49 



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be of great value in assessing the importance of pathways for the 

 transport of persistent organics into the Arctic. Prime Minister 

 Mulroney also announced that Canada will build an atmospheric 

 monitoring station in the Russian Arctic to examine persistent 

 organics, thereby complementing the actions planned under the AMAP 

 and the Rovaniemi Declaration. 



A second example of bilateral cooperation is the joint 

 Norwegian-Russian investigation of former Soviet nuclear dump 

 sites in the Barents Sea, which will begin on August 15, 1992. A 

 Canadian will participate in this activity, collecting samples for 

 analysis in Canada, and Norway has been informed of our 

 willingness to take part in future related studies. The full 

 extent of nuclear disposal practises used by the former Soviet 

 Union in the Arctic is only now becoming known, and the potential 

 environmental impact must be assessed. Theoretical considerations 

 suggest that the degree to which radionuclides are dispersed 

 following leakage from a marine dump site container will depend on 

 the physico-chemical form in which the radionuclides are released. 

 Many radionuclides such as plutonium-239 and 240 have a high 

 affinity for particles and are therefore likely to be incorporated 

 into sediments in a very localised area. However, some other 

 radionuclides, such as cesium-137, strontium-90, technetium-99 and 

 tritium would be mobilised much more easily and, therefore, 

 ultimately would be widely dispersed throughout the Arctic Ocean. 

 The most widely studied test case at this time is probably that of 

 the U.S. B-52 bomber armed with nuclear weapons which crashed 

 through the sea ice near Thule, Greenland, in 1968. Although a 

 major plutonium spill into the environment occurred, after 25 

 years little of this material appears to have migrated beyond 

 fifty kilometres of the crash site (11) . 



An additional factor which must be considered in this 

 regard is the ambient background of radioactivity already present 

 in the Arctic Ocean. The level of radionuclides is similar to 

 those in other oceans in the world, and the sources can be ranked 

 in decreasing order of significance as follows: natural sources 

 (e.g. polonium) , atmospheric weapons testing, the Sellaf ield 

 nuclear fuel reprocessing plant in the United Kingdom and, 

 finally, Chernobyl (12, 13). While the state of our knowledge 

 should be further advanced by the time the international 

 scientific conference on Radioactivity in the Arctic and Antarctic 

 convenes in Kirkenes, Norway, in August, 1993, there clearly 

 remains much to be learned. 



. . ./6 



