Radionuclide concentrations in bivalves collected along the coastal United States

In 1990, the National Oceanic and Atmospheric Administationʹs National Status and Trends Program initiated a study of artificial radionuclides (241Am, 239 + 240Pu, 238Pu, 137Cs, 110Ag, 90Sr, 65Zn, 60Co, and 58Co) in oysters and mussels collected along the coastal US. The results of this study show that activation products 110Ag, 65Zn, 60Co and 58Co are sometimes present close to nuclear facilities. In addition, based on a nonparametric Kruskal-Wallis statistical test, it appears that 241Am and 137Cs concentrations as well as 241Am/239 + 240Pu and 137Cs/40K activity ratios are highest along the West Coast of the US. For 238Pu, 239 + 240Pu, and 90Sr activities and the other ratios, the differences observed in the distribution of the radionuclides between the various coasts are not statistically significant. There is also a statistical difference between the values of the 239 + 240Pu/90Sr ratio in oysters vs mussels collected along the East Coast and of the 241Am/239 + 240Pu ratio between two species of mussels collected along the West Coast. Finally, when the NOAA results for 241Am, 239 + 240Pu, and 137Cs 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.