POTENTIAL RADIONUCLIDE TRANSPORT PATHWAYS FROM SEA-FLOOR DUMPSITES - KAMCHATKA REGION OF THE NORTH PACIFIC-OCEAN

Encapsulated nuclear waste materials, dumped by Russia, are present at two deepwater seafloor locations in the offshore north-west Pacific O cean, south-east of the Kamchatka Peninsula. This paper assesses poten tial pathways by which these wastes might, if released from their cont ainers, disperse away from the dumpsites and through the surrounding o cean. A review of large-scale ocean circulation theory and of field an d model results suggests that mean abyssal currents are north-eastward to eastward from the dumpsite locations and would advect leaking mate rials toward the north-eastern Pacific. Results of advective and diffu sive horizontal plume transport models are consistent with this sense of flow, Trajectory speeds are, however, subject to considerable uncer tainty. Our results suggest that as little as 5 years or as long as 10 0 years might be required for material to be transported from the dump sites to the north-east Pacific, Dilution by 4 or 5 orders of magnitu de is predicted during this transit. Vertical mixing or upwelling are necessary in order to transport contaminants upward from north-east Pa cific abyssal waters to the near-surface layers before they can potent ially impact productive coastal regions, such as those off Alaska. Inf ormation concerning such upwelling mechanisms is inadequate for estima tion of rates or to identify geographical areas that might be at risk, (C) 1997 Elsevier Science Ltd. All rights reserved.