Radionuclide concentrations in benthic invertebrates from amchitka and kiska islands in the Aleutian Chain, Alaska

Concentrations of 13 radionuclides (Cs-137, I-129, Co-60, Eu-152, Sr-90, Tc-99, Am-241, Pu-238, Pu-239,Pu-249, U-234, U-235, U-236, U-238 were examined in seven species of invertebrates from Amchitka and Kiska Islands, in the Aleutian Chain of Alaska, using gamma spectroscopy, inductively coupled plasma mass spectroscopy, and alpha spectroscopy. Amchitka Island was the site of three underground nuclear test (1965-1971), and we tested the null hypotheses that there were no differences in radionuclide concentrations between Amchitka and the reference site (Kiska) and there were no differences among species. The only radionuclides where composite samples were above the Minimum Detectable Activity (MDA) were Cs-137, Am-241, Pu-239,Pu-249, U-234, U-235, U-236, and U-238. Green sea urchin ( Strongylocentrotus polyacanthus), giant chiton (Cryptochiton stelleri), plate limpets (Tectura scutum) and giant Pacific octopus (Enteroctopus dofleini) were only tested for Cs-137; octopus was the only species with detectable levels of Cs-137 (0.262 +/- 0.029 Bq/ kg, wet weight). Only rock jingle (Pododesmus macroschisma), blue mussel (Mytilus trossulus) and horse mussel (Modiolus modiolus) were analyzed for the actinides. There were no interspecific differences in Am-241 and Pu-239,Pu-240, and almost no samples above the MDA for Pu-238 and U-236. Horse mussels had significantly higher concentrations of U-234 (0.844 +/- 0.804 Bq/ kg) and U-238 (0.730 +/- 0.646) than the other species (both isotopes are naturally occurring). There were no differences in actinide concentrations between Amchitka and Kiska. In general, radionuclides in invertebrates from Amchitka were similar to those from uncontaminated sites in the Northern Hemisphere, and below those from the contaminated Irish Sea. There is a clear research need for authors to report the concentrations of radionuclides by species, rather than simply as 'shellfish', for comparative purposes in determining geographical patterns, understanding possible effects, and for estimating risk to humans from consuming different biota.