Monitoring of radiocaesium in Norwegian natural areas

Cesium-137 is analysed in plants and animals sampled in various areas in Norway, in addition to samples of jaws of moose, deer and reindeer. A few of the results are given. Radiocesium in mosses and lichens show little seasonal variation. Species of lichens from extremely exposed ridges show a steady decrease over the years. It is suggested that this is because the species had a varying content of water in their thalli at the time of fallout. Snow covered lichens were water saturated at the thaw when melt water containing pollution hit them. The ecological half-life for these species is 5-7 years. There were large differences in measurements of cesium between sites, from 4500 Bq/m2 to 50000 Bq/m2. Mosses and lichens overall have a much higher value than vasculars which have a controlled absorption of cesium in root hairs whilst mosses and lichens absorb throughout their whole surface. (AB)