Degradation kinetics and mobility of chlortetracycline, tylosin, and monensin in an agricultural soil in Northumberland County, Ontario

A robust high-throughput method was developed to extract the three growth-promoting antibiotics, tylosin (TYL), chlortetracycline (CTC), and monensin (MON) from soil with analysis by Electrospray Liquid Chromatography tandem Mass Spectrometry (ESI-LCMS-MS). Dissipation rate studies in a farm field soil revealed TYL, CTC, and MON followed first order dissipation kinetics with half-lives of 4.5, 24, and 3.3 days with manure addition, and 6.1, 21, and 3.8 days without manure. Manure application significantly increased TYL dissipation rate, perhaps due to the introduced microbial flora, but had no significant effect on CTC or MON. CTC was the only antibiotic detected at 25 to 35 cm depth and only up to 2% of the initial concentration in a sandy loam soil. These antibiotics are therefore expected to primarily degrade in agricultural soils with similar or more retentive soil properties before moving to a greater depth or to groundwater in significant concentrations in most agricultural systems.