Author(s): Suna Ekin Kali; Haoyu Wei; Godecke-Tobias Blecken; Maria Viklander; Helene Osterlund
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Abstract: Urban stormwater runoff transports complex contaminant mixtures to receiving waters, where sediments act as long-term sinks. This study combined in vitro bioassays and targeted chemical analyses to assess sediment toxicity along rural–urban gradients in four Swedish streams. Five bioassays targeting receptor-mediated and oxidative-stress responses were applied to sediment extracts, and results were compared with chemical profiles of 82 stormwater-related contaminants. Estrogenic activity was highest at rural or agriculturally influenced sites, whereas AhR and Nrf2 were strongest downstream of urban areas, reflecting urban stormwater inputs. However, bioassay responses often diverged from chemical concentrations, and iceberg modelling showed that known contaminants explained only parts of the observed effects. We demonstrate the importance of effect-based tools for capturing toxicity beyond the analytical scope of conventional chemical monitoring.
Year: 2026