Estimation of radioactive 137-cesium transportation by litter fall, stem flow and through fall in the forests of Fukushima

Since the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011, large areas of the forests around Fukushima have become highly contaminated by radioactive nuclides. To predict the future dynamics of radioactive caesium ((137)Cs) in the forest catchment, it is important to measure each component of its movement within the forest. Two years after the accident, the authors estimated the annual transportation of (137)Cs from the forest canopy to the floor by litter fall, through fall and stem flow. Seasonal variations in (137)Cs transportation and differences between forests types were also determined. The total amount of (137)Cs transported from the canopy to the floor in two deciduous and cedar plantation forests ranged between 3.9 and 11.0 kBq m(-2) year(-1). In addition, the authors observed that (137)Cs transportation with litter fall increased in the defoliation period, simply because of the increased amount of litter fall. The authors concluded that the findings demonstrated that (137)Cs transportation with through fall and stem flow increased in the rainy season, and (137)Cs flux by litter fall was higher in cedar plantation compared with that of mixed deciduous forest, while the opposite result was obtained for stem flow.

Authors: Endo I, Ohte N, Iseda K, Tanoi K, Hirose A, Kobayashi NI, Murakami M, Tokuchi N, Ohashi M. ;Full Source: Journal of Environmental Radioactivity. 2015 Aug 29. pii: S0265-931X(15)30069-2. doi: 10.1016/j.jenvrad.2015.07.027. [Epub ahead of print] ;