AN EVALUATION OF RATIO SYSTEMS IN RADIOECOLOGICAL STUDIES

Replicate samples of soil, Juncus squarrosus and Calluna vulgaris were taken within a grid system on an organic peatland soil site in Irelan d. A similar sampling survey was carried out on an organic rich forest soil site in Sweden, where Vaccinium myrtillus and Vaccinium vitis-id aea with corresponding soil samples were taken within a Picea abies st and. The data were used to investigate the relationship between soil a nd plant Cs-137 content and to examine the validity of using ratios to describe this relationship. Findings from both countries were in agre ement. There were no significant changes in plant Cs-137 concentration associated with increasing soil content. When data from both countrie s were merged and treated as a single data set, a significant overall positive correlation (95% confidence level) between soil and plant Cs- 137 levels was observed. Concentration ratios and transfer factors wer e calculated for Cs-137 and K-40 uptake from soils to plants. Both rat io types exhibited a clearly defined decrease associated with increasi ng soil concentrations for both radionuclides. Findings demonstrate se rious problems with the use of ratios for the evaluation of radionucli de transfer.