Concentrations of Free and Conjugated Estrogens, Antibiotics, and Their Degradates At Various Landscape Positions In An Agricultural Watershed Receiving Poultry Manure.

Animal hormones and veterinary antibiotics can enter the aquatic environment as a result of application of animal manure on agricultural landscapes.  We know very little about how the concentrations of these chemicals vary spatially across various locations and with time over the year.  We investigated the transport of hormones and antibiotics in an agricultural watershed located in the coastal plain soils of Delaware which was subject to land-application of raw poultry manure.  Specific questions that were addressed were: What are the various forms (parent and transformation byproducts) of hormones and antibiotics in agricultural runoff? How do the concentrations of these chemicals vary with landscape positions? What are the concentrations of these compounds in runoff components such as surface runoff, subsurface drainage, and sediment?  Hormones that were investigated include: Estrone (E1), Estradiol (E2β and E2α), Estriol (E3), and their sulfate and glucuronide conjugates; whereas, antibiotics included chlortetracycline (CTC), sulfamethazine (SMZ), and their 14 degradation byproducts.  Poultry manure was applied to the fields at a rate of 9 Mg ha^-1 in early spring (April, 2010).  Sampling was performed for surface runoff, subsurface drainage, and sediment for nine storm events extending over 180 days after manure application (March-October, 2010).  Runoff was sampled at the edge of the field, and at upland and lowland riparian positions.  Samples were analyzed by LC-MS/MS technique.  Concentrations of hormones and antibiotics were low (<50ngL^-1) for most of the samples and decreased from field-edge to the riparian zone.  Estrogen concentrations were not detected in sediments, but concentrations of antibiotics were elevated (> 50ngg^-1).  Overall, our results suggest that typical agronomic application of poultry litter in Delaware (once in every three years) may not pose a significant threat in terms of release of hormones or antibiotics to agricultural runoff.