural radionuclides in the ocean


    Amount of seawater on Earth: Approximately 1.4 billion km3


    Abundance of major natural radionuclides

    千兆ベクレル 1e15 Bq

  • Marine radionuclides (natural vs. man-made)