Antibiotics easily remain in sediments after migrating from the surface to the subsurface due to water-rock interactions, posing a risk of secondary release to groundwater. To investigate the vertical distribution characteristics and environmental impact factors of antibiotics, five 30 m quaternary sediment columns were drilled and stratified near the hospital, and five major classes of antibiotics and sulfonamide metabolites were tested and analyzed. The results showed that:① the antibiotic content in the sediments ranged from 3.05 to 107.03 μg·kg-1, and all of the target antibiotics were detected except lomefloxacin, of which ofloxacin and oxytetracycline were the most important antibiotics in the study area. ② The antibiotics did not show a strict downward trend in the vertical direction but varied with the lithological stratification. ③ Antibiotics were primarily deposited in the clay layer and varied with the fluctuation of the groundwater level. ④ The results of redundancy analysis between antibiotics and environmental factors suggested that pH and TOC controlled the fate and transformation of antibiotics through influencing the adsorption of antibiotics by sediments. The risk of antibiotic contamination from hospital wastewater seepage into the subsurface environment should be taken seriously.
Keywords: antibiotics; borehole sediments; environmental factors; metals; vertical distribution.