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

Omura, Yoshihito*; Matsukura, Kimiyo*; Abe, Junichi*; Hosaka, Kentaro*; Tamaoki, Masanori*; Dohi, Terumi   ; Kakishima, Makoto*; Seaward, M. R. D.*

Cs 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 in two dominant species, Dirinaria applanata and Physcia orientalis, and the air dose rate (Sv/h) at the sampling sites were investigated. Cs in P. orientalis measured about 1 year after the Fukushima nuclear accident was correlated (r=0.80) more closely with the air dose rate than those measured after about 2 years (r=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.