Determination of ~(137)Cs activities in surface sediments and derived sediment accumulation rates in Thessaloniki Gulf, Greece

摘要

Surficial and core samples collected from the eastern Thessaloniki Gulf, located in the NW Aegean Sea, were analyzed for their sedimentation rate and inventories of ~(137)Cs and ~(210)Pb. The study of the spatial radionuclide dispersion in the specific region is essential for the assessment of marine pollution levels. The sedimentation rates were calculated from the vertical distribution of ~(137)Cs and excess ~(210)Pb in the sediment cores. The spatial distri bution of ~(137)Cs was studied with respect to sediment characteristics such as the grain size of the sample and the organic carbon content. The activity concentrations were measured by means of gamma ray spectrometry using HPGe detector for ~(137)Cs and gross alpha counting using alpha counter for ~(210)Pb. The average sedimentation rate along the sediment cores is characterized by a consistent pattern and varies from 0.18 ± 0.02 to 0.22 ± 0.03 cm year~(-1). The ~(137)Cs inventories varied from 205 ± 15 to 602 ± 39 Bq m~(-2), while the ~(210)Pb inventories of the studied cores exhibited average value of 140 ± 9 Bq m~(-2). Elevated ~(137)Cs activities were observed compared to cer tain Mediterranean marine areas; however, they were lower than the reported values in the Black Sea.