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Mediterranean Sea: Radionuclides

  1. Roberta Delfanti,
  2. Carlo Papucci

Published Online: 15 DEC 2011

DOI: 10.1002/9781119951438.eibc0444

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Delfanti, R. and Papucci, C. 2011. Mediterranean Sea: Radionuclides. Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. ENEA-Marine Environment Research Centre, La Spezia, Italy

Publication History

  1. Published Online: 15 DEC 2011


The main sources of anthropogenic radioactivity in the Mediterranean Sea are fallout from atmospheric nuclear weapon testing and from the Chernobyl accident in 1986, while the releases from the nuclear industry are small. Consequently, the present radionuclide levels in the marine environment are of no concern from the radiological point of view. However, the Mediterranean Sea is an ideal environment to show how both coastal and open-sea processes act to redistribute radionuclides in the different compartments of the marine environment. In fact, the Mediterranean Sea is considered a miniature ocean, where all the processes characterizing the global ocean take place on smaller space and timescales. For these reasons, in the past decades it had largely been used as a “laboratory basin” for process studies. In this framework, anthropogenic and natural radionuclides were often measured to be used as tracers of water mass dynamics, transit and renewal times, particle dynamics, sediment accumulation, etc. In this article, we first briefly describe the physical and biogeochemical characteristics of the Mediterranean Sea. After reviewing and quantifying the sources of radioactivity, we mainly focus on two radionuclides: (i) 137Cs: conservative in the open sea, the most abundant anthropogenic radionuclide, and, among these, the main contributor to radioactive dose to the population, and (ii) the very long-lived 239,240Pu: nonconservative and the most abundant among transuranics. We describe their distribution and time trend in seawater, sediments, and biota, define their budgets in the basin, quantify the exchanges at the Gibraltar and Turkish Straits, and indicate future trends. We also report levels and distributions of selected natural radionuclides: (i) 238U, with 234Th as the main tracer for particle dynamics and whose concentration in the Mediterranean slightly differs from that in the oceans, and (ii) 210Po, which is efficiently accumulated by marine organisms and is the main contributor to radioactive dose to the population. Finally, we identify topics for future research, mainly related to the application of nuclear techniques to the study of oceanographic processes.


  • Mediterranean Sea;
  • anthropogenic radionuclides;
  • natural radionuclides;
  • seawater;
  • vertical distribution;
  • sediments;
  • biota;
  • radionuclides' inventories