An early survey of the radioactive contamination of soil due to the Fukushima Dai-ichi Nuclear Power Plant accident, with emphasis on plutonium analysis

Radioactivity concentrations of 131I, 134Cs and 137Cs in river water in the Greater Tokyo Metropolitan area after the Fukushima Daiichi Nuclear Power Plant Accident

“…The highest concentration was observed to be 2.5 ± 0.2 Bq/L for 137 Cs in the Edogawa River water on March 31. An activity ratio of 134 Cs/ 137 Cs for this sample is approximately one, which is consistent with the values reported for radiocesium derived from the FDNPP accident (e.g., Kinoshita et al, 2011;Sakaguchi et al, 2012;Yamamoto et al, 2012), suggesting that 134 Cs and 137 Cs detected in river samples of this study originated from the FDNPP accident. These radiocesium nuclides must have become aerosols near the FDNPP accident site and transferred to the surrounding environment, which were then deposited on the ground as fallout.…”

Export of <sup>134</sup> Cs and <sup>137</sup> Cs in the Fukushima river systems at heavy rains by Typhoon Roke in September 2011

“…The 134 Cs / 137 Cs activity ratio for all samples is about 1.0, corrected to 11 March 2011. These values are consistent with those of surface soil samples at 0-5 cm depth (Yamamoto et al, 2012;Matsunaga et al, 2013). Therefore, radiocesium derived from the Fukushima Dai-ichi NPP was transported from the deposited surface to rivers.…”

Isotopic determination of U, Pu and Cs in environmental waters following the Fukushima Daiichi Nuclear Power Plant accident

“…Additional data on Pu in soil samples are also available from the recent work of Yamamoto et al (2012). This work and the afore-mentioned studies serve to clarify the extent and fate of potentially harmful radionuclides in the natural environment following the Fukushima accident.…”