Cesium-137 monitoring using mosses from W. Macedonia, N. Greece.

(137)Cs activities in mosses and substrate (soil, bark) collected from W. Macedonia, Greece were measured 20 years after the Chernobyl reactor accident. Archive material from previous studies was also used for comparison and diachronic estimation of the radio-contamination status. A gradual decrease was detected which depended on various factors such as the collected species, location, growth rate and substrate. Maximum accumulation capacity of (137)Cs was observed in the epilithic mosses in comparison to the epiphytic ones. The (137)Cs content in the bark of the two broad-leaved species (oak and fagus) was higher than that of the conifer (pinus). Bark specimens of about 50 cm height were in general more contaminated than those of 200 cm. Autoradiography revealed an amount of (137)Cs distributed more or less uniformly in moss thalli. The high (137)Cs activities found in mosses 20 years after Chernobyl suggest that these primitive plants are effective, suitable and inexpensive biological detectors of the distribution and burden of radionuclide fallout pattern.