Removal, fate, and bioavailability of fluoroquinolone antibiotics in a phytoremediation system with four wetland plants: Combing dynamic DGT and traditional methods.

Phytoremediation is considered an effective technology for remediating antibiotic-contaminated water; however, its underlying mechanisms remain poorly understood. Therefore, this study investigated the phytoremediation potential of fluoroquinolone antibiotics (FQs) by different wetland plant species. The phytoremediation rates of ΣFQs were 46-69 %, and rhizosphere microorganism degradation (accounting for 90-93 %) dominated the FQ removal over that of plant uptake and hydrolysis. Dissipation of the FQs in the hydroponic system followed a first-order kinetic model. The joint action of the more powerful absorptive capacity of plants and stronger microbial degradation ability in the rhizosphere was the reason that Cyperus papyrus showed significantly higher FQ phytoremediation rates than the other three plant species, which implied that the plant species is a critical factor affecting phytoremediation efficiency. The FQ distribution in plant tissues decreased from root > stem > leaf, suggesting that FQs were more concentrated in the roots than in the aboveground tissues. Negative correlations between the diffusive gradient in thin films and root concentrations implied that these wetland plant species took up FQs mainly via active transport mechanism (requiring some vectors, perhaps via exudates); whereas, the process of root-to-stem transfer and upward transport represented passive transport, which mainly depended on transpiration. These results facilitate an improved understanding of phytoremediation processes and improve their future applications.