137Cs concentrations in foliose lichens within Tsukuba-city as a reflection of radioactive fallout from the Fukushima Dai-ichi Nuclear Power Plant accident

Cs-137 concentrations in ten species of foliose lichens collected within Tsukuba-city in August 2013 ranged from 1.7 to 35 kBq/kg. The relationships between Cs-137 in two dominant species, Dirinaria applanata and Physcia orientalis, and the air dose rate (mu Sv/h) at the sampling sites were investigated. Cs-137 in P. orientails measured about 1 year after the Fukushima nuclear accident was correlated (r(2) = 0.80) more closely with the air dose rate than those measured after about 2 years (r(2) = 0.65), possibly demonstrating its continued value as a biomonitor to reflect ambient fall-out levels. In contrast, those of Dirinaria applanata were not correlated with the air dose rate in either year. (C) 2014 Elsevier Ltd. All rights reserved.