Driving mechanism of suspended minerals on the multi-level bioavailability of citalopram in Daphnia magna

Minerals modulated the multi-level bioavailability of CIT in D. magna . • Illite caused severe damages to the digestive system at 100 μg/L-CIT. • Montmorillonite obviously aggravated the oxidative stress of CIT. • Sensitive responses of feeding and swimming behaviors were observed. The impacts of water conservancy projects on the ecological risk of pollutants have raised intensive concerns in recent years. The widespread occurrence of antidepressant citalopram (CIT) could pose potential threats to the aquatic non-organisms and even human health. However, information regarding the bioavailability of CIT in the presence of suspended minerals is still limited. In this study, the driving mechanism of kaolinite, montmorillonite (Mon), and illite on the multi-level bioavailability of CIT was investigated in Daphnia magna . Corresponding to the inhibition of feeding behavior, the CIT-associated minerals in the gastrointestinal tracts caused severe cell swelling, cavitation and microvilli degeneration, especially for CIT+illite group. All co-exposure of minerals and CIT significantly alleviated the cellulase activity, while kaolinite further aggravated the inhibition of CIT on trypsin activity at 100 μg/L. Decreased CIT body burden, swimming activities were observed in the presence of three minerals at 10 μg/L, whereas no remarkable function at 100 μg/L. Sensitive oxidative stress was observed for CIT+Mon group with significant increase of reactive oxygen species, total antioxidant capacity, catalase as well as the inhibition of catalase and glutathione S-transferase genes expression. Illite obviously aggravated the biological effects of CIT at both concentrations, whereas Mon was effective only at low concentrations with the most limited action of kaolinite. The feeding and swimming behaviours of D. magna represented the comprehensive stress response among the correlation of biomarkers. The rapid and extensive release of CIT from minerals in gastrointestinal fluids indicates the critical role of secondary release in modulating its bioavailability. Download: Download high-res image (357KB) Download: Download full-size image