Natural and artificial radioactive pollution in sediment and soil samples of the Bosphorus, Istanbul.

This study focused on the determination of natural (238U, 232Th, and 40K) and artificial (137Cs) radionuclide concentrations both in 55 sediment samples collected from various depths in the Bosphorus and 5 soil samples from the coastline of the Bosphorus, Istanbul, using gamma-ray spectrometry with an HPGe detector. The mean activity concentrations of natural 238U, 232Th, and 40K and anthropogenic 137Cs were determined to be 11.41 ± 0.21 Bq kg-1, 6.87 ± 0.16 Bq kg-1, 369.61 ± 3.41 Bq kg-1, and 6.54 ± 0.11 Bq kg-1, respectively, in the sediment samples. The average activity concentrations of 238U, 232Th, 40K, and 137Cs radionuclides in the soil samples were also measured to be 11.65 ± 0.18 Bq kg-1, 9.55 ± 0.15 Bq kg-1, 369.43 ± 3.09 Bq kg-1, and 4.57 ± 0.09 Bq kg-1, respectively. Radiological contour maps based on the activity concentrations of natural and artificial radionuclides in the sediment samples for the Bosphorus, Istanbul, were created. The total annual effective doses due to soil samples were calculated to be 34.58 µSv y-1.

Radiation doses due to smoking different types of tobacco leaves grown in Turkey.

The activity concentrations of 238U, 232Th, 40 K and 137Cs radionuclides in 25 samples of tobacco leaves grown in Turkey have been measured using a high purity co-axial germanium detector. The measured activity concentrations for 238U ranged from 3.6 to 22.5 Bq kg-1 with an average of 9.8 Bq kg-1, for 232Th from 0.8 to 11.0 Bq kg-1 with an average of 2.4 Bq kg-1, and for 40 K from 360.3 to 1,479.5 Bq kg-1 with an average of 810.0 Bq kg-1. The concentrations of 137Cs, the residue of fallout from the Chernobyl reactor accident, were found to range from 0.2 to 2.1 Bq kg-1 with an average of 0.5 Bq kg-1. The results indicate that the average activity concentrations of 238U and 232Th lie within the range of measured values worldwide, whereas for 40 K the average was found to be higher. The average annual effective radiation doses from the inhalation of the corresponding tobacco smoke by an adult smoking 20 cigarettes per day was deduced to be 93.3 µSv y-1 for 238U, 193.2 µSv y-1 for 232Th, 5.6 µSv y-1 for 40 K, and 292.1 µSv y-1 in total. The average annual effective dose from 137Cs was calculated to be 8.5 nSv y-1. The resulting average annual effective radiation doses of 0.3 mSv due to the inhalation of natural radiation sources in tobacco were compared with studies worldwide and found much smaller than the worldwide average effective dose of 1.26 mSv. It is concluded that smoking may contribute a non-negligible fraction to the annual effective dose depending on cigarette consumption and activity concentration in tobacco. This study is the first in which natural and anthropogenic radioactivity in tobacco in Turkey was measured. Therefore, it is considered as a baseline study. Further studies are needed to investigate the role of tobacco refinement in the observed reduction of 238U concentration of refined tobacco.