PLUTONIUM ISOTOPES, CS-137, SR-90 AND NATURAL RADIOACTIVITY IN MARINE-SEDIMENTS FROM GHAZAOUET (ALGERIA)

Samples of marine surface sediments of different grain sizes collected in Ghazaouet, a small bay on the western coast of Algeria, have been examined to measure alpha-, beta- and gamma-radioactivity. The purpose of this study is to detect any radioactive contamination. Using a com bination of direct gamma spectrometry, radiochemical separation and al pha-spectrometry, and beta-counting, activity levels of the most signi ficant naturally-occurring radio-isotopes (Po-210, Pb-210, Ra-226, etc .) were determined in the samples. Natural radionuclides have shown re latively high activities. The analysis of these samples revealed measu rable quantities of some artificial radio-nuclides, namely: Pu-238 (fr om 0.02 to 0.05 Bq kg(-1) ash), Pu-239+240 (from 0.3 to 0.6 Bq kg(-1) ash), Cs-137 (from 6.9 to 8.5 Bq kg(-1) ash) and Sr-90 (from 1.4 to 7. 4 Bq kg(-1) ash). Concentration ratios of Pu-238 to Pu-239+240 and Cs- 137 to Pu-239+240 obtained seem to confirm that this artificial radio- activity is due mainly to nuclear-testing fallout. Copyright (C) 1996 Elsevier Science Limited