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Transuranium elements such as Np, Pu and Am, are considered to be the most important radioactive elements in view of their biological toxicity and environmental impact. Concentrations of 237Np, Pu isotopes and 241Am in two sediment cores collected from Peter the Great Bay of Japan Sea were determined using radiochemical separation combined with inductively coupled plasma mass spectrometry (ICP-MS) measurement. The 239,240Pu and 241Am concentrations in all sediment samples range from 0.01 Bq/kg to 2.02 Bq/kg and from 0.01 Bq/kg to 1.11 Bq/kg, respectively, which are comparable to reported values in the investigated area. The average atomic ratios of 240Pu/239Pu (0.20 ± 0.02 and 0.21 ± 0.01) and 241Am/239+240Pu activity ratios (3.32 ± 2.76 and 0.45 ± 0.17) in the two sediment cores indicated that the sources of Pu and Am in this area are global fallout and the Pacific Proving Grounds through the movement of prevailing ocean currents, and no measurable release of Np, Pu and Am from the local K-431 nuclear submarine incident was observed. The extremely low 237Np/239Pu atomic ratios ((2.0–2.5) × 10−4) in this area are mainly attributed to the discrepancy of their different chemical behaviors in the ocean due to the relatively higher solubility of 237Np compared to particle active plutonium isotopes. It was estimated using two end members model that 23% ± 6% of transuranium radionuclides originated from the Pacific Proving Grounds tests, and the rest (ca. 77%) from global fallout. [Display omitted] • Distribution of transuranium radionuclides in the sediment cores were investigated. • The contribution of transuranium from PPG was estimated to be 23 ± 6 %. • No measurable release of transuranium from K-431 incident was observed. • 237Np/239Pu atomic ratio might be unsuitable for the source identification. [ABSTRACT FROM AUTHOR]

Rapid bioassay method for plutonium in urine samples are employed to assess the possible internal dose resulting from exposure to plutonium in the event of a radiological and nuclear emergency. In this work, a rapid method for the determination of plutonium isotopes (239Pu and 240Pu) in large volume of urine samples was developed using tandem quadrupole ICP-MS combined with a high-efficiency sample introduction system (APEX-Ω). The mixture gases of NH 3 and He was employed to effectively eliminate the tailing of 238U and the uranium hydride ions (238U1H+and 238U1H 2 +) and significantly improve the measurement sensitivity of plutonium. The method was validated by analyzing urine samples spiked with known amounts of 239Pu and 240Pu ranging from 1 to 60 fg. The detection limits for the method were estimated to be 0.83 fg for 239Pu, 0.14 fg for 240Pu in 1 L of urine. [Display omitted] • Tandem quadrupole ICP-MS was utilized to measure Pu isotopes in large volume of urine samples. • The interference of 238U (0.23 cps) would be much less a concern at 4.0 mL min−1 NH 3 and 3.0 mL min−1 He. • The detection limits of 239Pu (0.83 fg/L) and 240Pu (0.14 fg/L) are suitable for Pu routine analysis of urine. [ABSTRACT FROM AUTHOR]