¹³⁵Cs/¹³⁷Cs Isotopic Ratio as a New Tracer of Radiocesium Released from the Fukushima Nuclear Accident

Abstract

Since the Fukushima Daiichi nuclear power plant (FDNPP) accident in 2011, intensive studies of the distribution of released fission products, in particular (134)Cs and (137)Cs, in the environment have been conducted. However, the release sources, that is, the damaged reactors or the spent fuel pools, have not been identified, which resulted in great variation in the estimated amounts of (137)Cs released. Here, we investigated heavily contaminated environmental samples (litter, lichen, and soil) collected from Fukushima forests for the long-lived (135)Cs (half-life of 2 × 10(6) years), which is usually difficult to measure using decay-counting techniques. Using a newly developed triple-quadrupole inductively coupled plasma tandem mass spectrometry method, we analyzed the (135)Cs/(137)Cs isotopic ratio of the FDNPP-released radiocesium in environmental samples. We demonstrated that radiocesium was mainly released from the Unit 2 reactor. Considering the fact that the widely used tracer for the released Fukushima accident-sourced radiocesium in the environment, the (134)Cs/(137)Cs activity ratio, will become unavailable in the near future because of the short half-life of (134)Cs (2.06 years), the (135)Cs/(137)Cs isotopic ratio can be considered as a new tracer for source identification and long-term estimation of the mobility of released radiocesium in the environment.

Analysis of External Surface Irregularities on Fukushima-Derived Fallout Particles

“…Such a contrasting size and form; combined with (i) differing radiocesium ratios ( 134 Cs/ 137 Cs) determined in previous works (Chino et al, 2016), (ii) the location at which the samples were obtained and (iii) reactor core modeling (Nishihara et al, 2012), has led many to speculate that each particulate type represents emission from a specific reactor at the Fukushima site (Shibahara et al, 2014;Zheng et al, 2014;Snow et al, 2016).…”

Effect of different Cs concentrations on overall plant growth and Cs distribution in soybean

“…Ever since this disaster, there has been concern about the transmission of these radioactive substances from agricultural soils into crops (Yasunari et al, 2011;Zheng et al, 2014). To address these concerns, the dynamics of RCs in the agricultural environment and agricultural crops have been analyzed, and agricultural products have been subjected to monitoring and inspections since the accident (Kinoshita et al, 2011;Nihei et al, 2015).…”

Monitoring Inspection for Radioactive Substances in Agricultural, Livestock, Forest and Fishery Products in Fukushima Prefecture

“…Radioactive materials released during the accident reached agricultural lands in Fukushima and neighboring prefectures and contaminated the soil and agricultural products (Yasunari et al 2011;Zheng et al 2014). To fulfill the requirements of the Food Sanitation Act in Japan (Law No.…”