PREDICTION OF CESIUM-134 AND SR-85 CROP UPTAKE BASED ON SOIL PROPERTIES

Nowadays, there is still the need to improve the quantification of par ameters that affect radionuclide mobility. With this aim, radiocesium and radiostrontium soil-to-plant transfer was measured in lysimeters i n a Calcic Luvisol, loamy soil and in a Fluvisol, loam-sandy soil, usi ng lettuce [Lactuca sativa L. cv. Kinemontepas] and pea plants [Pisum sativum L. cv. Kelvedon Wonder]. Weighted Concentration Ratios (WCR), expressed as kg soil/kg plant, were calculated for different growth st ages. Weighted Concentration Ratios were in general higher for Sr-85 t han for Cs-134, and also higher in the loam-sandy than in the loamy so il. To predict plant uptake, we evaluated a set of soil properties to define a prediction factor for the relative transfer in the two soils using cation exchange capacity (CEC) and radionuclide available fracti on (f(av))for radiostrontium, and soil solution composition, solid-liq uid distribution coefficient, and radionuclide available fraction for radiocesium. The ratios of WCR in the loam-sandy and loamy soil were c ompared with the prediction factor. There was good agreement in lettuc e for Sr-85 (ratio of WCR was 5.4 for seedling and 3.9 for commercial samples, whereas prediction factor was 3,1) and for Cs-134 (ratio of W CR was 5.1 for seedling and 5.5 for commercial samples, the prediction factor being 5.1), although for pea only the relative root uptake of radiocesium in seedling pea was well predicted (the ratio of WCR was 8 .8, the prediction factor being 9.1). These soil parameters improved f ormer predictions based solely on the f(av), although factors dependin g on plant physiology should be better evaluated.