238Pu Concentrations in the Marine Environment at San Clemente Island

Abstract

The concentration of plutonium and other radionuclides measured in samples of surface sediments, seawater and brown algae collected from the region offshore from North Light Harbor Pier at San Clemente Island, CA, are presented and discussed.Between 1967 and May 1978, different forms of nuclear fuels used in operational or proposed SNAP (Systems for Nuclear Auxillary Power) devices were tested at this site to evaluate the effects of seawater on the heat sources. The principal radionuclide in the heat sources tested was 238P~. During tests of materials containing significant quantities of z38Pu, small amounts of the radionuclide in the solid sources dissolved and migrated from the test chambers, either in solution or in association with particulate material, to the local marine environment. Currents dispersed this released z38Pu so that presently a small increase in concentration above that of fallout background is evident in the surface 3.0-cm layer of near shore sediment that extends over a 3.0-kmz area surrounding the pier. The 238Pu associated with this sediment is slowly redissolving and is in a form that can be taken up by marine algae. Except for a 0.025-kmz region around the pier, the total plutonium (z38Pu + 239+uoPu) in the surface 3.0-cm layer of sediment is within the range of total fallout plutonium reported in Atlantic and Pacific surface deposits from overlying water depths less than 100m. We estimate that more z3sPu was released during testing than the amounts accountable in the local surface sediments. Some of this 238Pu has undoubtedly migrated outside the region that we sampled, and dilution of the 238Pu with fallout levels in the environment has effectively obscured its detection elsewhere. Subsurface sediment deposits in the region may have inventories of excess 238Pu. Analysis of 238Pu concentrations in core samples is still in progress.

Radionuclides in marine macroalgae from Amchitka and Kiska Islands in the Aleutians: establishing a baseline for future biomonitoring

“…Algae have been used to examine exposure around industries using nuclear operations (Hung et al, 1998;Noshkin et al, 1981), and often accumulate higher levels of radionuclides than other organisms (Bonotto et al, 1981). Fucus and other seaweeds are frequently used as bioindicators of radionuclides in marine environments (Ben and Bonotto, 1991;FASSET, 2004).…”

Artificial Radionuclides Database in the Pacific Ocean: HAM Database

“…Scientific papers, reports, and books 1960-1995 [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60].…”