Estimation of vertical migration velocity of (137)Cs 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 (137)Cs 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 (137)Cs even after the 26-y period of Chernobyl accident. From the data for the vertical distribution of (137)Cs in soil profiles, the mean annual migration velocity of (137)Cs 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 (137)Cs were found for both coniferous and mixed forest sites. The mean annual velocity of (137)Cs in the forests sites with Pinus nigra var pallasiana was significantly higher than sites with Pinus brutia. External dose-rates from the (137)Cs 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 (137)Cs within the soil depth profiles. It is clearly seen that both levels and spatial distribution patterns of the external dose-rates from (137)Cs were influenced considerably with the vertical migration rate and the vertical distribution of (137)Cs.