Natural radionuclide activities in forest soil horizons of Mount IDA/Kazdagi, Turkey

Natural radioactivity distribution of K-40, U-238, and Th-232 isotopes in forest soils was investigated by using gamma-ray spectrometry. An extensive radioecological study was carried out between 2010 and 2013 in Mount IDA/Kazdagi, located in Edremit region in Turkey. A total of 341 soil samples were collected from the surface and organic horizons (O-L, O-F+O-H, and A) in 118 soil profiles. The distributions of natural radioactivity levels in these horizons and corresponding absorbed dose rates from outdoors terrestrial gamma radiation throughout the region were mapped in detail. Mean K-40 activity values over the combined horizons varied between 43 and 1,008 Bq kg(-1); whereas, mean Ra-226 and Th-232 concentrations over the combined horizons ranged between 5-152 and 6-275 Bq kg(-1), respectively. Our data indicate that the radioactivity values of the study sites were within the universal normal range. The significant variation among the Th-232, Ra-226, and K-40 activities and gamma dose rate might be due to the geological variation in the study sites.