97 



chemical, physical, and biological baseline data to understand 

 environmental processes and to assess the potential threat of 

 radioactive contamination to the Alaskan economy or the health of 

 U.S. citizens. Twenty -three multi-national and multidisciplinary 

 cruises (FIGURE 1), including the U.S. submarine CAVALLA, have 

 collected water, sediment, and biological samples in the eastern 

 Arctic near the dump sites, in the Ob, Yenisey and Anadyr River 

 systems, the Kara, Laptev, East Siberian, and Beaufort Seas and 

 across the Arctic Basin. Processes investigated include: 



• ice uptake and movement of radionuclides and sediment; 



• density driven currents on Arctic shelves; 



• sediment dynamics in the Kara Sea; 



• interactions between colloids and radionuclides in the 

 Arctic river systems; 



• corrosion of disposal barrier materials; 



• identification of sentinel organisms for the monitoring 

 and evaluation of Arctic radionuclide contamination; 



• radionuclide levels and bioconcentration in Arctic 

 animals; 



• deposition of radionuclides due to interactions with 

 phytoplankton; and 



• sublethal biological effects from radionuclide 

 contamination . 



Transport modeling efforts account for marine surface and 

 subsurface layers, coastal currents, estuarine and river water, 

 and ground water over a broad range of spatial and temporal 

 scales. Near -field modeling at dump sites includes sediment re- 

 distribution physics and biology. Model validation and 

 integration are key ongoing activities that build upon decades of 

 previous research. 



A major data compilation effort at the Naval Research 

 Laboratory (NRL) uses a Geographic Information System to analyze 

 changes in marine radionuclide levels over space and time. The 

 three largest contamination signals in the Arctic region can be 

 seen in Cesium-137 distributions in the surface layer {0-50m) of 

 the ocean. Fallout from atmospheric bomb tests, which ceased in 

 the early 1960's, resulted in elevated levels (10-20 Bq/m3) 

 throughout the region that have since decayed considerably. 

 Radioactive waste discharges from the Sellafield re-processing 

 facility, which peaked during the early 1980 's, can now be traced 

 (10-30 Bq/m3) throughout the eastern Arctic basin following the 

 major oceanic current systems. Trace amounts of this source have 

 recently been detected in the Ji/estern Arctic as well. In the 

 1990 "s, the Sellafield signal has decreased and the effects of 

 the Chernobyl accident dominate, particularly in the Baltic (over 

 100 Bq/m3) . Signatures of these events can also be seen in 

 sediment cores throughout the region (FIGURE 2) . At this time, 

 concentrations in Alaskan waters remain at background levels. 



