Atmospheric effects of Fukushima nuclear accident: A review from a sight of atmospheric monitoring

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, which occurred in March 2011, has released large amounts of radionuclides (such as radioiodine and radiocesium) into the atmosphere, resulting in the contamination of terrestrial and marine environments. To assess radiological and environmental effects of the FDNPP-derived radionuclides, huge amounts of radioactive monitoring activities have been conducted to environmental samples. In this paper, we review results of atmospheric radioactivity monitoring for the FDNPP accident. Learning from atmospheric radioactivity monitoring of the FDNPP accident is as follows; 1. At the initial stage of accident, large spatiotemporal variability of emitted radionuclides near the FDNPP site occurred at short (less than 1 h) time scale and small (less than 10 km) space scale due to complicated emissions of radionuclides and variable flow of Fukushima radioactive plume, 2. Chemical form of FDNPP-derived radionuclides, in which a typical example is coexistence of 137Cs-bearing submicron particles and 137Cs-bearing large hot particles in the plume, is important to have better understanding of their atmospheric behaviors as do released mechanisms and their fate in environment, 3. Atmospheric effects of the FDNPP accident continue over 8 years, in which high activity levels of the FDNPP-derived 137Cs in surface air and deposition have continued at least until the end of 2018 owing to the post-accident release and resuspension because most of the FDNPP-derived 137Cs deposited on the ground surface still remains in the soil surface as a potential source of atmospheric 137Cs. •The atmospheric effects of radiocesium derived from the Fukushima Daiichi Nuclear Power Plant accident was reviewed.•The maximum activity of 137Cs in surface air near the FDNPP was 13.6 kBq m−3 just after vent operation of Reactor Unit 1.•High radioactive particles with enriched radiocesium were released in the environment.•The late atmospheric effects of the FDNPP-derived radiocesium continued in the end of 2018.•The annual 137Cs deposition showed a small peak in 2017.