Radiocesium and lead in the lichen species Parmelia sulcata sampled in three regions around Chernobyl: assessment of concentrations in 1990

In summer 1990, four years after the Chernobyl accident, an IAEA coordinated survey was carried out in order to assess the radiological consequences and to study the possible effects of releases of (heavy) metals into the environment. Within the framework of this survey, lichens (Parmelia sulcata) were sampled in the Novozybkov, Bragin and Ovruc regions around Chernobyl and 137Cs and Pb levels were determined by γ-ray spectroscopy and Graphite Furnace-Atomic Absorption Spectrometry (GF-AAS), respectively. The geographical distributions of 137Cs and Pb are markedly different. The Pb levels in lichens are relatively low and do not suggest cause for concern. The lichen 137Cs levels are one to two orders of magnitude higher than levels determined in 1986 in Poland, Greece or The Netherlands. Corrections for physical decay and biological half-life resulted in initial 1986 ''hot spot'' 137Cs levels in Parmelia sulcata measured up to 1630 kBq kg-1. Lichen 137Cs levels reflect 137Cs soil deposition data, except for soil deposition classes >15 kBq m-2, where use of lichen data may lead to underestimates of actual deposition. (Author)