Radiocesium concentrations in invertebrates and their environmental media at two distances from the Fukushima Dai-ichi Nuclear Power Plant during 3-6 years after the 2011 accident.

Activity concentrations of the radioactive cesium (Cs and Cs) were investigated in invertebrates at two sites of moderately high and higher air radiation dose rates, 14 km and 11 km distances, respectively, from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) from 2013 to 2016. At a14-km point, the Cs concentrations of soils in coniferous and broadleaf forests increased from 2013 to 2014, and thereafter declined until 2016. The Cs concentrations of the phytophagous beetle Anomala cuprea (Hope) rapidly decreased by 76.