Diffusive Gradients in Thin films as a tool for arsenic speciation in the estuarine environments

Although we are able to routinely monitor concentrations of trace elements in the environment, this information generally serves as a poor predictor of their potential bioavailability and toxicity. To thoroughly evaluate the ecotoxicological status of any environment, we have to focus on the determination of the labile fraction of trace elements in addition to conventional analysis. This especially applies to arsenic (As) – redox-sensitive element that occurs in the environment in a form of various species whose bioavailability and impact on living organisms may be diametrically different.
The Diffusive Gradients in Thin Films (DGT) in-situ passive sampling technique which directly discriminates free ions and weak complexes has been shown to be a suitable tool for the evaluation of trace elements’ labile fraction in the aquatic environment (Gontijo et al., 2016; Rodríguez et al., 2021). To evaluate the speciation of labile As in the natural waters, the DGT samplers with various sorbents for total As (organic + inorganic fraction), AsIII, or AsV were deployed in the Scheldt estuary along the salinity gradient and in the coastal zone (Zeebrugge harbour). Water samples were taken at both stations and were processed by filtration (on 0.45 μm) in order to describe As distribution between particulate, dissolved as well as labile (DGT-determined) fractions in the water column. The results will be presented at the conference.