Investigation of Radiological Hazards in the Soil of Mazandaran Province, Iran

Introduction: This paper aimed to outline the procedure for determining the activity concentrations of naturally occurring radionuclides (i.e., ۲۲۶Ra, ۲۳۲Th, and ۴۰K) in surface soil samples collected from Mazandaran province, Iran. Material and Methods: In total, ۶۱ samples were collected between longitude ۵۰˚ ۳۴′ and ۵۴˚ ۱۰′ east and latitude ۳۵˚ ۴۷′ and ۳۶˚ ۳۵′ north from uncultivated locations of Mazandaran province, Iran. The measurements were performed by the gamma spectrometry system using a High Purity Germanium detector. Results: The mean levels of ۲۲۶Ra, ۲۳۲Th, and ۴۰K were found to be ۲۰ Bqkg-۱ (without considering high-level areas), ۳۳ Bqkg-۱, and ۴۲۱ Bqkg-۱, respectively. The results were compared with those of different countries across the world. The radiological hazard to the natural radioactivity was assessed by calculating the absorbed dose rate, the radium equivalent activity, the external and internal hazard indices, and the outdoor and indoor annual effective dose rate. The mean radium equivalent without considering three high-level areas was estimated at ۱۰۰.۸ Bqkg-۱. Conclusion: Results indicated that no radiological risk may threat the residents of the areas under study, except for regions near the hot spring in Sadat Shahr and Lavich, Iran. Without considering high-level areas, the mean radium equivalent activity was ۱۰۰.۸ Bqkg-۱ that was about ۷۳% lower than the permissible maximum. Moreover, internal and external hazard indices were less than the unit. The mean absorbed dose rate, as well as the outdoor and indoor annual effective dose rates were ۴۸.۵۶ nGyh-۱, ۲۳۸.۴ µSv y-۱, and ۲۹۲.۶ µSv y-۱, respectively.

کلیدواژه ها:

Exposure ، External Hazard Index ، Internal Hazard Index ، gamma spectrometry ، Radioactivity ، radium equivalent