Analysis of aquatic colloids in trace concentrations by laser induced breakdown detection

Aquatic colloids are omnipresent in natural water. Due to their small size of 10 to 1000 nm, these particles stay suspended and follow the aquifer flow field with little retardation. Their large specific surface along with high chemical reactivity makes them ideal carriers for pollutants, especially for polyvalent cations as are the actinides. However, their dilute concentration requires analytical methods of highest sensitivity, as provided by the laser induced breakdown detection. We present recent developments along with in-situ measurements in an underground laboratory, time resolved observation of aggregation kinetics and determination of actinide solubility constants. (orig.)