Radioactivity levels of recent sediments in the Butrint Lagoon and the adjacent coast of Albania.

Abstract Sediment samples have been collected in the Butrint area, located in the south-west Albania to determine the radioactivity levels of 40 K, 137 Cs, 212 Bi, 212 Pb, 214 Bi, 214 Pb, 226 Ra and 228 Ac on the bed of the lagoon and adjacent sea, using direct counting gamma spectroscopy. The concentration of 137 Cs and 40 K varied from 2.8 to 37.5 Bq/kg and from 266 to 675 Bq/kg dry weight (dw), respectively (central values). The average concentrations of 238 U and 232 Th daughter products varied from 8 to 27 Bq/kg and from 13 to 40 Bq/kg dw, respectively. The measured 235 U activity ranged from 0.7 to 2.5 Bq/kg dw. Samples of different sedimentary properties, studied for the radioactivity concentration, revealed an inversely proportional relation between grain size and a linear combination of measured specific activities of 226 Ra, 232 Th ( 228 Ac, 212 Bi and 212 Pb), 40 K and 137 Cs.