Sorption of tylosin on agricultural soils

The wide use of manure on farms could cause pharmaceutical chemicals (such as antibiotics) to be transported to surface aquatic and groundwater systems. The purpose of this study was to assess sorption and mobility of tylosin (TYL), the most used antibiotic compound in swine industry, in topsoils. Sorption of TYL was measured for the three soils using a batch technique. The experimental data showed that the sorption could attain apparent equilibrium within 24 h, and little or insignificant desorption hysteresis was observed. The Freundlich isotherm equation fit the data well, with the nonlinearity parameter n ranging from 0.83 to 1.03. The single-point distribution coefficients (KD) were in a narrow range from 1.7 to 12 L kg. The KD values correlated well with soil pH, but poorly with the soil organic carbon content. The study indicated that the mobility of TYL is less than that of smaller and polar antibiotics and that the soil-bound TYL could readily be transported to groundwater.