Riverine Suspended Particulate Matter as a Hotspot of Antibiotics in the Yellow River Delta, China: Occurrence, Distribution, and Main Drivers

This study systematically elucidated the spatiotemporal distributions, partitioning behaviors, and environmental risks of 46 antibiotics in water and the suspended particulate matter (SPM) in the Yellow River Delta. Totally, 12 and 18 antibiotics were pervasively detected in water and SPM in two seasons, contributed predominantly by fluoroquinolones and followed by tetracyclines and sulfonamides. The total antibiotic concentrations displayed significant spatial and seasonal variations in water (151–4.72 × 103 ng/L), with a higher concentration observed in estuaries in spring, resulting from varying consumption patterns, external pollution emissions, and natural attentions. The spatiotemporal trends in SPM (118–8.84 × 103 ng/g) were parallel with water, indicating SPM served as a critical sink and an internal pollution source of antibiotics, when hydrodynamic conditions changed. The dominant occurrence of fluoroquinolones and several tetracyclines and sulfonamides in SPM suggested that the partitioning coefficient (Kd) was an important indicator to determine antibiotic sorption potentials onto SPM, which were associated with the differences in the physicochemical properties of antibiotics and SPM and water chemistry. Environmental risk assessment revealed cinoxacin and enoxacin universally exhibited potential risks for the ecosystem and resistance development from medium to high, and special attention should be given to the high joint risks of the co-occurrence of multiple antibiotics in the Yellow River Delta.