A 50-year record of quinolone and sulphonamide antimicrobial agents in Seine River sediments

Even though sediments may represent a reservoir for antimicrobial agents, little is known about the persistence of these molecules over time or their accumulation. In this study, six antimicrobial agents, oxolinic acid, flumequine, nalidixic acid, norfloxacin, sulphamethoxazole and trimethoprim, were investigated in a sediment core from the Seine River. This work aimed to (1) measure antimicrobial agent contamination levels in the sediment and identify their origins, (2) obtain information on the persistence of these compounds in sediment over long periods (> 4 years) and (3) show the existence of a historical record in sediment of river contamination by antimicrobial agents. Sedimentary records were collected in a regularly flooded area at the side of the Seine River downstream of urban Paris. Dating was performed using environmental Cs-137 and Pb-210 radioisotopes. Antimicrobial agents were extracted and purified using Soxhlet extraction and solid phase extraction. Chromatographic separation of the compounds was achieved with Ultra Performance (TM) liquid chromatography tandem mass spectrometry. Antimicrobial agent residues were detected in river sediment deposits to a depth exceeding 80 cm, corresponding to sediment deposits dating from the early 1960s. Five out of six antimicrobial agents were detected: norfloxacin, flumequine, oxolinic acid, nalidixic acid and sulphamethoxazole. Dating of the slices shows evidence of a correspondence between commercialisation of the compounds and their occurrence in the successive sediment deposits. In general, the results from previous studies justify the assumption of relative persistence of these compounds, although no experiments were conducted over periods as long as several decades. Our results show that antimicrobial agents can persist in sediment for up to 30 to 40 years, which raise concerns about the environmental effects of such long-term exposure on aquatic organisms.