Objective The aim of the present research programme is to study the complexation behaviour of actinide ions with humic substances in natural aquifer systems and hence to quantify the commonly found in all groundwaters in different concentrations have a strong tendency towards complexation with actinide ions. This in one of the major geochemical reactions but hitherto least quantified. Therefore, the effect of humic substances on the actinide migration is poorly understood. In the present research programme the complexation of actinide ions with humic substances will be described thermodynamically. This description will be based on a model being as simple as possible to allow an easy introduction of the resulting reaction constants into geochemical modelling of the actinide migration.The aim of the present research programme is to study the complexation behaviour of actinide ions with humic substances in natural aquifer systems and hence to quantify the effect of humic substances on the actinide migration. Aquatic humic substances commonly found in all groundwaters in different concentrations have a strong tendency towards complexation with actinide ions. This is one of the major geochemical reactions but hitherto least quantified. Therefore, the effect of humic substances on the actinide migration is poorly understood. In the present research programme the complexation of actinide ions with humic substances will be described thermodynamically. This description will be based on a model being as simple as possible to allow an easy introduction of the resulting constants into geochemical modelling of the actinide migration.A study has been conducted to determine an effective ligand concentration of a given humic acid. This is a parameter being used for the evaluation of the complexation constant of a metal ion for bulk polyelectrolytes like humic or fulvic acid. Time resolved laser fluorescent spectroscopy (TRLFS) is further developed for its application to the humate complexation study of trivalent metal ions. The effect of humic acid on the interaction of metal ions with inorganic colloids is examined systematically, together with the humate complexation of neptunium(V). This study is of experimental significance for understanding the effect of metal ion concentration on the humate complexation.Work programme: The programme consists of the following three main tasks: Task 1: Complexation reactions of actinide ions with well characterized reference and site-specific humic and fulvic acids.Task 2: Competition reactions with major cations in natural groundwaters.Task 3: Validation of the complexation data in natural aquatic systems by comparison of calculation with spectroscopic experiment. Fields of science natural sciencesphysical sciencescondensed matter physicssoft matter physicsnatural scienceschemical sciencesnuclear chemistryradiation chemistrynatural sciencesphysical sciencesopticslaser physicsnatural sciencesphysical sciencesopticsspectroscopy Programme(s) FP2-RADWASTOM 4C - Specific research and technical development programme (Euratom) in the field of management and storage of radioactive waste, 1990-1994 Topic(s) A.4.3 - Radionuclide migration in the geosphere Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator TECHNICAL UNIVERSITY OF MUNICH EU contribution No data Address Walther-Meissner-Strasse 3 85748 Garching Germany See on map Total cost No data Participants (3) Sort alphabetically Sort by EU Contribution Expand all Collapse all Commissariat à l'Energie Atomique (CEA) France EU contribution No data Address Centre d'Études de Fontenay-aux-Roses 92265 Fontenay-aux-Roses See on map Total cost No data JOHANNES GUTENBERG UNIVERSITAET MAINZ Germany EU contribution No data Address FRITZ-STRASSMANN-WEG 2 55128 MAINZ See on map Total cost No data KATHOLIEKE UNIVERSITEIT LEUVEN Belgium EU contribution No data Address 92,Kardinaal Mercierlaan 92 3001 HEVERLEE See on map Total cost No data
