Distribution of radiocaesium in an Austrian forest stand

Within an Austrian spruce stand, vertical distribution of radiocaesium in s oil as well as Cs-137 concentration in different forest ecosystem compartme nts including spruce and surface water were investigated 10 years after the Chernobyl accident. The total Cs-137 inventory in the forest was estimated to be 46 kBq m(-2) (ref. date: 86-05-01). From the collected data annual i nput rates via litterfall of 0.48% per year and output rates through waterf lows of only 0.02% per year were derived. The results identify the high imp ortance of forest soils as a sink for radiocaesium. The estimated ecologica l residence half-times turned out to be highest in the organic soil horizon s (1-3 years per cm), whereas in mineral horizons the values decrease signi ficantly. As a consequence, soil inventory represents more than 95% of the total, whereas only approximately 3.3% of the Cs-137 inventory is stored in the living biomass of spruce trees and a further 0.5% in the phytomass of understorey vegetation. (C) 1999 Elsevier Science B.V. All rights reserved.