Activity concentrations of natural radionuclides and Cs-137 in soils of coniferous forest sites in West Anatolia

The surveys of natural gamma-emitting radionuclides and Cs-137 in surface soils of coniferous forest sites in and around Izmir were conducted during 2003-2004. The soil samples were collected from three different depths of 15 forest sites, particularly local wild edible mushrooms areas. The average activity concentrations and ranges of the natural radionuclides in the soils were as follows: 30 (14-51) Bq kg(-1) of Ra-226; 40 (17-79) Bq kg(-1) of Th-232; and 581 (308-879) Bq kg(-1) of K-40. Moreover, the values of Cs-137 activity concentrations averaged over the depth sections varied from 20 to 82 Bq kg(-1) with a mean value of 52 Bq kg(-1). Accordingly, the levels of the studied natural radionuclides in the forest soils were within the range specified by UNSCEAR (2000) report for regular soils as well as the agricultural soils from the West Anatolia, while the measured activity levels of Cs-137 in the forest soils were still high in contrast to agricultural soils after 16 years from the deposition of Chernobyl fallout.