Vertical distribution of ¹³⁷Cs in the contaminated soil of a spruce forest in Southern Germany 12 years after regeneration cutting

The Chernobyl fallout of 1986 contaminated soils in Southern Germany. Levels of ¹³⁷Cs activity still remain high in forest soils. The contamination of forest food products still poses a serious problem for consumer health. Silvicultural interventions may offer an option to reduce the bioavailability of ¹³⁷Cs. The objective of this study is to investigate a possible effect of canopy opening and clearcutting as well as the selection of conifers and broadleaves for stand regeneration on the vertical soil profile of ¹³⁷Cs. The investigation uses a long-term silvicultural experiment on the artificial regeneration of a spruce stand 30 km southwest of the town Augsburg, Germany. 12 years after silvicultural intervention soil samples were taken horizon-wise and analysed to compare among the treatments. A suite of soil physical and chemical properties was determined per horizon including ¹³⁷Cs radioactivity, total carbon, texture, and cation exchange capacity. The results show that (i) the ¹³⁷Cs contamination at this site is high compared to other sites in Central Europe, (ii) regeneration cuttings did not markedly change the vertical ¹³⁷Cs profile in general within one decade, (iii) clear cutting modified the boundary between the organic soil layer and the mineral soil with expectable effects on the future ¹³⁷Cs bioavailability.