Abstract:Antibiotics used in livestock production may be present in manure and slurry as the parent compound and/or metabolites. The environments may therefore be exposed to these antibiotics due to the application of animal manure to agricultural land. In order to understand the potential effects of long-term application of antibiotics-contained animal manure on agricultural soils, laboratory studies were conducted to characterize two typical antibiotic compounds (tylosin,C46H77NO17 and oxytetracycline,C22H24N2O9HCl) with regard to sorption and transport in seven agricultural soils, collected from the Changjiang and Zhujiang deltas of China. Both transfer and adsorption behaviors of the antibiotics were related with species of antibiotics and soil properties. Distribution coefficients (Kd values) determined by botch equilibrium method varied between 43L kg-1 and 3018L kg-1 for oxytetracyclin, and 2.3L kg-1 and 175L kg-1 for tylosin. Oxytetracyclin was more strongly sorbed in all the soils investigated than tylosin. The adsorption amount of antibiotic compounds on the soils was correlated positively with the contents of clay, organic matter and iron oxides. Soil column leaching experiments indicated that there were a significant difference in the transport of the two antibiotic compounds between sandy soil and clayey soil, which due to the difference in their respective sorption capabilities. Very low concentrations of the two antibiotic compounds were detected in the leachates from clayey soil column, indicating a much lower mobility of antibiotics in the clayey soil. However, significant amount of tylosin compound was recovered in the leachates from sandy soil, indicating that tylosin compound was not stable in sandy soil, and it had a high mobility in the soil.