Occurrence of antibiotics in reclaimed water, and their uptake dynamics, phytotoxicity, and metabolic fate in Lolium perenne L

Reclaimed water (RW) has been extensively used for irrigation in agriculture, yet the occurrence of antibiotics in real RW, and their toxicity, uptake dynamics and metabolic fate still needs comprehensive exploration. In this study, we investigated the residual concentrations of nineteen antibiotics in the RW from four wastewater treatment plants, and determined their toxicity on plant at environment-relevant concentration. Total found concentrations of these antibiotics ranged from 623.66 ng L−1 to 1536.96 ng L−1, which decreased 10.3 and 19.4 % of roots' length and weight. Uptake dynamics analysis of the most hazardous antibiotic, norfloxacin (NFX) showed increasing amounts in the roots and leaves up to 3087.71 μg g−1. Ryegrass also can remove >80 % of 100 μg L−1 NFX being achieved by biodegradation through ring cleavage, decarboxylation, defluorination, hydrogenation, methylation and oxidation. Toxicity assessment of the identified byproducts showed their more toxic effect on fish, daphnia and algae. This study extended our understanding of the fate of antibiotics in plants during irrigation with reclaimed water, and emphasized its safety and pollutants' biomagnification concerns. [Display omitted] •Totally residual concentrations of antibiotics in four different reclaimed water were up to 1536.96 ng L-1.•Lolium perenne L. showed efficient removal (>80%) of fluoroquinolone and sulfonamide antibiotics.•Antibiotic mixture at environment-relevant concentration significantly disrupted the development of plants.•Bioaccumulated norfloxacin (the most hazardous antibiotic) in leaves and roots can reach 3087.71 μg g-1.•Rng cleavage, decarboxylation, defluorination, hydrogenation, methylation and oxidation of norfloxacin were proposed for its degradation.