Monitoring of Chernobyl fallout 137Cs in semi-natural coniferous forest of central Sweden

Wien

1996

S. 275-283

20 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200131577

Monitoring of the behaviour of 137Cs in semi-natural coniferous forest ecosystem of central Sweden was investigated between 1990 and 1994. Results demonstrated that soil in the area of study is thin layer characterised with high organic matter fraction and acidic pH. Most of Chernobyl fallout deposited 137Cs retained in the upper 5 cm with venial migration into deeper layers of soil profile. The activity concentration of 137Cs in the dominant plants showed some variation, which presumed to be due to high variations in the different soil parameters and species-specificity of plants in 137Cs uptake. Fractionation of soil bound 137Cs using Sequential Extracted Procedure predicted that easily extractable 137Cs fraction that includes water soluble and NH4OAc exchangeable comprises ~25% of total soil radiocaesium inventory in the upper 5 cm layer of forest soil. These fractions, represent the soil mobile 137Cs in the forest ecosystem. About 37% of total forest soil 137Cs inventury could be accounted for soil organically bound 137Cs that include oxidizable and acid digestible organic matter. These fractions require a long term bio-degradation process by soil micro-organisms, before becoming available for plant uptake. More over a substantial fraction of 137Cs was firmly bount onto soil compartment of organic and/or mineral nature as a residual (36%). This means that binding processes of 137Cs onto humic forest soil with high fraction of organic matter and acidic reaction is time dependent. The most distinguished soil parameters that might influenced 137Cs transfer to and/or uptake by natural plants in the area of study were soil OM%, and soil pH. Soil biological activity might also be considered, (although it was not determined in this study). The long term 137Cs availability in this type of forest soil must be related to the organically bound 137Cs fractions.