Assessment of absorbed dose rate in air over plowed arable lands in Sinnar State, central Sudan.
The absorbed gamma-dose rate in air at a height of 1 m above ground level was calculated from activity concentrations of gamma-emitting radionuclides in arable soil samples collected from eight locations within Sinnar State using the published Dose Rate Conversion Factors. Measurements were carried out using high-resolution gamma-spectrometry. On average, the activity concentrations obtained were 38 +/- 8 ((232)Th), 17 +/- 2 ((226)Ra), 174 +/- 19 ((40)K) and 0.9 +/- 0.2 Bq kg(-1) for the fallout radionuclide (137)Cs. The average value obtained here for (232)Th is slightly higher than the corresponding world-average. The calculated absorbed dose rate in air at a height of 1 m for all sampled locations ranges from 31 to 47 nGy h(-1) with an average value of 39 +/- 7 nGy h(-1) which is characteristic of normal background radiation areas. The corresponding annual effective dose was 47.8 +/- 6 microSv y(-1). The major contribution to the total absorbed dose rate comes from (232)Th, which amounts to 61%. Recalculation of the absorbed dose rate-based gamma-energies of individual nuclides from uranium and thorium decay series and (40)K showed that the greater part of the absorbed dose from the uranium series is due to (214)Bi, whereas for the (232)Th series it is equally attributed to (228)Ac and (208)Tl.
Sam
A K
AK
Sudan Atomic Energy Commission, Khartoum, Sudan. adam_sam@hotmail.com
Elmahadi
Moawia M
MM
D000396:Air Pollutants, Radioactive / Q000032:analysis*; D005720:Gamma Rays; D006801:Humans; D011197:Potassium Radioisotopes / Q000032:analysis; D011834:Radiation Monitoring / Q000379:methods*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D013397:Sudan; D013910:Thorium / Q000032:analysis; D014501:Uranium / Q000032:analysis
D000396:Air Pollutants, Radioactive; D011197:Potassium Radioisotopes; D012990:Soil Pollutants, Radioactive; D014501:Uranium; D013910:Thorium