Local variation of soil contamination with radioactive cesium at a farm in Fukushima.

Radioactive cesium concentration in soil was measured at 27 sections with 5 points per section, and surface dose of ground was measured at 10 sections with 13 points per section at a farm in Fukushima to assess local variation of soil contamination with radioactive cesium. As for the cesium in soil, averages of the coefficient of variance (CV) and the maximum/minimum ratio in each section were 49% and 4.9, respectively. As for the surface dose, average of its CV in each section was 20% and the maximum/minimum ratio reached a maximum of 3.0. These findings suggest that exact evaluation of soil contamination with cesium is difficult. Small changes or differences in soil contamination may not be detected in studies of the environmental radioactivity.