Speciation of pharmaceutical products and trace metals within the aqueous/sediment/colloidal fractions in a suburban watershed with both lab-experimental and field approaches (Egoutier, France)

Pharmaceutical products (PPs) and trace metals (TMs) released in the environment are likely to damage water quality and soils, by accumulating in hotspots. Suburban hydrosystems, especially small ones, are particularly sensitive to that kind of pollution. In some urban watersheds, contamination is mainly observed within interface sediments of retention areas, such as the Beulie pond in the Egoutier watershed, France (Ledieu et al., 2021). After determining their concentrations and their sources, the fate of these substances remains unclear. Thus, the current study aims to understand the speciation of emerging contaminants in the continuum of water-colloids-sediment. To answer this problematic, we decided to study sediment samples from the Beulie pond, collected at the sediment/water interface. Particles size and distribution within sediments were determined, as well as clays composition. TMs and PPs, also total organic carbon, were quantified. The objective is to use those data to create a spatially representative Beulie bulk sample, to perform further experiments. We will especially proceed to a sequential extraction (Tessier et al., 1979), which must enable us to get a first outlook of contaminants speciation in the continuum of water-colloids-sediment.