In the week of the 27^th of March, new types of passive samplers have been deployed in the Mur/Mura river in Leoben. The passive sampling method is based on the diffusive gradients in thin films (DGT) technique and allows for the time-integrated assessment of dissolved strontium concentrations and isotope ratios, providing a robust tracer of geochemical signatures within the river catchment.

Originally designed by Stefan Wagner for applications in terrestrial soilshttps://pubs.acs.org/doi/full/10.1021/acs.analchem.2c00546, the method is now further developed and extended within the Bachelor’s project of Antonia Siebenbrunner at MUL for in situ deployments in natural freshwater systems.

The passive sampling devices are typically deployed for a short period of time, e.g., 1-7 days, during which the dissolved analyte fractions are continuously taken up into the passive samplers via diffusion. Thereby, the approach cancels out short-term fluctuations in the dissolved analyte fractions, providing a more representative measure of their natural levels in the river. Moreover, the approach effectively enables in situ matrix separation and analyte pre-concentration during sampling, potentially facilitating sample preparation for subsequent isotopic analysis and hence reducing the cost of analysis.

In the river Mur the DGT passive samplers are exposed to extreme weather conditions, algae, floating wood, etc. To protect them, we had to get creative: Using a self-made rope-structure, protective nets, and a buoy-anchor setup, the DGTs could be deployed safely in the river.

We would like to sincerely thank Finanzreferent KommR Willibald Mautner (Stadt Leoben), DI Günther Findenig (RHV Leoben), the BH Leoben (Wasserrecht), as well as the local fisheries association (Arbeiter-Fischerei-Verein Leoben) for their support during the course of this project.