RADIONUCLIDE CONCENTRATIONS BIVALVES COLLECTED ALONG THE COASTAL UNITED-STATES

In 1990, the National Oceanic and Atmospheric Administration's National Status and Trends Program initiated a study of artificial radionuclides (Am-241, Pu-239+240, Pu-238, Cs-137, Ag-110, Sr-90, Zn-65, Co-60, and Co-58) in oysters and mussels collected along the coastal US. The results of this study show that activation products Ag-110, Zn-65, Co-60 and Co-58 are sometimes present close to nuclear facilities. In addition, based on a nonparametric Kruskal-Wallis statistical test, it appears that Am-241 and Cs-137 concentrations as well as Am-241/Pu-239+240 and Cs-137/K-40 activity ratios are highest along the West Coast of the US. For Pu-238, Pu-239+240, and Sr-90 activities and the other ratios, the differences observed in the distribution of the radio-nuclides between the various coasts are not statistically significant. There is also a statistical difference between the values of the Pu-239+240/Sr-90 ratio in oysters vs mussels collected along the East Coast and of the Am-241/Pu-239+240 ratio between two species of mussels collected along the West Coast. Finally, when the NOAA results for Am-241, Pu-239+240, and Cs-137 are compared with those of an earlier (1976-1978) Mussel Watch Program sponsored by the Environmental Protection Agency, the statistical Sign Test generally shows a significant decrease in the concentrations between the mid-1970s and the early 1990s.