Utilisation de l'ICP-MS pour l'analyse d'éléments en trace dans les eaux souterraines karstiques

Before attempting to determine trace element concentrations in karstic water samples, a number of preliminary experiments have to be carried out. The high levels of calcium in these waters can affect the accuracy of the measure due to the formation of polyatomic interferences. Short-term reproducibility (a few minutes) was found to be good for all selected elements, but long-term reproducibility (a few months) indicated problems with the determination of Ni and Cr. The low trace element levels found in karstic waters were compatible with the detection limits. To illustrate the utility of such measurements, an example of results obtained for a karstic aquifer at Lamalou (Herault, France) are presented and provided additional information on the structure of the aquifer.