Explaining the accelerated degradation of ciprofloxacin, sulfamethazine, and erythromycin in different soil exposure scenarios by their aqueous extractability.
Antibiotics are frequently introduced into agricultural soils with the application of sewage sludge or farm organic fertilizers. Repeated exposure of soils to a pollutant can enrich for microbial populations that metabolize the chemical, reducing its environmental persistence. In London, Canada, soils from a long-term field experiment have received different concentrations of antibiotics annually for several years. The purpose of the present study was to assess the bioavailability of sulfamethazine, erythromycin, or ciprofloxacin through aqueous extractions with borax or EDTA solutions and their biodegradation following different soil exposure scenarios. Control soils and soils treated annually in the field with 10 mg antibiotics per kg were sampled, supplemented in the laboratory with radiolabeled antibiotic either added directly or carried in dairy manure. Sulfamethazine and erythromycin were initially more bioavailable than ciprofloxacin, with aqueous extractabilities representing 60, 36, and 8%, respectively. Sulfamethazine and erythromycin were degraded in soils, with a larger fraction mineralized in the long-term exposed soil (20 and 65%, respectively) than in control soil (0.4 and 3%, respectively) after 7 days of incubation. In contrast, ciprofloxacin was not mineralized neither in control nor long-term exposed soils. The mineralized fractions were similar for antibiotics added directly to soil or carried in dairy manure.
['Goulas|Anaïs|A|', 'Sabourin|Lyne|L|', 'Asghar|Farah|F|', 'Haudin|Claire-Sophie|CS|', 'Benoit|Pierre|P|', 'Topp|Edward|E|']
D000383:Agriculture D000900:Anti-Bacterial Agents D001673:Biodegradation, Environmental D002170:Canada D002939:Ciprofloxacin D004917:Erythromycin D005308:Fertilizers D008131:London D008372:Manure D012722:Sewage D012987:Soil D013418:Sulfamethazine
Bioavailability Mineralization Adaptation Antimicrobial Organic waste product Radiotracer Soil microcosm Spiking method