Natural radioactivity measurements and evaluation of radiological hazards in sediment of Aliaa Bay, zmir (Turkey)

Abstract

The activity concentration of natural Ra-226, Th-232, and K-40 radionuclides was examined in some selected locations in Aliaga Bay of Izmir district, Turkey. Sediment samples from 30 locations were collected and analyzed for radionuclides activity concentration by gamma-ray spectrometry using a high-purity germanium HPGe gamma-ray detector. The activity concentrations of the sediment samples range from 23.5 +/- 1.7 to 59.5 +/- 1.6 Bq kg(-1) for Ra-226, 37.5 +/- 0.9 to 64.4 +/- 0.6 Bq kg(-1) for Th-232, and 354.7 +/- 5.6 to 978.4 +/- 5.8 Bq kg(-1) for K-40. Based on the obtained results, the radiological parameters were evaluated. The mean values for absorbed dose rate, annual effective dose equivalent, radium equivalent activity, external hazard index, and excess lifetime cancer risk were determined and found as 81.64 nGy h(-1), 100.13 mu Sv y(-1), 173.31 Bq kg(-1), 0.47, and 0.40, respectively. Calculated radiological parameters of sediment samples were compared with the World Standard Value. The results obtained in this study were found to be above the globally standard limit for most locations. Statistical data such as skewness and kurtosis were calculated, and frequency distribution, Pearson's correlation analysis, box plot, factor analysis, and cluster analysis were applied in order to assess the distribution of radiological parameters and relationship between them.