Forty-eight surface-soil samples were collected around the Bayanwula prospective uranium mining area before extraction started and analyzed by gamma spectrometry for natural and fallout radionuclides and by ICP-MS for other metals. Mean uranium-238 activity was below the Chinese and world means the authors cite, and the radiological hazard indices were within the acceptable limits used. The study reports uranium only as activity, not as mass concentration.
Key numbers
- Uranium-238 activity in surface soil: mean 25.81 ± 9.58 Bq/kg dry weight (abstract, p. 1); individual samples 7 to 58 Bq/kg (Table 2, pp. 7 to 8). The table summary row prints 26 ± 6 Bq/kg.
- Comparison values in Table 2: mean in China 40 Bq/kg, world average 35 Bq/kg (Table 2, p. 8).
- Minimum detectable activity for uranium-238: 3.7 Bq/kg (p. 3).
- Uranium-238 was derived from the thorium-234 gamma line at 63.3 keV (p. 3).
- Annual effective dose from soil gamma radiation 83.1 ± 3.8 µSv (abstract, p. 1).
Methods (brief)
Surface soils were dried, sealed and counted for 86,400 s on a high-purity germanium gamma spectrometer; other metals were measured by ICP-MS, and hazard indices and soil-ingestion health risks were calculated with standard formulas.
Evidence fitness
Supports a statement that pre-mining surface soil in this area had uranium-238 activity in the normal range. It does not report uranium in crops or water and does not measure human exposure; the area is uncultivated grassland.
Limitations
Activity is inferred from a daughter nuclide assuming equilibrium; no mass concentrations for uranium; single sampling campaign; the abstract and table means differ slightly.
Related evidence
Update history
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