Persistence of Cs-137 in the litter layers of forest soil horizons of Mount IDA/Kazdagi, Turkey

In 2010-2012, an extensive study was performed in forest sites of Mount IDA (Kazdagi)/Edremit 26 years after the Chernobyl accident. The Cs-137 activity concentrations were determined by gamma-ray spectrometry in the forest soil layers (O-L, O-F + O-H and A horizons) separately. Based on 341 surface soil samples and 118 soil profiles, activity concentrations of 137Cs in O-L horizons varied between 0.25 +/- 0.14 and 70 +/- 1 Bq kg(-1), while the ranges of Cs-137 activity concentrations in O-F + O-H and A horizons were 13 +/- 1-555 +/- 3 Bq kg(-1) and 2 +/- 1-253 +/- 2 Bq kg(-1), respectively. Cesium-137 deposition in the study area was estimated to be in the range of 1-39 kBq m(-2) and a linear relationship between the deposition of Cs-137 and the altitude was observed. The distributions of Cs-137 activities in O-L, O-F + O-H and A horizons throughout the region were mapped in detail. The highest Cs-137 activities were found in O-F + O-H horizons, with markedly lower Cs-137 activity in mineral horizons of soil profiles. It is observed that Cs-137 content of humus layer increases with the thickness of the humus layer for coniferous forest sites. The Cs-137 activity concentrations were higher than the recommended screening limits (150 Bq kg(-1)) at some of the investigated areas. The current activity concentration of top soil layers indicates that over many years since the initial deposition, Cs-137 activity is keeping still high in the organic horizons. (C) 2014 Elsevier Ltd. All rights reserved.