| Popis: |
In 1993, surface soil samples (0–15 cm) were collected from different regions of Algeria, in order to evaluate their radioactivity. The samples were analysed by direct gamma spectrometry and radiochemical separation to determine 238 U, 232 Th and their daughters, 40 K, 137 Cs and plutonium isotope concentrations. In addition to the natural radionuclides, whose concentrations were in the normal range of values compared to those in the literature, soil samples showed a low level of contamination by 137 Cs and plutonium isotopes. The 137 Cs and 239 + 240 Pu concentrations varied from 15 to 35 Bq kg −1 dry weight and from 0.24 to 0.61 Bq kg −1 dry weight, respectively. The 238 Pu concentration was found to be around 0.015 Bq kg −1 dry weight. Concentration ratios of 239 + 240 Pu to 137 Cs ranged from 0.015 to 0.023 and those of 238 Pu to 239 + 240 Pu from 0.015 to 0.022, although the results of the latter are near the detection limit and might be unreliable. The main sources that may have contributed to this contamination are nuclear weapons testing fallout and possibly the Chernobyl accident. |
Full Text from ScienceDirect