Plutonium isotopes,137Cs,90Sr 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 α-, β- and γ-radioactivity. The purpose of this study is to detect any radioactive contamination. Using a combination of direct gamma spectrometry, radiochemical separation and α-spectrometry, and β-counting, activity levels of the most significant naturally-occurring radioisotopes (210Po,210Pb,226Ra, etc.) were determined in the samples. Natural radionuclides have shown relatively high activities. The analysis of these samples revealed measurable quantities of some artificial radionuclides, namely:238Pu (from 0.02 to 0.05Bq kg−1 ash),239 + 240Pu (from 0.3 to 0.6Bq kg−1 ash),137Cs (from 6.9 to 8.5Bq kg−1 ash) and90Sr (from 1.4 to 7.4Bq kg−1 ash). Concentration ratios of238Pu to239 + 240Pu and137Cs to239 + 240Pu obtained seem to confirm that this artificial radioactivity is due mainly to nuclear-testing fallout.