Trace metal speciation in aquatic systems through voltammetric techniques.

Chemical speciation studies are a key tool for the understanding of the behavior, fate and bioavailability
(toxicity) of trace metals in aquatic environments. For trace metal speciation, electrochemical methods and
especially voltammetric techniques like CLE/CSV (Competitive Ligand Equilibration/Cathodic Stripping
Voltammetry) are widely used. The use of voltammetry is attractive because modern voltammetric analysers
are simple, low-cost, able to do speciation studies and to measure several trace metal simultaneously with a
high sensitivity. Voltammetry permits to measure the total concentration of trace metals in natural waters
(after UV destruction) and to determine labile trace metal fraction. In relation to DET/DGT (diffusive
equilibrium in thin films / diffusive gradient in thin films), this technique permits to obtain the fraction of
natural metal complexing ligands.
The aim of this research is to assess the fate of these pollutants in rivers and estuaries and to determine the
consequences in terms of risk assessment. In situ, microcosmos and in vitro measurements will be done.
Data obtained like the conditional stability constant or the concentration of natural ligands are to be
integrated in models (see section 7).