THE CS-137 CS-134 RATIO IN FUNGI AS AN INDICATOR OF THE MAJOR MYCELIUM LOCATION IN FOREST SOIL/

Since 1987, Cs-134 and Cs-137 activities have been measured in about 2 50 soil samples and about 350 samples of different fungal species grow n in a coniferous forest in Bavaria, Germany. Variations of Cs-137/Cs- 134 ratios are less than 10% within samples from the same soil horizon and year. Similarly, Cs-137/Cs-134 ratios vary within less than 10% i n mushroom sample of the same species and year. In contrast, the speci fic activities of Cs-134 and Cs-137 in soil samples of the same horizo n and in mushroom samples of the same species vary by up to one order of magnitude. Two approaches are presented to estimate mycelium locati on of fungi. In the static approach, Cs-137/Cs-134 ratios in soil and mushrooms, corrected to May 1986 and averaged over 1987-1994, are anal ysed. These ratios range from 1.74 +/- 0.06 in the L-horizon to 2.41 /- 0.46 in the B-horizon. The corresponding ratios measured in 14 fung al species vary between 1.73 +/- 0.12 (Lepista nebularis) and 2.16 +/- 0.26 (Russula cyanoxantha). By comparing these ratios, information on the major mycelium location can be gained. In the dynamic approach, t he change with time of the Cs-137/Cs-134 ratio in 14 fungal species an d in different layers of forest soil is compared. At the investigated site, both approaches yield similar results. The advantages of both me thods are discussed. (C) 1997 Elsevier Science Limited.