Level of natural and artificial radioactivity in Algeria

A national environmental sampling program was carried out during 1993 to determine natural and artificial radionuclides contents in the (0-15 cm) upper layer of the soil. The main objective was to establish a radioactive reference level in the whole territory, since I-131, Cs-134 and Cs-137 were detected in most of the analysed samples collected right after the Chernobyl accident (May 1986). Soil samples were analysed by direct counting by gamma-ray spectrometry. In addition, terrestrial gamma-ray dose rates in air have been measured out of doors throughout Algeria. In each of the 48 administrative divisions of the country selected sites were chosen to collect soil samples and measure gamma-ray dose rates. The gamma-emitting radionuclides resulting from the radioactive decay of U-238 and Th-232, K-40 and Cs-137 were detected in most of the analysed samples. Radioactivity concentrations in Bq kg(-1) dry mass in soil samples of Ra-226, Pb-214, Bi-214, Pb-212, Ac-228, K-40 and Cs-137 range between (5-176), (2-107), (3-65), (2-97), (3-144), (36-1405) and (0.3-41) respectively. In addition, six selected soil samples were analysed to determine plutonium isotopes contents. Radioactivity concentrations in Po kg(-1) dry mass of Pu-238 and Pu239 + 240 vary between (0.012-0.013) and (0.24-0.61) respectively. The dose rates in air measured over the whole country were found to range between 20 and 133 nGy h(-1). Presence of Cs-137 has been clearly observed. An approach has been made to determine its origin, considering the global fallout, the Chernobyl accident and the French nuclear bomb tests in the 60s as the main potential sources. It is concluded that Algeria has indeed been affected by the Chernobyl accident. (C) 1998 Elsevier Science Ltd. All rights reserved.