GAMMA-EMITTING AND ALPHA-EMITTING RADIONUCLIDES IN SOME ALGERIAN SOILSAMPLES

In 1993, surface soil samples (0-15 cm) were collected from different regions of Algeria, in order to evaluate their radioactivity. The samp les were analysed by direct gamma spectrometry and radiochemical separ ation to determine U-238, Th-232 and their daughters, K-40, Cs-137 and plutonium isotope concentrations. In addition to the natural radionuc lides, whose concentrations were in the normal range of values compare d to those in the literature, soil samples showed a low level of conta mination by Cs-137 and plutonium isotopes. The Cs-137 and Pu239+240 co ncentrations varied from 15 to 35 Bq kg(-1) dry weight and from 0.24 t o 0.61 Bq kg(-1) dry weight, respectively. The Pu-238 concentration wa s found to be around 0.015 Bq kg(-1) dry weight. Concentration ratios of Pu239+240 to Cs-137 ranged from 0.015 to 0.023 and those of Pu-238 to Pu239+240 from 0.015 to 0.022, although the results of the latter a re near the detection limit and might be unreliable. The main sources that may have contributed to this contamination are nuclear weapons te sting fallout and possibly the Chernobyl accident. (C) 1997 Published by Elsevier Science Ltd.