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Equation to predict the 137Cs leaching dynamic from evergreen canopies after a radio-cesium deposit



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​Journal of Environmental Radioactivity / Volume 147, pages 100-107, septembre 2015

Type de document > *Article de revue

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Unité de recherche > IRSN/PRP-ENV/SERIS/L2BT

Auteurs > LOFFREDO Nicolas, ONDA Yuichi, HURTEVENT Pierre, COPPIN Frédéric

Date de publication > 01/09/2015


The Fukushima Daiishi nuclear power plant (FDNPP) accident led to a massive radionuclide deposition mainly onto Japanese forest canopies. In our previous study, an improved double exponential (IDE) equation including rainfall intensity was proposed to estimate the 137Cs hydrological transport from evergreen canopies to the ground. This equation used two types of parameters, kinetic (k1 and k2) and leachable stock (A1 and A2). Those parameters have been estimated by adjusting them in the IDE equation in order to accurately describe the measured cumulative leached 137Cs from canopies (k1 = 4.2E-04–5.0E-04 d−1, k2 = 1.2E-02–1.7E-02 d−1, A1 = 62–99 kBq/m2, A2 = 25–61 kBq/m2).

In this study, we linked the total leachable stock (Aleachable, a parameter of the IDE equation corresponding to A1 + A2) to a physiological criteria (the canopy closure CC, which can be measured with a simple camera equipped with a fish-eye objective). Furthermore, the kinetic parameters measured for Japanese cedar (k1 = 5.0E-04 d−1, k2 = 1.2E-02 d−1, and r12 = 0.22 (r12 = A1/A2) could also be used for two other coniferous species: Japanese cypress and spruce. This suggests that these parameters could be constants for coniferous forests.