Vertical sup(137)Cs distribution in the bark of Japanese cedar trees in 2012 after the Fukushima Dai-ichi Nuclear Power Plant accident
2019
Ogawa, H. (Fukushima Prefectural Forestry Research Centre (Japan)) | Yokota, K. | Arai, S. | Sakurai, S. | Yoshida, H.
Vertical sup(137)Cs distribution in the barks of Japanese cedar (Cryptomeria japonica) trees in the initial phase after the Fukushima Dai-ichi Nuclear Power Plant accident was investigated in several forests in Fukushima prefecture in 2012. 12 trees that were felled in 7 forests were used in the present study. sup(137)Cs concentration in bark samples taken at various heights were determined using a NaI spectrometer. In order to compare the vertical sup(137)Cs distribution in the bark of each tree, sup(137)Cs concentration was normalized to that at the lowest height from the ground. An increase of sup(137)Cs concentration from the bottom to the tree top was clearly observed for 9 trees. The inner barks were almost constant at any vertical positions. Large part of the sup(137)Cs in the barks existed in the outer barks. These results indicated that the vertical distribution of the outer sup(137)Cs contamination on the barks in 2012 had a common sup(137)Cs concentration profiles against the tree top with the different contamination levels of the forests and different height of the tree.
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