||Particle-size fractionated speciation of Pu isotopes in surface soils from Inner Mongolia (China) and its implications for Asian Dust monitoring
Dong, Wei ,
Zheng, JianGuo, Qiuju
Applied Radiation and Isotopes
136 , 2017-02 , Elsevier
For the first time, Pu isotopes in surface soil of Inner Mongolia have been analyzed after size fractionation using SF-ICP-MS. 239+240Pu activities ranged from 0.101±0.012 mBq/g to 0.519±0.022 mBq/g depending on grain size, with the mass-weighted activity of 0.231±0.014 mBq/g. By contrast, 240Pu/239Pu atom ratios ranged narrowly from 0.169±0.023 to 0.200±0.029 with the activity-weighted ratio of 0.182±0.021, indicating global fallout character. The 239+240Pu activities increased with decreasing particle size and a spherical model could well simulate 239+240Pu activities as a function of particle diameter when less than 600 μm, and the soil particle surface sorption phenomenon of Pu isotopes in natural soil samples was revealed. Furthermore, 239+240Pu activity in fine particles sized less than 53 μm had good consistency with that in atmospheric depositions of Japan since the 2000s, suggesting new Asian Dust sources (i.e. central Inner Mongolia) other than the well-known Chinese deserts.