SOLID-SOLUTION DISTRIBUTIONS OF RADIONUCLIDES IN ACID SOILS - APPLICATION OF THE WHAM CHEMICAL SPECIATION MODEL

The Windermere Humic Aqueous Model (WHAM) is tested with the data from laboratory experiments on three acid soils from the British Uplands. The model is reasonably successful at blind-predicting values of K-D ( solid-solution distribution coefficients) of Co, Sr, and Am on the bas is of their interactions with soil humic matter. The competitive effec ts of aluminum are calculated to exert a strong influence on trace ele ment binding. Organic matter interactions only explain the data for Cs in the case of the most organic-rich soil, the K-D values are substan tially underestimated in the other cases, presumably reflecting the pr esence in the soils of minerals bearing sites with high specificity to ward Cs+. Calculations for soils in situ show the importance of bindin g by dissolved organic matter in determining the K-D values for strong ly complexed radionuclides such as Th and Am.