Submitted to: Journal of Hazardous Materials
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/21/2010
Publication Date: 10/30/2010
Citation: Sung-Chul, K., Davis, J.G., Truman, C.C., Ascough II, J.C., Carlson, K. 2009. Simulated rainfall study for transport of veterinary antibiotics - mass balance analysis. Journal of Hazardous Materials. 175:836-843. Interpretive Summary: Antibiotics are essential for human and animal health, yet when not managed properly, can end up contaminating the environment. Information is lacking on the governing transport mechanisms controlling antibiotic movement as a non-point source pollutant. We used rainfall simulation to quantify antibiotic transport by surface runoff from an agricultural field in Colorado. Transport of seven commonly used veterinary antibiotics was evaluate in runoff and on sediment collected during the rainfall simulation. Amount of antibiotic in surface soil was also determined. The antibiotic, monensin, had the highest concentration in runoff, while the antibiotic, erythromycin, had the highest concentration on sediments. Chemical properties of the antibiotics controlled their mobility. Results indicate that runoff and erosion control can reduce antibiotic transport in the environment.
Technical Abstract: Occurrence of human and veterinary antibiotics has been reported in various environmental compartments. Yet, there is a lack of information verifying the transport mechanisms from source to environment, particularly the transport of veterinary antibiotics as a non-point source pollutant. A rainfall simulation study was conducted to address surface runoff as a possible transport mechanism of veterinary antibiotics introduced in the field and mass balance was calculated with supplementary surface and depth soil measurement. Seven veterinary antibiotics that are the most abundantly used in agriculture for therapeutic and non-therapeutic (growth-promotion) purposes were examined in this study, including tetracycline (TC), chlortetracycline (CTC), sulfathiazole (STZ), sulfamethazine (SMZ), erythromycin (TEM), tylosin (TYL), and monensin (MNS). Runoff in aqueous and sediment phases was collected every 5 min for 1 h with varied rainfall intensity and additional surface (0-2 cm) and depth (2-30 cm)soil samples were collected after rainfall simulation for mass balance analysis. Quantification of antibiotic concentration in all collected samples was based on solid phase extraction (SPE) followed by measurement with high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). MNS showed the highest concentration in runoff aqueous samples (0.22 mg plot-1), while ETM showed the highest concentration in runoff sediment samples (0.08 mg plot-1). The highest concentration of each applied antibiotic in surface soil samples occurred at different locations. This result might indicate the mobility of these compounds in surface soil varies due to different physicochemical properties among the antibiotics. Further, the analysis results showed that all of the subject antibiotics had penetrated into the subsurface; yet, no residuals were found for STZ, suggesting this compound might have penetrated even deeper into the soil. These results indicate that aqueous or sediment erosion control might reduce the transport of veterinary antibiotics in the environment.