Volume 40, May 2005ECORAD 2004
|Page(s)||S497 - S502|
|Published online||17 June 2005|
Ecological half-times of 137Cs and 90Sr in forest and freshwater ecosystems
Fachhochschule Ravensburg-Weingarten, University of Applied Sciences, 88250 Weingarten, Germany
More than 200 data sets from the literature of measured time series of activity concentrations and transfer factors concerning: (1) soil, green plants, mushrooms, and game in forests and (2) water, particulate matter, and fish in rivers, reservoirs and lakes in Europe have been analyzed. We used a sum of up to 3 exponential functions to evaluate ecological half-times (T). In fresh water systems we fitted lognormal distributions of T for 137Cs (e.g. in the water of 32 European lakes, T = (0.3*2.2) years and T = (5.7*3.9) years as geometric mean value and standard deviation). Pronounced seasonal variations were observed in suspended matter of Lake Lugano, reflecting the bio-mass cycle of this lake. In forests, ecological half-times for 137Cs can also be fitted by a lognormal distribution. For Central Europe T 12 years. Extraordinarily high 137Cs activity concentrations were observed recently in wild boar in Germany. For Eastern Europe the physical half-time is dominant and in some components of the ecosystem the activity concentration is still increasing.
© EDP Sciences, 2005
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