Spatial variability of radioactive cesium fallout on grasslands estimated in various scales

Abstract

Large releases of radionuclides from the Fukushima Daiichi Nuclear Power Plant have resulted in serious radioactive pollution over a wide region over Eastern Japan and the livestock industry has suffered serious damage as a result. In this study, the spatial variability of fallout radioactive cesium (Cs) on two grasslands (a pasture and a meadow) was estimated in various scales and the number of samples needed to determine the mean deposition density of radioactive Cs was calculated. In both grasslands, variances between sampling points were quite large compared with the repeated measurements. Because deposited radioactive Cs levels were higher in the pasture than in the meadow, the mean square of inter-sampling points and repeated measurements were larger in the pasture than in the meadow. Mean contamination levels of radioactive Cs in the pasture ranged from 143.0 (site A L ) to 172.8 kBq m À2 (paddock Z). The coefficients of variation ranged from 4.8 (site D) to 38.7% (whole pasture). Mean contamination levels of radioactive Cs in the meadow ranged from 59.6 (site Q) to 68.3 kBq m À2 (site O L ). The coefficients of variation ranged from 4.9 (site R) to 10.2% (whole meadow). Sampling numbers that were necessary to get the mean deposition density of radioactive Cs in the range ±10% with a 95% confidence interval were 57.5 for the pasture and 4.0 for the meadow. The significant relationship between the investigated area and the minimum sampling numbers with an allowable error of ±10% with a 95% confidence interval estimated by bootstrapping showed that 29 samples are necessary to estimate the reliable mean of fallout Cs on 1 ha of the pasture. For the meadow, the number of samples for reliable mean estimation was 1-5, being independent of the investigated area.

Variations in radioactive cesium accumulation in wheat germplasm from fields affected by the 2011 Fukushima nuclear power plant accident

“…Saito et al reported that the RCs deposition in soil was heterogeneous, varying greatly even within a small area (9.0 m 2 , n = 5), and the CVs of the RCs concentrations for five soil samples collected at one location averaged 0.36 40 . Tsuiki and Maeda also showed large variations in soil RCs concentrations in a particular pasture (CV = 0.12, 144 m 2 , n = 144) and meadow (CV = 0.08, 500 m 2 , n = 25) 41 . The field used in this study could have had considerable variation in RCs concentration.…”

Cs-137 in the natural environment of the Gorce Mountains (Poland)

“…The CV value is slightly above the variability interval of the literature data oscillating (for an area of approximately 0.1–1 km) in the range 10–30 % (cf. juxtaposition in [ 14 ] and [ 15 – 16 ]). The CV value slightly higher than quoted by other authors, can be explained by the undulations of the Gorce Mts.…”

Radioactive Cesium Concentration in Silage Corn (<i>Zea Mays</i> L.) and Italian Ryegrass (<i>Lolium Multiflorum</i> Lam.) Cultivated with Three Different Tillage Methods after the Fukushima Daiichi Nuclear Power Plant Accident

“…To prevent radioactive cesium (Cs) contamination of forage crops, various countermeasures were examined and then immediately implemented (Tsuiki & Maeda 2012a, 2012b, Kobayashi et al 2013, Harada et al 2014, Ogura et al 2014, Yamamoto et al 2014, Shinano 2015, Sunaga et al 2015, Kobayashi et al 2016, Komissarov et al 2017. Those studies and subsequent implementation of countermeasures utilized information and knowledge mainly obtained after the Chernobyl accident in 1986 (Alexakhin 1993, Konoplev et al 1993, Lembrechts 1993, Lönsjö et al1989, Nisbet et al 1993, Segal 1993, Roed et al 1996, Fesenko et al 2007.…”