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  • Description of spatial patt...
    Grubich, Andry; Makarevich, V.I.; Zhukova, O.M.

    Journal of environmental radioactivity, 12/2013, Letnik: 126
    Journal Article

    Spatial distributions of activity density (kBq/m2) and activity concentration (Bq/kg) are studied on sites with non-cultivated soils. Fitting datasets with lognormal, Weibull and normal distributions with sampling size n ≥ 60 showed that radionuclide deposition (90Sr, 137Cs, 238Pu, 239+240Pu, 241Am) due to Chernobyl fallout no more than in 10% of cases are described by Weibull distribution, and in the rest of the cases – by lognormal distribution. However asymptotics of “righthand tail” of empirical (sample) distribution quite often differs from the right-hand tail asymptotics of lognormal distribution. Thereby lognormal distribution is only an approximate statistical model of radionuclides' spatial pattern. Estimates of site surface area with “hot spots” are considered. Also distributions of 137Cs and 134Cs activity concentration on the territory contaminated by Fukushima fallout are reviewed. Characteristics of activity concentration for Fukushima and Chernobyl fallouts are collated. The results obtained make it possible to suggest that in both cases spatial contaminations of soil are described by approximately the same statistical models. •90Sr, 137Cs, 238Pu, 239Pu, 241Am datasets are described by lognormal distribution.•The right-hand tail of empirical distribution differs from lognormal distribution.•An assumption of lognormality is an idealization.