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摘要
Low-level alpha spectrometry techniques using semiconductor detectors (PIPS) and liquid scintillation (LKB Quantulus 1220(TM)) were used to determine the activity concentration of (238)u, (234)u, Th-230, Ra-226, Th-232, and Pb-210 in soil samples. The soils were collected from an old disused uranium mine located in southwest Spain. The soils were sampled from areas with different levels of influence from the installation and hence had different levels of contamination. The vertical profiles of the soils (down to 40 cm depth) were studied in order to evaluate the vertical distribution of the natural radionuclides. To determine the origin of these natural radionuclides the Enrichment Factor was used. Also, study of the activity ratios between radionuclides belonging to the same radioactive series allowed us to assess the different types of behaviors of the radionuclides involved. The vertical profiles for the radionuclide members of the U-238 series were different at each sampling point, depending on the level of influence of the installation. However, the profiles of each point were similar for the long-lived radionuclides of the U-238 series (U-238, U-234, Th-230, and Ra-226). Moreover, a major imbalance was observed between Pb-210 and Ra-226 in the surface layer, due to Rn-222 exhalation and the subsequent surface deposition of Pb-210.
- 出版日期2014-1
