We have examined the distribution of individual Pu isotopes (239Pu, 240Pu, and 241Pu) in seawater from the Gulf of Maine (GOM). Samples were size-fractionated with a 1 kD cross-flow ultrafiltration (CFF) membrane. Subfractioned samples were radiochemically purified and Pu isotopes were analyzed using a three-stage thermal ionization mass spectrometer (TIMS). To our knowledge, this is the first time that both size class and Pu isotopic data have been obtained for sea water samples. Within measurement uncertainties a single 240Pu/239Pu atom ratio of about 0.18 was found for all sample collection depths and sample size fractions. This signifies a current, single Pu source in GOM waters, namely global fallout, and suggests that no measurable isotopic fractionation occurred during CFF processing. The majority of Pu was found in the low molecular weight fraction (
Revised: May 17, 2002 |
Published: February 1, 2001
Citation
Dai M.H., K.O. Buesseler, J.M. Kelley, J.E. Andrews, S.M. Pike, and J.F. Wacker. 2001.Size-Fractionated Plutonium Isotopes in a Coastal Environment.Journal of Environmental Radioactivity 53, no. 1:9-25.PNNL-SA-34278.