Determination of plutonium 240/239 ratios in Lake Ontario sediments

• Published in: Journal of the American Society for Mass Spectrometry Vol. 2; no. 3; pp. 240 - 244
• Main Authors: Green, L.W., Miller, F.C., Sparling, J.A., Joshi, S.R.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-05-1991; Elsevier Science
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Miscellaneous; Plutonium Isotopes; Radioactive pollution; Chemical analysis; Thermal ionization; Atmospheric fallout; Detection limit; Trace compound; Isotopic composition; Sediments; Mass spectrometry
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1016/1044-0305(91)80050-H

A thermal ionization mass spectrometric procedure was developed for determination of 240/239 ratios in subpicogram quantities of plutonium (Pu), and was applied to Pu extracted from Lake Ontario sediment. The detection limit was ∼ 4 fg of Pu and the precision of 240/239 ratio measurement was ∼ 7% in the 0.07–0.42 pg range. Results of sediment analyses at various depths showed in all cases 240/239 ratios near the mean global fallout value of 0.176 ± 0.014. The lack of variability of the ratios with depth negated the use of Pu, present in excess in the near-surface samples due to leakage from a nearby reprocessing plant, as a geochronological meter. The 240/239 ratio of the leakage Pu appeared to be very similar to that of fallout Pu.