Atmospheric radionuclides from Fukushima Dai-ichi nuclear accident detected in Lanzhou, China

After the Fukushima Dai-ichi nuclear power plant accident on March 11, 2011, the radioactivity released from the accident was transported around the globe by atmospheric processes. The radioactivity monitoring program on atmospheric particulate in Lanzhou, China was activated by GSCDC to detect the input radionuclides through atmospheric transport. Several artificial radionuclides were detected and measured in aerosol samples from March 26 to May 2, 2011. The peaked activity concentrations (in mBq/m(3)) were: 1.194 (I-131), 0.231 (Cs-137), 0.173 (Cs-134) and 0.008 (Cs-136), detected on April 6, 2011. The average activity ratio of I-131/Cs-137 and Cs-134/Cs-137 in air were 13.5 and 0.78. The significant increase of Cs-137 activity concentration, one order of magnitude higher than pre-Fukushima accident levels, in ground level aerosol was observed in 2013, as its resuspension from soil. The back-trajectory analysis simulated by NOAA-ARL HYSPLIT shows a direct transfer of the air masses released from Fukushima to Lanzhou across the Pacific Ocean, North America and Europe at the height close to 9000 m AGL. The value of effective dose for inhalation is close to one millionth of the annual limit for the general public.