Natural radioactivity levels and related risk assessment in soil samples from Sakarya, Turkey

An evaluation of the environmental radioactivity levels in soil samples from Sakarya province (Turkey) was undertaken in order to create a comprehensive radiological map of Sakarya. A total of 85 soil samples collected from different parts of the city were analysed using NaI(Tl) γ-ray spectrometry. It was found that the mean activity concentrations of natural radionuclides 226Ra, 232Th and 40K were 23.2 ± 2.5, 21.0 ± 3.4 and 371 ± 25.9 Bqkg−1, respectively, all falling below the worldwide mean values. Accordingly, in order to assess the radiological risk, radium equivalent activity (Ra eq), absorbed gamma dose rate (D), annual effective dose equivalent (AED), and external hazard index (H ex) were estimated and found to have mean values of 30.93 nGyh−1, 37.93 μSvy−1, 64.14 Bqkg−1 and 0.18 Bqkg−1, respectively. Also, the results were statistically analysed to make recommendations for further regulation.