Research in actinide geochemistry:Do we need speciation information at the molecular level ?

摘要

Radionuclide sorption to rock or sediment surfaces in the vicinity of a nuclear waste reposi-tory contributes significantly to the overall safety performance of a given disposal concept.State-of-the-art speciation techniques as laser-and X-ray spectroscopy are becoming more and more involved into the elucidation of sorption mechanisms and to the quantification of surface speciation.They are extremely valuable tools to gain fundamental understanding as a basis for the development of geochemical sorption models which in turn are needed to predict ra-dionuclide behaviour in the environment.Within the present paper,examples are given on how molecular scale information obtained from spectroscopic techniques can assist to decrease uncertainties of geochemical model as-sumptions and thus to enhance the confidence in model predictions.It is also shown that the interpretation of laboratory and field scale radionuclide migration experiments requires the application of speciation methods.The combination of spectroscopic studies with wet chemical experiments on actinide interaction with mineral and colloid surfaces is discussed as an appropriate strategy to assess and to quantify radionuclide migration.