Soil-to-plant transfer of 137Cs and 40K in an Atlantic blanket bog ecosystem

The transfer of Cs-137 and K-40 from soil to vegetation was studied in an Atlantic blanket bog ecosystem along the Atlantic coast of Ireland where the dominant vegetation is a mixture of Calluna vulgaris, Eriophorum vaginatum and Sphagnum mosses. The impact of soil chemistry and nutritional status of vegetation on the uptake of both radionuclides was also examined. Cesium-137 transfer factors values ranged from 1.9 to 9.6 and accumulation of Cs-137 was higher in the leaves of C. vulgaris than in the stems. Transfer factors values for Cs-137 in both C. vulgaris and E. vaginatum were similar indicating that for the vegetation studied, uptake is not dependent on plant species. The uptake of Cs-137 in bog vegetation was found to be positively correlated with the nutrient status of vegetation, in particular the secondary nutrients, calcium and magnesium. Potassium-40 transfer factors ranged from 0.9 to 13.8 and uptake was higher in E. vaginatum than in C. vulgaris, however, unlike Cs-137, the concentrations of K-40 within the leaves and stems of C. vulgaris were similar. The concentration of both Cs-137 and K-40 found in moss samples were in general lower than those found in vascular plants.