@article{oai:repo.qst.go.jp:00045361, author = {Zheng, Jian and Yamada, Masatoshi and Wu, Fengchang and Liao, Haiqing and 鄭 建 and 山田 正俊 and Ｗｕ Ｆｅｎｇｃｈａｎｇ and Ｌｉａｏ Ｈａｉｑｉｎｇ}, issue = {1}, journal = {Journal of Environmental Radioactivity}, month = {Jan}, note = {The total 239+240Pu activities and 240Pu/239Pu atom ratios in surface soil samples (0-5 cm) in the Kumtag Desert in western Gansu Province, and in a soil core sample in Lanzhou were investigated using a sector-field ICP-MS. In the surface soil samples, 239+240Pu activities in fine particles (<150 m) were 1.3 to 2.1 times of those in coarse particles which ranged from 0.005 to 0.157 mBq/g. Atom ratios of 240Pu/239Pu in the surface soils ranged from 0.168 to 0.192 with a mean of 0.182  0.008. The mean ratio was similar to the typical global fallout value although the Kumtag Desert was believed to have received close-in fallout derived from Chinese nuclear weapons tests mainly conducted in the 1970s. Furthermore, the mean 240Pu/239Pu atom ratio observed in the soil core sample in Lanzhou was similar to the typical global fallout value. In the soil core sample, 239+240Pu activities in the various layers ranged from 0.012 to 0.23 mBq/g, and the inventory of 239+240Pu (32.4 Bq/m2, 0 -23 cm) was slightly lower than that expected from global fallout (42 Bq/m2) at the same latitude. Rapid downward migration of Pu isotopes was observed in Lanzhou soil core sample layers. The contribution of the 10 cm-deep top layers of surface soils to total inventory was only 17 %, while the contribution of deeper layers (10-23 cm) was as high as 83 %. The 239+240Pu activity levels and 240Pu/239Pu atom ratios in soils in Gansu Province, China are similar to those in atmospheric deposition samples collected in the spring in recent years in Japan. \nKeywords: Pu isotope pollution; SF-ICP-MS; Soils; Global fallout.}, pages = {71--75}, title = {Characterization of Pu concentration and its isotopic composition in soils of Gansu in northwestern China}, volume = {100}, year = {2009} }