Analysis of plutonium isotopes in marine samples by radiometric, ICP-MS and AMS techniques

IAEA reference materials (radionuclides in the marine environment) collected in areas affected by nuclear reprocessing plants and nuclear weapons tests have been analysed by semiconductor alpha-spectrometry (SAS), liquid scintillation spectrometry (LSS) and mass spectrometric techniques (high resolution ICP-MS and AMS) with the aim of developing analytical procedures and to study the geochemical behavior of plutonium in the marine environment. The Pu results obtained by SAS, ICP-MS and AMS were in reasonably good agreement (R² = 0.99). The mean atom ratios of ²⁴⁰Pu/²³⁹Pu in IAEA reference materials, IAEA-134, 135 and 381 were (0.212±0.010), (0.211±0.004) and (0.242±0.004), respectively. IAEA-384 (Fangataufa Lagoon Sediment) gave a ^24OPu/²³⁹Pu mean atom ratio of 0.051±0.001. The results of ²⁴¹Pu obtained by ICP-MS and LSS also show reasonable agreement (R² = 0.91). Pu isotopic signatures were useful in tracing Pu origin and in interpreting biogeochemical processes involving Pu in the marine environment.