ИСТИНА

Quantitative characteristics of dissolved and particulate radiocesium wash-off from contaminated watersheds after the FDNPP accident are calculated based on published monitoring data and results of field experiments on standard USLE (Universal Soil Loss Equation) runoff plots. Comparative analysis has been carried out for radiocesium wash-off parameters and distribution coefficient Ka in rivers and surface runoff on Fukushima and Chernobyl contaminated areas for the first years after the accidents. The radiocesium distribution coefficient in Fukushima rivers was 1-2 orders of magnitude higher than correspondent values for rivers and surface runoff of the Chemobyl zone. This suggests higher ability of Fukushima soils and sediments to bind radiocesium. The normalized dissolved wash-off coefficients for Fukushima river watersheds are I-2 orders of magnitude lower than corresponding values for the Chernobyl zone. Normalized particulate wash-off coefficients are comparable for Fukushima and Chemobyl. The radiocesium wash-off parameters obtained from runoff plots can be applied for the scale of real watersheds in the environment.