History of plutonium composition of fallout in the Northeastern U.S. from contemporary measurements

The analyses of lake sediments from the northeastern U.S. provide depositional histories of137Cs and239+240Pu from both global fallout and fallout from the Nevada Test Site (NTS) detonations in the 1950's. These results provide an independent verification and extension of the temporal trend of the240Pu/239Pu atom ration of global fallout to earlier times. This data supports the findings of other studies of fallout in the atmospheric and marine environment.