Artificial radioactivity in environmental media (air, rainwater, soil, vegetation) in Austria after the Fukushima nuclear accident

Several environmental media in Austria were monitored for artificial radionuclides released during the Fukushima nuclear accident. Air (up to 1.2 mBq/m(3) particulate I-131) and rainwater (up to 5.2 Bq/L I-131) proved to be the media best suited for the environmental monitoring, allowing also a temporal resolution of the activity levels. Significant regional differences in the wet deposition of I-131 with rain could be observed within the city of Vienna during the arrival of the contaminated air masses. Forward-trajectory analysis supported the hypothesis that the contaminated air masses coming from the northwest changed direction to northeast over Northern Austria, leading to a strong activity concentration gradient over Vienna. In the course of the environmental monitoring of the Fukushima releases, this phenomenon-significant differences of I-131 activity concentrations in rainwater on a narrow local scale (8.1 km)-appears to be unique. Vegetation (grass) was contaminated with I-131 and/or Cs-137 at a low level. Soil (up to 22 Bq/kg Cs-137) was only affected by previous releases (nuclear weapon tests, Chernobyl). Here, also significant local differences can be observed due to different deposition rates during the Chernobyl accident. The effective ecological half-lives of Cs-137 in soil were calculated for four locations in Austria. They range from 7 to 30 years. No Austrian sample investigated herein exceeded the detection limit for Cs-134; hence, the Fukushima nuclear accident did not contribute significantly to the total radiocesium inventory in Austrian environmental media. The levels of detected radioactivity were of no concern for public health.