147 Artificial Radionuclides in the Western North Pacific: A Review G. H. HONG 1 , M. BASKARAN 2 and P. P. POVINEC 3 1 Korea Ocean R and D Institute, Ansan P.O. Box 29 Kyonggi 425-600, Republic of Korea 2 Department of Geology, Wayne State University, Detroit, MI 48202, U.S.A. 3 Marine Environment Laboratory, International Atomic Energy Agency, Monaco 98000, Monaco Abstract. Artificial radionuclides in the marine environment pose a significant concern along various political, health and environmental aspects since they were introduced as a by-product from the nuclear weapon testing, particularly in the northwestern Pacific Ocean. While radiological concern is confined only in special cases, the introduction of artificial radionuclides has been proven to be very useful tracers for the ocean processes. Various input of artificial radionuclides to the Pacific Ocean were compiled. Time series variation of the artificial radionuclides in the surface waters and in the water column was described. Finally, retrospective studies in the artificial radionuclide concentrations in the surface water was proposed using the dated corals taken from the northwest Pacific Proper away from the influence of coastal ocean. Keywords: artificial radionuclides, input, temporal change, behavior, coral records 1. INTRODUCTION The present sources of anthropogenic radionuclides in the marine environment, consisting of stratospheric and tropospheric fallout from atmospheric nuclear testing, accidental releases from civilian and military nuclear facilities including satellites, radioactive waste dumping in the Pacific Ocean are reviewed. The total activity of anthropogenic radionculides in the world’s ocean from fallout from nuclear weapons testing has been estimated to be more than 10 5 PBq (1 PBq = 10 15 Bq), with tritium contributing more than 99% to this inventory. The single largest contribution to radioactivity in the marine environment from accidental releases from land based nuclear installations has come from the accident at the Chernobyl nuclear power station in April 1986. We have chosen 90 Sr, 137 Cs and Pu isotopes as representative of anthropogenic radionuclides to study their distribution and behavior in the Pacific Ocean. On a global scale, 137 Cs and 210 Po, the most representative of anthropogenic ( 137 Cs) and natural ( 210 Po) marine radioactivity, the average annual individual doses from ingestion of marine food was estimated to be 0.03 µSv from 137 Cs and 9 µSv from 210 Po. The annual dose of 137 Cs for a hypothetical critical group consuming 100 kg of fish and 10 kg of shellfish per year would be 3 µSv, while the Global Environmental Change in the Ocean and on Land, Eds., M. Shiyomi et al., pp. 147–172. © by TERRAPUB, 2004.