The super(137)Cs/ super(134)Cs ratio in fungi as an indicator of the major mycelium location in forest soil

• Published in: Journal of environmental radioactivity 1997-01, Vol.35 (2), p.129-148
• Main Authors: Ruehm, W, Kammerer, L, Hiersche, L, Wirth, E
• Format: Article
• Language: English
• ISSN: 0265-931X

Since 1987, super(134)Cs and super(137)Cs activities have been measured in about 250 soil samples and about 350 samples of different fungal species grown in a coniferous forest in Bavaria, Germany. Variations of super(137)Cs/ super(134)Cs ratios are less than 10% within samples from the same soil horizon and year. Similarly, super(137)Cs / super(134)Cs ratios vary within less than 10% in mushroom samples of the same species and year. In contrast, the specific activities of super(134)Cs and super(137)Cs in soil samples of the same horizon and in mushroom samples of the same species vary by up to one order of magnitude. Two approaches are presented to estimate mycelium location of fungi. In the static approach, super(137)Cs/ super(134)Cs ratios in soil and mushrooms, corrected to May 1986 and averaged over 1987-1994, are analysed. These ratios range from 1.74 plus or minus 0.06 in the L-horizon to 2.41 plus or minus 0.46 in the B-horizon. The corresponding ratios measured in 14 fungal species vary between 1.73 plus or minus 0.12 (Lepista nebularis) and 2.16 plus or minus 0.26 (Russula cyanoxantha). By comparing these ratios, information on the major mycelium location can be gained. In the dynamic approach, the change with time of the super(137)Cs/ super(134)Cs ratio in 14 fungal species and in different layers of forest soil is compared. At the investigated site, both approaches yield similar results. The advantages of both methods are discussed.