Seasonal differences, source, and fate of antibiotics in a plain river network-informed watershed

Abstract

The source apportionment and ecological risk assessment of antibiotics in plain river network areas have become a research hotspot. In this study, the Changxing Plain River Network in the Taihu Lake Basin was chosen as the research area, where the Positive Matrix Factorization (PMF) model was used for source apportionment and the Risk Quotient (RQ) and Hazard Index (HI) method were applied for ecological risk assessment. Seasonal variations revealed that antibiotic concentrations were higher during the dry season (N.D-138 ng/L) compared to the wet season (N.D ∼ 22 ng/L), with concentrations in the Jiapu River significantly exceeding those in the other three rivers. PMF model identified four major pollution sources: aquaculture (11 %), diffuse pollution (42 %), urban sewage (30 %), and agriculture (17 %), with diffuse pollution being the largest contributor to antibiotic pollution. Antibiotic flux calculations indicated that the Jiapu River contributed the highest antibiotic load to Taihu Lake, followed by the Changxing River. Ecological risk analysis based on RQ values revealed that erythromycin (ERY), sulfamethoxazole (SMX), and enrofloxacin (ENO) posed moderate risks during the dry season. This study underscores the impacts of various human activities on riverine antibiotic emissions; highlights the need for effective regulation of urban and diffuse pollution; and provides a scientific basis for the formulation of pollution prevention strategies for antibiotic management in Taihu Lake.