Traceability analysis and risk assessment of river antibiotics based on dissolved organic matter spectral features and the positive matrix factorization receptor model.

Identifying pollution sources is crucial for controlling antibiotic contamination and preventing risks to aquatic environments. This study quantified four categories of antibiotics (quinolones,macrolides, sulfonamides, and tetracyclines) in Dafeng River during the dry season using SPE-UHPLC-MS，analyzing their sources and risks. The source apportionment results for antibiotics using the Positive Matrix Factorization (PMF) model were validated against those identified based on Dissolved Organic Matter (DOM) fluorescence characteristics. Redundancy Analysis (RDA) was employed to clarify the relationship between specific source risks in the PMF model and DOM fluorescence characteristics. The findings include: (1) A total of 43 antibiotics were detected, with concentrations ranging from 19.04 to 1037.11 ng/L. The overall significant risk rate (RQ ≥ 0.01) was 55.1 %. (2) Excitation-Emission Matrix coupled with Parallel Factor Analysis (EEM-PARAFAC) identified three fluorescence components in the watershed's water body DOM: fulvic-like (C1), humic-like (C2), and tyrosine-like (C3). (3) The PMF model identified five pollution sources for antibiotics. Livestock discharge was the predominant source of concentration, while sewage treatment plants posed the primary source risk, consistent with the DOM spectroscopy results. (4) The RDA demonstrated a close relationship between DOM fluorescence characteristics and specific source risks of antibiotics.