AMS measurements of C-14 and I-129 in seawater around radioactive waste dump sites

According to a recent IAEA compilation of inventories of radioactive wastes dumped in the world ocean, a total of 85 PBq of radioactive wastes were du mped, in the Atlantic (45 PBq), the Pacific (1.4 PBq) and the Arctic (38 PB q) Oceans and their marginal seas between 1946 and 1993, mostly in the form of low-level wastes. H-3 and C-14 formed an important part of the beta-act ivity of these dumped wastes. Because of its long half-life, 14C will be th e main constituent in possible leakages from the wastes in the future. On t he other hand, C-14 and I-129 are important radioactive tracers which have been artificially introduced into the oceans. Small amounts of C-14 and I-1 29 can be easily measured by accelerator mass spectrometry (AMS) on mg-size samples of carbon and iodine extracted from 500 mi seawater samples. The h igh analytical sensitivity enables one therefore to find even trace amounts of C-14 and I-129 which could be released from radioactive wastes, and to compare the measured levels with the global distribution of these radionucl ides. The IAEAs Marine Environment Laboratory (IAEA-MEL) has been engaged i n an assessment program related to radioactive waste dumping in the oceans since 1992 and has participated in several expeditions to the Atlantic, Arc tic, Indian and Pacific Oceans to sample seawater, biota and sediment for r adiological assessment studies. In the present paper, we report on methods of C-14 and I-129 measurements in seawater by AMS and present data on the N E Atlantic, the Arctic and the NW Pacific Ocean dumping sites. A small incr ease of C-14 was observed at the NE Atlantic dumping site. (C) 2000 Elsevie r Science B.V. All rights reserved.