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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 237 Np, Pu isotopes and 241 Am 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 239,240 Pu and 241 Am 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 240 Pu/ 239 Pu (0.20 ± 0.02 and 0.21 ± 0.01) and 241 Am/ 239+240 Pu 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 237 Np/ 239 Pu 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 237 Np 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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

To accurately determine ultra-trace Pu isotopes in small environmental samples, we explored ICP-MS/MS in NH 3 -He mode, and investigated mechanism of 238 U interference removal and measurement sensitivity improvement for plutonium isotopes. The interference of uranium and uranium hydrides was effectively eliminated using 0.4 mL/min NH 3 as reaction gas by shifting them to U(NH m ) n + and UH(NH m ) n + Pu sensitivity (13,900 Mcps/(mg/L)) mainly due to ion focusing effect of Pu by helium gas. On this basis, the purification of plutonium using a single AG1- × 4 column was proved to be sufficient for accurate determination of plutonium isotopes by the developed detection method, and the detection limits for the method were estimated to be 0.16 fg (0.4 μBq) for -7 , while remaining excellent 239 Pu sensitivity (13,900 Mcps/(mg/L)) mainly due to ion focusing effect of Pu by helium gas. On this basis, the purification of plutonium using a single AG1- × 4 column was proved to be sufficient for accurate determination of plutonium isotopes by the developed detection method, and the detection limits for the method were estimated to be 0.16 fg (0.4 μBq) for 239 Pu. The method was validated by analyzing plutonium isotopes in certificated reference materials and reported environmental samples of only 1-2 g. The analytical results of ultra-trace Pu isotopes in small amounts (∼1 g) of lake sediments obtained by the developed method were successfully applied to sediment dating.240 Pu and 0.039 fg (0.15 mBq) for 241 Pu. The method was validated by analyzing plutonium isotopes in certificated reference materials and reported environmental samples of only 1-2 g. The analytical results of ultra-trace Pu isotopes in small amounts (∼1 g) of lake sediments obtained by the developed method were successfully applied to sediment dating., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Concentrations of 239 Pu and 240 Pu in 163 surface soil samples and five soil cores collected from the northeast and north China were analyzed using the radiochemical separation combined with inductively coupled plasma mass spectrometry measurement. The average 240 Pu/ 239 Pu atomic ratios (0.185 ± 0.018) for all surface soil samples indicated that the global fallout is the major source of plutonium in the studied region. The 239,240 Pu concentrations of the surface soil ranged from 0.002 mBq/g to 4.82 mBq/g, lying in the range of the reported results in the areas with similar latitude, except for a few samples. The distribution of 239,240 Pu in this region is controlled by the deposition of plutonium in the atmosphere and its preservation in the soil, which were affects by multi-factors such as topography, climate, utilization of the land and vegetation coverage. The analytical results could be used as the baseline data for the assessment of the impact of nuclear activities in the past and the future., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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]