Artificial radionuclides in the East Sea (Sea of Japan) proper and Peter the Great Bay

Over the past decade there has been growing concern over dumping of radioac tive waste in the East Sea (Sea of Japan) proper and adjacent coastal water s. Here we show that the evolution of activity concentrations of Cs-137 and Pu239+240 in the East Sea, and existing levels of radioactive contaminatio n in waters, sediments and biota from Peter the Great Bay (Russia) can be l argely attributed to global fallout deposition. The former sequence of data includes results from the AWARES cruise (Active Watch of Artificial Radion uclides in the East Sea) conducted between 26 October and 1 November 1993 a bout ten days after 14 GBq of liquid radioactive waste was dumped into the East Sea. The activity concentration of Cs-137 and Pu239+240 in surface wat ers ranged between 2.7-3.5 Bq m(-3) and 3.5-20.8 mBq m(-3), respectively, a nd were not different to levels observed during August 1993 prior to the Ru ssian dumping operation in October. Isotopic ratios also indicate the absen ce of any significant anthropogenic radioactive contamination in the region other than from global fallout deposition. (C) 1999 Elsevier Science Ltd. All rights reserved.