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Saturday, 12 July 2014

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

American Chemical Society — Environmental Science & Technology (pdf), Apr. 29, 2014 (emphasis added): 135Cs/137Cs Isotopic Ratio as a New Tracer of Radiocesium Released from the Fukushima Nuclear Accident [...] many important issues with respect to its atmospheric transport, deposition processes, and distributions in terrestrial and marine environments remain to be investigated. It has been estimated that ∼80% of the atmospherically released 137Cs was deposited in the western North Pacific Ocean, in addition to [...] 137Cs directly discharged into the ocean [...] continuous input of 137Cs into the ocean due to river runoff of the 137Cs deposited in heavily contaminated Fukushima forest soil can be expected. Recent studies have revealed the start of the transport of the Fukushima accident-sourced 137Cs into the ocean interior [...] it is predicted that in 30 years the Fukushima accident-derived 137Cs will come back to the ocean surface in the western North Pacific Ocean off the Fukushima coast through its transport by the Kuroshio current. Thus, to understand the environmental behavior and the fate of Fukushima accident-sourced radionuclides in the environment, a powerful Cs tracer is strongly required, because the currently widely used 134Cs/137Cs activity ratio tracer will become unavailable in several years because of the rapid decay of 134Cs [...] 135Cs has a half-life of 2 × 10^6 [2.3 million] years; therefore, we are confident that the 135Cs/137Cs isotopic ratio can be considered as a new powerful tracer for long-term source identification and environmental behavior studies. [...]

This study was supported [...] partially by the Agency for Natural Resources and Energy, the Ministry of Economy, Trade and Industry (METI), Japan [7 of study's 8 authors are from Japan's National Institute of Radiological Sciences]

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