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Abstract: The background radiation level of 137Cs at the urban atmosphere of Thessaloniki has been increased during the recent decade only due to the Fukushima accident fallout. Since then, no other signal of 137Cs was observed until the winter period of 2013, when slightly elevated 137Cs concentrations were measured. The 137Cs signals observed were up to 12 μBq m−3, mainly during holidays and weekends followed by lower or even non-detectable activities in the next working days. Those episodes are attributed to the increase of biomass products combustion for residential heating as this year the tax of oil for heating was drastically raised as a consequence of the financial crisis. A preliminary survey of various wood products as well as of bottom ashes from different domestic burning devices is presented. 137Cs concentrations up to 11 Bq kg−1 were measured in wood products and up to 500 Bq kg−1 in ash samples. [Copyright &y& Elsevier]

The determination procedure of low 137 Cs concentrations in air using γ-spectrometry is essential wherever the net counts are smaller than the background of the spectrum. Such measurements have performed in April 2020 during the Chernobyl wildfires period. A significant event recorded in Thessaloniki's atmosphere during April 12, 2020, with 25.7 ± 0.7 μBq m -3 of 137 Cs, was measured. Besides, a minor incident with a lower 137 Cs concentration of 9.6 ± 0.8 μBq m -3 has occurred on April 21, 2020. The above results resemble to a previous one noticed during winter 2013, when signals up to 12.1 ± 0.8 μBq m -3 of 137 Cs detected in the atmosphere, due to extensive use of 137 Cs contaminated wood for residential heating. The results obtained demonstrate that no radiation hazard rose for the general public due to inhalation of the 137 Cs in the air of Thessaloniki, Greece. Moreover, the residence time of the aerosol-bound 137 Cs has estimated. The data presented are useful for basic simulation-inputs and comparison with global atmospheric models, which also discussed after comparison with the back trajectories predicted by the NOAA-HYSPLIT model., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Fossil bones and sediments from different horizons of the Upper Miocene paleontological site of Platania, Drama-Greece were studied using 238 U, 235 U, 232 Th series and 40 K measurements obtained by γ-spectroscopy. Additionally, SEM and XRF analysis was applied to bone and sediment samples while a lithological analysis of the sediments was also carried out. The 226 Ra/ 238 U ratios in the fossilization layers are attributed to the 238 U depletion from the sediment and its incorporation into the fossils. The 226 Ra/ 231 Pa ratio indicates that the absorption of the isotopes started long before 4.2 Ma ago. The 232 Th/ 40 K profile demonstrate two distinct geological substrates, the lower corresponding to the Upper Miocene whereas the upper to the Upper Pleistocene-Holocene. Among them mediates a Mn-rich layer associated with the "Zanclean flood" during Pliocene. One layer above the "Glacial maximum event" during the Early Pleistocene was recorded. The natural radioactive sedimentary profile obtained reproduces the paleo-climatic conditions in Southeast Europe, which could be useful for the future., (Copyright © 2018 Elsevier Ltd. All rights reserved.)