Atmospheric deposition of radionuclides (7Be, 210Pb, 134Cs, 137Cs and 40K) during 2000–2012 at Rokkasho, Japan, and impact of the Fukushima Dai-ichi Nuclear Power Plant accident

We measured the concentrations of several radionuclides in atmospheric deposition samples collected in the period from 2000 to 2012 at Rokkasho, Japan. Monthly 7Be deposition rates were higher in winter/spring and fall, and monthly 210Pb deposition rates were highest in winter/spring. Following the accident at the Fukushima Dai-ichi Nuclear Power Plant in March 2011, the radiocesium (134Cs and 137Cs) deposition rate rapidly increased until it reached the maximum in April 2011, after which the deposition rate of 137Cs decreased with a half-time of 22 days before remaining constant throughout 2012.