Transport mechanisms for veterinary pharmaceuticals from beef cattle feedyards to wetlands: Is aerial deposition a contributing source?

Abstract Veterinary pharmaceuticals from beef cattle feedyards have, with increasing frequency, been identified as contaminants in aquatic systems. Transport of these pharmaceuticals has generally been assumed to be via manure land application, surface runoff, or groundwater percolation. However, veterinary pharmaceuticals in airborne particulate matter downwind of beef cattle feedyards have recently been documented, indicating that aerial transport and deposition are a potential transport mechanism in arid and semi-arid environments. In this study, 35 hydrologically discrete playa wetlands within 15 km of beef cattle feedyards were examined for occurrence of six steroid hormones and eight antibiotics. 17α-trenbolone, estrone, estradiol, tetracycline, chlortetracycline, oxytetracycline, tylosin, and monensin were all detected in either water or sediment samples. Concentrations for the majority of analytes were