Chemical and toxicological profiling of large rivers using mobile passive sampling and comparison to large volume active sampling

Abstract : Risks associated with complex mixtures of chemicals in freshwaters are difficult to predict. Efficient sampling methods and sensitive effect based tools can significantly improve the risk assessment. Novel mobile “enhanced” passive sampling system was applied within the Joint Danube Survey 3 in 2013. The partitioning samplers for non-polar compounds, i.e. silicone rubber sheets, and an adsorption sampler for polar compounds based on Empore SPE disks integrated water pollutants in time and space over 8 river stretches. Spot sampling of high water volumes was conducted by large volume solid phase extraction at 22 sites along the river. Up to 500 L of water were passed through extraction system containing neutral sorbent Chromabond HR-X, anionic exchanger Chromabond HR-XAW, and cationic exchanger Chromabond HR-XCW. Extracts of samples were subjected to analysis of organic pollutants and to toxicological profiling. Spatial profiles of a broad range of organic pollutants and studied toxicological endpoints were identified. In many cases the integrative character of passive sampling allowed measurement of compounds at pg L-1 levels. Besides oxidative stress response, toxic equivalents were detected in a similar range for active and passive sampling. The passive sampling reflected the physical-chemical characteristics of the compounds driving individual effects. While the PXR-mediated and estrogenic effect potentials were detected namely in Empore samplers, thus were elicited mainly by polar chemicals, AhR-mediated effect potential was primarily detected in silicone rubber samples, which reflects significant contribution of less polar compounds. The bioanalytical equivalent concentration approach was used to characterize the contribution of the detected chemicals to observed toxic potentials and identify the main toxicity drivers. The fraction of biological effects explained by the detected chemicals in samples from passive sampling of water from the Danube river differed depending on the studied effect and the type of sampler. Our study demonstrates the utility of the integrated approach using toxicological profiling to characterize pollutant mixtures along with chemical analysis in monitoring of fresh water quality and good applicability of passive sampling and large volume solid phase extraction in this assessment. This research was supported by EU FP7 Project SOLUTIONS (no. 603437).