Abstract
Concentrations of 239Pu and 240Pu 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 240Pu/239Pu 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 239,240Pu 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 239,240Pu 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.
Highlights
Since the 1940s, artificial radionuclides, such as 238,239,240Pu, 137Cs and 131I, have been released to the environment by nuclear weapons tests, nuclear accidents, nuclear power plants and nuclear fuel reproc essing facilities (UNSCEAR, 2000)
The 239Pu and 240Pu level in all 163 surface soil samples are shown in Fig. 2, in which 239,240Pu activity concentrations (239Pu plus 240Pu) were calculated for easy comparison with the reported data measured by alpha spectrometry. 239,240Pu concentrations range from 0.002 mBq/g to 4.82 mBq/g, which are comparable to the reported values (0.002–0.880) in surface soil from the region without direct contami nation (Dong, 2010; Wang et al, 2013; Xing, 2015; Xu, 2014; Zhang and Hou, 2019; Zhang et al, 2019), with a few exceptional high data
This distribution generally agrees with the normal latitude distri bution of global fallout radionuclides in north hemisphere (Kelley et al, 1999; Thakur et al, 2017; UNSCEAR, 2000), i.e., the concentration of deposited plutonium in the environment gradually increases with the latitude in 30–50 ◦N
Summary
Since the 1940s, artificial radionuclides, such as 238,239,240Pu, 137Cs and 131I, have been released to the environment by nuclear weapons tests, nuclear accidents, nuclear power plants and nuclear fuel reproc essing facilities (UNSCEAR, 2000). A 240Pu/239Pu atomic ratio of 0.178 ± 0.023 in the environ mental samples only received global fallout of the atmospheric nuclear tests was observed. The 240Pu/239Pu atomic ratio of weapons-grade plutonium was reported to be 0.01–0.07, but much higher values of 0.23–0.67 were observed in the releases from nuclear power plants (Smith et al, 1995; Varga, 2007; Warneke, 2002; Yamamoto et al, 2004), and 240Pu/239Pu atomic ratios of 0.38–0.41 for releases from the Chernobyl accident and 0.32–0.33 for Fukushima accident were observed (Boulyga et al, 1997; Wendt et al, 1999; Zheng et al, 2013), respectively. Based on the 240Pu/239Pu atomic ratio, the plutonium could be used for the evaluation of the contribution of nuclear activity in the soil (Dong, 2010; Ni et al, 2018; Xing, 2015; Xu, 2014; Zhang and Hou, 2019; Zhang et al, 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
