Contribution mechanism of dexamethasone natural attenuation in rivers via intertwined photolytic-biological degradation: DOM-driven photolysis, microbial responses, and QSTR-RQ model-based risk assessment

Key Points

• Dexamethasone degradation occurs through interconnected photolytic and biological processes, highlighting the importance of natural attenuation.
• Key evidence includes the role of dissolved organic matter (DOM) in promoting photolysis as a significant degradation pathway.
• Analysis of microbial responses showed enhanced biodegradation rates under varying environmental conditions, suggesting adaptability.
• These findings highlight the need for QSTR-RQ model applications to assess risks associated with pharmaceutical contaminants in aquatic ecosystems.