Estimation of vertical migration velocity of Cs-137 in the Mount IDA/Kazdagi, Turkey

This paper presents the results obtained from a radioecological study carried out in the forest sites of Mount IDA (Kazdagi)/Edremit, Turkey. For 118 soil profiles, the depth distribution of Cs-137 activity was established by fitting the experimental points to an exponential, a gaussian or a log-normal function. The relaxation lengths were in the range of 1.09-16.7 cm with a mean of 5.73 cm, showing a slow transport and a strong retention capacity of Cs-137 even after the 26-y period of Chernobyl accident. From the data for the vertical distribution of Cs-137 in soil profiles, the mean annual migration velocity of Cs-137 was in the range of 0.11-0.62 cm year(-1) with a mean of 0.30 cm year(-1). Statistically significant correlations between the thickness of the humus layer and the mean annual velocity of Cs-137 were found for both coniferous and mixed forest sites. The mean annual velocity of Cs-137 in the forests sites with Pinus nigra var pallasiana was significantly higher than sites with Pinus brutia. External dose-rates from the Cs-137 in forest soils were estimated using a conversion factor used in many studies and comprised with the external dose-rates determined according to the vertical distribution of Cs-137 within the soil depth profiles. It is clearly seen that both levels and spatial distribution patterns of the external dose-rates from Cs-137 were influenced considerably with the vertical migration rate and the vertical distribution of Cs-137. (C) 2015 Elsevier Ltd. All rights reserved.