^243,244Cm in Columbia River sediments

Abstract

Holm and Persson¹ have described the presence in lichens of ²⁴⁴Cm resulting from the testing of nuclear devices. As the retention of transuranic radionuclides by lichens differs markedly as discussed by the above authors, integrated inventories of ²⁴⁴Cm (mCi km⁻²) resulting from fallout were not computed, nor were samples earlier than 1961–62 analysed to determine possible curium isotope production during testing in 1952–58. We have now measured ^243,244Cm as well as ²³⁸Pu, ^239,240pu and ²⁴¹Am in sediments from the Columbia River which show that (1) ^243,244Cm was produced in weapons tests before 1961, and (2) the total ^243,244Cm activity produced during testing was 1–3% that of ^239,240Pu. Even though the Columbia River received large amounts of radioactivity as a consequence of the operation of plutonium production reactors on the Hanford Reservation², we believe that the ^243,244Cm reported here is entirely derived from fallout and that our ability to detect these isotopes in river sediment is due to the concentrating effect of erosional processes on land which mobilize material containing ^243,244Cm (and Other transuranic radionuclides) to the river, where they are subsequently sedimented.