As a prerequisite for most evaluations of radionuclide transport pathways in marine systems, it is necessary to obtain basic information on the sorption potential of contaminants onto particulate matter. Kd values for use in modeling radionuclide dispersion in the Kara Sea have been determined as part of several international programs addressing the problem of radioactive debris residing in Arctic Seas. Field and laboratory Kd experiments were conducted for the following radionuclides associated with nuclear waste: americium, europium, plutonium, cobalt, cesium and strontium. Emphasis has been placed on two regions in the Kara Sea: (i) the Novaya Zemlya Trough (NZT) and (ii) the mixing zones of the Ob and Yenisey Rivers (RMZ). Short-term batch Kd experiments were performed at-sea on ambient water column samples and on samples prepared both at-sea and in the laboratory by mixing filtered bottom water with small amounts of surficial bottom sediments (particle concentrations in samples = 1-30 mg/l). Within both regions, Kd values for individual radionuclides vary over two to three orders of magnitude. The relative particle affinities for radionuclides in the two regions are americium approximately equal to europium > plutonium > cobalt > cesium > strontium. The values determined in this study agree with minimum values given in the IAEA Technical Report [IAEA, 1985. Sediment Kd's and Concentration Factors for Radionuclides in the Marine Environment. Technical Report No. 247. International Atomic Energy Agency, Vienna.]. Given the importance of Kd's in assessments of critical transport pathways for radionuclide contaminants, we recommend that Kd ranges of values for specific elements rather than single mean values be incorporated into model simulations of radionuclide dispersion.

The Arctic seas are influenced by radioactive contamination from both military and civilian sources such as global fallout, river transport, discharges from reprocessing plants and Chernobyl fallout. A joint Norwegian American field expedition was carried out to the Kara Sea in August-September 1995. An expedition to the Eastern Barents sea was conducted in September 1996. The investigation was funded by the Norwegian Ministry of Defence, The Norwegian Defence Research Establishment and Naval Research Laboratory. Both expeditions were conducted on the Norwegian Defence Research Establishment's ship H. U. Sverdrup II. In 1995 sea water, sediment samples and sea birds were collected along the east coast of Novaya Zemlya, in the East Novaya Zemlya Trough, east of the Kara Strait, along the Yamal and Taimyr peninsulas and in the Ob and Yenisey estuaries. In 1996 sea water and sediments were sampled along the west coast of Novaya Zemlya, west of the Kara Strait, in the Pechora Sea and outside Cape Kanin and along the Kola Peninsula.