Journal Article Simultaneous determination of radiocesium (135Cs, 137Cs) and plutonium (239Pu, 240Pu) isotopes in river suspended particles by ICP-MS/MS and SF-ICP-MS

Cao, Liguo  ,  鄭, 建  ,  Tsukada, Hirofumi  ,  Pan, Shaoming  ,  王, 鍾堂  ,  田上, 恵子  ,  内田, 滋夫

159pp.55 - 63 , 2016-06 , Elsevier
Due to the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, long-term monitoring of radiocesium (135Cs and 137Cs) and Pu isotopes (239Pu and 240Pu) in river suspended particles is necessary to study the transport and fate of these long-lived radioisotopes in the land-ocean system. However, it is expensive and technically difficult to collect samples of suspended particles from river and ocean. Thus, simultaneous determination of multi-radionuclides remains as a challenging topic. In this study, for the first time, we reported an analytical method for simultaneous determination of radicesium (135Cs and 137Cs) and Pu isotopes (239Pu and 240Pu) in suspended particles with small sample size (1-2 g). Radiocesium and Pu were sequentially pre-concentrated using ammonium molybdophosphate and ferric hydroxide co-precipitation, respectively. After the two-stage ion-exchange chromatography separation from the matrix elements, radiocesium and Pu isotopes were finally determined by ICP-MS/MS and SF-ICP-MS, respectively. The interfering elements of U (238U1H+ and 238U2H+ for 239Pu and 240Pu) and Ba (135Ba+ and 137Ba+ for 135Cs and 137Cs) were sufficiently removed with the decontamination factors of 1-8 × 106 and 1 × 104, respectively, with the developed method. Soil reference materials were utilized for method validation, and the obtained 135Cs/137Cs and 240Pu/239Pu atom ratios, and 239+240Pu activities showed a good agreement with the certified values. In addition, the developed method was applied to analyze radicoesium and Pu in the suspended particles of land waters collected from Fukushima Prefecture after the FDNPP accident. The 135Cs/137Cs atom ratios (0.333 to 0.391) and 137Cs activities (23.4 to 152 Bq/g) suggested radiocesium were mainly originated from the accident released radioactive contaminates, while Pu contamination caused by the accident in suspended particles can be neglected duo to the 240Pu/239Pu atom ratios (0.182-0.208) within the range of global fallout.

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