The influence of fungi on the long-term behaviour of radiocaesium in Norwegian sheep

Results from 11 years of live monitoring of sheep from a grazing area in No rway formed the basis for a study of the importance of ingested fungal frui t bodies in determining radiocaesium activity concentrations in sheep grazi ng freely on mountain pasture. The Cs-137 activity concentration due to ing ested vegetation decreased with an estimated effective ecological half-life of 7.0 +/- 2.6 years. The contribution from ingested fungal fruit bodies t o radiocaesium activity concentrations in the sheep was up to 75-85% in the years when fruit bodies were most abundant. The study demonstrates that us ing a simple exponential function in assessments of long-term consequences of radiocaesium fallout for grazing sheep may be inappropriate. (C) 1998 El sevier Science B.V. All rights reserved.